diff --git a/src/ebusd/bushandler.cpp b/src/ebusd/bushandler.cpp
index 0fd7f244..f4d3ec2b 100755
--- a/src/ebusd/bushandler.cpp
+++ b/src/ebusd/bushandler.cpp
@@ -109,7 +109,7 @@ bool ScanRequest::notify(result_t result, const SlaveSymbolString& slave) {
   if (result == RESULT_OK) {
     if (m_message == m_messageMap->getScanMessage()) {
       Message* message = m_messageMap->getScanMessage(dstAddress);
-      if (message != NULL) {
+      if (message != nullptr) {
         m_message = message;
         m_message->storeLastData(m_index, m_master);  // expected to work since this is a clone
       }
@@ -128,7 +128,7 @@ bool ScanRequest::notify(result_t result, const SlaveSymbolString& slave) {
     }
     if (result == RESULT_OK) {
       ostringstream output;
-      result = m_message->decodeLastData(true, NULL, -1, 0, &output);  // decode data
+      result = m_message->decodeLastData(true, nullptr, -1, 0, &output);  // decode data
       string str = output.str();
       m_busHandler->setScanResult(dstAddress, m_notifyIndex+m_index, str);
     }
@@ -422,7 +422,7 @@ result_t BusHandler::handleSymbol() {
   unsigned int timeout = SYN_TIMEOUT;
   symbol_t sendSymbol = ESC;
   bool sending = false;
-  BusRequest* startRequest = NULL;
+  BusRequest* startRequest = nullptr;
 
   // check if another symbol has to be sent and determine timeout for receive
   switch (m_state) {
@@ -435,16 +435,16 @@ result_t BusHandler::handleSymbol() {
     break;
 
   case bs_ready:
-    if (m_currentRequest != NULL) {
+    if (m_currentRequest != nullptr) {
       setState(bs_ready, RESULT_ERR_TIMEOUT);  // just to be sure an old BusRequest is cleaned up
     } else if (m_remainLockCount == 0) {
       startRequest = m_nextRequests.peek();
-      if (startRequest == NULL && m_pollInterval > 0) {  // check for poll/scan
+      if (startRequest == nullptr && m_pollInterval > 0) {  // check for poll/scan
         time_t now;
         time(&now);
         if (m_lastPoll == 0 || difftime(now, m_lastPoll) > m_pollInterval) {
           Message* message = m_messages->getNextPoll();
-          if (message != NULL) {
+          if (message != nullptr) {
             m_lastPoll = now;
             PollRequest* request = new PollRequest(message);
             result_t ret = request->prepare(m_ownMasterAddress);
@@ -458,7 +458,7 @@ result_t BusHandler::handleSymbol() {
           }
         }
       }
-      if (startRequest != NULL) {  // initiate arbitration
+      if (startRequest != nullptr) {  // initiate arbitration
         sendSymbol = startRequest->m_master[0];
         sending = true;
       }
@@ -488,21 +488,21 @@ result_t BusHandler::handleSymbol() {
     break;
 
   case bs_sendCmd:
-    if (m_currentRequest != NULL) {
+    if (m_currentRequest != nullptr) {
       sendSymbol = m_currentRequest->m_master[m_nextSendPos];  // unescaped command
       sending = true;
     }
     break;
 
   case bs_sendCmdCrc:
-    if (m_currentRequest != NULL) {
+    if (m_currentRequest != nullptr) {
       sendSymbol = m_crc;
       sending = true;
     }
     break;
 
   case bs_sendResAck:
-    if (m_currentRequest != NULL) {
+    if (m_currentRequest != nullptr) {
       sendSymbol = m_crcValid ? ACK : NAK;
       sending = true;
     }
@@ -558,7 +558,7 @@ result_t BusHandler::handleSymbol() {
     } else {
       sending = false;
       timeout = SYN_TIMEOUT;
-      if (startRequest != NULL && m_nextRequests.remove(startRequest)) {
+      if (startRequest != nullptr && m_nextRequests.remove(startRequest)) {
         m_currentRequest = startRequest;  // force the failed request to be notified
       }
       setState(bs_skip, result);
@@ -604,7 +604,7 @@ result_t BusHandler::handleSymbol() {
   time_t now;
   time(&now);
   if (result != RESULT_OK) {
-    if (sending && startRequest != NULL && m_nextRequests.remove(startRequest)) {
+    if (sending && startRequest != nullptr && m_nextRequests.remove(startRequest)) {
       m_currentRequest = startRequest;  // force the failed request to be notified
     }
     if ((m_generateSynInterval != SYN_TIMEOUT && difftime(now, m_lastReceive) > 1)
@@ -672,7 +672,7 @@ result_t BusHandler::handleSymbol() {
     return RESULT_OK;
 
   case bs_ready:
-    if (startRequest != NULL && sending) {
+    if (startRequest != nullptr && sending) {
       if (!m_nextRequests.remove(startRequest)) {
         // request already removed (e.g. due to timeout)
         return setState(bs_skip, RESULT_ERR_TIMEOUT);
@@ -754,7 +754,7 @@ result_t BusHandler::handleSymbol() {
       if (!m_crcValid) {
         return setState(bs_skip, RESULT_ERR_ACK);
       }
-      if (m_currentRequest != NULL) {
+      if (m_currentRequest != nullptr) {
         if (isMaster(m_currentRequest->m_master[1])) {
           messageCompleted();
           return setState(bs_sendSyn, RESULT_OK);
@@ -773,7 +773,7 @@ result_t BusHandler::handleSymbol() {
         m_crc = 0;
         m_nextSendPos = 0;
         m_command.clear();
-        if (m_currentRequest != NULL) {
+        if (m_currentRequest != nullptr) {
           return setState(bs_sendCmd, RESULT_ERR_NAK, true);
         }
         return setState(bs_recvCmd, RESULT_ERR_NAK);
@@ -792,18 +792,18 @@ result_t BusHandler::handleSymbol() {
   case bs_recvResCrc:
     m_crcValid = recvSymbol == m_crc;
     if (m_crcValid) {
-      if (m_currentRequest != NULL) {
+      if (m_currentRequest != nullptr) {
         return setState(bs_sendResAck, RESULT_OK);
       }
       return setState(bs_recvResAck, RESULT_OK);
     }
     if (m_repeat) {
-      if (m_currentRequest != NULL) {
+      if (m_currentRequest != nullptr) {
         return setState(bs_sendSyn, RESULT_ERR_CRC);
       }
       return setState(bs_skip, RESULT_ERR_CRC);
     }
-    if (m_currentRequest != NULL) {
+    if (m_currentRequest != nullptr) {
       return setState(bs_sendResAck, RESULT_ERR_CRC);
     }
     return setState(bs_recvResAck, RESULT_ERR_CRC);
@@ -831,7 +831,7 @@ result_t BusHandler::handleSymbol() {
     return setState(bs_skip, RESULT_ERR_ACK);
 
   case bs_sendCmd:
-    if (!sending || m_currentRequest == NULL) {
+    if (!sending || m_currentRequest == nullptr) {
       return setState(bs_skip, RESULT_ERR_INVALID_ARG);
     }
     m_nextSendPos++;
@@ -849,7 +849,7 @@ result_t BusHandler::handleSymbol() {
     return setState(bs_recvCmdAck, RESULT_OK);
 
   case bs_sendResAck:
-    if (!sending || m_currentRequest == NULL) {
+    if (!sending || m_currentRequest == nullptr) {
       return setState(bs_skip, RESULT_ERR_INVALID_ARG);
     }
     if (!m_crcValid) {
@@ -886,13 +886,13 @@ result_t BusHandler::handleSymbol() {
     {
       Message* message;
       message = m_messages->find(m_command);
-      if (message == NULL) {
+      if (message == nullptr) {
         message = m_messages->find(m_command, true);
-        if (message != NULL && message->getSrcAddress() != SYN) {
-          message = NULL;
+        if (message != nullptr && message->getSrcAddress() != SYN) {
+          message = nullptr;
         }
       }
-      if (message == NULL || message->isWrite()) {
+      if (message == nullptr || message->isWrite()) {
         // don't know this request or definition has wrong direction, deny
         return setState(bs_skip, RESULT_ERR_INVALID_ARG);
       }
@@ -936,12 +936,12 @@ result_t BusHandler::handleSymbol() {
 }
 
 result_t BusHandler::setState(BusState state, result_t result, bool firstRepetition) {
-  if (m_currentRequest != NULL) {
+  if (m_currentRequest != nullptr) {
     if (result == RESULT_ERR_BUS_LOST && m_currentRequest->m_busLostRetries < m_busLostRetries) {
       logDebug(lf_bus, "%s during %s, retry", getResultCode(result), getStateCode(m_state));
       m_currentRequest->m_busLostRetries++;
       m_nextRequests.push(m_currentRequest);  // repeat
-      m_currentRequest = NULL;
+      m_currentRequest = nullptr;
     } else if (state == bs_sendSyn || (result != RESULT_OK && !firstRepetition)) {
       logDebug(lf_bus, "notify request: %s", getResultCode(result));
       bool restart = m_currentRequest->notify(
@@ -955,13 +955,13 @@ result_t BusHandler::setState(BusState state, result_t result, bool firstRepetit
       } else {
         m_finishedRequests.push(m_currentRequest);
       }
-      m_currentRequest = NULL;
+      m_currentRequest = nullptr;
     }
   }
 
   if (state == bs_noSignal) {  // notify all requests
     m_response.clear();  // notify with empty response
-    while ((m_currentRequest = m_nextRequests.pop()) != NULL) {
+    while ((m_currentRequest = m_nextRequests.pop()) != nullptr) {
       bool restart = m_currentRequest->notify(RESULT_ERR_NO_SIGNAL, m_response);
       if (restart) {  // should not occur with no signal
         m_currentRequest->m_busLostRetries = 0;
@@ -982,7 +982,7 @@ result_t BusHandler::setState(BusState state, result_t result, bool firstRepetit
       || (result != RESULT_OK && state == bs_skip && m_state != bs_ready)) {
     logDebug(lf_bus, "%s during %s, switching to %s", getResultCode(result), getStateCode(m_state),
         getStateCode(state));
-  } else if (m_currentRequest != NULL || state == bs_sendCmd || state == bs_sendCmdCrc || state == bs_sendCmdAck
+  } else if (m_currentRequest != nullptr || state == bs_sendCmd || state == bs_sendCmdCrc || state == bs_sendCmdAck
       || state == bs_sendRes || state == bs_sendResCrc || state == bs_sendResAck || state == bs_sendSyn) {
     logDebug(lf_bus, "switching from %s to %s", getStateCode(m_state), getStateCode(state));
   }
@@ -1098,7 +1098,7 @@ void BusHandler::messageCompleted() {
           result = message->storeLastData(0, idData);
           if (result == RESULT_OK) {
             ostringstream output;
-            result = message->decodeLastData(true, NULL, -1, 0, &output);
+            result = message->decodeLastData(true, nullptr, -1, 0, &output);
             if (result == RESULT_OK) {
               string str = output.str();
               setScanResult(slaveAddress, 0, str);
@@ -1118,7 +1118,7 @@ void BusHandler::messageCompleted() {
         result_t result = message->storeLastData(m_command, m_response);
         if (result == RESULT_OK) {
           ostringstream output;
-          result = message->decodeLastData(true, NULL, -1, 0, &output);
+          result = message->decodeLastData(true, nullptr, -1, 0, &output);
           if (result == RESULT_OK) {
             string str = output.str();
             setScanResult(dstAddress, 0, str);
@@ -1138,7 +1138,7 @@ void BusHandler::messageCompleted() {
     }
     m_grabbedMessages[key].setLastData(m_command, m_response);
   }
-  if (message == NULL) {
+  if (message == nullptr) {
     if (dstAddress == BROADCAST) {
       logNotice(lf_update, "%s unknown BC cmd: %s", prefix, m_command.getStr().c_str());
     } else if (master) {
@@ -1153,7 +1153,7 @@ void BusHandler::messageCompleted() {
     result_t result = message->storeLastData(m_command, m_response);
     ostringstream output;
     if (result == RESULT_OK) {
-      result = message->decodeLastData(false, NULL, -1, 0, &output);
+      result = message->decodeLastData(false, nullptr, -1, 0, &output);
     }
     if (result < RESULT_OK) {
       logError(lf_update, "unable to parse %s %s from %s / %s: %s", circuit.c_str(), name.c_str(),
@@ -1182,7 +1182,7 @@ void BusHandler::messageCompleted() {
 result_t BusHandler::prepareScan(symbol_t slave, bool full, const string& levels, bool* reload,
     ScanRequest** request) {
   Message* scanMessage = m_messages->getScanMessage();
-  if (scanMessage == NULL) {
+  if (scanMessage == nullptr) {
     return RESULT_ERR_NOTFOUND;
   }
   if (m_device->isReadOnly()) {
@@ -1205,7 +1205,7 @@ result_t BusHandler::prepareScan(symbol_t slave, bool full, const string& levels
     slaves.push_back(slave);
     if (!*reload) {
       Message* message = m_messages->getScanMessage(slave);
-      if (message == NULL || message->getLastChangeTime() == 0) {
+      if (message == nullptr || message->getLastChangeTime() == 0) {
         *reload = true;
       }
     }
@@ -1234,7 +1234,7 @@ result_t BusHandler::prepareScan(symbol_t slave, bool full, const string& levels
   result_t result = (*request)->prepare(m_ownMasterAddress);
   if (result < RESULT_OK) {
     delete *request;
-    *request = NULL;
+    *request = nullptr;
     return result == RESULT_ERR_EOF ? RESULT_EMPTY : result;
   }
   return RESULT_OK;
@@ -1244,7 +1244,7 @@ result_t BusHandler::startScan(bool full, const string& levels) {
   if (m_runningScans > 0) {
     return RESULT_ERR_DUPLICATE;
   }
-  ScanRequest* request = NULL;
+  ScanRequest* request = nullptr;
   bool reload = true;
   result_t result = prepareScan(SYN, full, levels, &reload, &request);
   if (result != RESULT_OK) {
@@ -1308,14 +1308,14 @@ void BusHandler::formatScanResult(ostringstream* output) const {
     for (symbol_t slave = 1; slave != 0; slave++) {  // 0 is known to be a master
       if (isValidAddress(slave, false) && !isMaster(slave) && (m_seenAddresses[slave]&SCAN_DONE) != 0) {
         Message* message = m_messages->getScanMessage(slave);
-        if (message != NULL && message->getLastUpdateTime() > 0) {
+        if (message != nullptr && message->getLastUpdateTime() > 0) {
           if (first) {
             first = false;
           } else {
             *output << endl;
           }
           *output << hex << setw(2) << setfill('0') << static_cast<unsigned>(slave);
-          message->decodeLastData(true, NULL, -1, 0, output);
+          message->decodeLastData(true, nullptr, -1, 0, output);
         }
       }
     }
@@ -1353,10 +1353,10 @@ void BusHandler::formatSeenInfo(ostringstream* output) const {
     if ((m_seenAddresses[address]&SCAN_DONE) != 0) {
       *output << ", scanned";
       Message* message = m_messages->getScanMessage(address);
-      if (message != NULL && message->getLastUpdateTime() > 0) {
+      if (message != nullptr && message->getLastUpdateTime() > 0) {
         // add detailed scan info: Manufacturer ID SW HW
         *output << " \"";
-        result_t result = message->decodeLastData(false, NULL, -1, OF_NAMES, output);
+        result_t result = message->decodeLastData(false, nullptr, -1, OF_NAMES, output);
         if (result != RESULT_OK) {
           *output << "\" error: " << getResultCode(result);
         } else {
@@ -1423,9 +1423,9 @@ void BusHandler::formatUpdateInfo(ostringstream* output) const {
     }
     if ((m_seenAddresses[address]&SCAN_DONE) != 0) {
       Message* message = m_messages->getScanMessage(address);
-      if (message != NULL && message->getLastUpdateTime() > 0) {
+      if (message != nullptr && message->getLastUpdateTime() > 0) {
         // add detailed scan info: Manufacturer ID SW HW
-        message->decodeLastData(true, NULL, -1, OF_NAMES|OF_NUMERIC|OF_JSON|OF_SHORT, output);
+        message->decodeLastData(true, nullptr, -1, OF_NAMES|OF_NUMERIC|OF_JSON|OF_SHORT, output);
       }
     }
     const vector<string>& loadedFiles = m_messages->getLoadedFiles(address);
@@ -1480,7 +1480,7 @@ result_t BusHandler::scanAndWait(symbol_t dstAddress, bool loadScanConfig, bool
   if (!isValidAddress(dstAddress, false) || isMaster(dstAddress)) {
     return RESULT_ERR_INVALID_ADDR;
   }
-  ScanRequest* request = NULL;
+  ScanRequest* request = nullptr;
   bool hasAdditionalScanMessages = m_messages->hasAdditionalScanMessages();
   result_t result = prepareScan(dstAddress, false, "", &reload, &request);
   if (result != RESULT_OK) {
@@ -1498,7 +1498,7 @@ result_t BusHandler::scanAndWait(symbol_t dstAddress, bool loadScanConfig, bool
     requestExecuted = m_finishedRequests.remove(request, true);
     result = requestExecuted ? request->m_result : RESULT_ERR_TIMEOUT;
     delete request;
-    request = NULL;
+    request = nullptr;
   }
   if (loadScanConfig) {
     string file;
diff --git a/src/ebusd/bushandler.h b/src/ebusd/bushandler.h
index 14f89571..e66a5544 100755
--- a/src/ebusd/bushandler.h
+++ b/src/ebusd/bushandler.h
@@ -380,7 +380,7 @@ class BusHandler : public WaitThread {
       m_generateSynInterval(generateSyn ? SYN_TIMEOUT*getMasterNumber(ownAddress)+SYMBOL_DURATION : 0),
       m_pollInterval(pollInterval), m_symbolLatencyMin(-1), m_symbolLatencyMax(-1), m_arbitrationDelayMin(-1),
       m_arbitrationDelayMax(-1), m_lastReceive(0), m_lastPoll(0),
-      m_currentRequest(NULL), m_currentAnswering(false), m_runningScans(0), m_nextSendPos(0),
+      m_currentRequest(nullptr), m_currentAnswering(false), m_runningScans(0), m_nextSendPos(0),
       m_symPerSec(0), m_maxSymPerSec(0),
       m_state(bs_noSignal), m_escape(0), m_crc(0), m_crcValid(false), m_repeat(false),
       m_grabMessages(true) {
@@ -396,17 +396,17 @@ class BusHandler : public WaitThread {
     stop();
     join();
     BusRequest* req;
-    while ((req = m_finishedRequests.pop()) != NULL) {
+    while ((req = m_finishedRequests.pop()) != nullptr) {
       delete req;
     }
-    while ((req = m_nextRequests.pop()) != NULL) {
+    while ((req = m_nextRequests.pop()) != nullptr) {
       if (req->m_deleteOnFinish) {
         delete req;
       }
     }
-    if (m_currentRequest != NULL) {
+    if (m_currentRequest != nullptr) {
       delete m_currentRequest;
-      m_currentRequest = NULL;
+      m_currentRequest = nullptr;
     }
   }
 
@@ -633,7 +633,7 @@ class BusHandler : public WaitThread {
    * @param full true for a full scan (all slaves), false for scanning only already seen slaves.
    * @param levels the current user's access levels.
    * @param reload true to force sending the scan message, false to send only if necessary (only for single slave).
-   * @param request the created @a ScanRequest (may be NULL with positive result if scan is not needed).
+   * @param request the created @a ScanRequest (may be nullptr with positive result if scan is not needed).
    * @return the result code.
    */
   result_t prepareScan(symbol_t slave, bool full, const string& levels, bool* reload, ScanRequest** request);
@@ -722,7 +722,7 @@ class BusHandler : public WaitThread {
   /** the queue of @a BusRequests that shall be handled. */
   Queue<BusRequest*> m_nextRequests;
 
-  /** the currently handled BusRequest, or NULL. */
+  /** the currently handled BusRequest, or nullptr. */
   BusRequest* m_currentRequest;
 
   /** whether currently answering a request from another participant. */
diff --git a/src/ebusd/datahandler.cpp b/src/ebusd/datahandler.cpp
index 6d72a32e..ba15bb05 100755
--- a/src/ebusd/datahandler.cpp
+++ b/src/ebusd/datahandler.cpp
@@ -28,7 +28,7 @@
 namespace ebusd {
 
 /** the final @a argp_child structure. */
-static const struct argp_child g_last_argp_child = {NULL, 0, NULL, 0};
+static const struct argp_child g_last_argp_child = {nullptr, 0, nullptr, 0};
 
 /** the list of @a argp_child structures. */
 static struct argp_child g_argp_children[
@@ -47,7 +47,7 @@ const struct argp_child* datahandler_getargs() {
     g_argp_children[count] = g_last_argp_child;
     return g_argp_children;
   }
-  return NULL;
+  return nullptr;
 }
 
 bool datahandler_register(UserInfo* userInfo, BusHandler* busHandler, MessageMap* messages,
diff --git a/src/ebusd/datahandler.h b/src/ebusd/datahandler.h
index 3e639f91..c73fa448 100755
--- a/src/ebusd/datahandler.h
+++ b/src/ebusd/datahandler.h
@@ -42,7 +42,7 @@ class DataHandler;
 
 /**
  * Helper function for getting the argp definition for all known @a DataHandler instances.
- * @return a pointer to the argp_child structure, or NULL.
+ * @return a pointer to the argp_child structure, or nullptr.
  */
 const struct argp_child* datahandler_getargs();
 
diff --git a/src/ebusd/main.cpp b/src/ebusd/main.cpp
index 26701774..9b9e4eba 100755
--- a/src/ebusd/main.cpp
+++ b/src/ebusd/main.cpp
@@ -67,8 +67,8 @@ using std::cout;
 /** the default path of the configuration files. */
 #define CONFIG_PATH "http://ebusd.eu/config/"
 
-/** the opened PID file, or NULL. */
-static FILE* pidFile = NULL;
+/** the opened PID file, or nullptr. */
+static FILE* pidFile = nullptr;
 
 /** true when forked into daemon mode. */
 static bool isDaemon = false;
@@ -125,11 +125,11 @@ static struct options opt = {
   100,  // dumpSize
 };
 
-/** the @a MessageMap instance, or NULL. */
-static MessageMap* s_messageMap = NULL;
+/** the @a MessageMap instance, or nullptr. */
+static MessageMap* s_messageMap = nullptr;
 
-/** the @a MainLoop instance, or NULL. */
-static MainLoop* s_mainLoop = NULL;
+/** the @a MainLoop instance, or nullptr. */
+static MainLoop* s_mainLoop = nullptr;
 
 /** the path prefix (including trailing "/") for retrieving configuration files from local files (empty for HTTP). */
 static string s_configLocalPrefix;
@@ -177,72 +177,72 @@ static const char argpdoc[] =
 
 /** the definition of the known program arguments. */
 static const struct argp_option argpoptions[] = {
-  {NULL,             0,        NULL,    0, "Device options:", 1 },
-  {"device",         'd',      "DEV",   0, "Use DEV as eBUS device (serial or [udp:]ip:port) [/dev/ttyUSB0]", 0 },
-  {"nodevicecheck",  'n',      NULL,    0, "Skip serial eBUS device test", 0 },
-  {"readonly",       'r',      NULL,    0, "Only read from device, never write to it", 0 },
-  {"initsend",       O_INISND, NULL,    0, "Send an initial escape symbol after connecting device", 0 },
-  {"latency",        O_DEVLAT, "USEC",  0, "Transfer latency in us [0 for USB, 10000 for IP]", 0 },
+  {nullptr,          0,        nullptr,    0, "Device options:", 1 },
+  {"device",         'd',      "DEV",      0, "Use DEV as eBUS device (serial or [udp:]ip:port) [/dev/ttyUSB0]", 0 },
+  {"nodevicecheck",  'n',      nullptr,    0, "Skip serial eBUS device test", 0 },
+  {"readonly",       'r',      nullptr,    0, "Only read from device, never write to it", 0 },
+  {"initsend",       O_INISND, nullptr,    0, "Send an initial escape symbol after connecting device", 0 },
+  {"latency",        O_DEVLAT, "USEC",     0, "Transfer latency in us [0 for USB, 10000 for IP]", 0 },
 
-  {NULL,             0,        NULL,    0, "Message configuration options:", 2 },
-  {"configpath",     'c',      "PATH",  0, "Read CSV config files from PATH (local folder or HTTP URL) [" CONFIG_PATH
+  {nullptr,          0,        nullptr,    0, "Message configuration options:", 2 },
+  {"configpath",     'c',      "PATH",     0, "Read CSV config files from PATH (local folder or HTTP URL) [" CONFIG_PATH
       "]", 0 },
-  {"scanconfig",     's',      "ADDR",  OPTION_ARG_OPTIONAL, "Pick CSV config files matching initial scan (ADDR="
+  {"scanconfig",     's',      "ADDR", OPTION_ARG_OPTIONAL, "Pick CSV config files matching initial scan (ADDR="
       "\"none\" or empty for no initial scan message, \"full\" for full scan, or a single hex address to scan, "
       "default is broadcast ident message). If combined with --checkconfig, you can add scan message data as "
       "arguments for checking a particular scan configuration, e.g. \"FF08070400/0AB5454850303003277201\".", 0 },
-  {"configlang",     O_CFGLNG, "LANG",  0,
+  {"configlang",     O_CFGLNG, "LANG",     0,
       "Prefer LANG in multilingual configuration files [system default language]", 0 },
-  {"checkconfig",    O_CHKCFG, NULL,    0, "Check CSV config files, then stop", 0 },
-  {"dumpconfig",     O_DMPCFG, NULL,    0, "Check and dump CSV config files, then stop", 0 },
-  {"pollinterval",   O_POLINT, "SEC",   0, "Poll for data every SEC seconds (0=disable) [5]", 0 },
-  {"inject",         'i',      NULL,    0, "Inject remaining arguments as already seen messages (e.g. "
+  {"checkconfig",    O_CHKCFG, nullptr,    0, "Check CSV config files, then stop", 0 },
+  {"dumpconfig",     O_DMPCFG, nullptr,    0, "Check and dump CSV config files, then stop", 0 },
+  {"pollinterval",   O_POLINT, "SEC",      0, "Poll for data every SEC seconds (0=disable) [5]", 0 },
+  {"inject",         'i',      nullptr,    0, "Inject remaining arguments as already seen messages (e.g. "
       "\"FF08070400/0AB5454850303003277201\")", 0 },
 
-  {NULL,             0,        NULL,    0, "eBUS options:", 3 },
-  {"address",        'a',      "ADDR",  0, "Use ADDR as own bus address [31]", 0 },
-  {"answer",         O_ANSWER, NULL,    0, "Actively answer to requests from other masters", 0 },
-  {"acquiretimeout", O_ACQTIM, "USEC",  0, "Stop bus acquisition after USEC us [9400]", 0 },
-  {"acquireretries", O_ACQRET, "COUNT", 0, "Retry bus acquisition COUNT times [3]", 0 },
-  {"sendretries",    O_SNDRET, "COUNT", 0, "Repeat failed sends COUNT times [2]", 0 },
-  {"receivetimeout", O_RCVTIM, "USEC",  0, "Expect a slave to answer within USEC us [25000]", 0 },
-  {"numbermasters",  O_MASCNT, "COUNT", 0, "Expect COUNT masters on the bus, 0 for auto detection [0]", 0 },
-  {"generatesyn",    O_GENSYN, NULL,    0, "Enable AUTO-SYN symbol generation", 0 },
+  {nullptr,          0,        nullptr,    0, "eBUS options:", 3 },
+  {"address",        'a',      "ADDR",     0, "Use ADDR as own bus address [31]", 0 },
+  {"answer",         O_ANSWER, nullptr,    0, "Actively answer to requests from other masters", 0 },
+  {"acquiretimeout", O_ACQTIM, "USEC",     0, "Stop bus acquisition after USEC us [9400]", 0 },
+  {"acquireretries", O_ACQRET, "COUNT",    0, "Retry bus acquisition COUNT times [3]", 0 },
+  {"sendretries",    O_SNDRET, "COUNT",    0, "Repeat failed sends COUNT times [2]", 0 },
+  {"receivetimeout", O_RCVTIM, "USEC",     0, "Expect a slave to answer within USEC us [25000]", 0 },
+  {"numbermasters",  O_MASCNT, "COUNT",    0, "Expect COUNT masters on the bus, 0 for auto detection [0]", 0 },
+  {"generatesyn",    O_GENSYN, nullptr,    0, "Enable AUTO-SYN symbol generation", 0 },
 
-  {NULL,             0,        NULL,    0, "Daemon options:", 4 },
-  {"accesslevel",    O_ACLDEF, "LEVEL", 0, "Set default access level to LEVEL (\"*\" for everything) [\"\"]", 0 },
-  {"aclfile",        O_ACLFIL, "FILE",  0, "Read access control list from FILE", 0 },
-  {"foreground",     'f',      NULL,    0, "Run in foreground", 0 },
-  {"enablehex",      O_HEXCMD, NULL,    0, "Enable hex command", 0 },
-  {"enabledefine",   O_DEFCMD, NULL,    0, "Enable define command", 0 },
-  {"pidfile",        O_PIDFIL, "FILE",  0, "PID file name (only for daemon) [" PID_FILE_NAME "]", 0 },
-  {"port",           'p',      "PORT",  0, "Listen for command line connections on PORT [8888]", 0 },
-  {"localhost",      O_LOCAL,  NULL,    0, "Listen for command line connections on 127.0.0.1 interface only", 0 },
-  {"httpport",       O_HTTPPT, "PORT",  0, "Listen for HTTP connections on PORT, 0 to disable [0]", 0 },
-  {"htmlpath",       O_HTMLPA, "PATH",  0, "Path for HTML files served by HTTP port [/var/ebusd/html]", 0 },
-  {"updatecheck",    O_UPDCHK, "MODE",  0, "Set automatic update check to MODE (on|off) [on]", 0 },
+  {nullptr,          0,        nullptr,    0, "Daemon options:", 4 },
+  {"accesslevel",    O_ACLDEF, "LEVEL",    0, "Set default access level to LEVEL (\"*\" for everything) [\"\"]", 0 },
+  {"aclfile",        O_ACLFIL, "FILE",     0, "Read access control list from FILE", 0 },
+  {"foreground",     'f',      nullptr,    0, "Run in foreground", 0 },
+  {"enablehex",      O_HEXCMD, nullptr,    0, "Enable hex command", 0 },
+  {"enabledefine",   O_DEFCMD, nullptr,    0, "Enable define command", 0 },
+  {"pidfile",        O_PIDFIL, "FILE",     0, "PID file name (only for daemon) [" PID_FILE_NAME "]", 0 },
+  {"port",           'p',      "PORT",     0, "Listen for command line connections on PORT [8888]", 0 },
+  {"localhost",      O_LOCAL,  nullptr,    0, "Listen for command line connections on 127.0.0.1 interface only", 0 },
+  {"httpport",       O_HTTPPT, "PORT",     0, "Listen for HTTP connections on PORT, 0 to disable [0]", 0 },
+  {"htmlpath",       O_HTMLPA, "PATH",     0, "Path for HTML files served by HTTP port [/var/ebusd/html]", 0 },
+  {"updatecheck",    O_UPDCHK, "MODE",     0, "Set automatic update check to MODE (on|off) [on]", 0 },
 
-  {NULL,             0,        NULL,    0, "Log options:", 5 },
-  {"logfile",        'l',      "FILE",  0, "Write log to FILE (only for daemon) [" PACKAGE_LOGFILE "]", 0 },
-  {"log",            O_LOG,    "AREAS LEVEL", 0, "Only write log for matching AREA(S) below or equal to LEVEL"
+  {nullptr,          0,        nullptr,    0, "Log options:", 5 },
+  {"logfile",        'l',      "FILE",     0, "Write log to FILE (only for daemon) [" PACKAGE_LOGFILE "]", 0 },
+  {"log",            O_LOG, "AREAS LEVEL", 0, "Only write log for matching AREA(S) below or equal to LEVEL"
       " (alternative to --logareas/--logevel, may be used multiple times) [all notice]", 0 },
-  {"logareas",       O_LOGARE, "AREAS", 0, "Only write log for matching AREA(S): main|network|bus|update|all"
+  {"logareas",       O_LOGARE, "AREAS",    0, "Only write log for matching AREA(S): main|network|bus|update|all"
       " [all]", 0 },
-  {"loglevel",       O_LOGLEV, "LEVEL", 0, "Only write log below or equal to LEVEL: error|notice|info|debug"
+  {"loglevel",       O_LOGLEV, "LEVEL",    0, "Only write log below or equal to LEVEL: error|notice|info|debug"
       " [notice]", 0 },
 
-  {NULL,             0,        NULL,    0, "Raw logging options:", 6 },
-  {"lograwdata",     O_RAW,    "bytes",  OPTION_ARG_OPTIONAL,
+  {nullptr,          0,        nullptr,    0, "Raw logging options:", 6 },
+  {"lograwdata",     O_RAW,    "bytes", OPTION_ARG_OPTIONAL,
       "Log messages or all received/sent bytes on the bus", 0 },
-  {"lograwdatafile", O_RAWFIL, "FILE",  0, "Write raw log to FILE [" PACKAGE_LOGFILE "]", 0 },
-  {"lograwdatasize", O_RAWSIZ, "SIZE",  0, "Make raw log file no larger than SIZE kB [100]", 0 },
+  {"lograwdatafile", O_RAWFIL, "FILE",     0, "Write raw log to FILE [" PACKAGE_LOGFILE "]", 0 },
+  {"lograwdatasize", O_RAWSIZ, "SIZE",     0, "Make raw log file no larger than SIZE kB [100]", 0 },
 
-  {NULL,             0,        NULL,    0, "Binary dump options:", 7 },
-  {"dump",           'D',      NULL,    0, "Enable binary dump of received bytes", 0 },
-  {"dumpfile",       O_DMPFIL, "FILE",  0, "Dump received bytes to FILE [/tmp/" PACKAGE "_dump.bin]", 0 },
-  {"dumpsize",       O_DMPSIZ, "SIZE",  0, "Make dump file no larger than SIZE kB [100]", 0 },
+  {nullptr,          0,        nullptr,    0, "Binary dump options:", 7 },
+  {"dump",           'D',      nullptr,    0, "Enable binary dump of received bytes", 0 },
+  {"dumpfile",       O_DMPFIL, "FILE",     0, "Dump received bytes to FILE [/tmp/" PACKAGE "_dump.bin]", 0 },
+  {"dumpsize",       O_DMPSIZ, "SIZE",     0, "Make dump file no larger than SIZE kB [100]", 0 },
 
-  {NULL,             0,        NULL,    0, NULL, 0 },
+  {nullptr,          0,        nullptr,    0, nullptr, 0 },
 };
 
 /** the global @a DataFieldTemplates. */
@@ -257,7 +257,7 @@ static map<string, DataFieldTemplates*> s_templatesByPath;
 /**
  * The program argument parsing function.
  * @param key the key from @a argpoptions.
- * @param arg the option argument, or NULL.
+ * @param arg the option argument, or nullptr.
  * @param state the parsing state.
  */
 error_t parse_opt(int key, char *arg, struct argp_state *state) {
@@ -267,7 +267,7 @@ error_t parse_opt(int key, char *arg, struct argp_state *state) {
   switch (key) {
   // Device options:
   case 'd':  // --device=/dev/ttyUSB0
-    if (arg == NULL || arg[0] == 0) {
+    if (arg == nullptr || arg[0] == 0) {
       argp_error(state, "invalid device");
       return EINVAL;
     }
@@ -301,7 +301,7 @@ error_t parse_opt(int key, char *arg, struct argp_state *state) {
 
   // Message configuration options:
   case 'c':  // --configpath=http://ebusd.eu/config/
-    if (arg == NULL || arg[0] == 0 || strcmp("/", arg) == 0) {
+    if (arg == nullptr || arg[0] == 0 || strcmp("/", arg) == 0) {
       argp_error(state, "invalid configpath");
       return EINVAL;
     }
@@ -417,14 +417,14 @@ error_t parse_opt(int key, char *arg, struct argp_state *state) {
 
   // Daemon options:
   case O_ACLDEF:  // --accesslevel=*
-    if (arg == NULL) {
+    if (arg == nullptr) {
       argp_error(state, "invalid accesslevel");
       return EINVAL;
     }
     opt->accessLevel = arg;
     break;
   case O_ACLFIL:  // --aclfile=/etc/ebusd/acl
-    if (arg == NULL || arg[0] == 0 || strcmp("/", arg) == 0) {
+    if (arg == nullptr || arg[0] == 0 || strcmp("/", arg) == 0) {
       argp_error(state, "invalid aclfile");
       return EINVAL;
     }
@@ -440,7 +440,7 @@ error_t parse_opt(int key, char *arg, struct argp_state *state) {
     opt->enableDefine = true;
     break;
   case O_PIDFIL:  // --pidfile=/var/run/ebusd.pid
-    if (arg == NULL || arg[0] == 0 || strcmp("/", arg) == 0) {
+    if (arg == nullptr || arg[0] == 0 || strcmp("/", arg) == 0) {
       argp_error(state, "invalid pidfile");
       return EINVAL;
     }
@@ -464,14 +464,14 @@ error_t parse_opt(int key, char *arg, struct argp_state *state) {
     }
     break;
   case O_HTMLPA:  // --htmlpath=/var/ebusd/html
-    if (arg == NULL || arg[0] == 0 || strcmp("/", arg) == 0) {
+    if (arg == nullptr || arg[0] == 0 || strcmp("/", arg) == 0) {
       argp_error(state, "invalid htmlpath");
       return EINVAL;
     }
     opt->htmlPath = arg;
     break;
   case O_UPDCHK:  // --updatecheck=on
-    if (arg == NULL || arg[0] == 0) {
+    if (arg == nullptr || arg[0] == 0) {
       argp_error(state, "invalid updatecheck");
       return EINVAL;
     }
@@ -487,7 +487,7 @@ error_t parse_opt(int key, char *arg, struct argp_state *state) {
 
   // Log options:
   case 'l':  // --logfile=/var/log/ebusd.log
-    if (arg == NULL || arg[0] == 0 || strcmp("/", arg) == 0) {
+    if (arg == nullptr || arg[0] == 0 || strcmp("/", arg) == 0) {
       argp_error(state, "invalid logfile");
       return EINVAL;
     }
@@ -496,7 +496,7 @@ error_t parse_opt(int key, char *arg, struct argp_state *state) {
   case O_LOG:  // --log=area(s) level
     {
       char* pos = strchr(arg, ' ');
-      if (pos == NULL) {
+      if (pos == nullptr) {
         argp_error(state, "invalid log");
         return EINVAL;
       }
@@ -547,7 +547,7 @@ error_t parse_opt(int key, char *arg, struct argp_state *state) {
     opt->logRaw = arg && strcmp("bytes", arg) == 0 ? 2 : 1;
     break;
   case O_RAWFIL:  // --lograwdatafile=/var/log/ebusd.log
-    if (arg == NULL || arg[0] == 0 || strcmp("/", arg) == 0) {
+    if (arg == nullptr || arg[0] == 0 || strcmp("/", arg) == 0) {
       argp_error(state, "invalid lograwdatafile");
       return EINVAL;
     }
@@ -567,7 +567,7 @@ error_t parse_opt(int key, char *arg, struct argp_state *state) {
     opt->dump = true;
     break;
   case O_DMPFIL:  // --dumpfile=/tmp/ebusd_dump.bin
-    if (arg == NULL || arg[0] == 0 || strcmp("/", arg) == 0) {
+    if (arg == nullptr || arg[0] == 0 || strcmp("/", arg) == 0) {
       argp_error(state, "invalid dumpfile");
       return EINVAL;
     }
@@ -633,15 +633,15 @@ void daemonize() {
 
   umask(S_IWGRP | S_IRWXO);  // set permissions of newly created files to 750
 
-  if (pidFile != NULL) {
-    setbuf(pidFile, NULL);  // disable buffering
+  if (pidFile != nullptr) {
+    setbuf(pidFile, nullptr);  // disable buffering
     if (lockf(fileno(pidFile), F_TLOCK, 0) < 0
       || fprintf(pidFile, "%d\n", getpid())  <= 0) {
       fclose(pidFile);
-      pidFile = NULL;
+      pidFile = nullptr;
     }
   }
-  if (pidFile == NULL) {
+  if (pidFile == nullptr) {
     logError(lf_main, "can't open pidfile: %s", opt.pidFile);
     exit(EXIT_FAILURE);
   }
@@ -650,7 +650,7 @@ void daemonize() {
 }
 
 void closePidFile() {
-  if (pidFile != NULL) {
+  if (pidFile != nullptr) {
     if (fclose(pidFile) != 0) {
       return;
     }
@@ -665,11 +665,11 @@ void shutdown() {
   // stop main loop and all dependent components
   if (s_mainLoop) {
     delete s_mainLoop;
-    s_mainLoop = NULL;
+    s_mainLoop = nullptr;
   }
   if (s_messageMap) {
     delete s_messageMap;
-    s_messageMap = NULL;
+    s_messageMap = nullptr;
   }
   // free templates
   for (const auto it : s_templatesByPath) {
@@ -735,13 +735,13 @@ void signalHandler(int sig) {
  * @param extension the filename extension the files have to match.
  * @param files the @a vector to which to add the matching files.
  * @param query the query string suffix for HTTP retrieval starting with "&", or empty.
- * @param dirs the @a vector to which to add found directories (without any name check), or NULL to ignore.
- * @param hasTemplates the bool to set when the templates file was found in the path, or NULL to ignore.
+ * @param dirs the @a vector to which to add found directories (without any name check), or nullptr to ignore.
+ * @param hasTemplates the bool to set when the templates file was found in the path, or nullptr to ignore.
  * @return the result code.
  */
 static result_t collectConfigFiles(const string& relPath, const string& prefix, const string& extension,
     vector<string>* files, const bool ignoreAddressPrefix = false, const string& query = "",
-    vector<string>* dirs = NULL, bool* hasTemplates = NULL) {
+    vector<string>* dirs = nullptr, bool* hasTemplates = nullptr) {
   const string relPathWithSlash = relPath.empty() ? "" : relPath + "/";
   if (!s_configUriPrefix.empty()) {
     string uri = s_configUriPrefix + relPathWithSlash + "?t=" + extension.substr(1) + query;
@@ -770,11 +770,11 @@ static result_t collectConfigFiles(const string& relPath, const string& prefix,
   }
   const string path = s_configLocalPrefix + relPathWithSlash;
   DIR* dir = opendir(path.c_str());
-  if (dir == NULL) {
+  if (dir == nullptr) {
     return RESULT_ERR_NOTFOUND;
   }
   dirent* d;
-  while ((d = readdir(dir)) != NULL) {
+  while ((d = readdir(dir)) != nullptr) {
     string name = d->d_name;
     if (name == "." || name == "..") {
       continue;
@@ -785,7 +785,7 @@ static result_t collectConfigFiles(const string& relPath, const string& prefix,
       continue;
     }
     if (S_ISDIR(stat_buf.st_mode)) {
-      if (dirs != NULL) {
+      if (dirs != nullptr) {
         dirs->push_back(relPathWithSlash + name);
       }
     } else if (S_ISREG(stat_buf.st_mode) && name.length() >= extension.length()
@@ -810,7 +810,7 @@ static result_t collectConfigFiles(const string& relPath, const string& prefix,
 DataFieldTemplates* getTemplates(const string& filename) {
   if (filename == "*") {
     unsigned long maxLength = 0;
-    DataFieldTemplates* best = NULL;
+    DataFieldTemplates* best = nullptr;
     for (auto it : s_templatesByPath) {
       if (it.first.size() > maxLength) {
         best = it.second;
@@ -862,7 +862,7 @@ static bool readTemplates(const string relPath, const string extension, bool ava
   string logPath = relPath.empty() ? "/" : relPath;
   logInfo(lf_main, "reading templates %s", logPath.c_str());
   string file = (relPath.empty() ? "" : relPath + "/") + "_templates" + extension;
-  result_t result = loadDefinitionsFromConfigPath(templates, file, verbose, NULL, &errorDescription, true);
+  result_t result = loadDefinitionsFromConfigPath(templates, file, verbose, nullptr, &errorDescription, true);
   if (result == RESULT_OK) {
     logInfo(lf_main, "read templates in %s", logPath.c_str());
     return true;
@@ -893,7 +893,7 @@ static result_t readConfigFiles(const string& relPath, const string& extension,
   readTemplates(relPath, extension, hasTemplates, verbose);
   for (const auto& name : files) {
     logInfo(lf_main, "reading file %s", name.c_str());
-    result_t result = loadDefinitionsFromConfigPath(messages, name, verbose, NULL, errorDescription);
+    result_t result = loadDefinitionsFromConfigPath(messages, name, verbose, nullptr, errorDescription);
     if (result != RESULT_OK) {
       return result;
     }
@@ -949,7 +949,7 @@ void executeInstructions(MessageMap* messages, bool verbose) {
 
 result_t loadDefinitionsFromConfigPath(FileReader* reader, const string& filename, bool verbose,
     map<string, string>* defaults, string* errorDescription, bool replace) {
-  istream* stream = NULL;
+  istream* stream = nullptr;
   time_t mtime = 0;
   if (s_configUriPrefix.empty()) {
     stream = FileReader::openFile(s_configLocalPrefix + filename, errorDescription, &mtime);
@@ -978,7 +978,7 @@ result_t loadConfigFiles(MessageMap* messages, bool verbose, bool denyRecursive)
     if (it.second != &s_globalTemplates) {
       delete it.second;
     }
-    it.second = NULL;
+    it.second = nullptr;
   }
   s_templatesByPath.clear();
 
@@ -1012,9 +1012,9 @@ result_t loadScanConfigFile(MessageMap* messages, symbol_t address, bool verbose
   size_t offset = 0;
   size_t field = 0;
   bool fromLocal = s_configUriPrefix.empty();
-  result_t result = (*identFields)[field]->read(data, offset, false, NULL, -1, 0, -1, &out);  // manufacturer name
+  result_t result = (*identFields)[field]->read(data, offset, false, nullptr, -1, 0, -1, &out);  // manufacturer name
   if (result == RESULT_ERR_NOTFOUND && fromLocal) {
-    result = (*identFields)[field]->read(data, offset, false, NULL, -1, OF_NUMERIC, -1, &out);  // manufacturer name
+    result = (*identFields)[field]->read(data, offset, false, nullptr, -1, OF_NUMERIC, -1, &out);  // manufacturer name
   }
   if (result == RESULT_OK) {
     manufStr = out.str();
@@ -1025,14 +1025,14 @@ result_t loadScanConfigFile(MessageMap* messages, symbol_t address, bool verbose
     out.str("");
     out.clear();
     offset += (*identFields)[field++]->getLength(pt_slaveData, MAX_LEN);
-    result = (*identFields)[field]->read(data, offset, false, NULL, -1, 0, -1, &out);  // identification string
+    result = (*identFields)[field]->read(data, offset, false, nullptr, -1, 0, -1, &out);  // identification string
   }
   if (result == RESULT_OK) {
     ident = out.str();
     out.str("");
     out.clear();
     offset += (*identFields)[field++]->getLength(pt_slaveData, MAX_LEN);
-    result = (*identFields)[field]->read(data, offset, NULL, -1, &sw);  // software version number
+    result = (*identFields)[field]->read(data, offset, nullptr, -1, &sw);  // software version number
     if (result == RESULT_ERR_OUT_OF_RANGE) {
       sw = (data.dataAt(offset) << 16) | data.dataAt(offset+1);  // use hex value instead
       result = RESULT_OK;
@@ -1040,7 +1040,7 @@ result_t loadScanConfigFile(MessageMap* messages, symbol_t address, bool verbose
   }
   if (result == RESULT_OK) {
     offset += (*identFields)[field++]->getLength(pt_slaveData, MAX_LEN);
-    result = (*identFields)[field]->read(data, offset, NULL, -1, &hw);  // hardware version number
+    result = (*identFields)[field]->read(data, offset, nullptr, -1, &hw);  // hardware version number
     if (result == RESULT_ERR_OUT_OF_RANGE) {
       hw = (data.dataAt(offset) << 16) | data.dataAt(offset+1);  // use hex value instead
       result = RESULT_OK;
@@ -1073,7 +1073,7 @@ result_t loadScanConfigFile(MessageMap* messages, symbol_t address, bool verbose
     out.str("");
     out.clear();
   }
-  result = collectConfigFiles(manufStr, addrStr + ".", ".csv", &files, false, query, NULL, &hasTemplates);
+  result = collectConfigFiles(manufStr, addrStr + ".", ".csv", &files, false, query, nullptr, &hasTemplates);
   if (result != RESULT_OK) {
     logError(lf_main, "unable to load scan config %2.2x: list files in %s %s", address, manufStr.c_str(),
         getResultCode(result));
@@ -1145,7 +1145,7 @@ result_t loadScanConfigFile(MessageMap* messages, symbol_t address, bool verbose
         }
         if (baseName.length() < 3 || baseName.find_first_of('.') != 2) {  // different from the scheme "ZZ."
           string errorDescription;
-          result = loadDefinitionsFromConfigPath(messages, name, verbose, NULL, &errorDescription);
+          result = loadDefinitionsFromConfigPath(messages, name, verbose, nullptr, &errorDescription);
           if (result == RESULT_OK) {
             logNotice(lf_main, "read common config file %s", name.c_str());
           } else {
@@ -1213,7 +1213,7 @@ bool parseMessage(const string& arg, bool onlyMasterSlave, MasterSymbolString* m
  * @return the exit code.
  */
 int main(int argc, char* argv[]) {
-  struct argp aargp = { argpoptions, parse_opt, NULL, argpdoc, datahandler_getargs(), NULL, NULL };
+  struct argp aargp = { argpoptions, parse_opt, nullptr, argpdoc, datahandler_getargs(), nullptr, nullptr };
   int arg_index = -1;
   setenv("ARGP_HELP_FMT", "no-dup-args-note", 0);
 
@@ -1287,7 +1287,7 @@ int main(int argc, char* argv[]) {
 
   // open the device
   Device *device = Device::create(opt.device, !opt.noDeviceCheck, opt.readOnly, opt.initialSend);
-  if (device == NULL) {
+  if (device == nullptr) {
     logError(lf_main, "unable to create device %s", opt.device);
     return EINVAL;
   }
diff --git a/src/ebusd/main.h b/src/ebusd/main.h
index 7e018b1c..f662879d 100755
--- a/src/ebusd/main.h
+++ b/src/ebusd/main.h
@@ -128,7 +128,7 @@ void executeInstructions(MessageMap* messages, bool verbose = false);
  * @param reader the @a FileReader instance to load with the definitions.
  * @param filename the relative name of the file being read.
  * @param verbose whether to verbosely log problems.
- * @param defaults the default values by name (potentially overwritten by file name), or NULL to not use defaults.
+ * @param defaults the default values by name (potentially overwritten by file name), or nullptr to not use defaults.
  * @param errorDescription a string in which to store the error description in case of error.
  * @param replace whether to replace an already existing entry.
  * @return @a RESULT_OK on success, or an error code.
diff --git a/src/ebusd/mainloop.cpp b/src/ebusd/mainloop.cpp
index e36d6c52..235d395e 100755
--- a/src/ebusd/mainloop.cpp
+++ b/src/ebusd/mainloop.cpp
@@ -114,14 +114,14 @@ MainLoop::MainLoop(const struct options& opt, Device *device, MessageMap* messag
     m_dumpFile = new RotateFile(opt.dumpFile, opt.dumpSize);
     m_dumpFile->setEnabled(opt.dump);
   } else {
-    m_dumpFile = NULL;
+    m_dumpFile = nullptr;
   }
   m_logRawEnabled = opt.logRaw != 0;
   if (opt.logRawFile[0] && strcmp(opt.logRawFile, opt.logFile) != 0) {
     m_logRawFile = new RotateFile(opt.logRawFile, opt.logRawSize, true);
     m_logRawFile->setEnabled(m_logRawEnabled);
   } else {
-    m_logRawFile = NULL;
+    m_logRawFile = nullptr;
   }
   m_logRawBytes = opt.logRaw == 2;
   m_logRawLastReceived = true;
@@ -131,7 +131,7 @@ MainLoop::MainLoop(const struct options& opt, Device *device, MessageMap* messag
     time_t mtime = 0;
     istream* stream = FileReader::openFile(opt.aclFile, &errorDescription, &mtime);
     if (stream) {
-      result = m_userList.readFromStream(stream, opt.aclFile, mtime, false, NULL, &errorDescription);
+      result = m_userList.readFromStream(stream, opt.aclFile, mtime, false, nullptr, &errorDescription);
       delete(stream);
     } else {
       result = RESULT_ERR_NOTFOUND;
@@ -165,7 +165,7 @@ MainLoop::MainLoop(const struct options& opt, Device *device, MessageMap* messag
   } else {
     logError(lf_main, "error registering data handlers");
   }
-  m_newlyDefinedMessages = opt.enableDefine ? new MessageMap(true, "", false) : NULL;
+  m_newlyDefinedMessages = opt.enableDefine ? new MessageMap(true, "", false) : nullptr;
 }
 
 MainLoop::~MainLoop() {
@@ -178,31 +178,31 @@ MainLoop::~MainLoop() {
   m_dataHandlers.clear();
   if (m_dumpFile) {
     delete m_dumpFile;
-    m_dumpFile = NULL;
+    m_dumpFile = nullptr;
   }
   if (m_logRawFile) {
     delete m_logRawFile;
-    m_logRawFile = NULL;
+    m_logRawFile = nullptr;
   }
-  if (m_network != NULL) {
+  if (m_network != nullptr) {
     delete m_network;
-    m_network = NULL;
+    m_network = nullptr;
   }
-  if (m_busHandler != NULL) {
+  if (m_busHandler != nullptr) {
     delete m_busHandler;
-    m_busHandler = NULL;
+    m_busHandler = nullptr;
   }
-  if (m_device != NULL) {
+  if (m_device != nullptr) {
     delete m_device;
-    m_device = NULL;
+    m_device = nullptr;
   }
   NetMessage* msg;
-  while ((msg = m_netQueue.pop()) != NULL) {
+  while ((msg = m_netQueue.pop()) != nullptr) {
     delete msg;
   }
   if (m_newlyDefinedMessages) {
     delete m_newlyDefinedMessages;
-    m_newlyDefinedMessages = NULL;
+    m_newlyDefinedMessages = nullptr;
   }
 }
 
@@ -367,7 +367,7 @@ void MainLoop::run() {
       }
       sinkSince = now;
     }
-    if (netMessage == NULL) {
+    if (netMessage == nullptr) {
       continue;
     }
     if (m_shutdown) {
@@ -406,7 +406,7 @@ void MainLoop::run() {
       m_messages->findAll("", "", levels, false, true, true, true, true, true, since, now, &messages);
       for (const auto message : messages) {
         ostream << message->getCircuit() << " " << message->getName() << " = " << dec;
-        message->decodeLastData(false, NULL, -1, 0, &ostream);
+        message->decodeLastData(false, nullptr, -1, 0, &ostream);
         ostream << endl;
       }
     }
@@ -791,7 +791,7 @@ result_t MainLoop::executeRead(const vector<string>& args, const string& levels,
     // find message
     Message* message = m_messages->find(master, false, true, false, false);
 
-    if (message == NULL) {
+    if (message == nullptr) {
       return RESULT_ERR_NOTFOUND;
     }
     if (!message->hasLevel(levels)) {
@@ -820,7 +820,7 @@ result_t MainLoop::executeRead(const vector<string>& args, const string& levels,
       ret = message->storeLastData(master, slave);
       ostringstream result;
       if (ret == RESULT_OK) {
-        ret = message->decodeLastData(false, NULL, -1, 0, &result);
+        ret = message->decodeLastData(false, nullptr, -1, 0, &result);
       }
       if (ret >= RESULT_OK) {
         logInfo(lf_main, "read hex %s %s cache update: %s", message->getCircuit().c_str(), message->getName().c_str(),
@@ -861,7 +861,7 @@ result_t MainLoop::executeRead(const vector<string>& args, const string& levels,
     string errorDescription;
     istringstream defstr("#\n" + args[argPos]);  // ensure first line is not used for determining col names
     m_newlyDefinedMessages->clear();
-    ret = m_newlyDefinedMessages->readFromStream(&defstr, "temporary", now, true, NULL, &errorDescription);
+    ret = m_newlyDefinedMessages->readFromStream(&defstr, "temporary", now, true, nullptr, &errorDescription);
     if (ret != RESULT_OK) {
       *ostream << "ERR: bad definition: " << errorDescription;
       return RESULT_OK;
@@ -878,13 +878,13 @@ result_t MainLoop::executeRead(const vector<string>& args, const string& levels,
     message = m_messages->find(circuit, name, levels, false);
   }
   // adjust poll priority
-  if (!newDefinition && message != NULL && pollPriority > 0 && message->setPollPriority(pollPriority)) {
+  if (!newDefinition && message != nullptr && pollPriority > 0 && message->setPollPriority(pollPriority)) {
     m_messages->addPollMessage(false, message);
   }
   verbosity |= valueName ? OF_VALUENAME : numeric ? OF_NUMERIC : 0;
   bool allowCache = !newDefinition && srcAddress == SYN && dstAddress == SYN && maxAge > 0 && params.length() == 0;
-  Message* cacheMessage = allowCache ? m_messages->find(circuit, name, levels, false, true) : NULL;
-  bool hasCache = cacheMessage != NULL;
+  Message* cacheMessage = allowCache ? m_messages->find(circuit, name, levels, false, true) : nullptr;
+  bool hasCache = cacheMessage != nullptr;
   if (!hasCache || (allowCache && message && message->getLastUpdateTime() > cacheMessage->getLastUpdateTime())) {
     cacheMessage = message;  // message is newer/better
   }
@@ -893,7 +893,7 @@ result_t MainLoop::executeRead(const vector<string>& args, const string& levels,
     if (verbosity & OF_NAMES) {
       *ostream << cacheMessage->getCircuit() << " " << cacheMessage->getName() << " ";
     }
-    ret = cacheMessage->decodeLastData(false, fieldIndex == -2 ? NULL : fieldName.c_str(), fieldIndex, verbosity,
+    ret = cacheMessage->decodeLastData(false, fieldIndex == -2 ? nullptr : fieldName.c_str(), fieldIndex, verbosity,
         ostream);
     if (ret != RESULT_OK) {
       if (ret < RESULT_OK) {
@@ -912,7 +912,7 @@ result_t MainLoop::executeRead(const vector<string>& args, const string& levels,
     return RESULT_OK;
   }  // else: read directly from bus
 
-  if (message == NULL) {
+  if (message == nullptr) {
     return RESULT_ERR_NOTFOUND;
   }
   if (message->getDstAddress() == SYN && dstAddress == SYN) {
@@ -926,7 +926,7 @@ result_t MainLoop::executeRead(const vector<string>& args, const string& levels,
   if (verbosity & OF_NAMES) {
     *ostream << message->getCircuit() << " " << message->getName() << " ";
   }
-  ret = message->decodeLastData(false, false, fieldIndex == -2 ? NULL : fieldName.c_str(), fieldIndex, verbosity,
+  ret = message->decodeLastData(false, false, fieldIndex == -2 ? nullptr : fieldName.c_str(), fieldIndex, verbosity,
       ostream);
   if (ret < RESULT_OK) {
     logError(lf_main, "read %s %s: decode %s", message->getCircuit().c_str(), message->getName().c_str(),
@@ -1023,7 +1023,7 @@ result_t MainLoop::executeWrite(const vector<string>& args, const string levels,
     // find message
     Message* message = m_messages->find(master, false, false, true, false);
 
-    if (message == NULL) {
+    if (message == nullptr) {
       return RESULT_ERR_NOTFOUND;
     }
     if (!message->hasLevel(levels)) {
@@ -1044,7 +1044,7 @@ result_t MainLoop::executeWrite(const vector<string>& args, const string levels,
       ret = message->storeLastData(master, slave);
       ostringstream result;
       if (ret == RESULT_OK) {
-        ret = message->decodeLastData(false, NULL, -1, 0, &result);
+        ret = message->decodeLastData(false, nullptr, -1, 0, &result);
       }
       if (ret >= RESULT_OK) {
         logInfo(lf_main, "write hex %s %s cache update: %s", message->getCircuit().c_str(),
@@ -1076,7 +1076,7 @@ result_t MainLoop::executeWrite(const vector<string>& args, const string levels,
     string errorDescription;
     istringstream defstr("#\n" + args[argPos]);  // ensure first line is not used for determining col names
     m_newlyDefinedMessages->clear();
-    ret = m_newlyDefinedMessages->readFromStream(&defstr, "temporary", now, true, NULL, &errorDescription);
+    ret = m_newlyDefinedMessages->readFromStream(&defstr, "temporary", now, true, nullptr, &errorDescription);
     if (ret != RESULT_OK) {
       *ostream << "ERR: bad definition: " << errorDescription;
       return RESULT_OK;
@@ -1092,7 +1092,7 @@ result_t MainLoop::executeWrite(const vector<string>& args, const string levels,
     message = m_messages->find(circuit, args[argPos], levels, true);
   }
 
-  if (message == NULL) {
+  if (message == nullptr) {
     return RESULT_ERR_NOTFOUND;
   }
   if (message->getDstAddress() == SYN && dstAddress == SYN) {
@@ -1115,7 +1115,7 @@ result_t MainLoop::executeWrite(const vector<string>& args, const string levels,
     return RESULT_OK;
   }
 
-  ret = message->decodeLastData(false, false, NULL, -1, 0, ostream);  // decode data
+  ret = message->decodeLastData(false, false, nullptr, -1, 0, ostream);  // decode data
   if (ret >= RESULT_OK && ostream->str().empty()) {
     logNotice(lf_main, "write %s %s: decode %s", message->getCircuit().c_str(), message->getName().c_str(),
         getResultCode(ret));
@@ -1341,7 +1341,7 @@ result_t MainLoop::executeFind(const vector<string>& args, const string& levels,
       if (found) {
         *ostream << endl;
       }
-      message->dump(NULL, withConditions, ostream);
+      message->dump(nullptr, withConditions, ostream);
     } else if (!fieldNames.empty()) {
       if (found) {
         *ostream << endl;
@@ -1360,7 +1360,7 @@ result_t MainLoop::executeFind(const vector<string>& args, const string& levels,
       } else if (hexFormat) {
         *ostream << message->getLastMasterData().getStr() << " / " << message->getLastSlaveData().getStr();
       } else {
-        result_t ret = message->decodeLastData(false, NULL, -1, verbosity, ostream);
+        result_t ret = message->decodeLastData(false, nullptr, -1, verbosity, ostream);
         if (ret != RESULT_OK) {
           *ostream << " (" << getResultCode(ret)
                    << " for " << message->getLastMasterData().getStr()
@@ -1493,7 +1493,7 @@ result_t MainLoop::executeDefine(const vector<string>& args, ostringstream* ostr
   time(&now);
   string errorDescription;
   istringstream defstr("#\n" + args[argPos]);  // ensure first line is not used for determining col names
-  return m_messages->readFromStream(&defstr, "temporary", now, true, NULL, &errorDescription, replace);
+  return m_messages->readFromStream(&defstr, "temporary", now, true, nullptr, &errorDescription, replace);
 }
 
 
@@ -1553,7 +1553,7 @@ result_t MainLoop::executeDecode(const vector<string>& args, ostringstream* ostr
   string errorDescription;
   DataFieldTemplates* templates = getTemplates("*");
   LoadableDataFieldSet fields("", templates);
-  result_t ret = fields.readFromStream(&defstr, "temporary", now, true, NULL, &errorDescription);
+  result_t ret = fields.readFromStream(&defstr, "temporary", now, true, nullptr, &errorDescription);
   if (ret != RESULT_OK) {
     return ret;
   }
@@ -1564,7 +1564,7 @@ result_t MainLoop::executeDecode(const vector<string>& args, ostringstream* ostr
     return ret;
   }
   slave.adjustHeader();
-  return fields.read(slave, 0, false, NULL, -1, verbosity, -1, ostream);
+  return fields.read(slave, 0, false, nullptr, -1, verbosity, -1, ostream);
 }
 
 
@@ -1585,13 +1585,13 @@ result_t MainLoop::executeEncode(const vector<string>& args, ostringstream* ostr
   string errorDescription;
   DataFieldTemplates* templates = getTemplates("*");
   LoadableDataFieldSet fields("", templates);
-  result_t ret = fields.readFromStream(&defstr, "temporary", now, true, NULL, &errorDescription);
+  result_t ret = fields.readFromStream(&defstr, "temporary", now, true, nullptr, &errorDescription);
   if (ret != RESULT_OK) {
     return ret;
   }
   istringstream datastr(args[argPos+1]);
   SlaveSymbolString slave;
-  ret = fields.write(UI_FIELD_SEPARATOR, 0, &datastr, &slave, NULL);
+  ret = fields.write(UI_FIELD_SEPARATOR, 0, &datastr, &slave, nullptr);
   if (ret != RESULT_OK) {
     return ret;
   }
diff --git a/src/ebusd/mainloop.h b/src/ebusd/mainloop.h
index a6c78bf7..0ccd0099 100755
--- a/src/ebusd/mainloop.h
+++ b/src/ebusd/mainloop.h
@@ -354,10 +354,10 @@ class MainLoop : public Thread, DeviceListener {
   /** the number of reconnects requested from the @a Device. */
   unsigned int m_reconnectCount;
 
-  /** the @a RotateFile for writing sent/received bytes in log format, or NULL. */
+  /** the @a RotateFile for writing sent/received bytes in log format, or nullptr. */
   RotateFile* m_logRawFile;
 
-  /** whether raw logging to @p logNotice is enabled (only relevant if m_logRawFile is NULL). */
+  /** whether raw logging to @p logNotice is enabled (only relevant if m_logRawFile is nullptr). */
   bool m_logRawEnabled;
 
   /** whether to log raw bytes instead of messages with @a m_logRawEnabled. */
@@ -372,7 +372,7 @@ class MainLoop : public Thread, DeviceListener {
   /** the last sent/received symbol.*/
   symbol_t m_logRawLastSymbol;
 
-  /** the @a RotateFile for dumping received data, or NULL. */
+  /** the @a RotateFile for dumping received data, or nullptr. */
   RotateFile* m_dumpFile;
 
   /** the @a UserList instance. */
@@ -397,7 +397,7 @@ class MainLoop : public Thread, DeviceListener {
   /** whether to enable the hex command. */
   const bool m_enableHex;
 
-  /** the MessageMap for handling newly defined messages for testing (if enabled), or NULL. */
+  /** the MessageMap for handling newly defined messages for testing (if enabled), or nullptr. */
   MessageMap* m_newlyDefinedMessages;
 
   /** set to true to shutdown. */
diff --git a/src/ebusd/mqtthandler.cpp b/src/ebusd/mqtthandler.cpp
index 9b686091..dc4f5579 100755
--- a/src/ebusd/mqtthandler.cpp
+++ b/src/ebusd/mqtthandler.cpp
@@ -43,31 +43,30 @@ using std::dec;
 
 /** the definition of the MQTT arguments. */
 static const struct argp_option g_mqtt_argp_options[] = {
-  {NULL,          0,      NULL,       0, "MQTT options:", 1 },
-  {"mqtthost",    O_HOST, "HOST",     0, "Connect to MQTT broker on HOST [localhost]", 0 },
-  {"mqttport",    O_PORT, "PORT",     0, "Connect to MQTT broker on PORT (usually 1883), 0 to disable [0]", 0 },
-  {"mqttuser",    O_USER, "USER",     0, "Connect as USER to MQTT broker (no default)", 0 },
-  {"mqttpass",    O_PASS, "PASSWORD", 0, "Use PASSWORD when connecting to MQTT broker (no default)", 0 },
-  {"mqtttopic",   O_TOPI, "TOPIC",    0, "Use MQTT TOPIC (prefix before /%circuit/%name or complete format) [ebusd]",
-      0 },
-  {"mqttretain",  O_RETA, NULL,       0, "Retain all topics instead of only selected global ones", 0 },
-  {"mqttjson",    O_JSON, NULL,       0, "Publish in JSON format instead of strings", 0 },
-  {"mqttignoreinvalid", O_IGIN, NULL, 0, "Ignore invalid parameters during init (e.g. for DNS not resolvable yet)", 0 },
+  {nullptr,       0,      nullptr,       0, "MQTT options:", 1 },
+  {"mqtthost",    O_HOST, "HOST",        0, "Connect to MQTT broker on HOST [localhost]", 0 },
+  {"mqttport",    O_PORT, "PORT",        0, "Connect to MQTT broker on PORT (usually 1883), 0 to disable [0]", 0 },
+  {"mqttuser",    O_USER, "USER",        0, "Connect as USER to MQTT broker (no default)", 0 },
+  {"mqttpass",    O_PASS, "PASSWORD",    0, "Use PASSWORD when connecting to MQTT broker (no default)", 0 },
+  {"mqtttopic",   O_TOPI, "TOPIC",       0, "Use MQTT TOPIC (prefix before /%circuit/%name or complete format) [ebusd]", 0 },
+  {"mqttretain",  O_RETA, nullptr,       0, "Retain all topics instead of only selected global ones", 0 },
+  {"mqttjson",    O_JSON, nullptr,       0, "Publish in JSON format instead of strings", 0 },
+  {"mqttignoreinvalid", O_IGIN, nullptr, 0, "Ignore invalid parameters during init (e.g. for DNS not resolvable yet)", 0 },
 
 #if (LIBMOSQUITTO_MAJOR >= 1)
-  {"mqttca",      O_CAFI, "CA",       0, "Use CA file or dir (ending with '/') for MQTT TLS (no default)", 0 },
-  {"mqttcert",    O_CERT, "CERTFILE", 0, "Use CERTFILE for MQTT TLS client certificate (no default)", 0 },
-  {"mqttkey",     O_KEYF, "KEYFILE",  0, "Use KEYFILE for MQTT TLS client certificate (no default)", 0 },
-  {"mqttkeypass", O_KEPA, "PASSWORD", 0, "Use PASSWORD for the encrypted KEYFILE (no default)", 0 },
+  {"mqttca",      O_CAFI, "CA",          0, "Use CA file or dir (ending with '/') for MQTT TLS (no default)", 0 },
+  {"mqttcert",    O_CERT, "CERTFILE",    0, "Use CERTFILE for MQTT TLS client certificate (no default)", 0 },
+  {"mqttkey",     O_KEYF, "KEYFILE",     0, "Use KEYFILE for MQTT TLS client certificate (no default)", 0 },
+  {"mqttkeypass", O_KEPA, "PASSWORD",    0, "Use PASSWORD for the encrypted KEYFILE (no default)", 0 },
 #endif
 
-  {NULL,          0, NULL,       0, NULL, 0 },
+  {nullptr,       0,      nullptr,       0, nullptr, 0 },
 };
 
 static const char* g_host = "localhost";  //!< host name of MQTT broker [localhost]
 static uint16_t g_port = 0;               //!< optional port of MQTT broker, 0 to disable [0]
-static const char* g_username = NULL;     //!< optional user name for MQTT broker (no default)
-static const char* g_password = NULL;     //!< optional password for MQTT broker (no default)
+static const char* g_username = nullptr;     //!< optional user name for MQTT broker (no default)
+static const char* g_password = nullptr;     //!< optional password for MQTT broker (no default)
 /** the MQTT topic string parts. */
 static vector<string> g_topicStrs;
 /** the MQTT topic field parts. */
@@ -77,11 +76,11 @@ static OutputFormat g_publishFormat = 0;  //!< the OutputFormat for publishing m
 static bool g_ignoreInvalidParams = false; //!< ignore invalid parameters during init
 
 #if (LIBMOSQUITTO_MAJOR >= 1)
-static const char* g_cafile = NULL;    //!< CA file for TLS
-static const char* g_capath = NULL;    //!< CA path for TLS
-static const char* g_certfile = NULL;  //!< client certificate file for TLS
-static const char* g_keyfile = NULL;   //!< client key file for TLS
-static const char* g_keypass = NULL;   //!< client key file password for TLS
+static const char* g_cafile = nullptr;    //!< CA file for TLS
+static const char* g_capath = nullptr;    //!< CA path for TLS
+static const char* g_certfile = nullptr;  //!< client certificate file for TLS
+static const char* g_keyfile = nullptr;   //!< client key file for TLS
+static const char* g_keypass = nullptr;   //!< client key file password for TLS
 #endif
 
 bool parseTopic(const string& topic, vector<string>* strs, vector<string>* fields);
@@ -89,7 +88,7 @@ bool parseTopic(const string& topic, vector<string>* strs, vector<string>* field
 /**
  * The MQTT argument parsing function.
  * @param key the key from @a g_mqtt_argp_options.
- * @param arg the option argument, or NULL.
+ * @param arg the option argument, or nullptr.
  * @param state the parsing state.
  */
 static error_t mqtt_parse_opt(int key, char *arg, struct argp_state *state) {
@@ -97,7 +96,7 @@ static error_t mqtt_parse_opt(int key, char *arg, struct argp_state *state) {
 
   switch (key) {
   case O_HOST:  // --mqtthost=localhost
-    if (arg == NULL || arg[0] == 0) {
+    if (arg == nullptr || arg[0] == 0) {
       argp_error(state, "invalid mqtthost");
       return EINVAL;
     }
@@ -113,7 +112,7 @@ static error_t mqtt_parse_opt(int key, char *arg, struct argp_state *state) {
     break;
 
   case O_USER:  // --mqttuser=username
-    if (arg == NULL) {
+    if (arg == nullptr) {
       argp_error(state, "invalid mqttuser");
       return EINVAL;
     }
@@ -121,7 +120,7 @@ static error_t mqtt_parse_opt(int key, char *arg, struct argp_state *state) {
     break;
 
   case O_PASS:  // --mqttpass=password
-    if (arg == NULL) {
+    if (arg == nullptr) {
       argp_error(state, "invalid mqttpass");
       return EINVAL;
     }
@@ -129,7 +128,7 @@ static error_t mqtt_parse_opt(int key, char *arg, struct argp_state *state) {
     break;
 
   case O_TOPI:  // --mqtttopic=ebusd
-    if (arg == NULL || arg[0] == 0 || strchr(arg, '#') || strchr(arg, '+') || arg[strlen(arg)-1] == '/') {
+    if (arg == nullptr || arg[0] == 0 || strchr(arg, '#') || strchr(arg, '+') || arg[strlen(arg)-1] == '/') {
       argp_error(state, "invalid mqtttopic");
       return EINVAL;
     }
@@ -152,21 +151,21 @@ static error_t mqtt_parse_opt(int key, char *arg, struct argp_state *state) {
 
 #if (LIBMOSQUITTO_MAJOR >= 1)
     case O_CAFI:  // --mqttca=file or --mqttca=dir/
-      if (arg == NULL || arg[0] == 0) {
+      if (arg == nullptr || arg[0] == 0) {
         argp_error(state, "invalid mqttca");
         return EINVAL;
       }
       if (arg[strlen(arg)-1] == '/') {
-        g_cafile = NULL;
+        g_cafile = nullptr;
         g_capath = arg;
       } else {
         g_cafile = arg;
-        g_capath = NULL;
+        g_capath = nullptr;
       }
       break;
 
     case O_CERT:  // --mqttcert=CERTFILE
-      if (arg == NULL || arg[0] == 0) {
+      if (arg == nullptr || arg[0] == 0) {
         argp_error(state, "invalid mqttcert");
         return EINVAL;
       }
@@ -174,7 +173,7 @@ static error_t mqtt_parse_opt(int key, char *arg, struct argp_state *state) {
       break;
 
     case O_KEYF:  // --mqttkey=KEYFILE
-      if (arg == NULL || arg[0] == 0) {
+      if (arg == nullptr || arg[0] == 0) {
         argp_error(state, "invalid mqttkey");
         return EINVAL;
       }
@@ -182,7 +181,7 @@ static error_t mqtt_parse_opt(int key, char *arg, struct argp_state *state) {
       break;
 
     case O_KEPA:  // --mqttkeypass=PASSWORD
-      if (arg == NULL) {
+      if (arg == nullptr) {
         argp_error(state, "invalid mqttkeypass");
         return EINVAL;
       }
@@ -196,7 +195,7 @@ static error_t mqtt_parse_opt(int key, char *arg, struct argp_state *state) {
   return 0;
 }
 
-static const struct argp g_mqtt_argp = { g_mqtt_argp_options, mqtt_parse_opt, NULL, NULL, NULL, NULL, NULL };
+static const struct argp g_mqtt_argp = { g_mqtt_argp_options, mqtt_parse_opt, nullptr, nullptr, nullptr, nullptr, nullptr };
 static const struct argp_child g_mqtt_argp_child = {&g_mqtt_argp, 0, "", 1};
 
 
@@ -211,7 +210,7 @@ bool mqtthandler_register(UserInfo* userInfo, BusHandler* busHandler, MessageMap
     list<DataHandler*>* handlers) {
   if (g_port > 0) {
     int major = -1;
-    mosquitto_lib_version(&major, NULL, NULL);
+    mosquitto_lib_version(&major, nullptr, nullptr);
     if (major != LIBMOSQUITTO_MAJOR) {
       logOtherError("mqtt", "invalid mosquitto version %d instead of %d", major, LIBMOSQUITTO_MAJOR);
       return false;
@@ -311,7 +310,7 @@ MqttHandler::MqttHandler(UserInfo* userInfo, BusHandler* busHandler, MessageMap*
   : DataSink(userInfo, "mqtt"), DataSource(busHandler), WaitThread(), m_messages(messages), m_connected(false),
     m_initialConnectFailed(false), m_lastUpdateCheckResult(".") {
   m_publishByField = false;
-  m_mosquitto = NULL;
+  m_mosquitto = nullptr;
   if (g_topicFields.empty()) {
     if (g_topicStrs.empty()) {
       g_topicStrs.push_back("");
@@ -332,8 +331,8 @@ MqttHandler::MqttHandler(UserInfo* userInfo, BusHandler* busHandler, MessageMap*
       }
     }
   }
-  m_globalTopic = getTopic(NULL, "global/");
-  m_mosquitto = NULL;
+  m_globalTopic = getTopic(nullptr, "global/");
+  m_mosquitto = nullptr;
   if (mosquitto_lib_init() != MOSQ_ERR_SUCCESS) {
     logOtherError("mqtt", "unable to initialize");
   } else {
@@ -391,7 +390,7 @@ MqttHandler::MqttHandler(UserInfo* userInfo, BusHandler* busHandler, MessageMap*
     if (ret == MOSQ_ERR_INVAL && !g_ignoreInvalidParams) {
       logOtherError("mqtt", "unable to connect (invalid parameters)");
       mosquitto_destroy(m_mosquitto);
-      m_mosquitto = NULL;
+      m_mosquitto = nullptr;
     } else if (ret != MOSQ_ERR_SUCCESS) {
       m_connected = false;
       m_initialConnectFailed = g_ignoreInvalidParams;
@@ -413,7 +412,7 @@ MqttHandler::~MqttHandler() {
   join();
   if (m_mosquitto) {
     mosquitto_destroy(m_mosquitto);
-    m_mosquitto = NULL;
+    m_mosquitto = nullptr;
   }
   mosquitto_lib_cleanup();
 }
@@ -501,10 +500,10 @@ void MqttHandler::notifyTopic(const string& topic, const string& data) {
   }
   logOtherInfo("mqtt", "received topic for %s %s", circuit.c_str(), name.c_str());
   Message* message = m_messages->find(circuit, name, m_levels, isWrite);
-  if (message == NULL) {
+  if (message == nullptr) {
     message = m_messages->find(circuit, name, m_levels, isWrite, true);
   }
-  if (message == NULL) {
+  if (message == nullptr) {
     logOtherError("mqtt", "%s message %s %s not found", isWrite?"write":"read", circuit.c_str(), name.c_str());
     return;
   }
@@ -543,8 +542,8 @@ void MqttHandler::run() {
   publishTopic(m_globalTopic+"running", "true", true);
   publishTopic(signalTopic, "false");
   mosquitto_message_callback_set(m_mosquitto, on_message);
-  string subTopic = getTopic(NULL, "#");
-  mosquitto_subscribe(m_mosquitto, NULL, subTopic.c_str(), 0);
+  string subTopic = getTopic(nullptr, "#");
+  mosquitto_subscribe(m_mosquitto, nullptr, subTopic.c_str(), 0);
   bool allowReconnect = false;
   while (isRunning()) {
     handleTraffic(allowReconnect);
@@ -675,7 +674,7 @@ void MqttHandler::publishMessage(const Message* message, ostringstream* updates)
     if (json) {
       *updates << "{";
     }
-    result_t result = message->decodeLastData(false, NULL, -1, outputFormat, updates);
+    result_t result = message->decodeLastData(false, nullptr, -1, outputFormat, updates);
     if (result != RESULT_OK) {
       logOtherError("mqtt", "decode %s %s: %s", message->getCircuit().c_str(), message->getName().c_str(),
           getResultCode(result));
@@ -692,7 +691,7 @@ void MqttHandler::publishMessage(const Message* message, ostringstream* updates)
   }
   for (size_t index = 0; index < message->getFieldCount(); index++) {
     string name = message->getFieldName(index);
-    result_t result = message->decodeLastData(false, NULL, index, outputFormat, updates);
+    result_t result = message->decodeLastData(false, nullptr, index, outputFormat, updates);
     if (result != RESULT_OK) {
       logOtherError("mqtt", "decode %s %s %s: %s", message->getCircuit().c_str(), message->getName().c_str(),
           name.c_str(), getResultCode(result));
@@ -706,7 +705,7 @@ void MqttHandler::publishMessage(const Message* message, ostringstream* updates)
 
 void MqttHandler::publishTopic(const string& topic, const string& data, bool retain) {
   logOtherDebug("mqtt", "publish %s %s", topic.c_str(), data.c_str());
-  mosquitto_publish(m_mosquitto, NULL, topic.c_str(), (uint32_t)data.size(),
+  mosquitto_publish(m_mosquitto, nullptr, topic.c_str(), (uint32_t)data.size(),
       reinterpret_cast<const uint8_t*>(data.c_str()), 0, g_retain || retain);
 }
 
diff --git a/src/ebusd/mqtthandler.h b/src/ebusd/mqtthandler.h
index f86bb818..91c39b14 100755
--- a/src/ebusd/mqtthandler.h
+++ b/src/ebusd/mqtthandler.h
@@ -131,7 +131,7 @@ class MqttHandler : public DataSink, public DataSource, public WaitThread {
   /** whether to publish a separate topic for each message field. */
   bool m_publishByField;
 
-  /** the mosquitto structure if initialized, or NULL. */
+  /** the mosquitto structure if initialized, or nullptr. */
   struct mosquitto* m_mosquitto;
 
   /** whether the connection to the broker is established. */
diff --git a/src/ebusd/network.cpp b/src/ebusd/network.cpp
index 60e7a5de..bc1c6123 100755
--- a/src/ebusd/network.cpp
+++ b/src/ebusd/network.cpp
@@ -111,13 +111,13 @@ void Connection::run() {
   while (!closed) {
 #ifdef HAVE_PPOLL
     // wait for new fd event
-    ret = ppoll(fds, nfds, &tdiff, NULL);
+    ret = ppoll(fds, nfds, &tdiff, nullptr);
 #else
 #ifdef HAVE_PSELECT
     // set readfds to inital checkfds
     fd_set readfds = checkfds;
     // wait for new fd event
-    ret = pselect(maxfd + 1, &readfds, NULL, &exceptfds, &tdiff, NULL);
+    ret = pselect(maxfd + 1, &readfds, nullptr, &exceptfds, &tdiff, nullptr);
 #endif
 #endif
     bool newData = false;
@@ -184,7 +184,7 @@ void Connection::run() {
   }
 
   delete m_socket;
-  m_socket = NULL;
+  m_socket = nullptr;
   logInfo(lf_network, "[%05d] connection closed", getID());
 }
 
@@ -193,21 +193,21 @@ Network::Network(const bool local, const uint16_t port, const uint16_t httpPort,
   : Thread(), m_netQueue(netQueue), m_listening(false) {
   m_tcpServer = new TCPServer(port, local ? "127.0.0.1" : "0.0.0.0");
 
-  if (m_tcpServer != NULL && m_tcpServer->start() == 0) {
+  if (m_tcpServer != nullptr && m_tcpServer->start() == 0) {
     m_listening = true;
   }
   if (httpPort > 0) {
     m_httpServer = new TCPServer(httpPort, "0.0.0.0");
     m_httpServer->start();
   } else {
-    m_httpServer = NULL;
+    m_httpServer = nullptr;
   }
 }
 
 Network::~Network() {
   stop();
   NetMessage* netMsg;
-  while ((netMsg = m_netQueue->pop()) != NULL) {
+  while ((netMsg = m_netQueue->pop()) != nullptr) {
     netMsg->setResult("ERR: shutdown", "", false, 0, true);
   }
   while (!m_connections.empty()) {
@@ -218,10 +218,10 @@ Network::~Network() {
     delete connection;
   }
 
-  if (m_tcpServer != NULL) {
+  if (m_tcpServer != nullptr) {
     delete m_tcpServer;
   }
-  if (m_httpServer != NULL) {
+  if (m_httpServer != nullptr) {
     delete m_httpServer;
   }
   join();
@@ -276,13 +276,13 @@ void Network::run() {
   while (true) {
 #ifdef HAVE_PPOLL
     // wait for new fd event
-    ret = ppoll(fds, nfds, &tdiff, NULL);
+    ret = ppoll(fds, nfds, &tdiff, nullptr);
 #else
 #ifdef HAVE_PSELECT
     // set readfds to inital checkfds
     fd_set readfds = checkfds;
     // wait for new fd event
-    ret = pselect(maxfd + 1, &readfds, NULL, NULL, &tdiff, NULL);
+    ret = pselect(maxfd + 1, &readfds, nullptr, nullptr, &tdiff, nullptr);
 #endif
 #endif
     if (ret == 0) {
@@ -317,7 +317,7 @@ void Network::run() {
 #endif
     if (newData) {
       TCPSocket* socket = (isHttp ? m_httpServer : m_tcpServer)->newSocket();
-      if (socket == NULL) {
+      if (socket == nullptr) {
         continue;
       }
       Connection* connection = new Connection(socket, isHttp, m_netQueue);
diff --git a/src/ebusd/network.h b/src/ebusd/network.h
index af9b9a0e..2b961fe1 100755
--- a/src/ebusd/network.h
+++ b/src/ebusd/network.h
@@ -48,8 +48,8 @@ class NetMessage {
    */
   explicit NetMessage(bool isHttp)
     : m_isHttp(isHttp), m_resultSet(false), m_disconnect(false), m_listening(false), m_listenSince(0) {
-    pthread_mutex_init(&m_mutex, NULL);
-    pthread_cond_init(&m_cond, NULL);
+    pthread_mutex_init(&m_mutex, nullptr);
+    pthread_cond_init(&m_cond, nullptr);
   }
 
   /**
@@ -138,7 +138,7 @@ class NetMessage {
    * @param listenSince set to the start time from which to add updates (inclusive).
    * @return whether the client is in listening mode.
    */
-  bool isListening(time_t* listenSince = NULL) {
+  bool isListening(time_t* listenSince = nullptr) {
     if (listenSince) {
       *listenSince = m_listenSince;
     }
@@ -278,7 +278,7 @@ class Network : public Thread {
   /** the command line @a TCPServer instance. */
   TCPServer* m_tcpServer;
 
-  /** the HTTP @a TCPServer instance, or NULL. */
+  /** the HTTP @a TCPServer instance, or nullptr. */
   TCPServer* m_httpServer;
 
   /** @a Notify object for shutdown procedure. */
diff --git a/src/lib/ebus/contrib/tem.cpp b/src/lib/ebus/contrib/tem.cpp
index 8eb469c0..09c36502 100755
--- a/src/lib/ebus/contrib/tem.cpp
+++ b/src/lib/ebus/contrib/tem.cpp
@@ -66,7 +66,7 @@ result_t TemParamDataType::readSymbols(size_t offset, size_t length, const Symbo
     if (outputFormat & OF_JSON) {
       *output << "null";
     } else {
-      *output << NULL_VALUE;
+      *output << nullptr_VALUE;
     }
     return RESULT_OK;
   }
@@ -94,7 +94,7 @@ result_t TemParamDataType::writeSymbols(const size_t offset, const size_t length
   unsigned int value;
   unsigned int grp, num;
 
-  if (input->str() == NULL_VALUE) {
+  if (input->str() == nullptr_VALUE) {
     value = m_replacement;  // replacement value
   } else {
     string token;
@@ -102,24 +102,24 @@ result_t TemParamDataType::writeSymbols(const size_t offset, const size_t length
       return RESULT_ERR_EOF;  // incomplete
     }
     const char* str = token.c_str();
-    if (str == NULL || *str == 0) {
+    if (str == nullptr || *str == 0) {
       return RESULT_ERR_EOF;  // input too short
     }
-    char* strEnd = NULL;
+    char* strEnd = nullptr;
     grp = (unsigned int)strtoul(str, &strEnd, 10);
-    if (strEnd == NULL || strEnd == str || *strEnd != 0) {
+    if (strEnd == nullptr || strEnd == str || *strEnd != 0) {
       return RESULT_ERR_INVALID_NUM;  // invalid value
     }
     if (input->eof() || !getline(*input, token, '-')) {
       return RESULT_ERR_EOF;  // incomplete
     }
     str = token.c_str();
-    if (str == NULL || *str == 0) {
+    if (str == nullptr || *str == 0) {
       return RESULT_ERR_EOF;  // input too short
     }
-    strEnd = NULL;
+    strEnd = nullptr;
     num = (unsigned int)strtoul(str, &strEnd, 10);
-    if (strEnd == NULL || strEnd == str || *strEnd != 0) {
+    if (strEnd == nullptr || strEnd == str || *strEnd != 0) {
       return RESULT_ERR_INVALID_NUM;  // invalid value
     }
     if (grp > 0x1f || num > 0x7f) {
diff --git a/src/lib/ebus/contrib/tem.h b/src/lib/ebus/contrib/tem.h
index 4e505c54..57a51283 100755
--- a/src/lib/ebus/contrib/tem.h
+++ b/src/lib/ebus/contrib/tem.h
@@ -47,7 +47,7 @@ class TemParamDataType : public NumberDataType {
    * @param id the type identifier.
    */
   explicit TemParamDataType(const string& id)
-    : NumberDataType(id, 16, 0, 0xffff, 0, 0xffff, 0, NULL) {}
+    : NumberDataType(id, 16, 0, 0xffff, 0, 0xffff, 0, nullptr) {}
 
   // @copydoc
   result_t derive(int divisor, size_t bitCount, const NumberDataType** derived) const override;
diff --git a/src/lib/ebus/contrib/test/test_tem.cpp b/src/lib/ebus/contrib/test/test_tem.cpp
index 4b06ebb9..fce0f255 100755
--- a/src/lib/ebus/contrib/test/test_tem.cpp
+++ b/src/lib/ebus/contrib/test/test_tem.cpp
@@ -53,7 +53,7 @@ class TestReader : public MappedFileReader {
  public:
   TestReader(DataFieldTemplates* templates, bool isSet, bool isMasterDest)
   : MappedFileReader::MappedFileReader(true), m_templates(templates), m_isSet(isSet), m_isMasterDest(isMasterDest),
-    m_fields(NULL) {}
+    m_fields(nullptr) {}
   result_t getFieldMap(const string& preferLanguage, vector<string>* row, string* errorDescription) const override {
     if (row->empty()) {
       row->push_back("*name");
@@ -90,7 +90,7 @@ class TestReader : public MappedFileReader {
 
 int main() {
   const DataType* type = DataTypeList::getInstance()->get("TEM_P");
-  if (type == NULL) {
+  if (type == nullptr) {
     cout << "datatype not registered" << endl;
     return 1;
   }
@@ -118,8 +118,8 @@ int main() {
   istringstream dummystr("#");
   string errorDescription;
   vector<string> row;
-  templates->readLineFromStream(&dummystr, "inline", false, &lineNo, &row, &errorDescription, false, NULL, NULL);
-  const DataField* fields = NULL;
+  templates->readLineFromStream(&dummystr, "inline", false, &lineNo, &row, &errorDescription, false, nullptr, nullptr);
+  const DataField* fields = nullptr;
   for (unsigned int i = 0; i < sizeof(checks) / sizeof(checks[0]); i++) {
     string check[5] = checks[i];
     istringstream isstr(check[0]);
@@ -146,9 +146,9 @@ int main() {
     bool failedWriteMatch = flags.find('W') != string::npos;
     string item;
 
-    if (fields != NULL) {
+    if (fields != nullptr) {
       delete fields;
-      fields = NULL;
+      fields = nullptr;
     }
 
     string errorDescription;
@@ -156,7 +156,7 @@ int main() {
     lineNo = 0;
     dummystr.clear();
     dummystr.str("#");
-    result = reader.readLineFromStream(&dummystr, "inline", false, &lineNo, &row, &errorDescription, false, NULL, NULL);
+    result = reader.readLineFromStream(&dummystr, "inline", false, &lineNo, &row, &errorDescription, false, nullptr, nullptr);
     if (result != RESULT_OK) {
       cout << "\"" << check[0] << "\": reader header error: " << getResultCode(result) << ", " << errorDescription
           << endl;
@@ -164,7 +164,7 @@ int main() {
       continue;
     }
     lineNo = baseLine + i;
-    result = reader.readLineFromStream(&isstr, __FILE__, false, &lineNo, &row, &errorDescription, false, NULL, NULL);
+    result = reader.readLineFromStream(&isstr, __FILE__, false, &lineNo, &row, &errorDescription, false, nullptr, nullptr);
     fields = reader.m_fields;
 
     if (result != RESULT_OK) {
@@ -172,8 +172,8 @@ int main() {
       error = true;
       continue;
     }
-    if (fields == NULL) {
-      cout << "\"" << check[0] << "\": create error: NULL" << endl;
+    if (fields == nullptr) {
+      cout << "\"" << check[0] << "\": create error: nullptr" << endl;
       error = true;
       continue;
     }
@@ -194,9 +194,9 @@ int main() {
       cout << "  parse \"" << sstr.getStr().substr(0, 2) << "\" error: " << getResultCode(result) << endl;
       error = true;
     }
-    result = fields->read(mstr, 0, false, NULL, -1, 0, -1, &output);
+    result = fields->read(mstr, 0, false, nullptr, -1, 0, -1, &output);
     if (result >= RESULT_OK) {
-      result = fields->read(sstr, 0, !output.str().empty(), NULL, -1, 0, -1, &output);
+      result = fields->read(sstr, 0, !output.str().empty(), nullptr, -1, 0, -1, &output);
     }
     if (failedRead) {
       if (result >= RESULT_OK) {
@@ -217,9 +217,9 @@ int main() {
     }
 
     istringstream input(expectStr);
-    result = fields->write(UI_FIELD_SEPARATOR, 0, &input, &writeMstr, NULL);
+    result = fields->write(UI_FIELD_SEPARATOR, 0, &input, &writeMstr, nullptr);
     if (result >= RESULT_OK) {
-      result = fields->write(UI_FIELD_SEPARATOR, 0, &input, &writeSstr, NULL);
+      result = fields->write(UI_FIELD_SEPARATOR, 0, &input, &writeSstr, nullptr);
     }
     if (failedWrite) {
       if (result >= RESULT_OK) {
@@ -240,7 +240,7 @@ int main() {
           writeMstr.getStr() + " " + writeSstr.getStr());
     }
     delete fields;
-    fields = NULL;
+    fields = nullptr;
   }
 
   delete templates;
diff --git a/src/lib/ebus/data.cpp b/src/lib/ebus/data.cpp
index af50ac16..3f47def2 100755
--- a/src/lib/ebus/data.cpp
+++ b/src/lib/ebus/data.cpp
@@ -84,7 +84,7 @@ void AttributedItem::appendJson(bool prependFieldSeparator, const string& name,
     plain = value == "false" || value == "true";
     if (!plain) {
       const char* str = value.c_str();
-      char* strEnd = NULL;
+      char* strEnd = nullptr;
       strtod(str, &strEnd);
       plain = strEnd && !*strEnd;
     }
@@ -269,7 +269,7 @@ result_t DataField::create(bool isWriteMessage, bool isTemplate, bool isBroadcas
         while (getline(stream, token, VALUE_SEPARATOR)) {
           FileReader::trim(&token);
           const char* str = token.c_str();
-          char* strEnd = NULL;
+          char* strEnd = nullptr;
           unsigned long id;
           if (strncasecmp(str, "0x", 2) == 0) {
             str += 2;
@@ -277,7 +277,7 @@ result_t DataField::create(bool isWriteMessage, bool isTemplate, bool isBroadcas
           } else {
             id = strtoul(str, &strEnd, 10);  // decimal
           }
-          if (strEnd == NULL || strEnd == str || id > MAX_VALUE) {
+          if (strEnd == nullptr || strEnd == str || id > MAX_VALUE) {
             *errorDescription = "value "+token+" in field "+formatInt(fieldIndex);
             result = RESULT_ERR_INVALID_LIST;
             break;
@@ -307,10 +307,10 @@ result_t DataField::create(bool isWriteMessage, bool isTemplate, bool isBroadcas
       FileReader::trim(&token);
       const DataField* templ = templates->get(token);
       size_t pos = token.find(LENGTH_SEPARATOR);
-      if (templ == NULL && pos != string::npos) {
+      if (templ == nullptr && pos != string::npos) {
         templ = templates->get(token.substr(0, pos));
       }
-      if (templ == NULL) {  // basetype[:len]
+      if (templ == nullptr) {  // basetype[:len]
         size_t length;
         string typeName;
         if (pos == string::npos) {
@@ -334,10 +334,10 @@ result_t DataField::create(bool isWriteMessage, bool isTemplate, bool isBroadcas
           result = RESULT_ERR_NOTFOUND;
           *errorDescription = "field type "+typeName+" in field "+formatInt(fieldIndex);
         } else {
-          SingleDataField* add = NULL;
+          SingleDataField* add = nullptr;
           result = SingleDataField::create(firstType ? name : "", row, dataType, partType, length, divisor,
             constantValue, verifyValue, &values, &add);
-          if (add != NULL) {
+          if (add != nullptr) {
             fields.push_back(add);
           } else {
             if (result == RESULT_OK) {
@@ -509,7 +509,7 @@ result_t SingleDataField::read(const SymbolString& data, size_t offset,
   if (offset + (remainder?1:m_length) > data.getDataSize()) {
     return RESULT_ERR_INVALID_POS;
   }
-  if (isIgnored() || (fieldName != NULL && m_name != fieldName) || fieldIndex > 0) {
+  if (isIgnored() || (fieldName != nullptr && m_name != fieldName) || fieldIndex > 0) {
     return RESULT_EMPTY;
   }
   result_t res = m_dataType->readRawValue(offset, m_length, data, output);
@@ -529,7 +529,7 @@ result_t SingleDataField::read(const SymbolString& data, size_t offset,
   if (offset + (remainder?1:m_length) > data.getDataSize()) {
     return RESULT_ERR_INVALID_POS;
   }
-  if (isIgnored() || (fieldName != NULL && m_name != fieldName) || fieldIndex > 0) {
+  if (isIgnored() || (fieldName != nullptr && m_name != fieldName) || fieldIndex > 0) {
     return RESULT_EMPTY;
   }
   bool shortFormat = outputFormat & OF_SHORT;
@@ -636,7 +636,7 @@ result_t SingleDataField::derive(const string& name, PartType partType, int divi
 
 bool SingleDataField::hasField(const char* fieldName, bool numeric) const {
   bool numericType = m_dataType->isNumeric();
-  return numeric == numericType && (fieldName == NULL || fieldName == m_name);
+  return numeric == numericType && (fieldName == nullptr || fieldName == m_name);
 }
 
 size_t SingleDataField::getLength(PartType partType, size_t maxLength) const {
@@ -663,7 +663,7 @@ bool SingleDataField::hasFullByteOffset(bool after) const {
 }
 
 size_t SingleDataField::getCount(PartType partType, const char* fieldName) const {
-  return isIgnored() || (partType != pt_any && partType != m_partType) || (fieldName != NULL && m_name != fieldName)
+  return isIgnored() || (partType != pt_any && partType != m_partType) || (fieldName != nullptr && m_name != fieldName)
   ? 0 : 1;
 }
 
@@ -742,7 +742,7 @@ result_t ValueListDataField::readSymbols(const SymbolString& input, size_t offse
     if (outputFormat & OF_JSON) {
       *output << "null";
     } else if (value == m_dataType->getReplacement()) {
-      *output << NULL_VALUE;
+      *output << nullptr_VALUE;
     }
   } else if (outputFormat & OF_NUMERIC) {
     *output << setw(0) << dec << value;
@@ -765,7 +765,7 @@ result_t ValueListDataField::readSymbols(const SymbolString& input, size_t offse
 result_t ValueListDataField::writeSymbols(size_t offset, istringstream* input,
     SymbolString* output, size_t* usedLength) const {
   const NumberDataType* numType = reinterpret_cast<const NumberDataType*>(m_dataType);
-  if (isIgnored() || input->str() == NULL_VALUE) {
+  if (isIgnored() || input->str() == nullptr_VALUE) {
     // replacement value
     return numType->writeRawValue(numType->getReplacement(), offset, m_length, output, usedLength);
   }
@@ -776,10 +776,10 @@ result_t ValueListDataField::writeSymbols(size_t offset, istringstream* input,
       return numType->writeRawValue(it->first, offset, m_length, output, usedLength);
     }
   }
-  char* strEnd = NULL;  // fall back to raw value in input
+  char* strEnd = nullptr;  // fall back to raw value in input
   unsigned int value;
   value = (unsigned int)strtoul(str, &strEnd, 10);
-  if (strEnd == NULL || strEnd == str || (*strEnd != 0 && *strEnd != '.')) {
+  if (strEnd == nullptr || strEnd == str || (*strEnd != 0 && *strEnd != '.')) {
     return RESULT_ERR_INVALID_NUM;  // invalid value
   }
   if (m_values.find(value) != m_values.end()) {
@@ -851,10 +851,10 @@ result_t ConstantDataField::writeSymbols(size_t offset, istringstream* input,
 }
 
 
-DataFieldSet* DataFieldSet::s_identFields = NULL;
+DataFieldSet* DataFieldSet::s_identFields = nullptr;
 
 DataFieldSet* DataFieldSet::getIdentFields() {
-  if (s_identFields == NULL) {
+  if (s_identFields == nullptr) {
     const NumberDataType* uchDataType = reinterpret_cast<const NumberDataType*>(
         DataTypeList::getInstance()->get("UCH"));
     const StringDataType* stringDataType = reinterpret_cast<const StringDataType*>(
@@ -936,7 +936,7 @@ size_t DataFieldSet::getLength(PartType partType, size_t maxLength) const {
 }
 
 size_t DataFieldSet::getCount(PartType partType, const char* fieldName) const {
-  if (partType == pt_any && fieldName == NULL) {
+  if (partType == pt_any && fieldName == nullptr) {
     return m_fields.size() - m_ignoredCount;
   }
   size_t count = 0;
@@ -1027,7 +1027,7 @@ result_t DataFieldSet::read(const SymbolString& data, size_t offset,
     if (result != RESULT_EMPTY) {
       found = true;
     }
-    if (findFieldIndex && !field->isIgnored() && (fieldName == NULL || fieldName == field->getName(-1))) {
+    if (findFieldIndex && !field->isIgnored() && (fieldName == nullptr || fieldName == field->getName(-1))) {
       if (fieldIndex == 0) {
         if (!found) {
           return RESULT_ERR_NOTFOUND;
@@ -1074,7 +1074,7 @@ result_t DataFieldSet::read(const SymbolString& data, size_t offset,
       found = true;
       leadingSeparator = true;
     }
-    if (findFieldIndex && !field->isIgnored() && (fieldName == NULL || fieldName == field->getName(-1))) {
+    if (findFieldIndex && !field->isIgnored() && (fieldName == nullptr || fieldName == field->getName(-1))) {
       if (fieldIndex == 0) {
         if (!found) {
           return RESULT_ERR_NOTFOUND;
@@ -1127,7 +1127,7 @@ result_t DataFieldSet::write(char separator, size_t offset, istringstream* input
     previousFullByteOffset = field->hasFullByteOffset(true);
   }
 
-  if (usedLength != NULL) {
+  if (usedLength != nullptr) {
     *usedLength = offset-baseOffset;
   }
   return RESULT_OK;
@@ -1201,7 +1201,7 @@ result_t LoadableDataFieldSet::getFieldMap(const string& preferLanguage, vector<
 
 result_t LoadableDataFieldSet::addFromFile(const string& filename, unsigned int lineNo, map<string, string>* row,
     vector< map<string, string> >* subRows, string* errorDescription, bool replace) {
-  const DataField* field = NULL;
+  const DataField* field = nullptr;
   result_t result = DataField::create(false, false, false, MAX_POS, m_templates, subRows, errorDescription, &field);
   if (result != RESULT_OK) {
     return result;
@@ -1262,7 +1262,7 @@ DataFieldTemplates::DataFieldTemplates(const DataFieldTemplates& other)
 void DataFieldTemplates::clear() {
   for (auto it : m_fieldsByName) {
     delete it.second;
-    it.second = NULL;
+    it.second = nullptr;
   }
   m_fieldsByName.clear();
 }
@@ -1383,7 +1383,7 @@ result_t DataFieldTemplates::addFromFile(const string& filename, unsigned int li
     firstFieldName = name.substr(colon+1);
     name = name.substr(0, colon);
   }
-  const DataField* field = NULL;
+  const DataField* field = nullptr;
   if (!subRows->empty()) {
     map<string, string>::iterator it = (*subRows)[0].find("name");
     if (it == (*subRows)[0].end() || it->second.empty()) {
@@ -1407,7 +1407,7 @@ result_t DataFieldTemplates::addFromFile(const string& filename, unsigned int li
 const DataField* DataFieldTemplates::get(const string& name) const {
   const auto ref = m_fieldsByName.find(name);
   if (ref == m_fieldsByName.end()) {
-    return NULL;
+    return nullptr;
   }
   return ref->second;
 }
diff --git a/src/lib/ebus/data.h b/src/lib/ebus/data.h
index 6b95e1be..31ae1364 100755
--- a/src/lib/ebus/data.h
+++ b/src/lib/ebus/data.h
@@ -215,7 +215,7 @@ class DataField : public AttributedItem {
    * @param isTemplate true for creating a template @a DataField.
    * @param isBroadcastOrMasterDestination true if the destination bus address is @a BRODCAST or a master address.
    * @param maxFieldLength the maximum allowed length of a single field (e.g. @a MAX_POS).
-   * @param templates the @a DataFieldTemplates to be referenced by name, or NULL.
+   * @param templates the @a DataFieldTemplates to be referenced by name, or nullptr.
    * @param rows the mapped field definition rows (may be modified).
    * @param errorDescription a string in which to store the error description in case of error.
    * @param returnField the variable in which to store the created instance.
@@ -258,10 +258,10 @@ class DataField : public AttributedItem {
   /**
    * Get the field count (excluding ignored fields).
    * @param partType the optional part to count, or @ pt_any.
-   * @param fieldName the optional field name to count, or NULL.
+   * @param fieldName the optional field name to count, or nullptr.
    * @return the field count (excluding ignored fields).
    */
-  virtual size_t getCount(PartType partType = pt_any, const char* fieldName = NULL) const = 0;
+  virtual size_t getCount(PartType partType = pt_any, const char* fieldName = nullptr) const = 0;
 
   /**
    * Get the specified field name.
@@ -280,7 +280,7 @@ class DataField : public AttributedItem {
 
   /**
    * Return whether the field is available.
-   * @param fieldName the name of the field to find, or NULL for any.
+   * @param fieldName the name of the field to find, or nullptr for any.
    * @param numeric true for a numeric field, false for a string field.
    * @return true if the field is available.
    */
@@ -290,7 +290,7 @@ class DataField : public AttributedItem {
    * Reads the numeric value from the @a SymbolString.
    * @param data the data @a SymbolString for reading binary data.
    * @param offset the additional offset to add for reading binary data.
-   * @param fieldName the name of the field to read, or NULL for the first field.
+   * @param fieldName the name of the field to read, or nullptr for the first field.
    * @param fieldIndex the optional index of the field (either named or overall), or -1.
    * @param output the variable in which to store the numeric value.
    * @return @a RESULT_OK on success,
@@ -325,7 +325,7 @@ class DataField : public AttributedItem {
    * @param separator the separator character between multiple fields.
    * @param offset the additional offset to add for writing binary data.
    * @param data the data @a SymbolString to write binary data to.
-   * @param usedLength the variable in which to store the used length in bytes, or NULL.
+   * @param usedLength the variable in which to store the used length in bytes, or nullptr.
    * @return @a RESULT_OK on success, or an error code.
    */
   virtual result_t write(char separator, size_t offset, istringstream* input,
@@ -407,7 +407,7 @@ class SingleDataField : public DataField {
   bool hasFullByteOffset(bool after) const;
 
   // @copydoc
-  size_t getCount(PartType partType = pt_any, const char* fieldName = NULL) const override;
+  size_t getCount(PartType partType = pt_any, const char* fieldName = nullptr) const override;
 
   // @copydoc
   virtual string getName(ssize_t fieldIndex) const {
@@ -466,7 +466,7 @@ class SingleDataField : public DataField {
    * @param input the @a istringstream to parse the formatted value from.
    * @param offset the offset in the @a SymbolString.
    * @param output the @a SymbolString to write the binary value to.
-   * @param usedLength the variable in which to store the used length in bytes, or NULL.
+   * @param usedLength the variable in which to store the used length in bytes, or nullptr.
    * @return @a RESULT_OK on success, or an error code.
    */
   virtual result_t writeSymbols(size_t offset, istringstream* input,
@@ -650,7 +650,7 @@ class DataFieldSet : public DataField {
   size_t getLength(PartType partType, size_t maxLength) const override;
 
   // @copydoc
-  size_t getCount(PartType partType = pt_any, const char* fieldName = NULL) const override;
+  size_t getCount(PartType partType = pt_any, const char* fieldName = nullptr) const override;
 
   // @copydoc
   string getName(ssize_t fieldIndex) const override;
@@ -663,11 +663,11 @@ class DataFieldSet : public DataField {
   /**
    * Returns the @a SingleDataField at the specified index.
    * @param index the index of the @a SingleDataField to return.
-   * @return the @a SingleDataField at the specified index, or NULL.
+   * @return the @a SingleDataField at the specified index, or nullptr.
    */
   const SingleDataField* operator[](size_t index) const {
     if (index >= m_fields.size()) {
-      return NULL;
+      return nullptr;
     }
     return m_fields[index];
   }
@@ -699,7 +699,7 @@ class DataFieldSet : public DataField {
 
 
  private:
-  /** the @a DataFieldSet containing the ident message @a SingleDataField instances, or NULL. */
+  /** the @a DataFieldSet containing the ident message @a SingleDataField instances, or nullptr. */
   static DataFieldSet* s_identFields;
 
  protected:
@@ -788,7 +788,7 @@ class DataFieldTemplates : public MappedFileReader {
   /**
    * Gets the template @a DataField instance with the specified name.
    * @param name the name of the template to get.
-   * @return the template @a DataField instance, or NULL.
+   * @return the template @a DataField instance, or nullptr.
    * Note: the caller may not free the returned instance.
    */
   const DataField* get(const string& name) const;
diff --git a/src/lib/ebus/datatype.cpp b/src/lib/ebus/datatype.cpp
index 94fc2e63..f7b430e3 100755
--- a/src/lib/ebus/datatype.cpp
+++ b/src/lib/ebus/datatype.cpp
@@ -142,7 +142,7 @@ result_t StringDataType::writeSymbols(size_t offset, size_t length, istringstrea
     for (size_t index = start, i = 0; i < count; index += incr, i++) {
       output->dataAt(offset + index) = (symbol_t)m_replacement;  // fill up with replacement
     }
-    if (usedLength != NULL) {
+    if (usedLength != nullptr) {
       *usedLength = count;
     }
     return RESULT_OK;
@@ -197,7 +197,7 @@ result_t StringDataType::writeSymbols(size_t offset, size_t length, istringstrea
   if (!remainder && i < count) {
     return RESULT_ERR_EOF;  // input too short
   }
-  if (usedLength != NULL) {
+  if (usedLength != nullptr) {
     *usedLength = (index-start)*incr;
   }
   return RESULT_OK;
@@ -243,13 +243,13 @@ result_t DateTimeDataType::readSymbols(size_t offset, size_t length, const Symbo
     case 2:  // date only
       if (!hasFlag(REQ) && symbol == m_replacement) {
         if (i + 1 != length) {
-          *output << NULL_VALUE << ".";
+          *output << nullptr_VALUE << ".";
           break;
         } else if (last == m_replacement) {
           if (length == 2) {  // number of days since 01.01.1900
-            *output << NULL_VALUE << ".";
+            *output << nullptr_VALUE << ".";
           }
-          *output << NULL_VALUE;
+          *output << nullptr_VALUE;
           break;
         }
       }
@@ -282,13 +282,13 @@ result_t DateTimeDataType::readSymbols(size_t offset, size_t length, const Symbo
     case 1:  // time only
       if (!hasFlag(REQ) && symbol == m_replacement) {
         if (length == 1) {  // truncated time
-          *output << NULL_VALUE << ":" << NULL_VALUE;
+          *output << nullptr_VALUE << ":" << nullptr_VALUE;
           break;
         }
         if (i > 0) {
           *output << ":";
         }
-        *output << NULL_VALUE;
+        *output << nullptr_VALUE;
         break;
       }
       if (hasFlag(SPE)) {  // minutes since midnight
@@ -359,7 +359,7 @@ result_t DateTimeDataType::writeSymbols(size_t offset, size_t length, istringstr
     for (size_t index = start, i = 0; i < count; index += incr, i++) {
       output->dataAt(offset + index) = (symbol_t)m_replacement;  // fill up with replacement
     }
-    if (usedLength != NULL) {
+    if (usedLength != nullptr) {
       *usedLength = count;
     }
     return RESULT_OK;
@@ -378,7 +378,7 @@ result_t DateTimeDataType::writeSymbols(size_t offset, size_t length, istringstr
       if (input->eof() || !getline(*input, token, '.')) {
         return RESULT_ERR_EOF;  // incomplete
       }
-      if (!hasFlag(REQ) && token == NULL_VALUE) {
+      if (!hasFlag(REQ) && token == nullptr_VALUE) {
         value = m_replacement;
         break;
       }
@@ -431,7 +431,7 @@ result_t DateTimeDataType::writeSymbols(size_t offset, size_t length, istringstr
       if (input->eof() || !getline(*input, token, LENGTH_SEPARATOR)) {
         return RESULT_ERR_EOF;  // incomplete
       }
-      if (!hasFlag(REQ) && token == NULL_VALUE) {
+      if (!hasFlag(REQ) && token == nullptr_VALUE) {
         value = m_replacement;
         if (length == 1) {  // truncated time
           if (i == 0) {
@@ -493,7 +493,7 @@ result_t DateTimeDataType::writeSymbols(size_t offset, size_t length, istringstr
   if (!remainder && i < count) {
     return RESULT_ERR_EOF;  // input too short
   }
-  if (usedLength != NULL) {
+  if (usedLength != nullptr) {
     *usedLength = (index-start)*incr;
   }
   return RESULT_OK;
@@ -654,7 +654,7 @@ result_t NumberDataType::readSymbols(size_t offset, size_t length, const SymbolS
     if (outputFormat & OF_JSON) {
       *output << "null";
     } else {
-      *output << NULL_VALUE;
+      *output << nullptr_VALUE;
     }
     return RESULT_OK;
   }
@@ -787,7 +787,7 @@ result_t NumberDataType::writeRawValue(unsigned int value, size_t offset, size_t
       output->dataAt(offset + index) = symbol;
     }
   }
-  if (usedLength != NULL) {
+  if (usedLength != nullptr) {
     *usedLength = length;
   }
   return RESULT_OK;
@@ -797,15 +797,15 @@ result_t NumberDataType::writeSymbols(size_t offset, size_t length, istringstrea
     SymbolString* output, size_t* usedLength) const {
   unsigned int value;
 
-  if (!hasFlag(REQ) && (isIgnored() || input->str() == NULL_VALUE)) {
+  if (!hasFlag(REQ) && (isIgnored() || input->str() == nullptr_VALUE)) {
     value = m_replacement;  // replacement value
   } else if (input->str().empty()) {
     return RESULT_ERR_EOF;  // input too short
   } else if (hasFlag(EXP)) {  // IEEE 754 binary32
     const char* str = input->str().c_str();
-    char* strEnd = NULL;
+    char* strEnd = nullptr;
     double dvalue = strtod(str, &strEnd);
-    if (strEnd == NULL || strEnd == str || *strEnd != 0) {
+    if (strEnd == nullptr || strEnd == str || *strEnd != 0) {
       return RESULT_ERR_INVALID_NUM;  // invalid value
     }
     if (m_divisor < 0) {
@@ -842,7 +842,7 @@ result_t NumberDataType::writeSymbols(size_t offset, size_t length, istringstrea
 #endif
   } else {
     const char* str = input->str().c_str();
-    char* strEnd = NULL;
+    char* strEnd = nullptr;
     if (m_divisor == 1) {
       if (hasFlag(SIG)) {
         long signedValue = strtol(str, &strEnd, 10);
@@ -854,12 +854,12 @@ result_t NumberDataType::writeSymbols(size_t offset, size_t length, istringstrea
       } else {
         value = (unsigned int)strtoul(str, &strEnd, 10);
       }
-      if (strEnd == NULL || strEnd == str || (*strEnd != 0 && *strEnd != '.')) {
+      if (strEnd == nullptr || strEnd == str || (*strEnd != 0 && *strEnd != '.')) {
         return RESULT_ERR_INVALID_NUM;  // invalid value
       }
     } else {
       double dvalue = strtod(str, &strEnd);
-      if (strEnd == NULL || strEnd == str || *strEnd != 0) {
+      if (strEnd == nullptr || strEnd == str || *strEnd != 0) {
         return RESULT_ERR_INVALID_NUM;  // invalid value
       }
       if (m_divisor < 0) {
@@ -912,8 +912,8 @@ bool DataTypeList::s_contrib_initialized = libebus_contrib_register();
 DataTypeList::DataTypeList() {
   add(new StringDataType("STR", MAX_LEN*8, ADJ, ' '));  // >= 1 byte character string filled up with space
   // unsigned decimal in BCD, 0000 - 9999 (fixed length)
-  add(new NumberDataType("PIN", 16, FIX|BCD|REV, 0xffff, 0, 0x9999, 1, NULL));
-  add(new NumberDataType("UCH", 8, 0, 0xff, 0, 0xfe, 1, NULL));  // unsigned integer, 0 - 254
+  add(new NumberDataType("PIN", 16, FIX|BCD|REV, 0xffff, 0, 0x9999, 1, nullptr));
+  add(new NumberDataType("UCH", 8, 0, 0xff, 0, 0xfe, 1, nullptr));  // unsigned integer, 0 - 254
   add(new StringDataType("IGN", MAX_LEN*8, IGN|ADJ, 0));  // >= 1 byte ignored data
   // >= 1 byte character string filled up with 0x00 (null terminated string)
   add(new StringDataType("NTS", MAX_LEN*8, ADJ, 0));
@@ -951,56 +951,56 @@ DataTypeList::DataTypeList() {
   add(new DateTimeDataType("TTH", 6, 0, 0, false, true, 30));
   // truncated time (only multiple of 15 minutes), 00:00 - 24:00 (minutes div 15 + hour * 4 as integer)
   add(new DateTimeDataType("TTQ", 7, 0, 0, false, true, 15));
-  add(new NumberDataType("BDY", 8, DAY, 0x07, 0, 6, 1, NULL));  // weekday, "Mon" - "Sun" (0x00 - 0x06) [eBUS type]
-  add(new NumberDataType("HDY", 8, DAY, 0x00, 1, 7, 1, NULL));  // weekday, "Mon" - "Sun" (0x01 - 0x07) [Vaillant type]
-  add(new NumberDataType("BCD", 8, BCD, 0xff, 0, 99, 1, NULL));  // unsigned decimal in BCD, 0 - 99
-  add(new NumberDataType("BCD", 16, BCD, 0xffff, 0, 9999, 1, NULL));  // unsigned decimal in BCD, 0 - 9999
-  add(new NumberDataType("BCD", 24, BCD, 0xffffff, 0, 999999, 1, NULL));  // unsigned decimal in BCD, 0 - 999999
-  add(new NumberDataType("BCD", 32, BCD, 0xffffffff, 0, 99999999, 1, NULL));  // unsigned decimal in BCD, 0 - 99999999
-  add(new NumberDataType("HCD", 32, HCD|BCD|REQ, 0, 0, 99999999, 1, NULL));  // unsigned decimal in HCD, 0 - 99999999
-  add(new NumberDataType("HCD", 8, HCD|BCD|REQ, 0, 0, 99, 1, NULL));  // unsigned decimal in HCD, 0 - 99
-  add(new NumberDataType("HCD", 16, HCD|BCD|REQ, 0, 0, 9999, 1, NULL));  // unsigned decimal in HCD, 0 - 9999
-  add(new NumberDataType("HCD", 24, HCD|BCD|REQ, 0, 0, 999999, 1, NULL));  // unsigned decimal in HCD, 0 - 999999
-  add(new NumberDataType("SCH", 8, SIG, 0x80, 0x81, 0x7f, 1, NULL));  // signed integer, -127 - +127
-  add(new NumberDataType("D1B", 8, SIG, 0x80, 0x81, 0x7f, 1, NULL));  // signed integer, -127 - +127
+  add(new NumberDataType("BDY", 8, DAY, 0x07, 0, 6, 1, nullptr));  // weekday, "Mon" - "Sun" (0x00 - 0x06) [eBUS type]
+  add(new NumberDataType("HDY", 8, DAY, 0x00, 1, 7, 1, nullptr));  // weekday, "Mon" - "Sun" (0x01 - 0x07) [Vaillant type]
+  add(new NumberDataType("BCD", 8, BCD, 0xff, 0, 99, 1, nullptr));  // unsigned decimal in BCD, 0 - 99
+  add(new NumberDataType("BCD", 16, BCD, 0xffff, 0, 9999, 1, nullptr));  // unsigned decimal in BCD, 0 - 9999
+  add(new NumberDataType("BCD", 24, BCD, 0xffffff, 0, 999999, 1, nullptr));  // unsigned decimal in BCD, 0 - 999999
+  add(new NumberDataType("BCD", 32, BCD, 0xffffffff, 0, 99999999, 1, nullptr));  // unsigned decimal in BCD, 0 - 99999999
+  add(new NumberDataType("HCD", 32, HCD|BCD|REQ, 0, 0, 99999999, 1, nullptr));  // unsigned decimal in HCD, 0 - 99999999
+  add(new NumberDataType("HCD", 8, HCD|BCD|REQ, 0, 0, 99, 1, nullptr));  // unsigned decimal in HCD, 0 - 99
+  add(new NumberDataType("HCD", 16, HCD|BCD|REQ, 0, 0, 9999, 1, nullptr));  // unsigned decimal in HCD, 0 - 9999
+  add(new NumberDataType("HCD", 24, HCD|BCD|REQ, 0, 0, 999999, 1, nullptr));  // unsigned decimal in HCD, 0 - 999999
+  add(new NumberDataType("SCH", 8, SIG, 0x80, 0x81, 0x7f, 1, nullptr));  // signed integer, -127 - +127
+  add(new NumberDataType("D1B", 8, SIG, 0x80, 0x81, 0x7f, 1, nullptr));  // signed integer, -127 - +127
   // unsigned number (fraction 1/2), 0 - 100 (0x00 - 0xc8, replacement 0xff)
-  add(new NumberDataType("D1C", 8, 0, 0xff, 0x00, 0xc8, 2, NULL));
+  add(new NumberDataType("D1C", 8, 0, 0xff, 0x00, 0xc8, 2, nullptr));
   // signed number (fraction 1/256), -127.99 - +127.99
-  add(new NumberDataType("D2B", 16, SIG, 0x8000, 0x8001, 0x7fff, 256, NULL));
+  add(new NumberDataType("D2B", 16, SIG, 0x8000, 0x8001, 0x7fff, 256, nullptr));
   // signed number (fraction 1/16), -2047.9 - +2047.9
-  add(new NumberDataType("D2C", 16, SIG, 0x8000, 0x8001, 0x7fff, 16, NULL));
+  add(new NumberDataType("D2C", 16, SIG, 0x8000, 0x8001, 0x7fff, 16, nullptr));
   // signed number (fraction 1/1000), -32.767 - +32.767, little endian
-  add(new NumberDataType("FLT", 16, SIG, 0x8000, 0x8001, 0x7fff, 1000, NULL));
+  add(new NumberDataType("FLT", 16, SIG, 0x8000, 0x8001, 0x7fff, 1000, nullptr));
   // signed number (fraction 1/1000), -32.767 - +32.767, big endian
-  add(new NumberDataType("FLR", 16, SIG|REV, 0x8000, 0x8001, 0x7fff, 1000, NULL));
+  add(new NumberDataType("FLR", 16, SIG|REV, 0x8000, 0x8001, 0x7fff, 1000, nullptr));
   // signed number (IEEE 754 binary32: 1 bit sign, 8 bits exponent, 23 bits significand), little endian
-  add(new NumberDataType("EXP", 32, SIG|EXP, 0x7f800000, 0x00000000, 0xffffffff, 1, NULL));
+  add(new NumberDataType("EXP", 32, SIG|EXP, 0x7f800000, 0x00000000, 0xffffffff, 1, nullptr));
   // signed number (IEEE 754 binary32: 1 bit sign, 8 bits exponent, 23 bits significand), big endian
-  add(new NumberDataType("EXR", 32, SIG|EXP|REV, 0x7f800000, 0x00000000, 0xffffffff, 1, NULL));
+  add(new NumberDataType("EXR", 32, SIG|EXP|REV, 0x7f800000, 0x00000000, 0xffffffff, 1, nullptr));
   // unsigned integer, 0 - 65534, little endian
-  add(new NumberDataType("UIN", 16, 0, 0xffff, 0, 0xfffe, 1, NULL));
+  add(new NumberDataType("UIN", 16, 0, 0xffff, 0, 0xfffe, 1, nullptr));
   // unsigned integer, 0 - 65534, big endian
-  add(new NumberDataType("UIR", 16, REV, 0xffff, 0, 0xfffe, 1, NULL));
+  add(new NumberDataType("UIR", 16, REV, 0xffff, 0, 0xfffe, 1, nullptr));
   // signed integer, -32767 - +32767, little endian
-  add(new NumberDataType("SIN", 16, SIG, 0x8000, 0x8001, 0x7fff, 1, NULL));
+  add(new NumberDataType("SIN", 16, SIG, 0x8000, 0x8001, 0x7fff, 1, nullptr));
   // signed integer, -32767 - +32767, big endian
-  add(new NumberDataType("SIR", 16, SIG|REV, 0x8000, 0x8001, 0x7fff, 1, NULL));
+  add(new NumberDataType("SIR", 16, SIG|REV, 0x8000, 0x8001, 0x7fff, 1, nullptr));
   // unsigned 3 bytes int, 0 - 16777214, little endian
-  add(new NumberDataType("U3N", 24, 0, 0xffffff, 0, 0xfffffe, 1, NULL));
+  add(new NumberDataType("U3N", 24, 0, 0xffffff, 0, 0xfffffe, 1, nullptr));
   // unsigned 3 bytes int, 0 - 16777214, big endian
-  add(new NumberDataType("U3R", 24, REV, 0xffffff, 0, 0xfffffe, 1, NULL));
+  add(new NumberDataType("U3R", 24, REV, 0xffffff, 0, 0xfffffe, 1, nullptr));
   // signed 3 bytes int, -8388607 - +8388607, little endian
-  add(new NumberDataType("S3N", 24, SIG, 0x800000, 0x800001, 0xffffff, 1, NULL));
+  add(new NumberDataType("S3N", 24, SIG, 0x800000, 0x800001, 0xffffff, 1, nullptr));
   // signed 3 bytes int, -8388607 - +8388607, big endian
-  add(new NumberDataType("S3R", 24, SIG|REV, 0x800000, 0x800001, 0xffffff, 1, NULL));
+  add(new NumberDataType("S3R", 24, SIG|REV, 0x800000, 0x800001, 0xffffff, 1, nullptr));
   // unsigned integer, 0 - 4294967294, little endian
-  add(new NumberDataType("ULG", 32, 0, 0xffffffff, 0, 0xfffffffe, 1, NULL));
+  add(new NumberDataType("ULG", 32, 0, 0xffffffff, 0, 0xfffffffe, 1, nullptr));
   // unsigned integer, 0 - 4294967294, big endian
-  add(new NumberDataType("ULR", 32, REV, 0xffffffff, 0, 0xfffffffe, 1, NULL));
+  add(new NumberDataType("ULR", 32, REV, 0xffffffff, 0, 0xfffffffe, 1, nullptr));
   // signed integer, -2147483647 - +2147483647, little endian
-  add(new NumberDataType("SLG", 32, SIG, 0x80000000, 0x80000001, 0xffffffff, 1, NULL));
+  add(new NumberDataType("SLG", 32, SIG, 0x80000000, 0x80000001, 0xffffffff, 1, nullptr));
   // signed integer, -2147483647 - +2147483647, big endian
-  add(new NumberDataType("SLR", 32, SIG|REV, 0x80000000, 0x80000001, 0xffffffff, 1, NULL));
+  add(new NumberDataType("SLR", 32, SIG|REV, 0x80000000, 0x80000001, 0xffffffff, 1, nullptr));
   add(new NumberDataType("BI0", 7, ADJ|REQ, 0, 0, 1));  // bit 0 (up to 7 bits until bit 6)
   add(new NumberDataType("BI1", 7, ADJ|REQ, 0, 1, 1));  // bit 1 (up to 7 bits until bit 7)
   add(new NumberDataType("BI2", 6, ADJ|REQ, 0, 2, 1));  // bit 2 (up to 6 bits until bit 7)
@@ -1056,10 +1056,10 @@ const DataType* DataTypeList::get(const string& id, size_t length) const {
   }
   auto it = m_typesById.find(id);
   if (it == m_typesById.end()) {
-    return NULL;
+    return nullptr;
   }
   if (length > 0 && !it->second->isAdjustableLength()) {
-    return NULL;
+    return nullptr;
   }
   return it->second;
 }
diff --git a/src/lib/ebus/datatype.h b/src/lib/ebus/datatype.h
index ad5bea2d..47199b38 100755
--- a/src/lib/ebus/datatype.h
+++ b/src/lib/ebus/datatype.h
@@ -58,7 +58,7 @@ using std::ostringstream;
 #define LENGTH_SEPARATOR ':'
 
 /** the replacement string for undefined values (in UI and CSV). */
-#define NULL_VALUE "-"
+#define nullptr_VALUE "-"
 
 /** the separator character used between fields (in UI only). */
 #define UI_FIELD_SEPARATOR ';'
@@ -134,7 +134,7 @@ enum PartType {
 /** bit flag for @a DataType: fixed width formatting. */
 #define FIX 0x20
 
-/** bit flag for @a DataType: value may not be NULL. */
+/** bit flag for @a DataType: value may not be nullptr. */
 #define REQ 0x40
 
 /** bit flag for @a DataType: binary representation is hex converted to decimal and interpreted as 2 digits
@@ -256,7 +256,7 @@ class DataType {
    * @param length the number of symbols to write, or @a REMAIN_LEN.
    * @param input the @a istringstream to parse the formatted value from.
    * @param output the @a SymbolString to write the binary value to.
-   * @param usedLength the variable in which to store the used length in bytes, or NULL.
+   * @param usedLength the variable in which to store the used length in bytes, or nullptr.
    * @return @a RESULT_OK on success, or an error code.
    */
   virtual result_t writeSymbols(size_t offset, size_t length, istringstream* input,
@@ -399,7 +399,7 @@ class NumberDataType : public DataType {
    * @param minValue the minimum raw value.
    * @param maxValue the maximum raw value.
    * @param divisor the divisor (negative for reciprocal).
-   * @param baseType the base @a NumberDataType for derived instances, or NULL.
+   * @param baseType the base @a NumberDataType for derived instances, or nullptr.
    */
   NumberDataType(const string& id, size_t bitCount, uint16_t flags, unsigned int replacement,
       unsigned int minValue, unsigned int maxValue, int divisor,
@@ -415,10 +415,10 @@ class NumberDataType : public DataType {
    * @param replacement the replacement value (no replacement if zero).
    * @param firstBit the offset to the first bit.
    * @param divisor the divisor (negative for reciprocal).
-   * @param baseType the base @a NumberDataType for derived instances, or NULL.
+   * @param baseType the base @a NumberDataType for derived instances, or nullptr.
    */
   NumberDataType(const string& id, size_t bitCount, uint16_t flags, unsigned int replacement,
-      int16_t firstBit, int divisor, const NumberDataType* baseType = NULL)
+      int16_t firstBit, int divisor, const NumberDataType* baseType = nullptr)
     : DataType(id, bitCount, flags|NUM, replacement), m_minValue(0), m_maxValue((1 << bitCount)-1), m_divisor(divisor),
       m_precision(0), m_firstBit(firstBit), m_baseType(baseType) {}
 
@@ -490,7 +490,7 @@ class NumberDataType : public DataType {
    * @param length the number of symbols to write, or @a REMAIN_LEN.
    * @param output the @a SymbolString to write the binary value to.
    * @param usedLength the variable in which to store the used length in bytes,
-   * or NULL.
+   * or nullptr.
    * @return @a RESULT_OK on success, or an error code.
    */
   result_t writeRawValue(unsigned int value, size_t offset, size_t length,
@@ -568,7 +568,7 @@ class DataTypeList {
    * Gets the @a DataType instance with the specified ID.
    * @param id the ID string (excluding optional length suffix).
    * @param length the length in bytes, or 0 for default.
-   * @return the @a DataType instance, or NULL if not available.
+   * @return the @a DataType instance, or nullptr if not available.
    * Note: the caller may not free the instance.
    */
   const DataType* get(const string& id, size_t length = 0) const;
diff --git a/src/lib/ebus/device.cpp b/src/lib/ebus/device.cpp
index 87ab87a1..b9f541d9 100755
--- a/src/lib/ebus/device.cpp
+++ b/src/lib/ebus/device.cpp
@@ -52,7 +52,7 @@ Device::~Device() {
 }
 
 Device* Device::create(const char* name, bool checkDevice, bool readOnly, bool initialSend) {
-  if (strchr(name, '/') == NULL && strchr(name, ':') != NULL) {
+  if (strchr(name, '/') == nullptr && strchr(name, ':') != nullptr) {
     char* in = strdup(name);
     bool udp = false;
     char* addrpos = in;
@@ -61,24 +61,24 @@ Device* Device::create(const char* name, bool checkDevice, bool readOnly, bool i
       addrpos += 4;
       portpos = strchr(addrpos, ':');
     }
-    if (portpos == NULL) {
+    if (portpos == nullptr) {
       free(in);
-      return NULL;  // invalid protocol or missing port
+      return nullptr;  // invalid protocol or missing port
     }
     result_t result = RESULT_OK;
     unsigned int port = parseInt(portpos+1, 10, 1, 65535, &result);
     if (result != RESULT_OK) {
       free(in);
-      return NULL;  // invalid port
+      return nullptr;  // invalid port
     }
     struct sockaddr_in address;
     memset(reinterpret_cast<char*>(&address), 0, sizeof(address));
     *portpos = 0;
     if (inet_aton(addrpos, &address.sin_addr) == 0) {
       struct hostent* h = gethostbyname(addrpos);
-      if (h == NULL) {
+      if (h == nullptr) {
         free(in);
-        return NULL;  // invalid host
+        return nullptr;  // invalid host
       }
       memcpy(&address.sin_addr, h->h_addr_list[0], h->h_length);
     }
@@ -114,7 +114,7 @@ result_t Device::send(symbol_t value) {
   if (m_readOnly || write(value) != 1) {
     return RESULT_ERR_SEND;
   }
-  if (m_listener != NULL) {
+  if (m_listener != nullptr) {
     m_listener->notifyDeviceData(value, false);
   }
   return RESULT_OK;
@@ -140,7 +140,7 @@ result_t Device::recv(unsigned int timeout, symbol_t* value) {
 
     fds[0].fd = m_fd;
     fds[0].events = POLLIN | POLLERR | POLLHUP | POLLRDHUP;
-    ret = ppoll(fds, nfds, &tdiff, NULL);
+    ret = ppoll(fds, nfds, &tdiff, nullptr);
     if (ret >= 0 && fds[0].revents & (POLLERR | POLLHUP | POLLRDHUP)) {
       ret = -1;
     }
@@ -152,7 +152,7 @@ result_t Device::recv(unsigned int timeout, symbol_t* value) {
     FD_ZERO(&exceptfds);
     FD_SET(m_fd, &readfds);
 
-    ret = pselect(m_fd + 1, &readfds, NULL, &exceptfds, &tdiff, NULL);
+    ret = pselect(m_fd + 1, &readfds, nullptr, &exceptfds, &tdiff, nullptr);
     if (ret >= 1 && FD_ISSET(m_fd, &exceptfds)) {
       ret = -1;
     }
@@ -178,7 +178,7 @@ result_t Device::recv(unsigned int timeout, symbol_t* value) {
     close();
     return RESULT_ERR_DEVICE;
   }
-  if (m_listener != NULL) {
+  if (m_listener != nullptr) {
     m_listener->notifyDeviceData(*value, true);
   }
   return RESULT_OK;
diff --git a/src/lib/ebus/device.h b/src/lib/ebus/device.h
index 937813ec..7c555f8f 100755
--- a/src/lib/ebus/device.h
+++ b/src/lib/ebus/device.h
@@ -72,7 +72,7 @@ class Device {
    */
   Device(const char* name, bool checkDevice, bool readOnly, bool initialSend)
     : m_name(name), m_checkDevice(checkDevice), m_readOnly(readOnly), m_initialSend(initialSend), m_fd(-1),
-      m_listener(NULL) {}
+      m_listener(nullptr) {}
 
   /**
    * Destructor.
@@ -85,7 +85,7 @@ class Device {
    * @param checkDevice whether to regularly check the device availability (only for serial devices).
    * @param readOnly whether to allow read access to the device only.
    * @param initialSend whether to send an initial @a ESC symbol in @a open().
-   * @return the new @a Device, or NULL on error.
+   * @return the new @a Device, or nullptr on error.
    * Note: the caller needs to free the created instance.
    */
   static Device* create(const char* name, bool checkDevice = true, bool readOnly = false,
@@ -191,7 +191,7 @@ class Device {
 
 
  private:
-  /** the @a DeviceListener, or NULL. */
+  /** the @a DeviceListener, or nullptr. */
   DeviceListener* m_listener;
 };
 
@@ -243,7 +243,7 @@ class NetworkDevice : public Device {
   NetworkDevice(const char* name, const struct sockaddr_in& address, bool readOnly, bool initialSend,
     bool udp)
     : Device(name, true, readOnly, initialSend), m_address(address), m_udp(udp),
-      m_buffer(NULL), m_bufSize(0), m_bufLen(0), m_bufPos(0) {}
+      m_buffer(nullptr), m_bufSize(0), m_bufLen(0), m_bufPos(0) {}
 
   /**
    * Destructor.
@@ -284,7 +284,7 @@ class NetworkDevice : public Device {
   /** true for UDP, false to TCP. */
   const bool m_udp;
 
-  /** the buffer memory, or NULL. */
+  /** the buffer memory, or nullptr. */
   symbol_t* m_buffer;
 
   /** the buffer size. */
diff --git a/src/lib/ebus/filereader.cpp b/src/lib/ebus/filereader.cpp
index 47474672..200a0170 100755
--- a/src/lib/ebus/filereader.cpp
+++ b/src/lib/ebus/filereader.cpp
@@ -40,18 +40,18 @@ istream* FileReader::openFile(const string& filename, string* errorDescription,
   struct stat st;
   if (stat(filename.c_str(), &st) != 0) {
     *errorDescription = filename;
-    return NULL;
+    return nullptr;
   }
   if (S_ISDIR(st.st_mode)) {
     *errorDescription = filename+" is a directory";
-    return NULL;
+    return nullptr;
   }
   ifstream* stream = new ifstream();
   stream->open(filename.c_str(), ifstream::in);
   if (!stream->is_open()) {
     *errorDescription = filename;
     delete(stream);
-    return NULL;
+    return nullptr;
   }
   if (time) {
     *time = st.st_mtime;
diff --git a/src/lib/ebus/filereader.h b/src/lib/ebus/filereader.h
index 2a342795..c660cf76 100755
--- a/src/lib/ebus/filereader.h
+++ b/src/lib/ebus/filereader.h
@@ -79,10 +79,10 @@ class FileReader {
    * Open a file as stream for reading.
    * @param filename the name of the file being read.
    * @param errorDescription a string in which to store the error description in case of error.
-   * @param time optional pointer to a @a time_t value for storing the modification time of the file, or NULL.
-   * @return the opened @a istream on success, or NULL on error.
+   * @param time optional pointer to a @a time_t value for storing the modification time of the file, or nullptr.
+   * @return the opened @a istream on success, or nullptr on error.
    */
-  static istream* openFile(const string& filename, string* errorDescription, time_t* time = NULL);
+  static istream* openFile(const string& filename, string* errorDescription, time_t* time = nullptr);
 
   /**
    * Read the definitions from a stream.
@@ -90,16 +90,16 @@ class FileReader {
    * @param filename the relative name of the file being read.
    * @param mtime a @a time_t value with the modification time of the file.
    * @param verbose whether to verbosely log problems.
-   * @param defaults the default values by name (potentially overwritten by file name), or NULL to not use defaults.
+   * @param defaults the default values by name (potentially overwritten by file name), or nullptr to not use defaults.
    * @param errorDescription a string in which to store the error description in case of error.
    * @param replace whether to replace an already existing entry.
-   * @param hash optional pointer to a @a size_t value for storing the hash of the file, or NULL.
-   * @param size optional pointer to a @a size_t value for storing the normalized size of the file, or NULL.
+   * @param hash optional pointer to a @a size_t value for storing the hash of the file, or nullptr.
+   * @param size optional pointer to a @a size_t value for storing the normalized size of the file, or nullptr.
    * @return @a RESULT_OK on success, or an error code.
    */
   virtual result_t readFromStream(istream* stream, const string& filename, const time_t& mtime, bool verbose,
-      map<string, string>* defaults, string* errorDescription, bool replace = false, size_t* hash = NULL,
-      size_t* size = NULL);
+      map<string, string>* defaults, string* errorDescription, bool replace = false, size_t* hash = nullptr,
+      size_t* size = nullptr);
 
   /**
    * Read a single line definition from the stream.
@@ -110,8 +110,8 @@ class FileReader {
    * @param row the definition row to clear and update with the read data (for performance reasons only).
    * @param errorDescription a string in which to store the error description in case of error.
    * @param replace whether to replace an already existing entry.
-   * @param hash optional pointer to a @a size_t value for updating with the hash of the line, or NULL.
-   * @param size optional pointer to a @a size_t value for updating with the normalized length of the line, or NULL.
+   * @param hash optional pointer to a @a size_t value for updating with the hash of the line, or nullptr.
+   * @param size optional pointer to a @a size_t value for updating with the normalized length of the line, or nullptr.
    * @return @a RESULT_OK on success, or an error code.
    */
   virtual result_t readLineFromStream(istream* stream, const string& filename, bool verbose,
@@ -146,12 +146,12 @@ class FileReader {
    * @param stream the @a istream to read from.
    * @param row the @a vector to which to add the fields. This will be empty for completely empty and comment lines.
    * @param lineNo the current line number (incremented with each line read).
-   * @param hash optional pointer to a @a size_t value for combining the hash of the line with, or NULL.
-   * @param size optional pointer to a @a size_t value to add the trimmed line length to, or NULL.
+   * @param hash optional pointer to a @a size_t value for combining the hash of the line with, or nullptr.
+   * @param size optional pointer to a @a size_t value to add the trimmed line length to, or nullptr.
    * @return true if there are more lines to read, false when there are no more lines left.
    */
   static bool splitFields(istream* stream, vector<string>* row, unsigned int* lineNo,
-      size_t* hash = NULL, size_t* size = NULL);
+      size_t* hash = nullptr, size_t* size = nullptr);
 
   /**
    * Format the specified hash as 8 hex digits to the output stream.
@@ -209,20 +209,20 @@ class MappedFileReader : public FileReader {
 
   // @copydoc
   result_t readFromStream(istream* stream, const string& filename, const time_t& mtime, bool verbose,
-      map<string, string>* defaults, string* errorDescription, bool replace = false, size_t* hash = NULL,
-      size_t* size = NULL) override;
+      map<string, string>* defaults, string* errorDescription, bool replace = false, size_t* hash = nullptr,
+      size_t* size = nullptr) override;
 
   /**
    * Extract default values from the file name.
    * @param filename the name of the file (without path)
    * @param defaults the default values by name to add to.
-   * @param destAddress optional pointer to a variable in which to store the numeric destination address, or NULL.
-   * @param software optional pointer to a in which to store the numeric software version, or NULL.
-   * @param hardware optional pointer to a in which to store the numeric hardware version, or NULL.
+   * @param destAddress optional pointer to a variable in which to store the numeric destination address, or nullptr.
+   * @param software optional pointer to a in which to store the numeric software version, or nullptr.
+   * @param hardware optional pointer to a in which to store the numeric hardware version, or nullptr.
    * @return true if the minimum parts were extracted, false otherwise.
    */
   virtual bool extractDefaultsFromFilename(const string& filename, map<string, string>* defaults,
-      symbol_t* destAddress = NULL, unsigned int* software = NULL, unsigned int* hardware = NULL) const {
+      symbol_t* destAddress = nullptr, unsigned int* software = nullptr, unsigned int* hardware = nullptr) const {
     return false;
   }
 
diff --git a/src/lib/ebus/message.cpp b/src/lib/ebus/message.cpp
index 1878fb43..f525b310 100755
--- a/src/lib/ebus/message.cpp
+++ b/src/lib/ebus/message.cpp
@@ -115,7 +115,7 @@ Message::Message(const string& circuit, const string& level, const string& name,
       m_id({pb, sb}), m_key(createKey(pb, sb, broadcast)),
       m_data(data), m_deleteData(deleteData),
       m_pollPriority(0),
-      m_usedByCondition(false), m_isScanMessage(true), m_condition(NULL),
+      m_usedByCondition(false), m_isScanMessage(true), m_condition(nullptr),
       m_lastUpdateTime(0), m_lastChangeTime(0), m_pollCount(0), m_lastPollTime(0) {
 }
 
@@ -123,7 +123,7 @@ Message::Message(const string& circuit, const string& level, const string& name,
 /**
  * Helper method for getting a default if the value is empty.
  * @param value the value to check.
- * @param defaults a @a vector of defaults, or NULL.
+ * @param defaults a @a vector of defaults, or nullptr.
  * @param pos the position in defaults.
  * @param replaceStar whether to replace a star in the default with the value.
  * If there is no star in the default and the value is empty, use the complete
@@ -433,7 +433,7 @@ result_t Message::create(const string& filename, const DataFieldTemplates* templ
   if (subIt != subRowDefaults.end()) {
     subRows->insert(subRows->begin(), subIt->second.begin(), subIt->second.end());
   }
-  const DataField* data = NULL;
+  const DataField* data = nullptr;
   if (subRows->empty()) {
     vector<const SingleDataField*> fields;
     data = new DataFieldSet("", fields);
@@ -610,7 +610,7 @@ void Message::setUsedByCondition() {
 }
 
 bool Message::isAvailable() {
-  return (m_condition == NULL) || m_condition->isTrue();
+  return (m_condition == nullptr) || m_condition->isTrue();
 }
 
 bool Message::hasField(const char* fieldName, bool numeric) const {
@@ -653,7 +653,7 @@ result_t Message::prepareMasterPart(size_t index, char separator, istringstream*
   for (size_t i = 2; i < m_id.size(); i++) {
     master->push_back(m_id[i]);
   }
-  result_t result = m_data->write(separator, getIdLength(), input, master, NULL);
+  result_t result = m_data->write(separator, getIdLength(), input, master, nullptr);
   if (result != RESULT_OK) {
     return result;
   }
@@ -667,7 +667,7 @@ result_t Message::prepareSlave(istringstream* input, SlaveSymbolString* slave) {
   }
   slave->clear();
   slave->push_back(0);  // length, will be set later
-  result_t result = m_data->write(UI_FIELD_SEPARATOR, 0, input, slave, NULL);
+  result_t result = m_data->write(UI_FIELD_SEPARATOR, 0, input, slave, nullptr);
   if (result != RESULT_OK) {
     return result;
   }
@@ -730,7 +730,7 @@ result_t Message::decodeLastData(bool master, bool leadingSeparator, const char*
   if (result < RESULT_OK) {
     return result;
   }
-  if (result == RESULT_EMPTY && (fieldName != NULL || fieldIndex >= 0)) {
+  if (result == RESULT_EMPTY && (fieldName != nullptr || fieldIndex >= 0)) {
     return RESULT_ERR_NOTFOUND;
   }
   return result;
@@ -763,7 +763,7 @@ result_t Message::decodeLastData(bool leadingSeparator, const char* fieldName,
       result = RESULT_OK;  // OK if at least one part was non-empty
     }
   }
-  if (result == RESULT_EMPTY && (fieldName != NULL || fieldIndex >= 0)) {
+  if (result == RESULT_EMPTY && (fieldName != nullptr || fieldIndex >= 0)) {
     return RESULT_ERR_NOTFOUND;
   }
   return result;
@@ -808,7 +808,7 @@ bool Message::isLessPollWeight(const Message* other) const {
 
 void Message::dumpHeader(const vector<string>* fieldNames, ostream* output) {
   bool first = true;
-  if (fieldNames == NULL) {
+  if (fieldNames == nullptr) {
     for (const auto& fieldName : defaultMessageFieldMap) {
       if (first) {
         first = false;
@@ -831,7 +831,7 @@ void Message::dumpHeader(const vector<string>* fieldNames, ostream* output) {
 
 void Message::dump(const vector<string>* fieldNames, bool withConditions, ostream* output) const {
   bool first = true;
-  if (fieldNames == NULL) {
+  if (fieldNames == nullptr) {
     for (const auto& fieldName : knownFieldNamesFull) {
       if (fieldName == FIELNAME_LEVEL) {
         continue;  // access level not included in default dump format
@@ -857,7 +857,7 @@ void Message::dump(const vector<string>* fieldNames, bool withConditions, ostrea
 
 void Message::dumpField(const string& fieldName, bool withConditions, ostream* output) const {
   if (fieldName == "type") {
-    if (withConditions && m_condition != NULL) {
+    if (withConditions && m_condition != nullptr) {
       m_condition->dump(false, output);
     }
     if (m_isPassive) {
@@ -976,7 +976,7 @@ void Message::decodeJson(bool leadingSeparator, bool appendDirection, bool addRa
       }
       size_t pos = (size_t)output->tellp();
       *output << ",\n    \"fields\": {";
-      result_t dret = decodeLastData(false, NULL, -1, outputFormat, output);
+      result_t dret = decodeLastData(false, nullptr, -1, outputFormat, output);
       if (dret == RESULT_OK) {
         *output << "\n    }";
       } else {
@@ -1023,9 +1023,9 @@ ChainedMessage::ChainedMessage(const string& circuit, const string& level, const
 ChainedMessage::~ChainedMessage() {
   for (size_t index = 0; index < m_ids.size(); index++) {
     delete m_lastMasterDatas[index];
-    m_lastMasterDatas[index] = NULL;
+    m_lastMasterDatas[index] = nullptr;
     delete m_lastSlaveDatas[index];
-    m_lastSlaveDatas[index] = NULL;
+    m_lastSlaveDatas[index] = nullptr;
   }
   free(m_lastMasterDatas);
   free(m_lastSlaveDatas);
@@ -1113,7 +1113,7 @@ result_t ChainedMessage::prepareMasterPart(size_t index, char separator, istring
     return RESULT_ERR_NOTFOUND;
   }
   MasterSymbolString allData;
-  result_t result = m_data->write(separator, 0, input, &allData, NULL);
+  result_t result = m_data->write(separator, 0, input, &allData, nullptr);
   if (result != RESULT_OK) {
     return result;
   }
@@ -1271,14 +1271,14 @@ void ChainedMessage::dumpField(const string& fieldName, bool withConditions, ost
 Message* getFirstAvailable(const vector<Message*>& messages, const MasterSymbolString* sameIdExtAs,
     const bool onlyAvailable = true) {
   for (auto message : messages) {
-    if (sameIdExtAs && !message->checkId(*sameIdExtAs, NULL)) {
+    if (sameIdExtAs && !message->checkId(*sameIdExtAs, nullptr)) {
       continue;
     }
     if (!onlyAvailable || message->isAvailable()) {
       return message;
     }
   }
-  return NULL;
+  return nullptr;
 }
 
 /**
@@ -1288,7 +1288,7 @@ Message* getFirstAvailable(const vector<Message*>& messages, const MasterSymbolS
  * @param onlyAvailable true to include only available messages (default true), false to also include messages that
  * are currently not available (e.g. due to unresolved or false conditions).
  */
-Message* getFirstAvailable(const vector<Message*>& messages, const Message* sameIdExtAs = NULL,
+Message* getFirstAvailable(const vector<Message*>& messages, const Message* sameIdExtAs = nullptr,
     const bool onlyAvailable = true) {
   for (auto message : messages) {
     if (sameIdExtAs && !message->checkId(*sameIdExtAs)) {
@@ -1298,7 +1298,7 @@ Message* getFirstAvailable(const vector<Message*>& messages, const Message* same
       return message;
     }
   }
-  return NULL;
+  return nullptr;
 }
 
 /**
@@ -1445,7 +1445,7 @@ result_t Condition::create(const string& condName, const map<string, string>& ro
 
 SimpleCondition* SimpleCondition::derive(const string& valueList) const {
   if (valueList.empty()) {
-    return NULL;
+    return nullptr;
   }
   string useValueList = valueList;
   string name = m_condName+useValueList;
@@ -1458,18 +1458,18 @@ SimpleCondition* SimpleCondition::derive(const string& valueList) const {
     vector<string> values;
     result = splitValues(useValueList, &values);
     if (result != RESULT_OK) {
-      return NULL;
+      return nullptr;
     }
     return new SimpleStringCondition(name, m_refName, m_circuit, m_level, m_name, m_dstAddress, m_field, values);
   }
   // numbers
   if (!isNumeric()) {
-    return NULL;
+    return nullptr;
   }
   vector<unsigned int> valueRanges;
   result = splitValues(useValueList, &valueRanges);
   if (result != RESULT_OK) {
-    return NULL;
+    return nullptr;
   }
   return new SimpleNumericCondition(name, m_refName, m_circuit, m_level, m_name, m_dstAddress, m_field, valueRanges);
 }
@@ -1496,7 +1496,7 @@ CombinedCondition* SimpleCondition::combineAnd(Condition* other) {
 
 result_t SimpleCondition::resolve(void (*readMessageFunc)(Message* message), MessageMap* messages,
     ostringstream* errorMessage) {
-  if (m_message == NULL) {
+  if (m_message == nullptr) {
     Message* message;
     if (m_name.length() == 0) {
       message = messages->getScanMessage(m_dstAddress);
@@ -1525,12 +1525,12 @@ result_t SimpleCondition::resolve(void (*readMessageFunc)(Message* message), Mes
       // clone the message with dedicated dstAddress if necessary
       uint64_t key = message->getDerivedKey(m_dstAddress);
       const vector<Message*>* derived = messages->getByKey(key);
-      if (derived == NULL) {
+      if (derived == nullptr) {
         message = message->derive(m_dstAddress, true);
         messages->add(true, message);
       } else {
         Message* first = getFirstAvailable(*derived, message);
-        if (first == NULL) {
+        if (first == nullptr) {
           *errorMessage << ": conditional derived message " << message->getCircuit() << "." << message->getName()
               << " for " << hex << setw(2) << setfill('0') << static_cast<unsigned>(m_dstAddress) << " not found";
           return RESULT_ERR_INVALID_ARG;
@@ -1540,7 +1540,7 @@ result_t SimpleCondition::resolve(void (*readMessageFunc)(Message* message), Mes
     }
 
     if (m_hasValues) {
-      if (!message->hasField(m_field.length() > 0 ? m_field.c_str() : NULL, isNumeric())) {
+      if (!message->hasField(m_field.length() > 0 ? m_field.c_str() : nullptr, isNumeric())) {
         *errorMessage << (isNumeric() ? ": numeric field " : ": string field ") << m_field << " not found";
         return RESULT_ERR_NOTFOUND;
       }
@@ -1551,7 +1551,7 @@ result_t SimpleCondition::resolve(void (*readMessageFunc)(Message* message), Mes
       messages->addPollMessage(true, message);
     }
   }
-  if (m_message->getLastUpdateTime() == 0 && readMessageFunc != NULL) {
+  if (m_message->getLastUpdateTime() == 0 && readMessageFunc != nullptr) {
     (*readMessageFunc)(m_message);
   }
   return RESULT_OK;
@@ -1575,7 +1575,7 @@ bool SimpleCondition::isTrue() {
 
 bool SimpleNumericCondition::checkValue(const Message* message, const string& field) {
   unsigned int value = 0;
-  result_t result = message->decodeLastDataNumField(field.length() == 0 ? NULL : field.c_str(), -1, &value);
+  result_t result = message->decodeLastDataNumField(field.length() == 0 ? nullptr : field.c_str(), -1, &value);
   if (result == RESULT_OK) {
     for (size_t i = 0; i+1 < m_valueRanges.size(); i+=2) {
       if (m_valueRanges[i] <= value && value <= m_valueRanges[i+1]) {
@@ -1590,7 +1590,7 @@ bool SimpleNumericCondition::checkValue(const Message* message, const string& fi
 
 bool SimpleStringCondition::checkValue(const Message* message, const string& field) {
   ostringstream output;
-  result_t result = message->decodeLastData(false, field.length() == 0 ? NULL : field.c_str(), -1, 0, &output);
+  result_t result = message->decodeLastData(false, field.length() == 0 ? nullptr : field.c_str(), -1, 0, &output);
   if (result == RESULT_OK) {
     string value = output.str();
     for (size_t i = 0; i < m_values.size(); i++) {
@@ -1755,7 +1755,7 @@ result_t MessageMap::add(bool storeByName, Message* message, bool replace) {
         }
       } else {
         Message *other = getFirstAvailable(keyIt->second, message);
-        if (other != NULL && (!conditional || !other->isConditional())) {
+        if (other != nullptr && (!conditional || !other->isConditional())) {
           unlock();
           return RESULT_ERR_DUPLICATE;  // duplicate key
         }
@@ -1838,7 +1838,7 @@ result_t MessageMap::add(bool storeByName, Message* message, bool replace) {
 }
 
 void MessageMap::remove(Message* message) {
-  if (message == NULL) {
+  if (message == nullptr) {
     return;
   }
   lock();
@@ -2010,9 +2010,9 @@ result_t MessageMap::addDefaultFromFile(const string& filename, unsigned int lin
       *errorDescription = "condition "+type+" already defined";
       return RESULT_ERR_DUPLICATE_NAME;
     }
-    SimpleCondition* condition = NULL;
+    SimpleCondition* condition = nullptr;
     result_t result = Condition::create(type, defaults, row, &condition);
-    if (condition == NULL || result != RESULT_OK) {
+    if (condition == nullptr || result != RESULT_OK) {
       *errorDescription = "invalid condition";
       return result;
     }
@@ -2077,12 +2077,12 @@ result_t MessageMap::readConditions(const string& filename, string* types, strin
       types->erase(0, pos+1);
     } else {
       bool store = false;
-      *condition = NULL;
+      *condition = nullptr;
       while ((pos=types->find(']')) != string::npos) {
         // simple condition
         string key = filename+":"+types->substr(1, pos-1);
         it = m_conditions.find(key);
-        Condition* add = NULL;
+        Condition* add = nullptr;
         if (it == m_conditions.end()) {
           // check for on-the-fly condition
           size_t sep = key.find_first_of("=<>", filename.length()+1);
@@ -2091,14 +2091,14 @@ result_t MessageMap::readConditions(const string& filename, string* types, strin
             if (it != m_conditions.end()) {
               // derive from another condition
               add = it->second->derive(key.substr(sep));
-              if (add == NULL) {
+              if (add == nullptr) {
                 *errorDescription = "derive condition with values "+key.substr(sep)+" failed";
                 return RESULT_ERR_INVALID_ARG;
               }
               m_conditions[key] = add;  // store derived condition
             }
           }
-          if (add == NULL) {
+          if (add == nullptr) {
             // shared condition not available
             *errorDescription = "condition "+types->substr(1, pos-1)+" not defined";
             return RESULT_ERR_NOTFOUND;
@@ -2229,7 +2229,7 @@ result_t MessageMap::readFromStream(istream* stream, const string& filename, con
 
 result_t MessageMap::addFromFile(const string& filename, unsigned int lineNo, map<string, string>* row,
     vector< map<string, string> >* subRows, string* errorDescription, bool replace) {
-  Condition* condition = NULL;
+  Condition* condition = nullptr;
   string types = AttributedItem::pluck("type", row);
   result_t result = readConditions(filename, &types, errorDescription, &condition);
   if (result != RESULT_OK) {
@@ -2242,9 +2242,9 @@ result_t MessageMap::addFromFile(const string& filename, unsigned int lineNo, ma
       return RESULT_ERR_INVALID_ARG;
     }
     types = types.substr(1);
-    Instruction* instruction = NULL;
+    Instruction* instruction = nullptr;
     result = Instruction::create(filename, types, condition, *row, getDefaults()[""], &instruction);
-    if (instruction == NULL || result != RESULT_OK) {
+    if (instruction == nullptr || result != RESULT_OK) {
       *errorDescription = "invalid instruction";
       return result;
     }
@@ -2308,11 +2308,11 @@ Message* MessageMap::getScanMessage(symbol_t dstAddress) {
     return m_broadcastScanMessage;
   }
   if (!isValidAddress(dstAddress, true) || isMaster(dstAddress)) {
-    return NULL;
+    return nullptr;
   }
   uint64_t key = m_scanMessage->getDerivedKey(dstAddress);
   const vector<Message*>* msgs = getByKey(key);
-  if (msgs != NULL) {
+  if (msgs != nullptr) {
     return msgs->front();
   }
   Message* message = m_scanMessage->derive(dstAddress, true);
@@ -2324,7 +2324,7 @@ result_t MessageMap::resolveConditions(bool verbose, string* errorDescription) {
   result_t overallResult = RESULT_OK;
   for (const auto& it : m_conditions) {
     Condition* condition = it.second;
-    result_t result = resolveCondition(NULL, condition, errorDescription);
+    result_t result = resolveCondition(nullptr, condition, errorDescription);
     if (result != RESULT_OK) {
       overallResult = result;
     }
@@ -2361,10 +2361,10 @@ result_t MessageMap::executeInstructions(void (*readMessageFunc)(Message* messag
         continue;
       }
       Condition* condition = instruction->getCondition();
-      bool execute = m_addAll || condition == NULL;
+      bool execute = m_addAll || condition == nullptr;
       if (!execute) {
         string errorDescription;
-        result_t result = resolveCondition(instruction->isSingleton()?readMessageFunc:NULL, condition,
+        result_t result = resolveCondition(instruction->isSingleton()?readMessageFunc:nullptr, condition,
             &errorDescription);
         if (result != RESULT_OK) {
           overallResult = result;
@@ -2474,7 +2474,7 @@ const vector<Message*>* MessageMap::getByKey(uint64_t key) const {
   if (it != m_messagesByKey.end()) {
     return &it->second;
   }
-  return NULL;
+  return nullptr;
 }
 
 Message* MessageMap::find(const string& circuit, const string& name, const string& levels, bool isWrite,
@@ -2501,7 +2501,7 @@ Message* MessageMap::find(const string& circuit, const string& name, const strin
       }
     }
   }
-  return NULL;
+  return nullptr;
 }
 
 void MessageMap::findAll(const string& circuit, const string& name, const string& levels,
@@ -2574,7 +2574,7 @@ Message* MessageMap::find(const MasterSymbolString& master, bool anyDestination,
   uint64_t baseKey = Message::createKey(master,
       anyDestination || master[1] != BROADCAST ? m_maxIdLength : m_maxBroadcastIdLength, anyDestination);
   if (baseKey == INVALID_KEY) {
-    return NULL;
+    return nullptr;
   }
   size_t maxIdLength = Message::getKeyLength(baseKey);
   for (size_t idLength = maxIdLength; true; idLength--) {
@@ -2636,7 +2636,7 @@ Message* MessageMap::find(const MasterSymbolString& master, bool anyDestination,
     }
   }
 
-  return NULL;
+  return nullptr;
 }
 
 void MessageMap::invalidateCache(Message* message) {
@@ -2656,7 +2656,7 @@ void MessageMap::invalidateCache(Message* message) {
 }
 
 void MessageMap::addPollMessage(bool toFront, Message* message) {
-  if (message != NULL && message->getPollPriority() > 0) {
+  if (message != nullptr && message->getPollPriority() > 0) {
     lock();
     message->m_lastPollTime = toFront ? 0 : m_pollMessages.size();
     m_pollMessages.push(message);
@@ -2749,7 +2749,7 @@ void MessageMap::clear() {
 
 Message* MessageMap::getNextPoll() {
   if (m_pollMessages.empty()) {
-    return NULL;
+    return nullptr;
   }
   Message* ret = m_pollMessages.top();
   m_pollMessages.pop();
@@ -2761,7 +2761,7 @@ Message* MessageMap::getNextPoll() {
 
 void MessageMap::dump(bool withConditions, ostream* output) const {
   bool first = true;
-  Message::dumpHeader(NULL, output);
+  Message::dumpHeader(nullptr, output);
   *output << endl;
   for (const auto it : m_messagesByName) {
     if (it.first[0] == FIELD_SEPARATOR) {  // skip instances stored multiple times (key starting with "-")
@@ -2777,7 +2777,7 @@ void MessageMap::dump(bool withConditions, ostream* output) const {
         } else {
           *output << endl;
         }
-        message->dump(NULL, withConditions, output);
+        message->dump(nullptr, withConditions, output);
       }
     } else {
       Message* message = getFirstAvailable(it.second);
@@ -2789,7 +2789,7 @@ void MessageMap::dump(bool withConditions, ostream* output) const {
       } else {
         *output << endl;
       }
-      message->dump(NULL, withConditions, output);
+      message->dump(nullptr, withConditions, output);
     }
   }
   if (!first) {
diff --git a/src/lib/ebus/message.h b/src/lib/ebus/message.h
index b614970a..cd0a7a6c 100755
--- a/src/lib/ebus/message.h
+++ b/src/lib/ebus/message.h
@@ -90,7 +90,7 @@ class Message : public AttributedItem {
    * @param data the @a DataField for encoding/decoding the message.
    * @param deleteData whether to delete the @a DataField during destruction.
    * @param pollPriority the priority for polling, or 0 for no polling at all.
-   * @param condition the @a Condition for this message, or NULL.
+   * @param condition the @a Condition for this message, or nullptr.
    */
   Message(const string& circuit, const string& level, const string& name,
       bool isWrite, bool isPassive, const map<string, string>& attributes,
@@ -98,7 +98,7 @@ class Message : public AttributedItem {
       const vector<symbol_t>& id,
       const DataField* data, bool deleteData,
       size_t pollPriority = 0,
-      Condition* condition = NULL);
+      Condition* condition = nullptr);
 
 
  private:
@@ -173,11 +173,11 @@ class Message : public AttributedItem {
   /**
    * Factory method for creating new instances.
    * @param filename the name of the file being read.
-   * @param templates the @a DataFieldTemplates to be referenced by name, or NULL.
+   * @param templates the @a DataFieldTemplates to be referenced by name, or nullptr.
    * @param rowDefaults the mapped message definition defaults.
    * @param subRowDefaults the mapped field definition defaults.
    * @param typeStr the single type of message to create.
-   * @param condition the @a Condition instance for the message, or NULL.
+   * @param condition the @a Condition instance for the message, or nullptr.
    * @param row the mapped message definition row (may be modified).
    * @param subRows the mapped field definition rows (may be modified).
    * @param errorDescription a string in which to store the error description in case of error.
@@ -333,7 +333,7 @@ class Message : public AttributedItem {
   /**
    * Check the ID against the master @a SymbolString data.
    * @param master the @a MasterSymbolString to check against.
-   * @param index the variable in which to store the message part index, or NULL to ignore.
+   * @param index the variable in which to store the message part index, or nullptr to ignore.
    * @return true if the ID matches, false otherwise.
    */
   virtual bool checkId(const MasterSymbolString& master, size_t* index) const;
@@ -380,7 +380,7 @@ class Message : public AttributedItem {
    * Return whether this @a Message depends on a @a Condition.
    * @return true when this @a Message depends on a @a Condition.
    */
-  bool isConditional() const { return m_condition != NULL; }
+  bool isConditional() const { return m_condition != nullptr; }
 
   /**
    * Return whether this @a Message is available (optionally depending on a @a Condition evaluation).
@@ -390,7 +390,7 @@ class Message : public AttributedItem {
 
   /**
    * Return whether the field is available.
-   * @param fieldName the name of the field to find, or NULL for any.
+   * @param fieldName the name of the field to find, or nullptr for any.
    * @param numeric true for a numeric field, false for a string field.
    * @return true if the field is available.
    */
@@ -487,7 +487,7 @@ class Message : public AttributedItem {
 
   /**
    * Decode a particular numeric field value from the last stored data.
-   * @param fieldName the name of the field to decode, or NULL for the first field.
+   * @param fieldName the name of the field to decode, or nullptr for the first field.
    * @param fieldIndex the optional index of the field (either named or overall), or -1.
    * @param output the variable in which to store the value.
    * @return @a RESULT_OK on success, or an error code.
@@ -533,14 +533,14 @@ class Message : public AttributedItem {
 
   /**
    * Write the message definition header or parts of it to the @a ostream.
-   * @param fieldNames the list of field names to write, or NULL for all.
+   * @param fieldNames the list of field names to write, or nullptr for all.
    * @param output the @a ostream to append the formatted value to.
    */
   static void dumpHeader(const vector<string>* fieldNames, ostream* output);
 
   /**
    * Write the message definition or parts of it to the @a ostream.
-   * @param fieldNames the list of field names to write, or NULL for all.
+   * @param fieldNames the list of field names to write, or nullptr for all.
    * @param withConditions whether to include the optional conditions prefix.
    * @param output the @a ostream to append the formatted value to.
    */
@@ -626,7 +626,7 @@ class Message : public AttributedItem {
   /** whether this is a special scanning @a Message instance. */
   bool m_isScanMessage;
 
-  /** the @a Condition for this message, or NULL. */
+  /** the @a Condition for this message, or nullptr. */
   Condition* m_condition;
 
   /** the last seen @a MasterSymbolString. */
@@ -669,7 +669,7 @@ class ChainedMessage : public Message {
    * @param data the @a DataField for encoding/decoding the chained message.
    * @param deleteData whether to delete the @a DataField during destruction.
    * @param pollPriority the priority for polling, or 0 for no polling at all.
-   * @param condition the @a Condition for this message, or NULL.
+   * @param condition the @a Condition for this message, or nullptr.
    */
   ChainedMessage(const string& circuit, const string& level, const string& name,
       bool isWrite, const map<string, string>& attributes,
@@ -678,7 +678,7 @@ class ChainedMessage : public Message {
       const vector< vector<symbol_t> >& ids, const vector<size_t>& lengths,
       const DataField* data, bool deleteData,
       size_t pollPriority = 0,
-      Condition* condition = NULL);
+      Condition* condition = nullptr);
 
   virtual ~ChainedMessage();
 
@@ -827,9 +827,9 @@ class Condition {
   /**
    * Derive a new @a SimpleCondition from this condition.
    * @param valueList the @a string with the new list of values.
-   * @return the derived @a SimpleCondition instance, or NULL if the value list is invalid.
+   * @return the derived @a SimpleCondition instance, or nullptr if the value list is invalid.
    */
-  virtual SimpleCondition* derive(const string& valueList) const { return NULL; }
+  virtual SimpleCondition* derive(const string& valueList) const { return nullptr; }
 
   /**
    * Write the condition definition or resolved expression to the @a ostream.
@@ -848,7 +848,7 @@ class Condition {
   /**
    * Resolve the referred @a Message instance(s) and field index(es).
    * @param messages the @a MessageMap instance for resolving.
-   * @param readMessageFunc the function to call for immediate reading of a @a Message from the bus, or NULL.
+   * @param readMessageFunc the function to call for immediate reading of a @a Message from the bus, or nullptr.
    * @param errorMessage a @a ostringstream to which to add optional error messages.
    * @return @a RESULT_OK on success, or an error code.
    */
@@ -892,7 +892,7 @@ class SimpleCondition : public Condition {
       const string& name, symbol_t dstAddress, const string& field, bool hasValues = false)
     : Condition(),
       m_condName(condName), m_refName(refName), m_circuit(circuit), m_level(level), m_name(name),
-      m_dstAddress(dstAddress), m_field(field), m_hasValues(hasValues), m_message(NULL) { }
+      m_dstAddress(dstAddress), m_field(field), m_hasValues(hasValues), m_message(nullptr) { }
 
   /**
    * Destructor.
@@ -961,7 +961,7 @@ class SimpleCondition : public Condition {
   /** whether a value has to be checked against. */
   const bool m_hasValues;
 
-  /** the resolved @a Message instance, or NULL. */
+  /** the resolved @a Message instance, or nullptr. */
   Message* m_message;
 };
 
@@ -1105,7 +1105,7 @@ class Instruction {
    * Factory method for creating a new instance.
    * @param relPath the relative path and/or filename context being loaded.
    * @param type the type of the instruction.
-   * @param condition the @a Condition for the instruction, or NULL.
+   * @param condition the @a Condition for the instruction, or nullptr.
    * @param row the definition row by field name.
    * @param defaults the default values by name.
    * @param returnValue the variable in which to store the created instance.
@@ -1233,11 +1233,11 @@ class MessageMap : public MappedFileReader {
     clear();
     if (m_scanMessage) {
       delete m_scanMessage;
-      m_scanMessage = NULL;
+      m_scanMessage = nullptr;
     }
     if (m_broadcastScanMessage) {
       delete m_broadcastScanMessage;
-      m_broadcastScanMessage = NULL;
+      m_broadcastScanMessage = nullptr;
     }
   }
 
@@ -1276,12 +1276,12 @@ class MessageMap : public MappedFileReader {
 
   // @copydoc
   bool extractDefaultsFromFilename(const string& filename, map<string, string>* defaults,
-      symbol_t* destAddress = NULL, unsigned int* software = NULL, unsigned int* hardware = NULL) const override;
+      symbol_t* destAddress = nullptr, unsigned int* software = nullptr, unsigned int* hardware = nullptr) const override;
 
   // @copydoc
   result_t readFromStream(istream* stream, const string& filename, const time_t& mtime, bool verbose,
-      map<string, string>* defaults, string* errorDescription, bool replace = false, size_t* hash = NULL,
-      size_t* size = NULL) override;
+      map<string, string>* defaults, string* errorDescription, bool replace = false, size_t* hash = nullptr,
+      size_t* size = nullptr) override;
 
   // @copydoc
   result_t addFromFile(const string& filename, unsigned int lineNo, map<string, string>* row,
@@ -1290,7 +1290,7 @@ class MessageMap : public MappedFileReader {
   /**
    * Get the scan @a Message instance for the specified address.
    * @param dstAddress the destination address, or @a SYN for the base scan @a Message.
-   * @return the scan @a Message instance, or NULL if the dstAddress is no slave.
+   * @return the scan @a Message instance, or nullptr if the dstAddress is no slave.
    */
   Message* getScanMessage(const symbol_t dstAddress = SYN);
 
@@ -1310,7 +1310,7 @@ class MessageMap : public MappedFileReader {
 
   /**
    * Resolve a @a Condition.
-   * @param readMessageFunc the function to call for immediate reading of a @a Message from the bus, or NULL.
+   * @param readMessageFunc the function to call for immediate reading of a @a Message from the bus, or nullptr.
    * @param condition the @a Condition to resolve.
    * @param errorDescription a string in which to store the error description in case of error.
    * @return @a RESULT_OK on success, or an error code.
@@ -1321,7 +1321,7 @@ class MessageMap : public MappedFileReader {
   /**
    * Run all executable @a Instruction instances.
    * @param readMessageFunc the function to call for immediate reading of a
-   * @a Message values from the bus required for singleton instructions, or NULL.
+   * @a Message values from the bus required for singleton instructions, or nullptr.
    * @param log the @a ostringstream to log success messages to (if necessary).
    * @return @a RESULT_OK on success, or an error code.
    */
@@ -1352,18 +1352,18 @@ class MessageMap : public MappedFileReader {
    * Get the infos for a loaded file.
    * @param filename the name of the configuration file (including relative path).
    * @param comment a string in which the comment is stored.
-   * @param hash optional pointer to a @a size_t value for storing the hash of the file, or NULL.
-   * @param size optional pointer to a @a size_t value for storing the normalized size of the file, or NULL.
-   * @param time optional pointer to a @a time_t value for storing the modification time of the file, or NULL.
+   * @param hash optional pointer to a @a size_t value for storing the hash of the file, or nullptr.
+   * @param size optional pointer to a @a size_t value for storing the normalized size of the file, or nullptr.
+   * @param time optional pointer to a @a time_t value for storing the modification time of the file, or nullptr.
    * @return true if the file info was found, false otherwise.
    */
-  bool getLoadedFileInfo(const string& filename, string* comment, size_t* hash = NULL, size_t* size = NULL,
-      time_t* time = NULL) const;
+  bool getLoadedFileInfo(const string& filename, string* comment, size_t* hash = nullptr, size_t* size = nullptr,
+      time_t* time = nullptr) const;
 
   /**
    * Get the stored @a Message instances for the key.
    * @param key the key of the @a Message.
-   * @return the found @a Message instances, or NULL.
+   * @return the found @a Message instances, or nullptr.
    * Note: the caller may not free the returned instances.
    */
   const vector<Message*>* getByKey(uint64_t key) const;
@@ -1375,7 +1375,7 @@ class MessageMap : public MappedFileReader {
    * @param levels the access levels to match.
    * @param isWrite whether this is a write message.
    * @param isPassive whether this is a passive message.
-   * @return the @a Message instance, or NULL.
+   * @return the @a Message instance, or nullptr.
    * Note: the caller may not free the returned instance.
    */
   Message* find(const string& circuit, const string& name, const string& levels, bool isWrite,
@@ -1415,7 +1415,7 @@ class MessageMap : public MappedFileReader {
    * @param withPassive true to include passive messages (default true).
    * @param onlyAvailable true to include only available messages (default true), false to also include messages that
    * are currently not available (e.g. due to unresolved or false conditions).
-   * @return the @a Message instance, or NULL.
+   * @return the @a Message instance, or nullptr.
    * Note: the caller may not free the returned instance.
    */
   Message* find(const MasterSymbolString& master, bool anyDestination = false, bool withRead = true,
@@ -1484,7 +1484,7 @@ class MessageMap : public MappedFileReader {
 
   /**
    * Get the next @a Message to poll.
-   * @return the next @a Message to poll, or NULL.
+   * @return the next @a Message to poll, or nullptr.
    * Note: the caller may not free the returned instance.
    */
   Message* getNextPoll();
diff --git a/src/lib/ebus/symbol.cpp b/src/lib/ebus/symbol.cpp
index 74ff12cb..0d410fac 100755
--- a/src/lib/ebus/symbol.cpp
+++ b/src/lib/ebus/symbol.cpp
@@ -56,11 +56,11 @@ static const symbol_t CRC_LOOKUP_TABLE[] = {
 
 unsigned int parseInt(const char* str, int base, unsigned int minValue, unsigned int maxValue,
     result_t* result, size_t* length) {
-  char* strEnd = NULL;
+  char* strEnd = nullptr;
 
   unsigned long ret = strtoul(str, &strEnd, base);
 
-  if (strEnd == NULL || strEnd == str || *strEnd != 0) {
+  if (strEnd == nullptr || strEnd == str || *strEnd != 0) {
     *result = RESULT_ERR_INVALID_NUM;  // invalid value
     return 0;
   }
@@ -69,7 +69,7 @@ unsigned int parseInt(const char* str, int base, unsigned int minValue, unsigned
     *result = RESULT_ERR_OUT_OF_RANGE;  // invalid value
     return 0;
   }
-  if (length != NULL) {
+  if (length != nullptr) {
     *length = (unsigned int)(strEnd - str);
   }
   *result = RESULT_OK;
@@ -78,11 +78,11 @@ unsigned int parseInt(const char* str, int base, unsigned int minValue, unsigned
 
 int parseSignedInt(const char* str, int base, int minValue, int maxValue,
     result_t* result, size_t* length) {
-  char* strEnd = NULL;
+  char* strEnd = nullptr;
 
   long ret = strtol(str, &strEnd, base);
 
-  if (strEnd == NULL || *strEnd != 0) {
+  if (strEnd == nullptr || *strEnd != 0) {
     *result = RESULT_ERR_INVALID_NUM;  // invalid value
     return 0;
   }
@@ -91,7 +91,7 @@ int parseSignedInt(const char* str, int base, int minValue, int maxValue,
     *result = RESULT_ERR_OUT_OF_RANGE;  // invalid value
     return 0;
   }
-  if (length != NULL) {
+  if (length != nullptr) {
     *length = (unsigned int)(strEnd - str);
   }
   *result = RESULT_OK;
diff --git a/src/lib/ebus/symbol.h b/src/lib/ebus/symbol.h
index 7893b5a5..e128e0f5 100755
--- a/src/lib/ebus/symbol.h
+++ b/src/lib/ebus/symbol.h
@@ -97,7 +97,7 @@ typedef unsigned char symbol_t;
  * @return the parsed value.
  */
 unsigned int parseInt(const char* str, int base, unsigned int minValue, unsigned int maxValue,
-    result_t* result, size_t* length = NULL);
+    result_t* result, size_t* length = nullptr);
 
 /**
  * Parse a signed int value.
@@ -110,7 +110,7 @@ unsigned int parseInt(const char* str, int base, unsigned int minValue, unsigned
  * @return the parsed value.
  */
 int parseSignedInt(const char* str, int base, int minValue, int maxValue,
-    result_t* result, size_t* length = NULL);
+    result_t* result, size_t* length = nullptr);
 
 /**
  * A string of unescaped bus symbols.
diff --git a/src/lib/ebus/test/test_data.cpp b/src/lib/ebus/test/test_data.cpp
index 3d93cf2a..00298ca0 100755
--- a/src/lib/ebus/test/test_data.cpp
+++ b/src/lib/ebus/test/test_data.cpp
@@ -52,7 +52,7 @@ class TestReader : public MappedFileReader {
  public:
   TestReader(DataFieldTemplates* templates, bool isSet, bool isMasterDest)
   : MappedFileReader::MappedFileReader(true), m_templates(templates), m_isSet(isSet), m_isMasterDest(isMasterDest),
-    m_fields(NULL) {}
+    m_fields(nullptr) {}
   result_t getFieldMap(const string& preferLanguage, vector<string>* row, string* errorDescription) const override {
     if (row->empty()) {
       row->push_back("*name");
@@ -512,8 +512,8 @@ int main() {
   istringstream dummystr("#");
   string errorDescription;
   vector<string> row;
-  templates->readLineFromStream(&dummystr, __FILE__, false, &lineNo, &row, &errorDescription, false, NULL, NULL);
-  const DataField* fields = NULL;
+  templates->readLineFromStream(&dummystr, __FILE__, false, &lineNo, &row, &errorDescription, false, nullptr, nullptr);
+  const DataField* fields = nullptr;
   for (unsigned int i = 0; i < sizeof(checks) / sizeof(checks[0]); i++) {
     string check[5] = checks[i];
     istringstream isstr(check[0]);
@@ -539,7 +539,7 @@ int main() {
     bool failedReadMatch = flags.find('R') != string::npos;
     bool failedWrite = flags.find('w') != string::npos;
     bool failedWriteMatch = flags.find('W') != string::npos;
-    const char* findName = flags.find('I') == string::npos ? NULL : "x";
+    const char* findName = flags.find('I') == string::npos ? nullptr : "x";
     ssize_t findIndex = -1;
     if (flags.find('i') != string::npos) {
       findIndex = parseSignedInt(flags.substr(flags.find('i')+1).c_str(), 10, 0, 9, &result);
@@ -561,13 +561,13 @@ int main() {
     bool isTemplate = flags.find('t') != string::npos;
     string item;
 
-    if (fields != NULL) {
+    if (fields != nullptr) {
       delete fields;
-      fields = NULL;
+      fields = nullptr;
     }
     if (isTemplate) {
       lineNo = baseLine + i;
-      result = templates->readLineFromStream(&isstr, __FILE__, false, &lineNo, &row, &errorDescription, false, NULL, NULL);
+      result = templates->readLineFromStream(&isstr, __FILE__, false, &lineNo, &row, &errorDescription, false, nullptr, nullptr);
       if (result != RESULT_OK) {
         cout << "\"" << check[0] << "\": template read error: " << getResultCode(result) << ", "
             << errorDescription << endl;
@@ -579,7 +579,7 @@ int main() {
     lineNo = 0;
     dummystr.clear();
     dummystr.str("#");
-    result = reader.readLineFromStream(&dummystr, __FILE__, false, &lineNo, &row, &errorDescription, false, NULL, NULL);
+    result = reader.readLineFromStream(&dummystr, __FILE__, false, &lineNo, &row, &errorDescription, false, nullptr, nullptr);
     if (result != RESULT_OK) {
       cout << "\"" << check[0] << "\": read header error: " << getResultCode(result) << ", " << errorDescription
           << endl;
@@ -587,7 +587,7 @@ int main() {
       continue;
     }
     lineNo = baseLine + i;
-    result = reader.readLineFromStream(&isstr, "", false, &lineNo, &row, &errorDescription, false, NULL, NULL);
+    result = reader.readLineFromStream(&isstr, "", false, &lineNo, &row, &errorDescription, false, nullptr, nullptr);
     fields = reader.m_fields;
     if (failedCreate) {
       if (result == RESULT_OK) {
@@ -603,8 +603,8 @@ int main() {
       error = true;
       continue;
     }
-    if (fields == NULL) {
-      cout << "\"" << check[0] << "\": create error: NULL" << endl;
+    if (fields == nullptr) {
+      cout << "\"" << check[0] << "\": create error: nullptr" << endl;
       error = true;
       continue;
     }
@@ -649,9 +649,9 @@ int main() {
 
     if (verbosity == 0) {
       istringstream input(expectStr);
-      result = fields->write(UI_FIELD_SEPARATOR, 0, &input, &writeMstr, NULL);
+      result = fields->write(UI_FIELD_SEPARATOR, 0, &input, &writeMstr, nullptr);
       if (result >= RESULT_OK) {
-        result = fields->write(UI_FIELD_SEPARATOR, 0, &input, &writeSstr, NULL);
+        result = fields->write(UI_FIELD_SEPARATOR, 0, &input, &writeSstr, nullptr);
       }
       if (failedWrite) {
         if (result >= RESULT_OK) {
@@ -673,7 +673,7 @@ int main() {
       }
     }
     delete fields;
-    fields = NULL;
+    fields = nullptr;
   }
 
   delete templates;
diff --git a/src/lib/ebus/test/test_device.cpp b/src/lib/ebus/test/test_device.cpp
index bc443b2d..7ae74607 100755
--- a/src/lib/ebus/test/test_device.cpp
+++ b/src/lib/ebus/test/test_device.cpp
@@ -25,7 +25,7 @@ using namespace ebusd;
 
 int main() {
   Device* device = Device::create("/dev/ttyUSB20", true, false, false);
-  if (device == NULL) {
+  if (device == nullptr) {
     cout << "unable to create device" << endl;
     return -1;
   }
diff --git a/src/lib/ebus/test/test_filereader.cpp b/src/lib/ebus/test/test_filereader.cpp
index 9889b777..95c53d21 100755
--- a/src/lib/ebus/test/test_filereader.cpp
+++ b/src/lib/ebus/test/test_filereader.cpp
@@ -201,7 +201,7 @@ int main(int argc, char** argv) {
       if (!stream) {
         result = RESULT_ERR_NOTFOUND;
       } else {
-        result = reader.readFromStream(stream, argv[argpos], time, false, NULL, &errorDescription, false, &hash, &size);
+        result = reader.readFromStream(stream, argv[argpos], time, false, nullptr, &errorDescription, false, &hash, &size);
       }
       cout << argv[argpos] << " ";
       if (result != RESULT_OK) {
diff --git a/src/lib/ebus/test/test_message.cpp b/src/lib/ebus/test/test_message.cpp
index 4686bb10..fab58926 100755
--- a/src/lib/ebus/test/test_message.cpp
+++ b/src/lib/ebus/test/test_message.cpp
@@ -50,7 +50,7 @@ void verify(bool expectFailMatch, string type, string input,
   }
 }
 
-DataFieldTemplates* templates = NULL;
+DataFieldTemplates* templates = nullptr;
 
 namespace ebusd {
 
@@ -186,14 +186,14 @@ int main() {
   istringstream dummystr("#");
   string errorDescription;
   vector<string> row;
-  templates->readLineFromStream(&dummystr, __FILE__, false, &lineNo, &row, &errorDescription, false, NULL, NULL);
+  templates->readLineFromStream(&dummystr, __FILE__, false, &lineNo, &row, &errorDescription, false, nullptr, nullptr);
   lineNo = 0;
   MessageMap* messages = new MessageMap("");
   dummystr.clear();
   dummystr.str("#");
-  messages->readLineFromStream(&dummystr, __FILE__, false, &lineNo, &row, &errorDescription, false, NULL, NULL);
+  messages->readLineFromStream(&dummystr, __FILE__, false, &lineNo, &row, &errorDescription, false, nullptr, nullptr);
   vector< vector<string> > defaultsRows;
-  Message* message = NULL;
+  Message* message = nullptr;
   vector<MasterSymbolString*> mstrs;
   vector<SlaveSymbolString*> sstrs;
   mstrs.resize(1);
@@ -222,7 +222,7 @@ int main() {
     lineNo = baseLine + i;
     cout << "line " << (lineNo+1) << " ";
     if (isTemplate) {
-      result = templates->readLineFromStream(&isstr, __FILE__, false, &lineNo, &row, &errorDescription, false, NULL, NULL);
+      result = templates->readLineFromStream(&isstr, __FILE__, false, &lineNo, &row, &errorDescription, false, nullptr, nullptr);
       if (result != RESULT_OK) {
         cout << "\"" << check[0] << "\": template read error: " << getResultCode(result) << ", " << errorDescription
             << endl;
@@ -236,7 +236,7 @@ int main() {
     }
     if (isstr.peek() == '*') {
       // store defaults or condition
-      result = messages->readLineFromStream(&isstr, __FILE__, false, &lineNo, &row, &errorDescription, false, NULL, NULL);
+      result = messages->readLineFromStream(&isstr, __FILE__, false, &lineNo, &row, &errorDescription, false, nullptr, nullptr);
       if (result != RESULT_OK) {
         cout << "\"" << check[0] << "\": default read error: " << getResultCode(result) << ", " << errorDescription << endl;
         error = true;
@@ -252,7 +252,7 @@ int main() {
       while (getline(stream, token, VALUE_SEPARATOR)) {
         if (pos >= mstrs.size()) {
           mstrs.resize(pos+1);
-        } else if (mstrs[pos] != NULL) {
+        } else if (mstrs[pos] != nullptr) {
           delete mstrs[pos];
         }
         mstrs[pos] = new MasterSymbolString();
@@ -270,7 +270,7 @@ int main() {
       while (getline(stream, token, VALUE_SEPARATOR)) {
         if (pos >= sstrs.size()) {
           sstrs.resize(pos+1);
-        } else if (sstrs[pos] != NULL) {
+        } else if (sstrs[pos] != nullptr) {
           delete sstrs[pos];
         }
         sstrs[pos] = new SlaveSymbolString();
@@ -287,7 +287,7 @@ int main() {
         continue;
       }
     } else {
-      if (mstrs[0] != NULL) {
+      if (mstrs[0] != nullptr) {
         delete mstrs[0];
       }
       mstrs[0] = new MasterSymbolString();
@@ -297,7 +297,7 @@ int main() {
         error = true;
         continue;
       }
-      if (sstrs[0] != NULL) {
+      if (sstrs[0] != nullptr) {
         delete sstrs[0];
       }
       sstrs[0] = new SlaveSymbolString();
@@ -311,14 +311,14 @@ int main() {
 
     if (isstr.peek() == EOF) {
       message = messages->find(*mstrs[0]);
-      if (message == NULL) {
-        cout << "\"" << check[2] << "\": find error: NULL" << endl;
+      if (message == nullptr) {
+        cout << "\"" << check[2] << "\": find error: nullptr" << endl;
         error = true;
         continue;
       }
       cout << "\"" << check[2] << "\": find OK" << endl;
     } else {
-      result = messages->readLineFromStream(&isstr, __FILE__, false, &lineNo, &row, &errorDescription, false, NULL, NULL);
+      result = messages->readLineFromStream(&isstr, __FILE__, false, &lineNo, &row, &errorDescription, false, nullptr, nullptr);
       if (failedCreate) {
         if (result == RESULT_OK) {
           cout << "\"" << check[0] << "\": failed create error: unexpectedly succeeded" << endl;
@@ -334,7 +334,7 @@ int main() {
         continue;
       }
       if (messages->size() == 0) {
-        cout << "\"" << check[0] << "\": create error: NULL" << endl;
+        cout << "\"" << check[0] << "\": create error: nullptr" << endl;
         error = true;
         continue;
       }
@@ -355,7 +355,7 @@ int main() {
       deque<Message*> msgs;
       messages->findAll("", "", "*", false, true, true, true, true, false, 0, 0, &msgs);
       if (msgs.empty()) {
-        message = NULL;
+        message = nullptr;
         cout << "\"" << check[0] << "\": create error: message not found" << endl;
         error = true;
         continue;
@@ -364,7 +364,7 @@ int main() {
       Message* foundMessage = messages->find(*mstrs[0], false, true, true, true, false);
       if (foundMessage == message) {
         cout << "  find OK" << endl;
-      } else if (foundMessage == NULL) {
+      } else if (foundMessage == nullptr) {
         cout << "  find error: message not found by master " << mstrs[0]->getStr() << endl;
         error = true;
         continue;
@@ -399,11 +399,11 @@ int main() {
           output.str("");
           output << str;
         } else {
-          message->dump(NULL, true, &output);
+          message->dump(nullptr, true, &output);
         }
         output << ": ";
       }
-      result = message->decodeLastData(false, NULL, -1,
+      result = message->decodeLastData(false, nullptr, -1,
           (decodeVerbose?OF_NAMES|OF_UNITS|OF_COMMENTS:0)|(decodeJson?OF_NAMES|OF_JSON:0), &output);
       if (result != RESULT_OK) {
         cout << "  \"" << check[2] << "\" / \"" << check[3] << "\": decode error: "
diff --git a/src/lib/utils/httpclient.cpp b/src/lib/utils/httpclient.cpp
index 72284254..6a75285f 100755
--- a/src/lib/utils/httpclient.cpp
+++ b/src/lib/utils/httpclient.cpp
@@ -58,9 +58,9 @@ bool HttpClient::parseUrl(const string& url, string& proto, string& host, uint16
   }
   port = 80;
   if (pos != string::npos) {
-    char* strEnd = NULL;
+    char* strEnd = nullptr;
     unsigned long value = strtoul(host.c_str()+pos+1, &strEnd, 10);
-    if (strEnd == NULL || *strEnd != '\0' || value < 1 || value > 65535) {
+    if (strEnd == nullptr || *strEnd != '\0' || value < 1 || value > 65535) {
       return false;
     }
     port = static_cast<uint16_t>(value);
@@ -182,30 +182,30 @@ bool HttpClient::request(const string& method, const string& uri, const string&
       // Last-Modified: Wed, 21 Oct 2015 07:28:00 GMT
       struct tm t;
       pos += strlen("\r\nLast-Modified: ") + 5;
-      char* strEnd = NULL;
+      char* strEnd = nullptr;
       t.tm_mday = (int)strtol(hdrs + pos, &strEnd, 10);
       if (strEnd != hdrs + pos + 2 || t.tm_mday < 1 || t.tm_mday > 31) {
         t.tm_mday = -1;
       }
       t.tm_mon = indexToMonth[((hdrs[pos+4]&0x10)>>1) | (hdrs[pos+5]&0x17)] - 1;
-      strEnd = NULL;
+      strEnd = nullptr;
       t.tm_year = (int)strtol(hdrs + pos + 7, &strEnd, 10);
       if (strEnd != hdrs + pos + 11 || t.tm_year < 1970 || t.tm_year >= 3000) {
         t.tm_year = -1;
       } else {
         t.tm_year -= 1900;
       }
-      strEnd = NULL;
+      strEnd = nullptr;
       t.tm_hour = (int)strtol(hdrs + pos + 12, &strEnd, 10);
       if (strEnd != hdrs + pos + 14 || t.tm_hour > 23) {
         t.tm_hour = -1;
       }
-      strEnd = NULL;
+      strEnd = nullptr;
       t.tm_min = (int)strtol(hdrs + pos + 15, &strEnd, 10);
       if (strEnd != hdrs + pos + 17 || t.tm_min > 59) {
         t.tm_min = -1;
       }
-      strEnd = NULL;
+      strEnd = nullptr;
       t.tm_sec = (int)strtol(hdrs + pos + 18, &strEnd, 10);
       if (strEnd != hdrs + pos + 20 || t.tm_sec > 59) {
         t.tm_sec = -1;
@@ -220,9 +220,9 @@ bool HttpClient::request(const string& method, const string& uri, const string&
     disconnect();
     return true;
   }
-  char* strEnd = NULL;
+  char* strEnd = nullptr;
   unsigned long length = strtoul(hdrs + pos + strlen("\r\nContent-Length: "), &strEnd, 10);
-  if (strEnd == NULL || *strEnd != '\r') {
+  if (strEnd == nullptr || *strEnd != '\r') {
     disconnect();
     response = "invalid content length ";
     return false;
diff --git a/src/lib/utils/httpclient.h b/src/lib/utils/httpclient.h
index 48c8b0c9..826841ef 100755
--- a/src/lib/utils/httpclient.h
+++ b/src/lib/utils/httpclient.h
@@ -100,10 +100,10 @@ class HttpClient {
    * @param uri the URI string.
    * @param body the optional body to send.
    * @param response the response body from the server (or the HTTP header on error).
-   * @param time optional pointer to a @a time_t value for storing the modification time of the file, or NULL.
+   * @param time optional pointer to a @a time_t value for storing the modification time of the file, or nullptr.
    * @return true on success, false on error.
    */
-  bool get(const string& uri, const string& body, string& response, time_t* time = NULL);
+  bool get(const string& uri, const string& body, string& response, time_t* time = nullptr);
 
   /**
    * Execute a POST request.
@@ -119,10 +119,10 @@ class HttpClient {
    * @param uri the URI string.
    * @param body the optional body to send.
    * @param response the response body from the server (or the HTTP header on error).
-   * @param time optional pointer to a @a time_t value for storing the modification time of the file, or NULL.
+   * @param time optional pointer to a @a time_t value for storing the modification time of the file, or nullptr.
    * @return true on success, false on error.
    */
-  bool request(const string& method, const string& uri, const string& body, string& response, time_t* time = NULL);
+  bool request(const string& method, const string& uri, const string& body, string& response, time_t* time = nullptr);
 
 private:
   /**
diff --git a/src/lib/utils/log.cpp b/src/lib/utils/log.cpp
index c2c55afb..ecf26021 100755
--- a/src/lib/utils/log.cpp
+++ b/src/lib/utils/log.cpp
@@ -39,7 +39,7 @@ static const char *facilityNames[] = {
   "update",
   "other",
   "all",
-  NULL
+  nullptr
 };
 
 /** the name of each @a LogLevel. */
@@ -49,7 +49,7 @@ static const char* levelNames[] = {
   "notice",
   "info",
   "debug",
-  NULL
+  nullptr
 };
 
 /** the current log level by log facility. */
@@ -63,7 +63,7 @@ LogFacility parseLogFacility(const char* facility) {
     return lf_COUNT;
   }
   char *input = strdup(facility);
-  char *opt = reinterpret_cast<char*>(input), *value = NULL;
+  char *opt = reinterpret_cast<char*>(input), *value = nullptr;
   int val = getsubopt(&opt, (char *const *)facilityNames, &value);
   if (val < 0 || val >= lf_COUNT || value || *opt) {
     free(input);
@@ -75,7 +75,7 @@ LogFacility parseLogFacility(const char* facility) {
 
 int parseLogFacilities(const char* facilities) {
   char *input = strdup(facilities);
-  char *opt = reinterpret_cast<char*>(input), *value = NULL;
+  char *opt = reinterpret_cast<char*>(input), *value = nullptr;
   int newFacilites = 0;
   while (*opt) {
     int val = getsubopt(&opt, (char *const *)facilityNames, &value);
@@ -98,7 +98,7 @@ LogLevel parseLogLevel(const char* level) {
     return ll_COUNT;
   }
   char *input = strdup(level);
-  char *opt = reinterpret_cast<char*>(input), *value = NULL;
+  char *opt = reinterpret_cast<char*>(input), *value = nullptr;
   int val = getsubopt(&opt, (char *const *)levelNames, &value);
   if (val < 0 || val >= ll_COUNT || value || *opt) {
     free(input);
@@ -133,7 +133,7 @@ LogLevel getFacilityLogLevel(LogFacility facility) {
 
 bool setLogFile(const char* filename) {
   FILE* newFile = fopen(filename, "a");
-  if (newFile == NULL) {
+  if (newFile == nullptr) {
     return false;
   }
   closeLogFile();
@@ -142,11 +142,11 @@ bool setLogFile(const char* filename) {
 }
 
 void closeLogFile() {
-  if (s_logFile != NULL) {
+  if (s_logFile != nullptr) {
     if (s_logFile != stdout) {
       fclose(s_logFile);
     }
-    s_logFile = NULL;
+    s_logFile = nullptr;
   }
 }
 
@@ -155,7 +155,7 @@ bool needsLog(const LogFacility facility, const LogLevel level) {
 }
 
 void logWrite(const char* facility, const char* level, const char* message, va_list ap) {
-  if (s_logFile == NULL) {
+  if (s_logFile == nullptr) {
     return;
   }
   struct timespec ts;
diff --git a/src/lib/utils/queue.h b/src/lib/utils/queue.h
index d471cf07..8c3c1f9a 100755
--- a/src/lib/utils/queue.h
+++ b/src/lib/utils/queue.h
@@ -41,8 +41,8 @@ class Queue {
    * Constructor.
    */
   Queue() {
-    pthread_mutex_init(&m_mutex, NULL);
-    pthread_cond_init(&m_cond, NULL);
+    pthread_mutex_init(&m_mutex, nullptr);
+    pthread_cond_init(&m_cond, nullptr);
   }
 
   /**
@@ -77,7 +77,7 @@ class Queue {
   /**
    * Remove the first item from the queue optionally waiting for the queue being non-empty.
    * @param timeout the maximum time in seconds to wait for the queue being filled, or 0 for no wait.
-   * @return the item, or NULL if no item is available within the specified time.
+   * @return the item, or nullptr if no item is available within the specified time.
    */
   T pop(int timeout = 0) {
     T item;
@@ -93,7 +93,7 @@ class Queue {
       }
     }
     if (m_queue.empty()) {
-      item = NULL;
+      item = nullptr;
     } else {
       item = m_queue.front();
       m_queue.pop_front();
@@ -137,13 +137,13 @@ class Queue {
 
   /**
    * Return the first item in the queue without removing it.
-   * @return the item, or NULL if no item is available.
+   * @return the item, or nullptr if no item is available.
    */
   T peek() {
     T item;
     pthread_mutex_lock(&m_mutex);
     if (m_queue.empty()) {
-      item = NULL;
+      item = nullptr;
     } else {
       item = m_queue.front();
     }
diff --git a/src/lib/utils/rotatefile.cpp b/src/lib/utils/rotatefile.cpp
index 5df2e741..062c9953 100755
--- a/src/lib/utils/rotatefile.cpp
+++ b/src/lib/utils/rotatefile.cpp
@@ -34,7 +34,7 @@ using std::streamsize;
 RotateFile::~RotateFile() {
   if (m_stream) {
     fclose(m_stream);
-    m_stream = NULL;
+    m_stream = nullptr;
   }
 }
 
@@ -45,7 +45,7 @@ bool RotateFile::setEnabled(bool enabled) {
   m_enabled = enabled;
   if (m_stream) {
     fclose(m_stream);
-    m_stream = NULL;
+    m_stream = nullptr;
   }
   if (enabled) {
     m_stream = fopen(m_fileName.c_str(), m_textMode ? "w" : "wb");
diff --git a/src/lib/utils/tcpsocket.cpp b/src/lib/utils/tcpsocket.cpp
index 354e8b73..f6a752d7 100755
--- a/src/lib/utils/tcpsocket.cpp
+++ b/src/lib/utils/tcpsocket.cpp
@@ -54,14 +54,14 @@ TCPSocket* TCPClient::connect(const string& server, const uint16_t& port, int ti
     struct hostent* he;
 
     he = gethostbyname(server.c_str());
-    if (he == NULL) {
-      return NULL;
+    if (he == nullptr) {
+      return nullptr;
     }
     memcpy(&address.sin_addr, he->h_addr_list[0], he->h_length);
   } else {
     ret = inet_aton(server.c_str(), &address.sin_addr);
     if (ret == 0) {
-      return NULL;
+      return nullptr;
     }
   }
 
@@ -70,7 +70,7 @@ TCPSocket* TCPClient::connect(const string& server, const uint16_t& port, int ti
 
   int sfd = socket(AF_INET, SOCK_STREAM, 0);
   if (sfd < 0) {
-    return NULL;
+    return nullptr;
   }
 #ifndef HAVE_PPOLL
 #ifndef HAVE_PSELECT
@@ -79,13 +79,13 @@ TCPSocket* TCPClient::connect(const string& server, const uint16_t& port, int ti
 #endif
   if (timeout > 0 && fcntl(sfd, F_SETFL, O_NONBLOCK) < 0) {  // set non-blocking
     close(sfd);
-    return NULL;
+    return nullptr;
   }
   ret = ::connect(sfd, (struct sockaddr *) &address, sizeof(address));
   if (ret != 0) {
     if (ret < 0 && (timeout <= 0 || errno != EINPROGRESS)) {
       close(sfd);
-      return NULL;
+      return nullptr;
     }
     if (timeout > 0) {
       struct timespec tdiff;
@@ -97,7 +97,7 @@ TCPSocket* TCPClient::connect(const string& server, const uint16_t& port, int ti
       memset(fds, 0, sizeof(fds));
       fds[0].fd = sfd;
       fds[0].events = POLLIN|POLLOUT;
-      ret = ppoll(fds, nfds, &tdiff, NULL);
+      ret = ppoll(fds, nfds, &tdiff, nullptr);
       if (ret == 1 && fds[0].revents & POLLERR) {
         ret = -1;
       }
@@ -107,20 +107,20 @@ TCPSocket* TCPClient::connect(const string& server, const uint16_t& port, int ti
       FD_ZERO(&writefds);
       FD_ZERO(&exceptfds);
       FD_SET(sfd, &readfds);
-      ret = pselect(sfd + 1, &readfds, &writefds, &exceptfds, &tdiff, NULL);
+      ret = pselect(sfd + 1, &readfds, &writefds, &exceptfds, &tdiff, nullptr);
       if (ret >= 1 && FD_ISSET(sfd, &exceptfds)) {
         ret = -1;
       }
 #endif
       if (ret == -1 || ret == 0) {
         close(sfd);
-        return NULL;
+        return nullptr;
       }
     }
   }
   if (timeout > 0 && fcntl(sfd, F_SETFL, 0) < 0) {  // set blocking again
     close(sfd);
-    return NULL;
+    return nullptr;
   }
   TCPSocket* s = new TCPSocket(sfd, &address);
   if (timeout > 0) {
@@ -164,7 +164,7 @@ int TCPServer::start() {
 
 TCPSocket* TCPServer::newSocket() {
   if (!m_listening) {
-    return NULL;
+    return nullptr;
   }
   socketaddress address;
   socklen_t len = sizeof(address);
@@ -173,7 +173,7 @@ TCPSocket* TCPServer::newSocket() {
 
   int sfd = accept(m_lfd, (struct sockaddr*) &address, &len);
   if (sfd < 0) {
-    return NULL;
+    return nullptr;
   }
   return new TCPSocket(sfd, &address);
 }
diff --git a/src/lib/utils/thread.cpp b/src/lib/utils/thread.cpp
index 260b2884..205a7d69 100755
--- a/src/lib/utils/thread.cpp
+++ b/src/lib/utils/thread.cpp
@@ -27,7 +27,7 @@ namespace ebusd {
 
 void* Thread::runThread(void* arg) {
   reinterpret_cast<Thread*>(arg)->enter();
-  return NULL;
+  return nullptr;
 }
 
 Thread::~Thread() {
@@ -38,7 +38,7 @@ Thread::~Thread() {
 }
 
 bool Thread::start(const char* name) {
-  int result = pthread_create(&m_threadid, NULL, runThread, this);
+  int result = pthread_create(&m_threadid, nullptr, runThread, this);
   if (result == 0) {
 #ifdef HAVE_PTHREAD_SETNAME_NP
 #ifndef __MACH__
@@ -55,7 +55,7 @@ bool Thread::join() {
   int result = -1;
   if (m_started) {
     m_stopped = true;
-    result = pthread_join(m_threadid, NULL);
+    result = pthread_join(m_threadid, nullptr);
     if (result == 0) {
       m_started = false;
     }
@@ -72,8 +72,8 @@ void Thread::enter() {
 
 WaitThread::WaitThread()
   : Thread() {
-  pthread_mutex_init(&m_mutex, NULL);
-  pthread_cond_init(&m_cond, NULL);
+  pthread_mutex_init(&m_mutex, nullptr);
+  pthread_cond_init(&m_cond, nullptr);
 }
 
 WaitThread::~WaitThread() {
diff --git a/src/lib/utils/thread.h b/src/lib/utils/thread.h
index b17ff6e7..de2e5e0b 100755
--- a/src/lib/utils/thread.h
+++ b/src/lib/utils/thread.h
@@ -43,7 +43,7 @@ class Thread {
   /**
    * Thread entry helper for pthread_create.
    * @param arg pointer to the @a Thread.
-   * @return NULL.
+   * @return nullptr.
    */
   static void* runThread(void* arg);
 
diff --git a/src/tools/ebusctl.cpp b/src/tools/ebusctl.cpp
index 56b6fd75..518a52d3 100755
--- a/src/tools/ebusctl.cpp
+++ b/src/tools/ebusctl.cpp
@@ -56,7 +56,7 @@ static struct options opt = {
   8888,         // port
   0,            // timeout
 
-  NULL,         // args
+  nullptr,         // args
   0             // argCount
 };
 
@@ -78,28 +78,28 @@ static char argpargsdoc[] = "\nCOMMAND [CMDOPT...]";
 
 /** the definition of the known program arguments. */
 static const struct argp_option argpoptions[] = {
-  {NULL,        0,   NULL, 0, "Options:", 1 },
-  {"server",  's', "HOST", 0, "Connect to " PACKAGE " on HOST (name or IP) [localhost]", 0 },
-  {"port",    'p', "PORT", 0, "Connect to " PACKAGE " on PORT [8888]", 0 },
-  {"timeout", 't', "SECS", 0, "Timeout for connection to " PACKAGE ", 0 for none [0]", 0 },
+  {nullptr,     0, nullptr, 0, "Options:", 1 },
+  {"server",  's', "HOST",  0, "Connect to " PACKAGE " on HOST (name or IP) [localhost]", 0 },
+  {"port",    'p', "PORT",  0, "Connect to " PACKAGE " on PORT [8888]", 0 },
+  {"timeout", 't', "SECS",  0, "Timeout for connection to " PACKAGE ", 0 for none [0]", 0 },
 
-  {NULL,        0,   NULL, 0, NULL, 0 },
+  {nullptr,     0, nullptr, 0, nullptr, 0 },
 };
 
 /**
  * The program argument parsing function.
  * @param key the key from @a argpoptions.
- * @param arg the option argument, or NULL.
+ * @param arg the option argument, or nullptr.
  * @param state the parsing state.
  */
 error_t parse_opt(int key, char *arg, struct argp_state *state) {
   struct options *opt = (struct options*)state->input;
-  char* strEnd = NULL;
+  char* strEnd = nullptr;
   unsigned int value;
   switch (key) {
   // Device settings:
   case 's':  // --server=localhost
-    if (arg == NULL || arg[0] == 0) {
+    if (arg == nullptr || arg[0] == 0) {
       argp_error(state, "invalid server");
       return EINVAL;
     }
@@ -107,7 +107,7 @@ error_t parse_opt(int key, char *arg, struct argp_state *state) {
     break;
   case 'p':  // --port=8888
     value = strtoul(arg, &strEnd, 10);
-    if (strEnd == NULL || strEnd == arg || *strEnd != 0 || value < 1 || value > 65535) {
+    if (strEnd == nullptr || strEnd == arg || *strEnd != 0 || value < 1 || value > 65535) {
       argp_error(state, "invalid port");
       return EINVAL;
     }
@@ -115,7 +115,7 @@ error_t parse_opt(int key, char *arg, struct argp_state *state) {
     break;
   case 't':  // --timeout=10
     value = strtoul(arg, &strEnd, 10);
-    if (strEnd == NULL || strEnd == arg || *strEnd != 0 || value < 1 || value > 3600) {
+    if (strEnd == nullptr || strEnd == arg || *strEnd != 0 || value < 1 || value > 3600) {
       argp_error(state, "invalid timeout");
       return EINVAL;
     }
@@ -173,13 +173,13 @@ string fetchData(ebusd::TCPSocket* socket, bool listening) {
   while (true) {
 #ifdef HAVE_PPOLL
     // wait for new fd event
-    ret = ppoll(fds, nfds, &tdiff, NULL);
+    ret = ppoll(fds, nfds, &tdiff, nullptr);
 #else
 #ifdef HAVE_PSELECT
     // set readfds to inital checkfds
     fd_set readfds = checkfds;
     // wait for new fd event
-    ret = pselect(maxfd + 1, &readfds, NULL, NULL, &tdiff, NULL);
+    ret = pselect(maxfd + 1, &readfds, nullptr, nullptr, &tdiff, nullptr);
 #endif
 #endif
 
@@ -248,8 +248,8 @@ bool connect(const char* host, uint16_t port, int timeout, char* const *args, in
   TCPSocket* socket = client->connect(host, port, timeout);
   bool ret;
 
-  bool once = args != NULL && argCount > 0;
-  ret = socket != NULL;
+  bool once = args != nullptr && argCount > 0;
+  ret = socket != nullptr;
   if (ret) {
     string message, sendmessage;
     do {
@@ -263,7 +263,7 @@ bool connect(const char* host, uint16_t port, int timeout, char* const *args, in
           if (i > 0) {
             message += " ";
           }
-          bool quote = strchr(args[i], ' ') != NULL && strchr(args[i], '"') == NULL;
+          bool quote = strchr(args[i], ' ') != nullptr && strchr(args[i], '"') == nullptr;
           if (quote) {
             message += "\"";
           }
@@ -314,9 +314,9 @@ bool connect(const char* host, uint16_t port, int timeout, char* const *args, in
  * @return the exit code.
  */
 int main(int argc, char* argv[]) {
-  struct argp argp = { argpoptions, parse_opt, argpargsdoc, argpdoc, NULL, NULL, NULL };
+  struct argp argp = { argpoptions, parse_opt, argpargsdoc, argpdoc, nullptr, nullptr, nullptr };
   setenv("ARGP_HELP_FMT", "no-dup-args-note", 0);
-  if (argp_parse(&argp, argc, argv, ARGP_IN_ORDER, NULL, &opt) != 0) {
+  if (argp_parse(&argp, argc, argv, ARGP_IN_ORDER, nullptr, &opt) != 0) {
     return EINVAL;
   }
   bool success = connect(opt.server, opt.port, opt.timeout, opt.args, opt.argCount);
diff --git a/src/tools/ebusfeed.cpp b/src/tools/ebusfeed.cpp
index a459b5a2..c0f253ba 100755
--- a/src/tools/ebusfeed.cpp
+++ b/src/tools/ebusfeed.cpp
@@ -83,25 +83,25 @@ static char argpargsdoc[] = "[DUMPFILE]";
 
 /** the definition of the known program arguments. */
 static const struct argp_option argpoptions[] = {
-  {"device", 'd', "DEV",  0, "Write to DEV (serial device) [/dev/ttyUSB60]", 0 },
-  {"time",   't', "USEC", 0, "Delay each byte by USEC us [10000]", 0 },
+  {"device", 'd', "DEV",     0, "Write to DEV (serial device) [/dev/ttyUSB60]", 0 },
+  {"time",   't', "USEC",    0, "Delay each byte by USEC us [10000]", 0 },
 
-  {NULL,       0, NULL,   0, NULL, 0 },
+  {nullptr,    0, nullptr,   0, nullptr, 0 },
 };
 
 /**
  * The program argument parsing function.
  * @param key the key from @a argpoptions.
- * @param arg the option argument, or NULL.
+ * @param arg the option argument, or nullptr.
  * @param state the parsing state.
  */
 error_t parse_opt(int key, char *arg, struct argp_state *state) {
   struct options *opt = (struct options*)state->input;
-  char* strEnd = NULL;
+  char* strEnd = nullptr;
   switch (key) {
   // Device settings:
   case 'd':  // --device=/dev/ttyUSB60
-    if (arg == NULL || arg[0] == 0) {
+    if (arg == nullptr || arg[0] == 0) {
       argp_error(state, "invalid device");
       return EINVAL;
     }
@@ -109,14 +109,14 @@ error_t parse_opt(int key, char *arg, struct argp_state *state) {
     break;
   case 't':  // --time=10000
     opt->time = (unsigned int)strtoul(arg, &strEnd, 10);
-    if (strEnd == NULL || strEnd == arg || *strEnd != 0 || opt->time < 1000 || opt->time > 100000000) {
+    if (strEnd == nullptr || strEnd == arg || *strEnd != 0 || opt->time < 1000 || opt->time > 100000000) {
       argp_error(state, "invalid time");
       return EINVAL;
     }
     break;
   case ARGP_KEY_ARG:
     if (state->arg_num == 0) {
-      if (arg == NULL || arg[0] == 0 || strcmp("/", arg) == 0) {
+      if (arg == nullptr || arg[0] == 0 || strcmp("/", arg) == 0) {
         argp_error(state, "invalid dumpfile");
         return EINVAL;
       }
@@ -139,13 +139,13 @@ error_t parse_opt(int key, char *arg, struct argp_state *state) {
  * @return the exit code.
  */
 int main(int argc, char* argv[]) {
-  struct argp argp = { argpoptions, parse_opt, argpargsdoc, argpdoc, NULL, NULL, NULL };
+  struct argp argp = { argpoptions, parse_opt, argpargsdoc, argpdoc, nullptr, nullptr, nullptr };
   setenv("ARGP_HELP_FMT", "no-dup-args-note", 0);
-  if (argp_parse(&argp, argc, argv, ARGP_IN_ORDER, NULL, &opt) != 0) {
+  if (argp_parse(&argp, argc, argv, ARGP_IN_ORDER, nullptr, &opt) != 0) {
     return EINVAL;
   }
-  Device* device = Device::create(opt.device, false, false, NULL);
-  if (device == NULL) {
+  Device* device = Device::create(opt.device, false, false, false);
+  if (device == nullptr) {
     cout << "unable to create device " << opt.device << endl;
     return EINVAL;
   }