diff --git a/src/ebusd/bushandler.cpp b/src/ebusd/bushandler.cpp
index 563ef425..b9b2aa57 100644
--- a/src/ebusd/bushandler.cpp
+++ b/src/ebusd/bushandler.cpp
@@ -808,19 +808,33 @@ result_t BusHandler::setState(BusState state, result_t result, bool firstRepetit
 
 void BusHandler::addSeenAddress(unsigned char address)
 {
-	if (!isValidAddress(address, false))
+	if (!isValidAddress(address, false)) {
 		return;
+	}
 	if (!isMaster(address)) {
+		if (!m_device->isReadOnly() && address==m_ownSlaveAddress) {
+			if (!m_addressConflict) {
+				m_addressConflict = true;
+				logError(lf_bus, "own slave address %2.2x is used by another participant", address);
+			}
+		}
 		m_seenAddresses[address] |= SEEN;
 		address = getMasterAddress(address);
-		if (address==SYN)
+		if (address==SYN) {
 			return;
+		}
 	}
 	if ((m_seenAddresses[address]&SEEN)==0) {
-		if (!m_answer || address!=m_ownMasterAddress) {
+		if (!m_device->isReadOnly() && address==m_ownMasterAddress) {
+			if (!m_addressConflict) {
+				m_addressConflict = true;
+				logError(lf_bus, "own master address %2.2x is used by another participant", address);
+			}
+		} else {
 			m_masterCount++;
-			if (m_autoLockCount && m_masterCount>m_lockCount)
+			if (m_autoLockCount && m_masterCount>m_lockCount) {
 				m_lockCount = m_masterCount;
+			}
 			logNotice(lf_bus, "new master %2.2x, master count %d", address, m_masterCount);
 		}
 		m_seenAddresses[address] |= SEEN;
@@ -1010,7 +1024,7 @@ void BusHandler::formatSeenInfo(ostringstream& output)
 	unsigned char address = 0;
 	for (int index=0; index<256; index++, address++) {
 		if (isValidAddress(address, false)
-		&& ((m_seenAddresses[address]&SEEN)!=0 || address==m_ownMasterAddress || address==m_ownSlaveAddress)) {
+		&& ((m_seenAddresses[address]&SEEN)!=0 || (!m_device->isReadOnly() && (address==m_ownMasterAddress || address==m_ownSlaveAddress)))) {
 			output << endl << "address " << setfill('0') << setw(2) << hex << static_cast<unsigned>(address);
 			unsigned char master;
 			if (isMaster(address)) {
@@ -1022,12 +1036,12 @@ void BusHandler::formatSeenInfo(ostringstream& output)
 			}
 			if (master != SYN)
 				output << " #" << setw(0) << dec << static_cast<unsigned>(getMasterNumber(master));
-			if (address==m_ownMasterAddress || (m_answer && address==m_ownSlaveAddress)) {
+			if (!m_device->isReadOnly() && (address==m_ownMasterAddress || address==m_ownSlaveAddress)) {
 				output << ", ebusd";
 				if (m_answer) {
 					output << " (answering)";
 				}
-				if ((m_seenAddresses[address]&SEEN)!=0) {
+				if (m_addressConflict && (m_seenAddresses[address]&SEEN)!=0) {
 					output << ", conflict";
 				}
 			}
@@ -1088,7 +1102,7 @@ bool BusHandler::enableGrab(bool enable)
 		return false;
 	}
 	if (!enable) {
-		m_grabbedMessages.clear(); // TODO check
+		m_grabbedMessages.clear();
 	}
 	m_grabMessages = enable;
 	return true;
diff --git a/src/ebusd/bushandler.h b/src/ebusd/bushandler.h
index 3d899442..e642f346 100644
--- a/src/ebusd/bushandler.h
+++ b/src/ebusd/bushandler.h
@@ -363,10 +363,11 @@ public:
 			const unsigned int lockCount, const bool generateSyn,
 			const unsigned int pollInterval)
 		: WaitThread(), m_device(device), m_reconnect(false), m_messages(messages),
-		  m_ownMasterAddress(ownAddress), m_ownSlaveAddress((unsigned char)(ownAddress+5)), m_answer(answer),
+		  m_ownMasterAddress(ownAddress), m_ownSlaveAddress((unsigned char)(ownAddress+5)),
+		  m_addressConflict(false), m_answer(answer),
 		  m_busLostRetries(busLostRetries), m_failedSendRetries(failedSendRetries),
 		  m_transferLatency(transferLatency), m_busAcquireTimeout(busAcquireTimeout), m_slaveRecvTimeout(slaveRecvTimeout),
-		  m_masterCount(1), m_autoLockCount(lockCount==0), m_lockCount(lockCount<=3 ? 3 : lockCount), m_remainLockCount(m_autoLockCount),
+		  m_masterCount(device->isReadOnly()?0:1), m_autoLockCount(lockCount==0), m_lockCount(lockCount<=3 ? 3 : lockCount), m_remainLockCount(m_autoLockCount),
 		  m_generateSynInterval(generateSyn ? SYN_TIMEOUT*getMasterNumber(ownAddress)+SYMBOL_DURATION : 0),
 		  m_pollInterval(pollInterval), m_lastReceive(0), m_lastPoll(0),
 		  m_currentRequest(NULL), m_runningScans(0), m_nextSendPos(0),
@@ -566,6 +567,9 @@ private:
 	/** whether to answer queries for the own master/slave address. */
 	const bool m_answer;
 
+	/** set to @p true once an address conflict with the own addresses was detected. */
+	bool m_addressConflict;
+
 	/** the number of times a send is repeated due to lost arbitration. */
 	const unsigned int m_busLostRetries;