diff --git a/src/lib/ebus/port.cpp b/src/lib/ebus/port.cpp
index e338a220..c9adc96c 100644
--- a/src/lib/ebus/port.cpp
+++ b/src/lib/ebus/port.cpp
@@ -69,7 +69,7 @@ ssize_t Device::sendBytes(const unsigned char* buffer, size_t nbytes)
 	return write(m_fd, buffer, nbytes);
 }
 
-ssize_t Device::recvBytes(const long timeout, size_t maxCount)
+ssize_t Device::recvBytes(const long timeout, size_t maxCount, unsigned char* buffer)
 {
 	if (isValid() == false)
 		return RESULT_ERR_DEVICE;
@@ -102,16 +102,26 @@ ssize_t Device::recvBytes(const long timeout, size_t maxCount)
 		ret = pselect(m_fd + 1, &readfds, NULL, NULL, &tdiff, NULL);
 #endif
 #endif
-
 		if (ret == -1) return RESULT_ERR_DEVICE;
 		if (ret == 0) return RESULT_ERR_TIMEOUT;
 	}
 
+	if (buffer != NULL) {
+		// read bytes from device directly into provided buffer
+		ssize_t nbytes = read(m_fd, buffer, maxCount);
+		if (nbytes == 0)
+			return RESULT_ERR_EOF;
+
+		return nbytes;
+	}
+
 	if (maxCount > sizeof(m_buffer))
 		maxCount = sizeof(m_buffer);
 
-	// read bytes from device
+	// read bytes from device into temporary buffer
 	ssize_t nbytes = read(m_fd, m_buffer, maxCount);
+	if (nbytes == 0)
+		return RESULT_ERR_EOF;
 
 	for (int i = 0; i < nbytes; i++)
 		m_recvBuffer.push(m_buffer[i]);
@@ -154,10 +164,11 @@ result_t DeviceSerial::openDevice(const string deviceName, const bool noDeviceCh
 	memset(&newSettings, '\0', sizeof(newSettings));
 
 	newSettings.c_cflag |= (B2400 | CS8 | CLOCAL | CREAD);
-	newSettings.c_lflag &= ~(ICANON | ECHO | ECHOE | ISIG);
-	newSettings.c_iflag |= IGNPAR;
+	newSettings.c_lflag &= ~(ICANON | ECHO | ECHOE | ISIG); // non-canonical mode
+	newSettings.c_iflag |= IGNPAR; // ignore parity errors
 	newSettings.c_oflag &= ~OPOST;
 
+	// non-canonical mode: read() blocks until at least one byte is available
 	newSettings.c_cc[VMIN]  = 1;
 	newSettings.c_cc[VTIME] = 0;
 
@@ -251,7 +262,8 @@ void DeviceNetwork::closeDevice()
 }
 
 
-Port::Port(const string deviceName, const bool noDeviceCheck, const bool logRaw, void (*logRawFunc)(const unsigned char byte),
+Port::Port(const string deviceName, const bool noDeviceCheck,
+		const bool logRaw, void (*logRawFunc)(const unsigned char byte, bool received),
 		const bool dumpRaw, const char* dumpRawFile, const long dumpRawMaxSize)
 	: m_deviceName(deviceName), m_noDeviceCheck(noDeviceCheck),
 	  m_logRaw(logRaw), m_logRawFunc(logRawFunc),
@@ -275,7 +287,7 @@ unsigned char Port::byte()
 	unsigned char byte = m_device->getByte();
 
 	if (m_logRaw == true && m_logRawFunc != NULL)
-		(*m_logRawFunc)(byte);
+		(*m_logRawFunc)(byte, true);
 
 	if (m_dumpRaw == true && m_dumpRawStream.is_open() == true) {
 		m_dumpRawStream.write((char*)&byte, 1);
diff --git a/src/lib/ebus/port.h b/src/lib/ebus/port.h
index 124dd147..a81fdb28 100644
--- a/src/lib/ebus/port.h
+++ b/src/lib/ebus/port.h
@@ -92,9 +92,10 @@ public:
 	 * @brief recvBytes read bytes from opened file descriptor.
 	 * @param timeout time for new input data [usec].
 	 * @param maxCount max size of receive buffer.
+	 * @param buffer optional direct buffer to write to (instead of queuing the data).
 	 * @return number of read bytes or -1 if an error has occured.
 	 */
-	ssize_t recvBytes(const long timeout, size_t maxCount);
+	ssize_t recvBytes(const long timeout, size_t maxCount, unsigned char* buffer=NULL);
 
 	/**
 	 * @brief fetch first byte from receive buffer.
@@ -208,7 +209,8 @@ public:
 	 * @param dumpRawFile the name of the file to dump raw data to.
 	 * @param dumpRawMaxSize the maximum size of @a m_dumpFile.
 	 */
-	Port(const string deviceName, const bool noDeviceCheck, const bool logRaw, void (*logRawFunc)(const unsigned char byte),
+	Port(const string deviceName, const bool noDeviceCheck,
+		const bool logRaw, void (*logRawFunc)(const unsigned char byte, bool received),
 		const bool dumpRaw, const char* dumpRawFile, const long dumpRawMaxSize);
 
 	/**
@@ -239,16 +241,27 @@ public:
 	 * @return number of written bytes or -1 if an error has occured.
 	 */
 	ssize_t send(const unsigned char* buffer, size_t nbytes = MAX_WRITE_SIZE)
-		{ return m_device->sendBytes(buffer, nbytes); }
+	{
+		ssize_t ret = m_device->sendBytes(buffer, nbytes);
+		if (ret>0 && m_logRaw == true && m_logRawFunc != NULL)
+			(*m_logRawFunc)(buffer[0], false);
+		return ret;
+	}
 
 	/**
 	 * @brief recv read bytes from opened file descriptor.
-	 * @param timeout max time out for new input data [usec].
+	 * @param timeout max time out for new input data [usec], or 0 for infinite.
 	 * @param maxCount max size of receive buffer.
-	 * @return number of read bytes or -1 if an error has occured.
+	 * @param buffer optional direct buffer to write to (instead of queuing the data).
+	 * @return number of read bytes (never 0) or a negative result_t code.
 	 */
-	ssize_t recv(const long timeout, size_t maxCount = MAX_READ_SIZE)
-		{ return m_device->recvBytes(timeout, maxCount); }
+	ssize_t recv(const long timeout, size_t maxCount = MAX_READ_SIZE, unsigned char* buffer=NULL)
+	{
+		ssize_t ret = m_device->recvBytes(timeout, maxCount, buffer);
+		if (buffer && ret>0 && m_logRaw == true && m_logRawFunc != NULL)
+			(*m_logRawFunc)(buffer[0], true);
+		return ret;
+	}
 
 	/**
 	 * @brief fetch first byte from receive buffer.
@@ -312,7 +325,7 @@ private:
 	bool m_logRaw;
 
 	/** a function to call for logging raw data, or NULL. */
-	void (*m_logRawFunc)(const unsigned char byte);
+	void (*m_logRawFunc)(const unsigned char byte, bool received);
 
 	/** whether dumping of raw data to a file is enabled. */
 	bool m_dumpRaw;