C / C++ / MFC

	m_hPort = CreateFile(sFile, GENERIC_READ | GENERIC_WRITE, 0, NULL, OPEN_EXISTING, FILE_FLAG_OVERLAPPED, NULL);<br />
<br />
	m_DCB.DCBlength = sizeof(DCB);<br />
	GetCommState(m_hPort, &m_DCB);<br />
	<br />
	// Define the serial port characteristics<br />
	m_DCB.BaudRate = m_stCalibration.BaudRate;<br />
	m_DCB.ByteSize = m_stCalibration.ByteSize;<br />
	m_DCB.Parity = m_stCalibration.Parity;<br />
	m_DCB.StopBits = m_stCalibration.StopBits;<br />
	m_DCB.fDtrControl = DTR_CONTROL_DISABLE;<br />
	m_DCB.fRtsControl = RTS_CONTROL_DISABLE;<br />
	SetCommState(m_hPort, &m_DCB);<br />
	SetCommMask(m_hPort, EV_CTS | EV_DSR | EV_ERR | EV_RXCHAR | EV_TXEMPTY);<br />
<br />
	// Create the port listener thread<br />
	m_pListenerThread = AfxBeginThread(listener, this, THREAD_PRIORITY_HIGHEST, 0, CREATE_SUSPENDED, NULL);<br />
<br />
	// Thread created successfully. AutoDelete can only be set, if thread is not running<br />
	m_pListenerThread->m_bAutoDelete = FALSE;<br />
	m_pListenerThread->ResumeThread();

listener (void)<br />
{<br />
	DWORD     dwBytesRead;<br />
	DWORD     dwBytesWritten;<br />
	DWORD     dwEventMask;<br />
	BYTE      szBuffer[MSGFRAME_MAX_LEN];<br />
	DWORD     dwOverlappedResult;<br />
	DWORD     dwLastError;<br />
	BOOL      bResult;<br />
	DWORD     dwDontCare;<br />
<br />
	memset(szBuffer, 0, MSGFRAME_MAX_LEN);<br />
<br />
	SetCommMask(m_hPort, EV_RXCHAR);<br />
	WaitCommEvent(m_hPort, &dwEventMask, &m_stReadOver);<br />
	while(1)<br />
	{<br />
		// Wait for incoming bytes<br />
		if(WaitForSingleObject(m_stReadOver.hEvent, 1000) == WAIT_TIMEOUT)<br />
		{<br />
			// No data available on port -> Check if port configuration is to be changed<br />
			checkCalibration();<br />
			continue;<br />
		}<br />
<br />
		dwOverlappedResult = GetOverlappedResult(m_hPort, &m_stReadOver, &dwDontCare, FALSE);<br />
		if (dwOverlappedResult != FALSE)<br />
		{<br />
			// Character(s) received<br />
			bResult = ReadFile(m_hPort, szBuffer, 1, &dwBytesRead, &m_stReadOver);<br />
			if(bResult != FALSE && dwBytesRead == 1)<br />
			{<br />
				// Interface received unformatted data to be forwarded to ring buffer<br />
				m_stRingBuffer.RingBuffer[m_stRingBuffer.dwEnd].yChar = *szBuffer;<br />
				m_stRingBuffer.dwEnd = m_stRingBuffer.RingBuffer[m_stRingBuffer.dwEnd].dwNext;<br />
				m_pRingBufferFilled->SetEvent();<br />
<br />
			}<br />
			else if (bResult == FALSE && GetLastError() != ERROR_IO_PENDING)<br />
			{<br />
				// ReadFile returns error<br />
			}<br />
<br />
			// Reset event and wait for new incomming events/characters<br />
			ResetEvent(m_stReadOver.hEvent);<br />
			WaitCommEvent(m_hPort, &dwEventMask, &m_stReadOver);<br />
		}<br />
	}<br />
	return;<br />
}