串口编程

开发平台：
Visual C++

SerialCom.cpp：源码内容
							#include "stdafx.h"
#include "SerialCom.h"
CSerial::CSerial()
{
	m_hComDev=NULL; 
	m_bOpened=FALSE;
	memset(dataRx,'',50);
}
CSerial::~CSerial()
{
	m_hComDev=NULL; 
	m_bOpened=FALSE;
}
BOOL CSerial::Open(int nPort, int nBaud)
{
	if( m_bOpened == TRUE) 
	{	
		MessageBox(0,"The Com Port has been opened.","",MB_OK);
		return( TRUE );
	}
	char szPort[15];
	DCB dcb;
	wsprintf( szPort, "COM%d", nPort );
	m_hComDev=CreateFile( "COM1", GENERIC_READ | GENERIC_WRITE, 0, NULL, OPEN_EXISTING, FILE_ATTRIBUTE_NORMAL | FILE_FLAG_OVERLAPPED, NULL );
	if(m_hComDev == INVALID_HANDLE_VALUE)
	{
		MessageBox(0,"The Com Port has been occupied!","",MB_OK);
		return  FALSE;
	}
	memset( &m_OverlappedRead, 0, sizeof( OVERLAPPED ) );
	memset( &m_OverlappedWrite, 0, sizeof( OVERLAPPED ) );
	COMMTIMEOUTS CommTimeOuts;
	CommTimeOuts.ReadIntervalTimeout = 0xFFFFFFFF;
	CommTimeOuts.ReadTotalTimeoutMultiplier = 0;
	CommTimeOuts.ReadTotalTimeoutConstant = 0;
	CommTimeOuts.WriteTotalTimeoutMultiplier = 0;
	CommTimeOuts.WriteTotalTimeoutConstant = 5000;
	SetCommTimeouts(m_hComDev, &CommTimeOuts);
	m_OverlappedRead.hEvent = CreateEvent( NULL, TRUE, FALSE, NULL);
	m_OverlappedWrite.hEvent = CreateEvent( NULL, TRUE, FALSE, NULL);
	dcb.DCBlength = sizeof( DCB );
	GetCommState( m_hComDev, &dcb );
	dcb.BaudRate = nBaud;
	dcb.ByteSize = 8;
	dcb.Parity = 0;
	if( !SetCommState( m_hComDev, &dcb) || !SetupComm( m_hComDev, 512,512) ||
		m_OverlappedRead.hEvent == NULL || m_OverlappedWrite.hEvent == NULL )
	{
		DWORD dwError = GetLastError();
		if( m_OverlappedRead.hEvent != NULL) CloseHandle( m_OverlappedRead.hEvent);
		if( m_OverlappedWrite.hEvent != NULL) CloseHandle( m_OverlappedWrite.hEvent);
		CloseHandle( m_hComDev );
		return FALSE;
	}
	m_bOpened = TRUE;
	return m_bOpened;
}
//***************************************************************************
int CSerial::InBufferCount( void )
{
	if( !m_bOpened || m_hComDev == NULL ) return( 0 );
	DWORD dwErrorFlags;
	COMSTAT ComStat;
	ClearCommError( m_hComDev, &dwErrorFlags, &ComStat );
	return (int)ComStat.cbInQue;
}
//***************************************************************************
DWORD CSerial::ReadData( void *buffer, DWORD dwBytesRead)
{
	if( !m_bOpened || m_hComDev == NULL ) return 0;
	BOOL bReadStatus;
	DWORD dwErrorFlags;
	COMSTAT ComStat;
	ClearCommError( m_hComDev, &dwErrorFlags, &ComStat );
	if( !ComStat.cbInQue ) return 0;
	dwBytesRead = min(dwBytesRead,(DWORD) ComStat.cbInQue);
//	SetFilePointer(m_hComDev,NULL,NULL,FILE_BEGIN);
	bReadStatus = ReadFile( m_hComDev, buffer, dwBytesRead, &dwBytesRead, &m_OverlappedRead );
	if( !bReadStatus )
	{
		if( GetLastError() == ERROR_IO_PENDING )
		{
			WaitForSingleObject( m_OverlappedRead.hEvent, 2000 );
			return dwBytesRead;
		}
		return 0;
	}
	return dwBytesRead;
}
//****************************************************************************
DWORD CSerial::SendData( const char *buffer, DWORD dwBytesWritten)
{
	if( !m_bOpened || m_hComDev == NULL ) return( 0 );
	BOOL bWriteStat;
//	SetFilePointer(m_hComDev,NULL,NULL,FILE_BEGIN);
	bWriteStat = WriteFile( m_hComDev, buffer, dwBytesWritten, &dwBytesWritten, &m_OverlappedWrite );
	if( !bWriteStat)
	{
		if ( GetLastError() == ERROR_IO_PENDING ) 
		{
			WaitForSingleObject( m_OverlappedWrite.hEvent, 1000 );
			return dwBytesWritten;
		}
		return 0;
	}
	return dwBytesWritten;
}
//****************************************************************************
BOOL CSerial::Close(void)
{
	m_bOpened = FALSE;
	return CloseHandle(m_hComDev);
}

						