readfile读串口老是直接返回true而且读到字节为0

readfile读串口总是直接返回true而且读到字节为0

OVERLAPPED m_osRead;

	memset(&m_osRead,0,sizeof(OVERLAPPED));

	m_osRead.hEvent = CreateEvent(NULL,TRUE,FALSE,NULL);


	COMSTAT ComStat;

	DWORD dwErrorFlags;

	DWORD dwWantRead = 12;

	BOOL bReadStat;


	ClearCommError(m_hCom,&dwErrorFlags,&ComStat);

	dwWantRead = min(dwWantRead,(DWORD)ComStat.cbInQue);

	bReadStat = ReadFile(m_hCom,buf,dwWantRead,dwRealRead,&m_osRead);

	if (!bReadStat)

	{

		if (GetLastError() == ERROR_IO_PENDING)

		{

			//WaitForSingleObject(m_osRead.hEvent,1000);

			GetOverlappedResult(m_hCom,&m_osRead,dwRealRead,TRUE);

		}

	}

	PurgeComm(m_hCom,PURGE_RXABORT|PURGE_RXCLEAR|PURGE_TXABORT|PURGE_TXCLEAR);

	return TRUE;

------解决方案--------------------
你先确定下位机有没有上传数据,或者你不用下位机,直接把串口的2和3脚短接就行了,上位机发什么就收什么
------解决方案--------------------
循环读试试。