异步写串口怎么不行????

mirroatl265 2014-04-08 10:39:38



hCom=CreateFile(_T("COM1"),//COM1口

		GENERIC_READ|GENERIC_WRITE, //允许读和写

		0, //独占方式

		NULL,

		OPEN_EXISTING, //打开而不是创建

		FILE_ATTRIBUTE_NORMAL|FILE_FLAG_OVERLAPPED, //重叠方式

		NULL);

	if(hCom==(HANDLE)-1)

	{

		AfxMessageBox(_T("打开COM失败!"));

		return FALSE;

	}



	SetupComm(hCom,100,100); //输入缓冲区和输出缓冲区的大小都是100



	COMMTIMEOUTS TimeOuts;

	//设定读超时

	TimeOuts.ReadIntervalTimeout=MAXDWORD;

	TimeOuts.ReadTotalTimeoutMultiplier=0;

	TimeOuts.ReadTotalTimeoutConstant=0;

	//在读一次输入缓冲区的内容后读操作就立即5返回，

	//而不管是否读入了要求的字符。





	//设定写超时

	TimeOuts.WriteTotalTimeoutMultiplier=100;

	TimeOuts.WriteTotalTimeoutConstant=500;

	SetCommTimeouts(hCom,&TimeOuts); //设置超时



	DCB dcb;

	GetCommState(hCom,&dcb);

	dcb.BaudRate=9600; //波特率为9600

	dcb.ByteSize=7; //每个字节有8位

	dcb.Parity=NOPARITY; //无奇偶校验位

	dcb.StopBits=TWOSTOPBITS; //两个停止位

	SetCommState(hCom,&dcb);



	PurgeComm(hCom,PURGE_TXCLEAR|PURGE_RXCLEAR);



OVERLAPPED m_osWrite;

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

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





	char lpOutBuffer[7];

	memset(lpOutBuffer,'\0',7);

	lpOutBuffer[0]='\x11';

	lpOutBuffer[1]='0';

	lpOutBuffer[2]='0';

	lpOutBuffer[3]='1';

	lpOutBuffer[4]='0';

	lpOutBuffer[5]='1';

	lpOutBuffer[6]='\x03';

	

	DWORD dwBytesWrite=7;

	COMSTAT ComStat;

	DWORD dwErrorFlags;

	BOOL bWriteStat;

	ClearCommError(hCom,&dwErrorFlags,&ComStat);

	bWriteStat=WriteFile(hCom,lpOutBuffer,

		dwBytesWrite,& dwBytesWrite,&m_osWrite);



	if(!bWriteStat)

	{

		if(GetLastError()==ERROR_IO_PENDING)

		{

			WaitForSingleObject(m_osWrite.hEvent,1000);

		}

	}



}



BOOL CRS485CommDlg::OnReceive(CString& s) 

{

	// TODO: Add your control notification handler code here

	OVERLAPPED m_osRead;

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

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



	COMSTAT ComStat;

	DWORD dwErrorFlags;

	

	char str[12];

	memset(str,'\0',12);

	DWORD dwBytesRead=12;//读取的字节数

	BOOL bReadStat;



	ClearCommError(hCom,&dwErrorFlags,&ComStat);

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

	bReadStat=ReadFile(hCom,str,

		12,&dwBytesRead,&m_osRead);

	if(dwBytesRead != 12)

		return FALSE;

	for(int i = 1 ; i < 12;i++)

		{

			if(str[i] == 27)

			{

				str[i] = _T('\0');

				break;

			}

		}



	if(!bReadStat)

	{

		if(GetLastError()==ERROR_IO_PENDING)

	    //GetLastError()函数返回ERROR_IO_PENDING,表明串口正在进行读操作

		{

			WaitForSingleObject(m_osRead.hEvent,300);

		    //使用WaitForSingleObject函数等待，直到读操作完成或延时已达到2秒钟

		    //当串口读操作进行完毕后，m_osRead的hEvent事件会变为有信号

		}

	}



	PurgeComm(hCom, PURGE_TXABORT|

		PURGE_RXABORT|PURGE_TXCLEAR|PURGE_RXCLEAR);

	//m_disp=str;

	s = str;

	return TRUE;