(急)线程监视串口问题!

Question

创建一个线程监视串口,当有一个字符来时,产生一个事件,现在出现一个问题,第一次可以正确接收到字符,第二次就接收不到了!跟踪了一下,发现线程都没有启动,可是设备确实向串口发回了数据啊!!??为什么会这样呢?

Answer 1

你产生事件后线程就结束了吧，你好好看看线程方面的资料，应该是触发事件之后又回到线程中去，使用waittimeoutobject这类的可以

Answer 2

代码在：http://www.vchelp.net/cndevforum/subject_view.asp?subject_id=59979&forum_id=34

Answer 3

DWORD willRead=0;
这段代码是仿照网上的啊！
UINT CommProc(LPVOID pParam)
{
CXXXXDlg *pDlg=(CXXXXDlg*)pParam;
DWORD dwMask,dwTrans;
COMSTAT comStat;
DWORD dwErrorFlags;
OVERLAPPED os={0};
os.hEvent=CreateEvent(NULL,TRUE,FALSE,NULL);
if(os.hEvent==NULL)
{
AfxMessageBox("CommProc CreateEvent failed");
return -1;
}
for( ; ; )
{
ClearCommError(h_Com,&dwErrorFlags,&comStat );
if(comStat.cbInQue)//串口接收字节数不为零
{
//无限等待WM_MYNOTIFY消息处理完
WaitForSingleObject(pDlg->m_hPostMsgEvent,INFINITE);
ResetEvent(pDlg->m_hPostMsgEvent);
willRead=comStat.cbInQue;
pDlg->PostMessage(WM_MYNOTIFY,EV_RXCHAR,0);
continue;
}

dwMask=0;
if(!WaitCommEvent(h_Com,&dwMask,&os))
{
switch (dwErrorFlags = GetLastError()) 
{ 
case ERROR_IO_PENDING: 
{ 
// This is a normal return value if there are no bytes
// to read at the port.
// Do nothing and continue
GetOverlappedResult(h_Com,&os,&dwTrans,TRUE);
//wait for until receiving any char
break;
}
case 87:
{
// Under Windows NT, this value is returned for some reason.
// I have not investigated why, but it is also a valid reply
// Also do nothing and continue.
GetOverlappedResult(h_Com,&os,&dwTrans,TRUE);
break;
}
default:
{
// All other error codes indicate a serious error has
// occured.  Process this error.
AfxMessageBox("error");
break;
}
}

}
}
CloseHandle(os.hEvent);
return 0;
}
 CString str_receive=_T("");
            
LRESULT CXXXXDlg:: OnCommNotify(WPARAM wParam,LPARAM lParam)
{
    m_pOutbuffer=new char[willRead];
memset(m_pOutbuffer, 0, willRead);
if((wParam&EV_RXCHAR)!=EV_RXCHAR)
{
SetEvent(m_hPostMsgEvent);
return 0L;
}
else
{
int i;
DWORD number=ReadComm(m_pOutbuffer,willRead);
CString string_receive=_T("");
for( i=0;i<(int)number;i++)
{
     string_receive=string_receive+m_pOutbuffer[i];
             str_receive+=string_receive;
             string_receive=_T("");
}
SetEvent(m_hPostMsgEvent);
}
delete []m_pOutbuffer;
return 0L;
}

Answer 4

我估计是线程结束，你可以debug, 在return前放breakpoint.

Answer 5

DWORD willRead=0;
UINT CommProc(LPVOID pParam)
{
    CTESTDlg *pDlg=(CTESTDlg*)pParam;
    OVERLAPPED os;
    DWORD dwMask, dwTrans;
    COMSTAT comStat;
    DWORD dwErrorFlags;
    memset(&os, 0, sizeof(OVERLAPPED));
    os.hEvent=CreateEvent(NULL, TRUE, FALSE, NULL);
    if(os.hEvent==NULL)
    {
        AfxMessageBox("CommProc CreateEvent failed");
        return -1;
    }
    for( ; ; )
    {
        ClearCommError(h_Com,&dwErrorFlags,&comStat );
        if(comStat.cbInQue)//串口接收字节数不为零
        {
            //无限等待WM_MYNOTIFY消息处理完
            WaitForSingleObject(pDlg->m_hPostMsgEvent,INFINITE);
            ResetEvent(pDlg->m_hPostMsgEvent);
            willRead=comStat.cbInQue;
            pDlg->PostMessage(WM_MYNOTIFY,EV_RXCHAR,0);
            continue;
        }
        
        dwMask=0;
        if(!WaitCommEvent(h_Com,&dwMask,&os))
        {
        if(GetLastError()==ERROR_IO_PENDING)
            // 无限等待重叠操作结果
                GetOverlappedResult(h_Com, &os, &dwTrans, TRUE);
////////////////////去掉这段代码就可已连续接收了////////////
    //        else
    //        {
    //            CloseHandle(os.hEvent);
    //            return (UINT)-1;
    //        }
////////////////////////////////////////////////////////////    
    }
    }    CloseHandle(os.hEvent);
    return 0;
}
但是我要连续发送4次以上，程序就死了！为什么啊！？