c++ - 应用程序未从COM端口接收串行数据-C++

我的应用程序没有从COM端口正确接收数据。这曾经工作。我不知道发生了什么我知道正确的数据正在通过线路发送/接收，因为我可以在协议分析器上看到它。

PC进入WAIT_OBJECT_0 + 1状态，但是缓冲区内容始终为零。我知道很多事情，但是如果有人能指出我做错了什么，我将非常感激。我可以根据要求添加/删除详细信息。谢谢。

编辑：附加信息

我已经能够验证PC是否拨打了ReadFileEx，并且它“成功”。但是，PC永远不会进入FileIOCompletionRoutine。有任何想法吗？ （我从代码中删除了错误处理，以简化工作。）而且，从我在MSDN网站上阅读的内容来看，FileIOCompletionRoutine似乎将在其自己的线程中被异步调用。那是对的吗？谢谢。

编辑：最终解决方案

这就是我想出的。显然，这里没有初始化和错误处理代码。我们不能使事情变得太简单。 :)

// Load event handles.
pHandles[0] = s_hSerialPortRxThreadExitEvent;
// OVERLAPPED structure event handle is loaded in loop.

while ( blContinue )
{
    // Wait for a communications event.
    if ( !::WaitCommEvent( s_hSerialPort, &dwEventMask, &s_ov ) )
    {
        if ( ::GetLastError() != ERROR_IO_PENDING )
        {
            blContinue = FALSE;
            continue;
        }
        else if ( ::WaitForSingleObject( pHandles[0], 0 ) == WAIT_OBJECT_0 )
        {
            // The thread-exit event has been signaled.  Get out of here.
            blContinue = FALSE;
            continue;
        }
    }
    else
    {
        // Load OVERLAPPED structure event handle.
        pHandles[1] = s_ov.hEvent;
    }

    if ( dwEventMask & EV_RXCHAR )
    {
        if ( !::ReadFile( s_hSerialPort, pBuf, RX_BUF_SIZE, NULL, &s_ov ) )
        {
            if ( ::GetLastError() == ERROR_IO_PENDING )
            {
                // Wait for events.
                dwObjectWaitState = ::WaitForMultipleObjects( 2, pHandles, FALSE, INFINITE );

                // Switch on event.
                switch ( dwObjectWaitState )
                {
                case WAIT_OBJECT_0:             // thread exit event signaled
                    blContinue = FALSE;
                    continue;

                case WAIT_OBJECT_0 + 1:         // OVERLAPPED structure event signalled
                    // Reset event first to mitigate underrun condition.
                    if ( !::ResetEvent( pHandles[1] ) )
                    {
                        blContinue = FALSE;
                        continue;
                    }

                    // Get the OVERLAPPED result.
                    if ( !::GetOverlappedResult( s_hSerialPort, &s_ov, &dwBytesRead, FALSE ) )
                    {
                        blContinue = FALSE;
                        continue;
                    }
                    break;

                default:                        // Error
                    blContinue = FALSE;
                    continue;
                }
            }
        }
        else if ( !::GetOverlappedResult( s_hSerialPort, &s_ov, &dwBytesRead, FALSE ) )
        {
            blContinue = FALSE;
            continue;
        }

        // If bytes were read...
        if ( dwBytesRead > 0 )
        {
            // Copy received data from local buffer to thread-safe serial port buffer.
            ::EnterCriticalSection( &s_csRxRingBuffer );
            blSuccess = s_pobjRxRingBuffer->Add( pBuf, dwBytesRead, TRUE );
            ::LeaveCriticalSection( &s_csRxRingBuffer );

            if ( !blSuccess )
            {
                blContinue = FALSE;
                continue;
            }

            // Set the received data event.
            if ( !::SetEvent( s_phEventIds[RECEIVE_EVENT] ) )
            {
                blContinue = FALSE;
                continue;
            }
        }
    }

    if ( dwEventMask & EV_TXEMPTY )
    {
        // Set the transmit complete event.
        if ( !::SetEvent( s_phEventIds[TRANSMIT_EVENT] ) )
        {
            blContinue = FALSE;
            continue;
        }
    }

} // end while ( blContinue );

最佳答案

我不知道我的代码是否错误，但是我看到您正在设置事件，并且在不通知操作系统的情况下等待事件，您应该先执行ReadFileEx（）来告诉操作系统当缓冲区中有数据要读取时，您正在等待事件，然后执行WFSO（）/ WFMO（），这是我在串行端口库（在接收器线程上）上执行的操作：

do
{
    byteRead = 0;
    readBuffer = 0;
    if(!::ReadFile(this->commHandle,&readBuffer,
                   1,NULL,&this->readOverlapIO))
    {
         if(GetLastError() == ERROR_IO_PENDING)
         {
             if(::WaitForSingleObject(this->readOverlapIO.hEvent,INFINITE) == WAIT_OBJECT_0)
             {
                 if(!::GetOverlappedResult(this->commHandle,&this->readOverlapIO,&byteRead,FALSE))
                 {
                     byteRead = 0;
                 }
             }
         }
    }
    else
    {
         if(!::GetOverlappedResult(this->commHandle,&this->readOverlapIO,&byteRead,FALSE))
         {
              byteRead = 0;
         }
    }
    if(byteRead > 0)
    {
          totalByteRead += this->ringBuffer.push(readBuffer,1);
    }
}while(byteRead);

我在这里使用事件信号来完成事件，如果需要，您可以将其更改为完成功能。