串口问题,急急急急急急

Question

我的串口程序 BuildCommDCB("COM1:115200,n,8,1",&dcb);使用了这一句以后，出现
以下问题
             Unhandled exception in callsu.exe (KERNEL32.DLL): 0xC0000005:Access Violation
在2k 和xp下调试均没有次错误，但是在98和me下有。 hCommDev=CreateFile("COM1",GENERIC_READ|GENERIC_WRITE,0,NULL,OPEN_EXISTING,FILE_ATTRIBUTE_NORMAL|FILE_FLAG_OVERLAPPED,NULL);
if(hCommDev!=(HANDLE)-1)
                         { flagcom=TRUE;                           dcb.BaudRate=9600;
   dcb.ByteSize=8;
   dcb.Parity=NOPARITY;
   dcb.StopBits=ONESTOPBIT;

                     //  BuildCommDCB("COM1:115200,n,8,1",&dcb);
                           SetCommState(hCommDev,&dcb);   //以上为初始化串口
     
                           COMMTIMEOUTS CommTimeOuts;
                           CommTimeOuts.ReadIntervalTimeout=MAXDWORD;
                           CommTimeOuts.ReadTotalTimeoutMultiplier=0;
                           CommTimeOuts.ReadTotalTimeoutConstant=0;
                           CommTimeOuts.WriteTotalTimeoutMultiplier=0;
                           CommTimeOuts.WriteTotalTimeoutConstant=1000;
                           SetCommTimeouts(hCommDev,&CommTimeOuts);
                           PurgeComm(hCommDev,PURGE_TXCLEAR);
                           PurgeComm(hCommDev,PURGE_RXCLEAR); //设置读写串口超时时间
                       
                         bReturn=WriteFile(hCommDev,strOutMsg,strlen(strOutMsg),&dwBytesWritten,NULL);
                         if(!bReturn)flagmodem=FALSE;
                 else flagmodem=TRUE;
                          }          else flagcom=FALSE;

Answer 1

操作系统不一样，98和me的api也不同吧

Answer 2

这个一般不用BuildCommDCB，而用SetCommState、GetCommState 
注意在SetCommState前要调用GetCommState；
BOOL NEAR SetupConnection() 
{       BOOL fRetVal; 
        DCB dcb; 
         
        if (!npGPSInfo) return(FALSE);         dcb.DCBlength=sizeof(DCB);         GetCommState(COMDEV(npGPSInfo),&dcb);         dcb.BaudRate=BAUDRATE(npGPSInfo); 
        dcb.ByteSize=BYTESIZE(npGPSInfo); 
        dcb.Parity=PARITY(npGPSInfo); 
        dcb.StopBits=STOPBITS(npGPSInfo);         dcb.fOutxDsrFlow=FALSE; 
        dcb.fDtrControl=DTR_CONTROL_ENABLE;         dcb.fOutxCtsFlow=FALSE; 
        dcb.fRtsControl=RTS_CONTROL_ENABLE; 
        dcb.fInX=dcb.fOutX=FALSE; 
        dcb.fBinary=TRUE; 
        dcb.fParity=TRUE;         fRetVal=SetCommState(COMDEV(npGPSInfo),&dcb); 
        return (fRetVal); 
}

Answer 3

还有很多办法，无非是打开COM口，用ms的MSCOMM控件也行！参考VCKBASE.COM下面是摘录的打开函数，一看就清楚了：
void CSerialPort::Open(int nPort, DWORD dwBaud, Parity parity, BYTE DataBits, StopBits stopbits, FlowControl fc, BOOL bOverlapped)
{
  //Validate our parameters
  ASSERT(nPort>0 && nPort<=255);  Close(); //In case we are already open  //Call CreateFile to open up the comms port
  CString sPort;
  sPort.Format(_T("\\\\.\\COM%d"), nPort);
  DWORD dwCreateProperty;
  if(bOverlapped) 
  {
     dwCreateProperty=FILE_ATTRIBUTE_NORMAL | FILE_FLAG_OVERLAPPED;
  }
  else
  {
 dwCreateProperty=FILE_ATTRIBUTE_NORMAL;
  }
  // bOverlapped ? FILE_FLAG_OVERLAPPED : 0
  m_hComm = CreateFile(sPort, GENERIC_READ | GENERIC_WRITE, 0, NULL, OPEN_EXISTING,dwCreateProperty, NULL);
  if (m_hComm == INVALID_HANDLE_VALUE)
  {
    TRACE(_T("Failed to open up the comms port\n"));
    AfxThrowSerialException();
  }  this->m_CurPortNum = nPort;
  //Create the event we need for later synchronisation use
  /*
  if(bOverlapped)
  {
m_hEvent = CreateEvent(NULL, FALSE, FALSE, NULL);
if (m_hEvent == NULL)
{
Close();
TRACE(_T("Failed in call to CreateEvent in Open\n"));
AfxThrowSerialException();
}
  }
  */
 
  m_bOverlapped = bOverlapped;
  
  //Get the current state prior to changing it
  DCB dcb;
  dcb.DCBlength = sizeof(DCB);
  GetState(dcb);  //Setup the baud rate
  dcb.BaudRate = dwBaud;   //Setup the Parity
  switch (parity)
  {
    case EvenParity:  dcb.Parity = EVENPARITY;  break;
    case MarkParity:  dcb.Parity = MARKPARITY;  break;
    case NoParity:    dcb.Parity = NOPARITY;    break;
    case OddParity:   dcb.Parity = ODDPARITY;   break;
    case SpaceParity: dcb.Parity = SPACEPARITY; break;
    default:          ASSERT(FALSE);            break;
  }  //Setup the data bits
  dcb.ByteSize = DataBits;  //Setup the stop bits
  switch (stopbits)
  {
    case OneStopBit:           dcb.StopBits = ONESTOPBIT;   break;
    case OnePointFiveStopBits: dcb.StopBits = ONE5STOPBITS; break;
    case TwoStopBits:          dcb.StopBits = TWOSTOPBITS;  break;
    default:                   ASSERT(FALSE);               break;
  }  //Setup the flow control 
  dcb.fDsrSensitivity = FALSE;
  switch (fc)
  {
    case NoFlowControl:
    {
      dcb.fOutxCtsFlow = FALSE;
      dcb.fOutxDsrFlow = FALSE;
      dcb.fOutX = FALSE;
      dcb.fInX = FALSE;
      break;
    }
    case CtsRtsFlowControl:
    {
      dcb.fOutxCtsFlow = TRUE;
      dcb.fOutxDsrFlow = FALSE;
      dcb.fRtsControl = RTS_CONTROL_HANDSHAKE;
      dcb.fOutX = FALSE;
      dcb.fInX = FALSE;
      break;
    }
    case CtsDtrFlowControl:
    {
      dcb.fOutxCtsFlow = TRUE;
      dcb.fOutxDsrFlow = FALSE;
      dcb.fDtrControl = DTR_CONTROL_HANDSHAKE;
      dcb.fOutX = FALSE;
      dcb.fInX = FALSE;
      break;
    }
    case DsrRtsFlowControl:
    {
      dcb.fOutxCtsFlow = FALSE;
      dcb.fOutxDsrFlow = TRUE;
      dcb.fRtsControl = RTS_CONTROL_HANDSHAKE;
      dcb.fOutX = FALSE;
      dcb.fInX = FALSE;
      break;
    }
    case DsrDtrFlowControl:
    {
      dcb.fOutxCtsFlow = FALSE;
      dcb.fOutxDsrFlow = TRUE;
      dcb.fDtrControl = DTR_CONTROL_HANDSHAKE;
      dcb.fOutX = FALSE;
      dcb.fInX = FALSE;
      break;
    }
    case XonXoffFlowControl:
    {
      dcb.fOutxCtsFlow = FALSE;
      dcb.fOutxDsrFlow = FALSE;
      dcb.fOutX = TRUE;
      dcb.fInX = TRUE;
      dcb.XonChar = 0x11;
      dcb.XoffChar = 0x13;
      dcb.XoffLim = 100;
      dcb.XonLim = 100;
      break;
    }
    default:
    {
      ASSERT(FALSE);
      break;
    }
  }
  
  //Now that we have all the settings in place, make the changes
  SetState(dcb);
}

Answer 4

同意xiaohedou(小黑豆)的，再看看baudrate 115200是否可行

Answer 5

问题已解决，SetCommState、GetCommState 可以正常运行，可是奇怪的是，在还是在98下
如果在对话框程序中使用BuildCommDCB是一切正常的，可是在D/V下就不行，而sk/xp中，对话框
和d/v中都正常，可能是microsoft的bug