send /receive frame serial line

[ikbel borcheni]

Hi,I use serial line communication(RS232) to send/receive data using 2 PC. The port COM is opened succesfully but the problem is that read(reception) and write(sending) functions do not work(there is no error in debugging).I use PORT COM1 and COM4

int CCommunicationSérie::OpenCom(DWORD bauderate,CString portcom)
{
 
//    DWORD m_EventMask;
    BOOL  m_bPortReady;    
    memset(&m_overlapped,0,sizeof(m_overlapped));
       m_hCom = CreateFile((LPCSTR)portcom,
        GENERIC_READ | GENERIC_WRITE,
        0,
        NULL,
        OPEN_EXISTING,
        FILE_FLAG_OVERLAPPED,                      
        NULL);               
    if(m_hCom==INVALID_HANDLE_VALUE)
        return 1;
    if ((m_bPortReady=GetCommState(m_hCom,&m_dcb))==0)
    {
        CloseHandle(m_hCom);
        return 2;
    }
 
    //ClearCommBreak(m_hCom);
    //FillMemory( &m_dcb,0, sizeof(m_dcb));
    //SetupComm( m_hCom, m_nInputBufferSize, m_nOutputBufferSize );
    //::GetCommMask( m_hCom, &m_EventMask );
   // ::SetCommMask( m_hCom, 0 );    
    m_dcb.fBinary=1;
    m_dcb.fParity=0;
    m_dcb.fNull = 0; 
    m_dcb.fDsrSensitivity=1;          
    m_dcb.fOutX=0;
    m_dcb.fInX=0;
 
    m_dcb.XonLim =500;
     m_dcb.XoffLim =1;
    m_dcb.EofChar = '$';
    m_dcb.fAbortOnError=1;
     m_dcb.fOutxDsrFlow=1;
    m_dcb.fOutxCtsFlow=1;
    m_dcb.fDtrControl=DTR_CONTROL_ENABLE;
    m_dcb.fRtsControl=RTS_CONTROL_ENABLE;      
    m_dcb.DCBlength = sizeof(DCB);
 
    m_dcb.BaudRate =bauderate;//9600
    m_dcb.ByteSize = 8;
    m_dcb.Parity =NOPARITY;
    m_dcb.StopBits =ONESTOPBIT;
 
      m_bPortReady=SetCommState(m_hCom, &m_dcb); 
       if(m_bPortReady==0) { CloseHandle(m_hCom);return 3;}
 
      }
 
 
    //vider les tampons
   PurgeComm(m_hCom,PURGE_TXABORT|PURGE_RXABORT|PURGE_TXCLEAR|PURGE_RXCLEAR); 
 MessageBoxA("ouverture du port","",MB_OK);    
   return 0;
}
 

writing:

 bool CCommunicationSérie::WriteCom()
 {
   DWORD NbBytesWritten=0;
  DWORD size=3;
 
 
  //LPBYTE write_buffer=new BYTE[1];write_buffer[0]=0x01;
  const char* write_buffer=new char[3];
 write_buffer="1$";
   if(WriteFile(m_hCom,(LPCVOID)write_buffer,size,&NbBytesWritten,&m_overlapped)==0)
   {
      delete[](write_buffer);
        MessageBoxA("erreur","",MB_OK);            
      return true;//error
   }
   //delete[](write_buffer); 
   MessageBoxA("succés","",MB_OK);              
   return false;
 
 }
 

reading

bool CCommunicationSérie::ReadCom()
{
  char* read_buffer=new char[5];    
  DWORD nNumberOfBytesToRead=3;
  DWORD NumberOfBytesRead;
  LPVOID ReadBuffer=NULL;
  DWORD size=3;
 
   DWORD dwErrorMask ;
   COMSTAT cs; // structure
 
   ClearCommError(m_hCom, &dwErrorMask , &cs); //initialise cs
   if( cs.cbInQue>=size)
   { 
     if (ReadFile (m_hCom,ReadBuffer,nNumberOfBytesToRead, &NumberOfBytesRead, &m_overlapped))
      {
        if (NumberOfBytesRead == size)
        {
           read_buffer=(char*)ReadBuffer;
                   MessageBoxA("sucées","",MB_OK);
            return false;
        }
      }
   MessageBoxA("erreur","",MB_OK);              
   return true;
   }
   MessageBoxA("erreur","",MB_OK);            
  return true; 
}
 

thanks for help

[Banfa]

Are you sure the hardware is right? That is are you sure that you are using the correct cable, a NULL modem?

You can easily check by just using a terminal program (HyperTerminal, dare I say it_. on each PC which should be able to communicate if the cable is correct.

[ikbel borcheni]

I'm using 2 USB to serial converters (one for each PC) and they are related with a plug (female female).

[Banfa]

You mean they are connected with a plug ?

Have you tried the connection using Hyper-terminal (or some other terminal program)?

A standard female-female converter is not a NULL modem. I NULL modem crosses some of the connections rather than providing a straight through connection which is important because you need to connect tx-line of 1 PC to the rx-line of the other and vice versa.

Like I said do not try to guess if your hardware is correct, test it and confirm that it is correct using Hyper Terminal.