RS232 port programming issue

Discussion in 'MFC' started by KaimTazz, Oct 11, 2007.

  1. KaimTazz

    KaimTazz New Member

    Aug 8, 2007
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    Hello Everybody,
    Please help me to solve the following trouble.
    I want to write an application to send and receive data through com port.
    I am using VC++ .Net 2003 for creating this MFC application.
    I write a Function to write data on com port as follows.
    void CSerialCommTesterDlg ::WriteData ()
    	BOOL ans;
    	int length=0 ;
             UpdateData ();
    	length = m_enter_text.GetAllocLength ();
    	ans=WriteFile(hComm , &m_enter_text, length, &dwWritten, &ovlw);
    	error_no = GetLastError ();
    	if(GetOverlappedResult(hComm ,&ovlw,&dwWritten ,TRUE)==S_OK )
    		m_idc_status.Format("No of Bytes send: %d", dwWritten );
    		UpdateData (FALSE);
    	error_no = GetLastError ();
    I have successfully initialized com port and set the DCB.
    WriteFile() function returns 0, that means it has failed.
    and GetLastError returns 997, i.e. I/O pending, but in this situation dwWritten in GetOverLappedResult() is still giving me the exact no. of bytes written.
    Thus I am not able to send data. Plz help
    Last edited by a moderator: Oct 11, 2007

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