Subj : rs232 access serialport
To   : borland.public.cpp.borlandcpp
From : Dj. Bouma
Date : Wed Sep 22 2004 12:20 am

Hello all,

can anyone help me out i'm new to this and cant seem to get the serialport
working.
if i start with CSerialComm.OpenSerialPort() , and it comes to
CreateFile(...) m_hCom gets a value
of 960 every time. the second cout gives me the value of 6 wich is imho an
invalid handle value.
i took out some code in order not to create a to big message.
My question is what am i doing wrong ? why isn't it getting a propper handle
?



[headerfile]
#include<windows.h>
#include<stdio.h>
#include<iostream.h>        // only needed for cout

class CSerialComm
{

public:

    bool     m_ComIsOpen;           // is comport already open
    bool     m_bPortReady;          // is port after initialisation ready
    HANDLE   m_hCom;                // handle to commport
    DCB      PortDCB;               // dcb objects to change
    DCB      OldDcb;                // origional DCB settings to restore
    COMMTIMEOUTS m_CommTimeouts;
    char     sBuffer[128];
    char     cPortName[5];          //comportname eg. COMxx



    CSerialComm();
    virtual ~CSerialComm();
    TCommPort();
    bool OpenSerialPort();
    bool CloseSerialPort();
    bool Write(char *buffer);
    bool Read(char *buffer, unsigned int ByteCount);

private:
    bool RestoreDcb();
    bool ReadConfig();

};
#endif


[cpp file]
#include "Tcomm.h"
#include "defenitions.h"

CSerialComm::CSerialComm()
   :m_ComIsOpen(false),
//   m_CommPort("COM1"),
   m_hCom(0)
{
}

CSerialComm::~CSerialComm()
{

    CloseHandle(m_hCom);
}

bool CSerialComm::OpenSerialPort()
{

  strcpy(cPortName,"COM1");

  m_hCom = CreateFile ( cPortName,GENERIC_READ | GENERIC_WRITE, 0, NULL,
                      OPEN_EXISTING, 0, NULL);
     printf( "hCom= : %d\n " , m_hCom );   <======================= h_mCom
gets a value of 960 every time

    cout << "after handle: 1 :" << GetLastError() << endl;  <=============
lasterror = 0

  // if fail to open the port, return FALSE.
  if ( m_hCom == INVALID_HANDLE_VALUE )
   {
    // Could not open the port.
      cout << "could not get propper handle: " << GetLastError() << endl;
      return FALSE;
   }
  else

    cout << "after if invalid handle: " << GetLastError() << endl;  <=====
lasterror = 6


    PortDCB.DCBlength = sizeof(DCB);
    cout << "sizeofdcb: " << GetLastError() << endl;  <===== lasterror = 6

  /* Get the default port setting information.*/
  if ( !GetCommState ( m_hCom, &PortDCB) );
   {
      /* got problems closeport */
      CloseSerialPort();
   }
 /* start populating object dcb */

[ cut out ]

  /* Configure the port according to the
     specs of the DCB structure.*/
  if( !SetCommState( m_hCom,&PortDCB ) );
    {
      /* commstate could not be set */
      CloseSerialPort();
    }
    /* we succeeded */
  m_ComIsOpen = TRUE ;
  return TRUE;
}

.