RS232

/* A sample program to illustrate setting up a serial port and writing one byte */

#include <windows.h>

int
main(int argc, char *argv[])
{
  DCB dcb;
  HANDLE hCom;
  BOOL fSuccess;
  char *pcCommPort = "COM1";
  char *buffer = "1234567890";
  unsigned int i;
  unsigned char karakter;
  COMMTIMEOUTS commtimeouts;
  COMSTAT comstat;

  DWORD byteswritten;

  hCom = CreateFile( pcCommPort,
                     GENERIC_READ | GENERIC_WRITE,
                     0,    // comm devices must be opened w/exclusive-access
                     NULL, // no security attributes
                     OPEN_EXISTING, // comm devices must use OPEN_EXISTING
                     0,    // not overlapped I/O
                     NULL  // hTemplate must be NULL for comm devices
                     );

  if (hCom == INVALID_HANDLE_VALUE) {
      // Handle the error.
      printf ("CreateFile failed with error %d.\n", GetLastError());
      return (1);
    }

  fSuccess =  SetupComm( hCom,     // handle to communications device
                         2100,  // size of input buffer
                         10  // size of output buffer
                         );
  if (!fSuccess) {
      printf ("Setupcomm failed with error %d.\n", GetLastError());
      return (2);
  }

  fSuccess = GetCommState(hCom, &dcb);

  if (!fSuccess) {
      // Handle the error.
      printf ("GetCommState failed with error %d.\n", GetLastError());
      return (3);
    }

  // Fill in the DCB: baud=57,600 bps, 8 data bits, no parity, and 1 stop bit.

  dcb.BaudRate = CBR_57600;                    // set the baud rate
  dcb.ByteSize = 8;                            // data size, xmit, and rcv
  dcb.Parity = NOPARITY;                       // no parity bit
  dcb.StopBits = ONESTOPBIT;                   // one stop bit
  dcb.fOutxCtsFlow = FALSE;                    // no CTS output flow control
  dcb.fOutxDsrFlow = FALSE;                    // no DSR output flow control
  dcb.fDtrControl = DTR_CONTROL_ENABLE;        // DTR always high = +12 v.
  dcb.fDsrSensitivity = FALSE;                 // pay no attention to DSR
  dcb.fTXContinueOnXoff = TRUE;                // XOFF continues Tx
  dcb.fOutX = FALSE;                           // XON/XOFF out flow control
  dcb.fInX = FALSE;                            // XON/XOFF in flow control
  dcb.fNull = FALSE;                           // enable null stripping
  dcb.fRtsControl = RTS_CONTROL_DISABLE;       // RTS always low = -12 v.


  fSuccess = SetCommState(hCom, &dcb);

  if (!fSuccess) {
      printf ("SetCommState failed with error %d.\n", GetLastError());
      return (4);
    }

  printf ("Serial port %s successfully reconfigured.\n", pcCommPort);

  printf ("Now trying to write a byte...\n");
  fSuccess = WriteFile( hCom,
                        buffer,
                        1,      // write one byte
                        &byteswritten,
                        NULL    // no overlapping
                        );
  if (!fSuccess) {
     printf ("WriteFile failed with error %d\n");
  }

  CloseHandle(hCom);
  return (0);
}