the said:
I am using windows xp professional.....can u help me or suggest some
book or site where i can get some material on it
You use the same primitives that you use for files to open a
communications port. Here is the code to open COM1 for instance:
HANDLE hComm;
char *gszPort = “COM1”;
hComm = CreateFile( gszPort,
GENERIC_READ | GENERIC_WRITE,
0,
0,
OPEN_EXISTING,
FILE_FLAG_OVERLAPPED,
0);
You use that handle to call ReadFile and WriteFile APIs. Communications
events are handled by SetCommMask, that defines the events that you want
to be informed about (break, clear-to-send, ring, rxchar, and others).
You can change the baud rate managing the device control block
(SetCommState), etc. As with network interfaces, serial line programming
is a black art.Here is an example that is distributed with the Microsoft
SDK:
#include <windows.h>
#include <stdio.h>
int main(int argc, char *argv[])
{
DCB dcb;
HANDLE hCom;
BOOL fSuccess;
char *pcCommPort = "COM1";
hCom = CreateFile( pcCommPort,
GENERIC_READ | GENERIC_WRITE,
0, // must be opened with exclusive-access
NULL, // no security attributes
OPEN_EXISTING, // 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);
}
// Build on the current configuration, and skip setting the size
// of the input and output buffers with SetupComm.
fSuccess = GetCommState(hCom, &dcb);
if (!fSuccess)
{
// Handle the error.
printf ("GetCommState failed with error %d.\n", GetLastError());
return (2);
}
// Fill in DCB: 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
fSuccess = SetCommState(hCom, &dcb);
if (!fSuccess)
{
// Handle the error.
printf ("SetCommState failed with error %d.\n", GetLastError());
return (3);
}
printf ("Serial port %s successfully reconfigured.\n", pcCommPort);
return (0);
}