I don't know if MFC provides a class library that addresses serial
communication. The old version of Visual Studio provided a non-MFC sample.
You may still be able to download it at this link:

http://msdn.microsoft.com/library/default.asp?url=/library/en-us/vcsample98/html
/vcsmpserialsampleforcommunicationsdemonstration.asp

In case you don't know, on Win32 every device is accessed by means of a
handle. Reads of the device are done by passing the handle to ReadFile() and
writes by passing the handle to WriteFile().

You will find a little _hack_ below which presumes the existence of a modem
on COM3, gets a handle to a the serial port, posts a read, sends the Hayes
command "identify" and reads the response.

It should get you started.

Regards,
Will

#include <windows.h>
#include <stdio.h>

int main(int argc, char **argv)
{
char         szBuffer[80];
DCB          dcb = {0};
DWORD        dwRead, dwWritten;
HANDLE       hComm;
OVERLAPPED   ovlr = {0}, ovlw = {0};
COMMTIMEOUTS cto;

// Create events for overlapped operation

ovlr.hEvent = CreateEvent(NULL, TRUE, FALSE, NULL);
ovlw.hEvent = CreateEvent(NULL, TRUE, FALSE, NULL);

// Open the port

hComm = CreateFile("\\\\.\\COM3", GENERIC_READ | GENERIC_WRITE,
           0, NULL, OPEN_EXISTING,
                FILE_ATTRIBUTE_NORMAL | FILE_FLAG_OVERLAPPED, NULL);

// Get the state of the device and modify it

dcb.DCBlength = sizeof(dcb);
GetCommState(hComm, &dcb);
dcb.BaudRate = CBR_9600;
SetCommState(hComm, &dcb);

// Set the timeout parameters (almost completely bogus here)

cto.ReadIntervalTimeout         = 1000;
cto.ReadTotalTimeoutConstant    = 1000;
cto.ReadTotalTimeoutMultiplier  = 1000;
cto.WriteTotalTimeoutConstant   = 1000;
cto.WriteTotalTimeoutMultiplier = 1000;

SetCommTimeouts(hComm, &cto);

// Send a command and receieve a response. Note that
//  we post the receive in advance of sending the
//   command in order not to miss anything

printf("\r\nSending: ATI1\r\n");

ReadFile (hComm, szBuffer, sizeof(szBuffer), &dwRead,    &ovlr);
WriteFile(hComm, "ATI1\r",  strlen("ATI1\r"),  &dwWritten, &ovlw);

// Wait for the receive to complete and display the response

if ( GetOverlappedResult(hComm, &ovlr, &dwRead, TRUE) )
{
 szBuffer[dwRead] = 0;
 printf("Received: %s\r\n", szBuffer);
}

// Close the device

CloseHandle(hComm);

return 0;
}

Hi Manu!

For C++ you could use:

CSerialPort v1.03 - Serial Port Wrapper
http://www.codeproject.com/sys­tem/cserialport.asp

Serial library for C++
http://www.codeproject.com/sys­tem/serial.asp

You always can use raw windows API.

Use CreateFile and open COMx file where x is the number of port to open.
Then I can use WriteFile and ReadFile functions...

You can configure the serial port using SetCommMask, SetupComm,
SetCommState, SetCommTimeouts...