Control.com - Nerds in Control

Sealevel Systems (http://www.sealevel.com) includes code samples on the software CD that ships with all serial products. This C++ code sample shows you how to open a COM port, and send & receive data. In this example, data is sent and read at 460K bps, but standard windows ports are limited to 115K bps.

----- Begin Code Sample -----

#include "stdafx.h"

#include 

#include 

#include 

int main(int argc, char* argv[])

{

    char INBUFFER[500];

    char OUTBUFFER[20];

    DWORD        bytes_read    = 0;    // Number of bytes read from port

    DWORD        bytes_written = 0;    // Number of bytes written to the port

    HANDLE       comport      = NULL;  // Handle COM port

 int   bStatus;

    DCB          comSettings;          // Contains various port settings

    COMMTIMEOUTS CommTimeouts;

    strcpy(&OUTBUFFER[0], "The quick brown fox jumped over the lazy dog. \n\r\0");

    // Open COM port

    if ((comport = 

         CreateFile("\\\\.\\COM5",                // open com5:

                    GENERIC_READ | GENERIC_WRITE, // for reading and writing

                    0,                            // exclusive access

                    NULL,                         // no security attributes

                    OPEN_EXISTING,              

                    FILE_ATTRIBUTE_NORMAL,

                    NULL)) == INVALID_HANDLE_VALUE)

    {

        // error processing code goes here

    }

    // Set timeouts in milliseconds

    CommTimeouts.ReadIntervalTimeout         = 0; 

    CommTimeouts.ReadTotalTimeoutMultiplier  = 0; 

    CommTimeouts.ReadTotalTimeoutConstant    = 100;

    CommTimeouts.WriteTotalTimeoutMultiplier = 0;

    CommTimeouts.WriteTotalTimeoutConstant   = 100;

    bStatus = SetCommTimeouts(comport,&CommTimeouts);

    if (bStatus != 0)

    {

        // error processing code goes here

    }

    // Set Port parameters.

    // Make a call to GetCommState() first in order to fill

    // the comSettings structure with all the necessary values.

    // Then change the ones you want and call SetCommState().

    GetCommState(comport, &comSettings);

    comSettings.BaudRate = 460800;

    comSettings.StopBits = ONESTOPBIT;

    comSettings.ByteSize = 8;

    comSettings.Parity   = NOPARITY;

    comSettings.fParity  = FALSE;

    bStatus = SetCommState(comport, &comSettings);

    if (bStatus == 0)

    {

        // error processing code goes here

    }

    while(!kbhit())

    {

  bStatus = WriteFile(comport,              // Handle

       &OUTBUFFER,      // Outgoing data

       48,              // Number of bytes to write

       &bytes_written,  // Number of bytes written

       NULL);

        if (bStatus != 0)

        {

            // error processing code here

        }

        bStatus = ReadFile(comport,   // Handle

                &INBUFFER,            // Incoming data

                500,                  // Number of bytes to read

                &bytes_read,          // Number of bytes read

                NULL);

        if (bStatus != 0)

        {

            // error processing code goes here

        }

        // code to do something with the data goes here

    }

    CloseHandle(comport);

 return 0;

}