Control.com - Nerds in Control

Hi, everyone.

I've got a project that sending control commands to the module (small device that moves camera pan and tilt) through serial port with C, C++, using VC++.

I want to send commands like these, "A50","B85".
then the device move.

I try to compile&run that open port and set the parameter the followings:

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

int main(int argc, char *argv[])
{
   DCB dcb;
   HANDLE hCom;
   BOOL fSuccess;
   char *pcCommPort = "COM2";

   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);
   }

   
   dcb.BaudRate = 9600;     // 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);

But I'm stuck with how to write the commands to serial port.
Does anybody can help???
Please reply.

A simple example would be to create a character string containing the data you want to send:

uchar StringA50[3] = {'A','5','0'};
uchar StringB85[3] = {'B','8','5'};

To send "A50" you would just issue the command:

status = WriteFile(hCom,              // Handle
                      &StringA50,         // Address of Outgoing data
                      3,           // Number of bytes to write
                      &bytes_written,       // Returned number of bytes written
                      NULL);

The number of bytes actually written (which should be 3) will be returned in bytes_written and the overall status returned in status. If status indicates an error, you can call GetLastError to see the actual error code returned.

If you want to dynamically build the strings you could :<br>
StringA50[0] = 'A';<br>
StringA50[1] = '5';<br>
StringA50[2] = '0';<br>
instead of defining them as constants.

Hope this helps. Sealevel Systems (http://www.sealevel.com) offers C++ and VB code samples on the CD that ships with their products. They offer RS-232/422/485 and Digital I/O products in a variety of interfaces and form factors, including PCI, USB, Ethernet, PC/104, and more. They also offer technical support and a Lifetime Warranty on their products.