A code to send data on the USB port for Windows

usb.cpp

#include <iostream>
#include <string>
#include <Windows.h>
#include <tchar.h>
#include <stdio.h>
#include <Winbase.h>

HANDLE hCom;

DWORD sendData (const char* data, DWORD size)
{
	DWORD numberOfBytesWritten;

	WriteFile(hCom,
	          data,
	          size,
		  &numberOfBytesWritten,
		  0);

	return numberOfBytesWritten;
}

void PrintCommState(DCB dcb)
{
    //  Print some of the DCB structure values
    _tprintf( TEXT("\nBaudRate = %d, ByteSize = %d, Parity = %d, StopBits = %d\n"),
              dcb.BaudRate,
              dcb.ByteSize,
              dcb.Parity,
              dcb.StopBits );
}

int init_usb(){
   DCB dcb;
   BOOL fSuccess;

   TCHAR *pcCommPort = TEXT("\\\\.\\COM28"); //  For COM Ports gretaer than 9

   //TCHAR *pcCommPort = TEXT("COM3"); // For COM Prts less than or equal to 9

   //Open a handle to the specified com port.
   hCom = CreateFile( pcCommPort,
                      GENERIC_READ | GENERIC_WRITE,
                      0,      //  must be opened with exclusive-access
                      NULL,   //  default 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);
   }

   //  Initialize the DCB structure.
   ZeroMemory(&dcb, sizeof(DCB));
   dcb.DCBlength = sizeof(DCB);

   //  Build on the current configuration by first retrieving all current
   //  settings.
  fSuccess = GetCommState(hCom, &dcb);

  if (!fSuccess)
   {
      //  Handle the error.
      printf ("GetCommState failed with error %d.\n", GetLastError());
      return (2);
   }

   PrintCommState(dcb);       //  Output to console the state of the COM Port before changing

   //  Fill in some DCB values and set the com state:

   dcb.BaudRate = CBR_38400;     //  baud rate
   dcb.ByteSize = 8;             //  data size, xmit and rcv
   dcb.Parity   = NOPARITY;      //  parity bit
   dcb.StopBits = ONESTOPBIT;    //  stop bit
   fSuccess = SetCommState(hCom, &dcb);

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

   //  Get the comm config again.
   fSuccess = GetCommState(hCom, &dcb);

   if (!fSuccess)
   {
      //  Handle the error.
      printf ("GetCommState failed with error %d.\n", GetLastError());
      return (2);
   }

   PrintCommState(dcb);       //  Output to console the state of the COM Port after making the desired changes to the COM Port

   _tprintf (TEXT("Serial port %s successfully reconfigured.\n"), pcCommPort);
}

int main(int argc, char** argv) {
	init_usb(); // initialize the usb

	char *ch = "MD2X1Y4N";
	int size = sendData(ch , sizeof("MD2X1Y4N") );
	if(size != sizeof("MD2X1Y4N")) printf("Error in sending\n");
	else printf("%d sent .Sent succeeded\n",size);

	return 0;
}