setting up serial port and writing to following online tutorials - c++

Question

i was reading some online tutorials on how to send a few bytes via the com port.
i solved some problems, but i get stuck on:
WriteFile(hSerial, bytes_to_send, 5, &bytes_written, NULL);
fprintf(stderr, "%d bytes written\n", bytes_written);
the code will output:
- Opening serial port...OK
- Sending bytes...0 bytes written
i would like to send some bytes via the com port to the uart on the micro controller.
this code looks very useful for what i need to do.
the code i'm using:
//
// serial.c / serial.cpp
// A simple serial port writing example
// Written by Ted Burke - last updated 13-2-2013
//
// To compile with MinGW:
//
// gcc -o serial.exe serial.c
//
// To compile with cl, the Microsoft compiler:
//
// cl serial.cpp
//
// To run:
//
// serial.exe
//
#include <windows.h>
#include <iostream>
#include <stdio.h>
using namespace std;
int main()
{
// Define the five bytes to send ("hello")
char bytes_to_send[5];
bytes_to_send[0] = 104;
bytes_to_send[1] = 101;
bytes_to_send[2] = 108;
bytes_to_send[3] = 108;
bytes_to_send[4] = 111;
// Declare variables and structures
HANDLE hSerial;
DCB dcbSerialParams = {0};
COMMTIMEOUTS timeouts = {0};
TCHAR *pcCommPort = TEXT("COM1");
// Open the highest available serial port number
fprintf(stderr, "Opening serial port...");
//hSerial = CreateFile( ComPortName,
// GENERIC_READ | GENERIC_WRITE,
// 0,
// NULL,
// OPEN_EXISTING,
// FILE_ATTRIBUTE_NORMAL,
// NULL);
hSerial = CreateFile(
pcCommPort, GENERIC_READ|GENERIC_WRITE, 0, NULL,
OPEN_EXISTING, FILE_ATTRIBUTE_NORMAL, NULL );
if (hSerial == INVALID_HANDLE_VALUE)
{
fprintf(stderr, "Error\n");
return 1;
}
else fprintf(stderr, "OK\n");
// Set device parameters (38400 baud, 1 start bit,
// 1 stop bit, no parity)
dcbSerialParams.DCBlength = sizeof(dcbSerialParams);
if (GetCommState(hSerial, &dcbSerialParams) == 0)
{
fprintf(stderr, "Error getting device state\n");
CloseHandle(hSerial);
return 1;
}
dcbSerialParams.BaudRate = CBR_38400;
dcbSerialParams.ByteSize = 8;
dcbSerialParams.StopBits = ONESTOPBIT;
dcbSerialParams.Parity = NOPARITY;
if(SetCommState(hSerial, &dcbSerialParams) == 0)
{
fprintf(stderr, "Error setting device parameters\n");
CloseHandle(hSerial);
return 1;
}
// Set COM port timeout settings
timeouts.ReadIntervalTimeout = 50;
timeouts.ReadTotalTimeoutConstant = 50;
timeouts.ReadTotalTimeoutMultiplier = 10;
timeouts.WriteTotalTimeoutConstant = 50;
timeouts.WriteTotalTimeoutMultiplier = 10;
if(SetCommTimeouts(hSerial, &timeouts) == 0)
{
fprintf(stderr, "Error setting timeouts\n");
CloseHandle(hSerial);
return 1;
}
// Send specified text (remaining command line arguments)
DWORD bytes_written, total_bytes_written = 0;
fprintf(stderr, "Sending bytes...");
if(!WriteFile(hSerial, bytes_to_send, 5, &bytes_written, NULL))
{
fprintf(stderr, "Error\n");
CloseHandle(hSerial);
return 1;
}
fprintf(stderr, "%d bytes written\n", bytes_written);
// Close serial port
fprintf(stderr, "Closing serial port...");
if (CloseHandle(hSerial) == 0)
{
fprintf(stderr, "Error\n");
return 1;
}
fprintf(stderr, "OK\n");
// exit normally
std::cin.get();
return 0;
}
further editing the code using GetLastError() results in:
OVERLAPPED o;
std::memset(&o, 0, sizeof(o));
o.Offset = FILE_WRITE_TO_END_OF_FILE;
o.OffsetHigh = -1;
if(!WriteFile(hSerial, bytes_to_send, 5, &bytes_written, &o))
{
//DWORD WINAPI GetLastError(void);
//wprintf(L"Format message failed with 0x%x\n", GetLastError()); // 0x3e3
printf("Error number: %ld\n", GetLastError()); 995 (0x3E3)
// The I/O operation has been aborted because of either a thread exit or an application request.
fprintf(stderr, "Error\n");
CloseHandle(hSerial);
return 1;
}
fprintf(stderr, "%d bytes written\n", bytes_written);
hyperterminal, can detect my app and want me to close it.
regards and thank you.