Serial communication in C using Loopback on cable - c

Question

I'm trying to create a simple Serial communication in C. I'm having some problems when receiving the data. I appears that the buffer size is not correct, or the data is not being retrieved from the Serial.
This is how I have created the code:
#include <stdio.h>
#include <conio.h>
#include <windows.h>
#define BUFFERLENGTH 256
int main () {
HANDLE comm;
BOOL wComm;
char buf[] = "abcd1234 \r\n";
DWORD dwNoBytesToWrite = sizeof(buf);
DWORD dwNoBytesWritten = 0;
BOOL Read_Status;
DWORD dwEventMask;
char SerialBuffer[BUFFERLENGTH+1];
char finalStr[BUFFERLENGTH+1] = "";
DWORD NoBytesRead;
int i = 0;
comm = CreateFileA("\\\\.\\COM7",
GENERIC_READ | GENERIC_WRITE, //Read/Write
0, // No Sharing
NULL, // No Security
OPEN_EXISTING,// Open existing port only
0, // Non Overlapped I/O
NULL);
if (comm == INVALID_HANDLE_VALUE)
printf("Error in opening serial port");
else
printf("opening serial port successful");
// set short timeouts on the comm port.
timeouts.ReadIntervalTimeout = 1;
timeouts.ReadTotalTimeoutMultiplier = 1;
timeouts.ReadTotalTimeoutConstant = 1;
timeouts.WriteTotalTimeoutMultiplier = 1;
timeouts.WriteTotalTimeoutConstant = 1;
if (!SetCommTimeouts(comm, &timeouts))
printf("setting port time-outs.");
//Config
dcbSerialParams.DCBlength = sizeof(dcbSerialParams);
Write_Status = GetCommState(comm, &dcbSerialParams); //retreives the current settings
if (Write_Status == FALSE) {
printf("\n Error! in GetCommState()");
CloseHandle(comm);
return 1;
}
dcbSerialParams.BaudRate = CBR_57600; // Setting BaudRate = 9600
dcbSerialParams.ByteSize = 8; // Setting ByteSize = 8
//dcbSerialParams.
dcbSerialParams.StopBits = ONESTOPBIT; // Setting StopBits = 1
dcbSerialParams.Parity = ODDPARITY; // Setting Parity = None
// Write Serial
wComm = WriteFile(
comm,
buf,
dwNoBytesToWrite,
&dwNoBytesWritten,
NULL
);
if (!wComm)
{
printf("Problem writing to comm");
}
// MASK
Read_Status = SetCommMask(comm, EV_RXCHAR);
if (Read_Status == FALSE)
printf("\n\nError! in Setting CommMask");
else
printf("\n\nSetting CommMask successfull");
// WAITING DATA
printf("\n\nWaiting for Data Reception");
Read_Status = WaitCommEvent(comm, &dwEventMask, NULL);
if (Read_Status == FALSE)
{
printf("\n Error! in Setting WaitCommEvent()");
}
else
{
//fflush(stdin);
printf("\n\nCharacters Received\n");
do
{
if (ReadFile(comm, SerialBuffer, BUFFERLENGTH, &NoBytesRead, NULL))
{
printf("%c", SerialBuffer[i]);
strcat(finalStr, SerialBuffer[i]);
i++;
}
} while (NoBytesRead > 0);
}
CloseHandle(comm);
return 0;
}
Here is what I'm receiving as the response: