C / C++ / MFC

#include "stdafx.h"

#include <stdio.h>
#include <conio.h>
#include <string.h>

#define STRICT
#define WIN32_LEAN_AND_MEAN
#include <windows.h>

int _tmain(int argc, _TCHAR* argv[])
{
	int ch;
    HANDLE screen = GetStdHandle(STD_OUTPUT_HANDLE);


	//---------------------------
    // Get keyboard mode
	printf("Getting keyboard mode\n");
    HANDLE keyboard = GetStdHandle(STD_INPUT_HANDLE);
    DWORD mode;
    if (!GetConsoleMode(keyboard, &mode))
	{
		printf ("GetConsoleMode failed with error %d.\n", 
			GetLastError());
	}
	// Set for raw reading
	printf("Setting keyboard mode\n");
    mode &= ~ ENABLE_PROCESSED_INPUT;
    if (!SetConsoleMode(keyboard, mode))
	{
		printf ("SetConsoleMode failed with error %d.\n", 
			GetLastError());
	}


	//---------------------------
    // Configure the comm port.
	printf("opening comm port\n");
	TCHAR *port_name = TEXT("COM1"); // Keyspan port
    HANDLE file;
    file = CreateFile(port_name,
        GENERIC_READ | GENERIC_WRITE,
        0, 
        NULL, 
        OPEN_EXISTING,
        0,
        NULL);
    if ( INVALID_HANDLE_VALUE == file) {
		printf ("CreateFile failed with error %d.\n", 
			GetLastError());
		CloseHandle(file);
        if ( _kbhit() ) {
            ch = _getch();
        }
        return 1;
    }

    // Get the current DCB.
	printf("Getting com state\n");
    DCB port;
	SecureZeroMemory(&port, sizeof(port));
    port.DCBlength = sizeof(port);
    if (!GetCommState(file, &port))
	{
		printf ("GetCommState failed with error %d.\n", 
			GetLastError());
		CloseHandle(file);
        if ( _kbhit() ) {
            ch = _getch();
        }
        return 1;
	}

	// Build the state using a convience function
	// By default disables Xon/Xoff and Hardware flow control
	// Enable Xon/Xoff by appending with x
	// Enable hardware by appending with p
	printf("Building com state\n");
	TCHAR *DCBsettings = TEXT("baud=9600 parity=n data=8 stop=1");
    if (!BuildCommDCB(DCBsettings, &port))
	{
		printf ("BuildCommDCB failed with error %d.\n", 
			GetLastError());
		CloseHandle(file);
        if ( _kbhit() ) {
            ch = _getch();
        }
        return 1;
	}

	// Set the com port state
	printf("Adjusting com settings\n");
    if (!SetCommState(file, &port))
	{
		printf ("SetCommState failed with error %d.\n", 
			GetLastError());
		CloseHandle(file);
        if ( _kbhit() ) {
            ch = _getch();
        }
        return 1;
	}

    // Set timeouts on the comm port.
	printf("Setting port time-outs.\n");
    COMMTIMEOUTS timeouts;
    timeouts.ReadIntervalTimeout = 1;
    timeouts.ReadTotalTimeoutMultiplier = 1;
    timeouts.ReadTotalTimeoutConstant = 1;
    timeouts.WriteTotalTimeoutMultiplier = 1;
    timeouts.WriteTotalTimeoutConstant = 1;
    if (!SetCommTimeouts(file, &timeouts))
	{
		printf ("SetCommTimeouts failed with error %d.\n", 
			GetLastError());
		CloseHandle(file);
        if ( _kbhit() ) {
            ch = _getch();
        }
        return 1;
	}


	//---------------------------
	// Write request for device id
	printf("Writing *idn?<cr> to port\n");
    char init[] = "*idn?\n";
    DWORD written;
    if (!WriteFile(file, init, sizeof(init), &written, NULL))
	{
		printf ("WriteFile failed with error %d.\n", 
			GetLastError());
	}
    if (written != sizeof(init))
	{
		printf("not all data written to port\n");
	}


	//---------------------------
    // basic terminal loop:
    char buffer[256];  
	// Make sure this is blanked for printf
	memset(&buffer[0], 0, sizeof(buffer));
    DWORD read;
    char dataReq[] = "fetch? 3\n";
	int i;
    do {
        // check for data on port and display it on screen.
        if( !ReadFile(file, buffer, sizeof(buffer), &read, NULL) )
		{
			// Read successful
			printf ("ReadFile failed with error %d.\n", 
				GetLastError());
		}
        if (read){
			printf ("Characters read = %d.\n", 
				read);
			// There is data in the buffer
			for(i=0; i<(read+1); i++)
			{
				printf("%d ", buffer[i]);
			}
			printf("\n");

			printf("%s\n", buffer);

			// Reset all elements to zero
			memset(&buffer[0], 0, sizeof(buffer));

			Sleep(1000); // Pause 1 second for the slow human

			// Now ask for a measurement
			printf("Writing fetch? 3<cr> to port\n");
			if (!WriteFile(file, dataReq, sizeof(dataReq), &written, NULL))
			{
				printf ("WriteFile failed with error %d.\n", 
					GetLastError());
			}
			if (written != sizeof(dataReq))
			{
				printf("not all data written to port\n");
			}

		}
        // check for keypress, and write any out the port.
        if ( _kbhit() ) {
            ch = _getch();
            WriteFile(file, &ch, 1, &written, NULL);
        }
    // until user hits ctrl-backspace.
    } while ( ch != 127);


	//---------------------------
    // Close everything.
    CloseHandle(keyboard);
    CloseHandle(file);
    return 0;
}

#include <TCHAR.H>

TCHAR szFilter[512];

memset(szFilter, 0, sizeof(szFilter));   // Zero szFilter
_tcscpy_s(szFilter, _countof(szFilter), _T("All files"));
int i = _tcslen(szFilter);
TCHAR Ch1 = szFilter[i + 2];      // Place a debug here .. Ch1 will be trash .. my nice zeroed buffer is toast

memset(szFilter, 0, sizeof(szFilter));    // Zero szFilter
_tcscpy_s(szFilter, _tcslen(_T("All files"))+1, _T("All files"));
TCHAR Ch2 = szFilter[i + 2];      // Place a debug here .. Ch2 will be 0 as expected