Question

I’m trying to communicate with a virtual serial port using MinGW on a Windows 7 x64 machine. According to the Device Manager my device is available at COM27. I have this code:

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

    int main()
    {
        HANDLE hComm;

        const WCHAR FileFullPath[] = {L"COM1"} ;


        hComm = CreateFile( (LPCTSTR)FileFullPath,
                            GENERIC_READ | GENERIC_WRITE,
                            0,
                            0,
                            OPEN_EXISTING,
                            FILE_FLAG_OVERLAPPED,
                            0);

        if (hComm == INVALID_HANDLE_VALUE) {
            printf("Invalid value: %d\r\n", GetLastError());
        }
    }

Which gives me a ERROR_FILE_NOT_FOUND (error code 2). Output:

Invalid value: 2

If I change the port name to COM1 (another port that I have), fails to create the file with error 1450, or ERROR_NO_SYSTEM_RESOURCES.

What am I doing wrong? I accept alternatives to MinGW, it’s not mandatory.

Answer 1

The COM port name should be \\.\COM1 (\\\\.\\COM1 after escaping the backslashes), not COM1.