Проблемы при передаче данных через COM порт

    
    DWORD fb;
    char rx, wx;
    
    wx = 0xff;
    if (!WriteFile(COM, &wx, 1, &fb, NULL) || (fb != 1))
    {
        printf("WriteFile1() failed\n");
        CloseHandle(COM);
        COM = 0;
        return -1;
    }
    
    if (!ReadFile(COM, &rx, 1, &fb, NULL))
    {
        printf("ReadFile() failed\n");
        CloseHandle(COM);
        COM = 0;
        return -1;
    }
    else if (fb != 1)
    {
        printf("Timeout\n");
        CloseHandle(COM);
        COM = 0;
        return -1;
    }

    DCB dcb;
    memset(&dcb, 0, sizeof(DCB));
    dcb.DCBlength = sizeof(DCB);
    GetCommState(COM, &dcb);
    dcb.BaudRate  = 19200;
    dcb.ByteSize  = 8;
    dcb.fBinary   = TRUE;
    dcb.fParity   = FALSE;
    dcb.Parity    = NOPARITY;
    dcb.StopBits  = 1;
    SetCommState(COM, &dcb);