typedef struct _COMMTIMEOUTS {
    DWORD ReadIntervalTimeout;          /* Maximum time between read chars. */
    DWORD ReadTotalTimeoutMultiplier;   /* Multiplier of characters.        */
    DWORD ReadTotalTimeoutConstant;     /* Constant in milliseconds.        */
    DWORD WriteTotalTimeoutMultiplier;  /* Multiplier of characters.        */
    DWORD WriteTotalTimeoutConstant;    /* Constant in milliseconds.        */
} COMMTIMEOUTS,*LPCOMMTIMEOUTS;