If no initialization is required, then return RETURN_SUCCESS.\r
If the serial device was successfully initialized, then return RETURN_SUCCESS.\r
If the serial device could not be initialized, then return RETURN_DEVICE_ERROR.\r
If no initialization is required, then return RETURN_SUCCESS.\r
If the serial device was successfully initialized, then return RETURN_SUCCESS.\r
If the serial device could not be initialized, then return RETURN_DEVICE_ERROR.\r