In order to enable a simple status reporting, most of the ML-R board feature a dedicated LED. It produces following signals:
- 1 short blink - everything is fine. That means that the device is alive and works without any problem.
- 2 short blinks - an event occurred that resulted in a warning. The problem is not serious and the device still works but it may be a good idea to check the reason. For example, if the device misses a CAN Bus message, it will report warning. Cycling power will reset the LED. If it is a CAN Bus device, a complete warning message will be sent to the main microcontroller.
- 3 short blinks - an error occurred and the device probably does not work normally. It still means that is alive, but a serious problem happened. Cycling power will reset the LED. If it is a CAN Bus device, a complete error message will be sent to the main microcontroller or at least transmission will be tried.
- LED off - the device doesn't work at all.
- Some other patterns are possible, like a long LED-on period for calibration and similar actions, to signal action start and end.
The LED consumes extremely small amount of current: 1 mA in average 10% of the time, so the average current is 100 μA.