Reading controller signals
When troubleshooting your system's sensor controllers, you may see different LEDs either constantly glowing or blinking. These LEDs can help you identify whether sensors or controllers are performing well and whether they need to be adjusted. To access these controllers you should remove the upper cover of the system. You can follow the step 1 of the Sensor Calibration guide to find out how to do that. Below is a picture of a controller and numbered zones of interest:
1 - Green blocked sensor LED. Indicates that something is blocking the sensors (is off on picture since nothing blocks the sensors)
2 - Green power LED. Indicates that controller is powered on
3 - Sensor signal LEDs. Explained below
4 - Connection to the sender sensor bar (red cable)
5 - Connection to the receiver (Empfänger) sensor bar (black cable)
Below is a picture of sensor signal LEDs up close:
RX - Receiver connection LED. Glows red is receiver is not connected
TX - Sender connection LED. Glows red if sender is not connected
B - LED displays mode of operation. Normally should blink once each 0.5 seconds
C, D, E, F - 4 LEDs indicate signal strength. LED D glowing green indicates best signal. LEDs C, D or E glowing yellow (only one at a time) indicate good signal. LED F glowing yellow indicates bad signal. Yellow glow rapidly switching between multiple LEDs indicates inconsistent signal strength between those levels. If all LEDs are off, then either something blocks the sensors or sensors can't see each other
Here is a sample video of a working controller with beams being shortly blocked. Pay attention to LED 1 that lights up and LEDs C, D, E, F that stop glowing when sensors get blocked since no signal passes through.
Here is a sample picture of a controller with sensor bars disconnected, thus red LEDs
Troubleshooting weak sensor signal issues
If both sensors (sender and receiver) are connected and face each other but the signal is not strong enough (LED F glowing or none of C, D, E, F glowing ) then it means that sensor bars are not perfectly aligned, so some signal strength gets lost because sender misses the receiver. To prevent this from happening fix one of the sensor bars as usual, so red glass part is facing parallel to the wall and towards to other sensor. Unscrew the opposite sensor bar so it can wiggle slightly. Try to tilt this sensor bar towards or away from the wall so that the red glass part faces the opposite sensor. You should see how signal strength changes depending on the tilt angle. If you can't reach a good signal with all sensors screwed in place it means that they are not correctly physically aligned. You would then need to adjust your setup until you see a good signal with all parts in place.
Below is the video that shows the change in signal strength depending on the tilt angle:
If after perfectly aligning both sensor bars the signal is still too weak, then check whether sensors are clean: Sensor Cleaning. Then perform Sensor Calibration. Check the signal strength again after cleaning.