I recently started experimenting with Shelly devices, and I must say, they’ve been a fantastic addition to my smart home setup. I installed two Shelly units behind some motion sensors, connecting them to the SW terminals. The idea was to have the Shelly devices control my lights based on motion detection. One of them worked seamlessly—both through the app and the motion sensor. However, the other unit was giving me some trouble. It responded perfectly through the app and FHEM but refused to trigger via the motion sensor. This inconsistency was puzzling, and I wanted to figure out what was going on.
After some research and trial and error, I realized that the issue might be related to the voltage on the SW port. When I measured it, I found 5V present even when the device was off. I started questioning whether this voltage could be causing the sensor to malfunction or not register the signal correctly. I tried different configurations, including negating the input signal, but nothing seemed to work. The device just wouldn’t trigger based on motion.
I decided to dive deeper into the problem. I reached out to the community for advice and found that others had encountered similar issues. Some suggested checking the wiring and ensuring that the ground connections were secure. Others recommended verifying the firmware version and updating if necessary. I followed these steps, but the problem persisted.
Then, I stumbled upon a suggestion to test the motion sensor independently. I disconnected it from the Shelly and used a multimeter to check its output. It turned out that the motion sensor itself was malfunctioning, which explained why the Shelly wasn’t responding. Replacing the sensor with a new one solved the problem, and now both Shelly units are working as intended.
This experience taught me the importance of systematically troubleshooting each component in a smart home setup. It’s easy to assume that the issue lies with the more complex device, but sometimes, the problem is with the simplest part of the system. I’m now more confident in diagnosing and resolving similar issues in the future. If you’re facing challenges with your Shelly devices or motion sensors, don’t hesitate to reach out to the community for support—it’s a invaluable resource!