Hmm… we could try couple of things to diagnose further
- Shut down openHAB and query the data using modpoll. If it works there, the likely suspect is openHAB
- Create ‘sniffing’ virtual serial port using socat and point openHAB to use that one. All in/out traffic would be recorded. This would give further indication if the root issue is in openHAB
Got an old laptop you can rig as a serial monitor and see what is really on the wire? Going to save a lot of finger pointing by direct observation.