Modbus binding for SMA PV Inverter

[FlArne (Arne)]

Hi There,

i am a proud owner of a new PV-System with a “SUNNY TRIPOWER 8.0” Inverter. This one can communicate via Modbus. I am using the attached thing to communicate with the Inverter.

I am using Openhab 2.4 (and i am affraid to update it because most of the things are working fine)

Anyway the communication with the Inverter is also running fine most of the time, Openhab shows me the correct Power most of the time, but then all of a sudden, the shown power drops by the factor of 2 (approx) and then jumps back to the correct power after a very short while.

Does someone have an idea what the problem could be? Tbh, i am rather thinking of an EMI/EMC Problem on the line then on a software issue in Openhab, what do you think?

Br, Arne

Bridge modbus_things.txt (3.1 KB)

[rossko57]

@FlArne

Tbh, i am rather thinking of an EMI/EMC Problem on the line

TCP/IP comms tend to work/not-work rather than present false data in response to interference (unlike serial comms).

More recent binding versions are better at handling unusual TCP fragmentation, which can in certain conditiions give undetected data changes; but that doesn’t help you, you cannot retrofit versions.

You might try giving everything less work to do, to improve the odds

Modbus performance management in openHAB 2

These notes apply to modbus binding version 2.x This is not a Modbus how-to, but rather a tuning guide for advanced users. Related - Modbus error management in openHAB OpenHAB performance issues with Modbus openHAB is often deployed on limited performance systems, and extensive use of Modbus devices can highlight limitations. That is not about Modbus technology in particular, but more about the side effects of any polling tech within openHAB. If you have only a handful of Modbus connected O…

[FlArne (Arne)]

So, maybe i should try the V3 of Openhab on another system in order to check, if the communications is also faulty. Thanks for the information.

[rossko57]

@FlArne

maybe i should try the V3 of Openhab

I doubt that will make any difference, of itself.

@rossko57

You might try giving everything less work to do, to improve the odds

applies to OH2 as well.

Bear in mind all this is based on skimpiest of info, some hard data might help. Actual numbers, frequency of problem, config, logs.

Separate issue, if you must stay on OH2, consider at least updating to “final version” 2.5.12. You will no longer find add-ons etc.available for OH2.4 due to repository changes.