Communication between OH4 instances

Hi Community,

I would like to knw what is the best way to communicate between two OH4 instances in my home. MQTT? Websocket?

The background:
I had run a good OH2.5 on Rpi3B+ for year and used Aotec Gen5 stick to control my zwave nodes.
This summer I migrated to OH4 running on Rpi4 but tthan I realized that my zwave stick does not works with Rpi4. This is a known issue so connected it through an usb2 hub. Now the stick works but the seems the radiationis week and the farest nods loose the signal often. Than I got an idea to restart my old Rpi3B+ and run the ZwaveJS2MQTT on it. It got better but this program did not recognized some of my zwave nodes (even if they are listed in teh library). Step forward I installed a pure OH4 on the Rpi3B+ and voila: it can manage the entire zwave network. So now I just need to solve the 2ways communication between the Rpi3B+ to the master OH4 on Rpi4 somehow…
I would prefer MQTT but I cannot see how to create MQTT client.

Thnaks for the ideas

The easiest to set up will be the Remote openHAB binding: Remote openHAB - Bindings | openHAB.

Zwave is a mesh network. If the farthest nodes lose signal, that means the mesh is not good. To improve the mesh it might be easier to get some cheap mains powered Zeave devices you can put between the nodes that do not work and the controller or other nodes. Smart plugs are good for this. They also make repeaters which only improve the mesh but don’t have any other function. At least with a smart plug you have the option to control something.

See MQTT Event Bus [;] for an MQTT Event Bus implementation.

See the Getting Started Tutorial, in particular Adding Things - Advanced | openHAB.

This isn’t really different from how you would have used ZwaveJS2MQTT with OH though. You create the MQTT Generic Thing for each device and create a Channel for each sensor/actuator.

But you don’t need to implement the MQTT stuff yourself with the Event Bus Rule Template and doing this sort of thing is the whole reason the Remote openHAB binding exists in the first place.

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The Remote Openhab binding does work very well, I am utilizing it to allow my HestiaPi thermostat communicate with my main openhab server, it’s much easier to set up automation with the new UI than it was with Openhab 2.5.

Thanks for the hints. I cannot find the OpenHab remote server binding in OH4. Is there any issue why it has not been upgraded to OH4 yet?


It is there :wink:

Yup, it is really easy to create. I created many generic MQTT things for my tasmota and zigbee staff but I was not aware that I can insert an new MQTT topic this way too.
Thanks again it is a perfect solution.

Ohh yeah, just my instance translated to Hungarian :crazy_face: