Controlling external smart switches using a Cerbo GX

Hi all,

I have a colleague who’s looking at getting a 8KVA Multiplus II with a Cerbo GX. He’s very interested in starting his swiming pool pump and geyser when his batteries are fully charged.

So I recommended to go the Pi / Home Assistant route, but he wants to know what is possible with the Cerbo GX directly.

My understanding is that the first relay is only for generators and not user controllable, right?
Or can you run cron jobs on the GX and control both relays (and thus use it to turn on/off an external contactor/bigger relay and thus switch on or off external devices)?

Any other software you can run directly on the GX?


You can set the first relay function to “manual” as well, and then you can control it via mqtt, modbus (I think?), or DBus. Yes, you can do that on the GX itself, but you will probably have to write your own code to do it.

Edit: Of course you can also run the large image, and just use nodered.


Morning, I am keep to learn how to control/automate my EW Link switches, using information from the Victron system. I have a Cerbo as part of the system, wifi connected. Typical items I would like to do are;

  • When batt < x%, switch on city power
  • When load > y kVA, switch off pool, etc

Regards, Wolley

NodeRED or HomeAssistant, is the intelligence you are looking for.

I use NodeRED to switch on a geyser if the loads are low, and off when I draw more than 500w from Eskom.