Multiple on/off inputs for monitoring

Sorry if this has already been covered, but what I’m looking for is sort of the opposite of all the posts that come up when I search for it.

I would like to monitor a number of items in my heating system, for example, zone control valves and circulators. Not control them, just monitor.

It’s easy to hook up a bunch of relays on a rail, their coils powered by the devices I’m trying to monitor.

I’ve already tried it out with one relay connected to a Visonic door/temp monitor. When the burner on my boiler fires, it closes the relay and the Visonic on/off signal shows up in HA.

I could buy a bunch more of those, but I’m wondering if there’s one device which can monitor multiple switches and send it all back to HA.

The signal back to HA could be wired or wireless Ethernet, Zigbee or Z-Wave. Ideally this device should be powered by the mains, so I’m not replacing batteries all the time. And obviously I’m looking for the simplest and most cost-effective way to do all that.


Searching for ’ Ethernet Digital Input / Output’ returns many results but the trick is finding one that is priced for hobbyists. Performing the same search on AliExpress produces a mixed-bag of results.

Just what I am looking for. Did you find anything to do it?

I did what I first proposed. I have a relay (contactor) powered by each zone control valve, and another powered by the burner circuit on the boiler. When any of those are “on” it closes the contacts, which are connected to the GPIO pins of the Raspberry Pi running HA. For a while I was using a Zigbee door sensor, with the reed switch replaced by a pair of wires connected to the GPIO pins. That worked well, too.

If I were to do it over, I might consider an ESP device to collect the data and send it to HA. With that I’d be able to monitor temperatures also, and the HA hardware wouldn’t have to be near the heating system. Depending on how many GPIO pins I’d need, I might need two ESPs.