Suggestion for a "watchdog" type automation feature

[red mirage]

I'm in the early stages of designing an automation to monitor my RF dog fence and alert my family when it goes offline. I'm using a ZEN17 input device to monitor the fence controller and it's powered by mains (or at least not powered by battery). I would like to add what I'd call a "watchdog" feature to this automation. This would essentially detect when the ZEN17 goes offline. Imagine a circuit breaker opens or wall adapter is unplugged and the ZEN17 is off. I would like my automation to be able to detect that event and report it as a fence fault.

My question is if there is a common pattern that is used in automations to detect and handle such a requirement? Is the "Node Status" the appropriate entity to check?
Update: No, "Node Status" does not update at all when power is removed from the device so that won't work.

How would you all implement this type of monitoring?

[hollow jackal]

entities can go in to unknown or unavailable but different integrations handle detecting devices offline differently. some use these states and some don't.
I don't know the specifics of how zwave actually works on a protocol level and how possible this would be.

Is there a sensor that republishes updates regularly even if no change e.g. every 10s or something? you could template a binary sensor that changes state of there has not been an update for x time.

example might be sensor usually publishes every 10 seconds so if its been 60 seconds since last update then set to offline.

Something like this:

If last updated remains below 60s then it says "on" else it goes "off" and switches from "Connected" to "Disconnected"

Make adjustments as needed for your use case but as long as you have something that continually publishes on the device then you should be able to use it to make a online/offline sensor.

[red mirage]

That's a good idea and I understand what you're suggesting. Thanks for the input and reply!