Help understanding Z-wave on/offline status

Pi 3 Model B a02082 (Sony, UK)
Linux raspberrypi 4.14.37-v7+ #1111 SMP Thu Apr 26 13:56:59 BST 2018 armv7l GNU/Linux
Raspbian GNU/Linux 9 (stretch)
debian_version 9.4
OpenHab 3.4.4 installed manually from Linux Stable Runtime

openjdk version “11.0.19” 2023-04-18 LTS
OpenJDK Runtime Environment Zulu11.64+19-CA (build 11.0.19+7-LTS)
OpenJDK Client VM Zulu11.64+19-CA (build 11.0.19+7-LTS, mixed mode)

AEON Labs ZW090 Z-Stick Gen5 US serial controller

I’m having a problem understanding on/offline status.

I have two Dome (Elexa Consumer Products) battery devices and a Zen 17 Multi relay. All of the devices were identified by the binding.

After I configured the Multi relay, I removed power from the unit and placed it back in its box until I could wire the device into the system.

I was surprised when OpenHab continued to report the unpowered device Online! This led to a discussion with the manufacturer.

In order to better understand the issue, I removed the battery from one of the Dome devices. Same behavior: OpenHab continued to report the device Online!

I restarted OpenHab, and the still unpowered Zen relay reported a Communication Error, which now makes sense, but the Dome device, currently sitting on my desk without the battery installed, is still being reported as Online!

This behavior is certainly not what one would expect from any system offering any level of security. What am I missing? There must be some periodic polling interval somewhere that confirms that the device is active on the network.

I have extensive Z-Wave logs.

Any ideas on what I am missing?

For the battery powered device, the device itself decides to communicate when ever it darn well pleases. This is to preserve the battery. There’s no polling of battery powered devices.

And to preserve the battery, it can be very long times between status update messages. Consequently, it can take a very long time for enough “are you there” messages from the controller to be lost before the controller can decide “yes, that device is gone or broken”. For example, I had a ZCombo smoke alarm (POC BTW, do not buy) that would report once every two to three days (the other two I had reported once a day, why? :person_shrugging: ).

Given this and the link @anon71759204 posted, it could be a week or more before the controller marks the device as DEAD. But also pay attention to this:

It should be noted that the controller will generally not consider battery devices as failed.

I can’t fully explain the mains powered device except to say that no enough messages were sent and not replied to for them before you restarted OH to mark the device as offline. When you restart I think the controller sends a “hey what’s up” type message to all the devices and repeats it if there’s no response so the three missed message threshold was finally met.