Relationship between Z-Wave USB and Devices

Hello,

This is my first post. I have a Raspberry Pi 4 and originally had a Zooz usb zwave stick (Zst10). I recently removed that stick from the Raspberry PI then used it on my laptop to do some firmware updates on some Zooz Z-wave plugs. When I reinserted the Zwave stick into the Raspberry Pi, all my devices were gone. I’m just trying to understand the relationship between the stick and the devices. My assumption is I broke a link to the database. To test, I built out new devices using the Zooz then replaced that stick (same usb plug) with a different Z-Wave USB stick which is not made by Zooz. Again, my devices disappeared. I though the stick would be a transparent device. Clearly I’m wrong. Can someone explain what I’m missing? I’d like to understand.

The stick - the coordinator - contains the information on actually interfacing with your ZWave network. So for all practical purposes consider that stick the container of the NVRAM file that IS your network. You can backup the contents and move it between sticks if you know your ZWave network keys.

When you move the stick your network moves with it.

Homeassistant uses ZWaveJS (possibly with ZWaveJS2MQTT) to read that data and interface with it it uses the USB path to find yoir stick and your keys to unlock it. Sonwhen it fires up it needs to find the stick. Uf you did not use the ‘by-id’ path to identify the path to your USB stick it can change between re-insertions.

Does that help?

So, if I understand it correctly, there is a memory module on the stick, which does save some crucial information even when power is disconnected?

exactly, its also encrypted - so whatever network keys were put in your configuration when you created it you MUST HAVE to access it.

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Nathan,

Thank you, that is crystal clear.

I thought I was imagining things. So for purposes of replacing a ZWave Coordinator, I should print a copy of the keys. (Are they included in the backup?) Secondly I should make the correct reference to the USB key. Could you tell me where I can view how Home Assistant is currently referencing the Z-wave coordinator? I’m afraid after the many, many installs and reinstalls, I may have missed that point. This has been about a two week learning curve in my spare time. Everything is working. I just want to ensure it is recoverable. If I did not make the correct reference, do I need to delete and re-add my Z-wave devices?

Thank you again.

You should keep a copy of your keys. WHERE? that’s up to you but whatever you use, treat it as a password. If someone has those keys, they can OWN your Z-Wave network. I keep mine as an entry in my password management app. (And I also strongly recommend everyone use password managers instead of trying to remember passwords anymore)

I use a supervised install. I just go to Config > Add ons > System > Host > Hardware (three button elipsis menu on bottom right:) There it lists all the hardware and how my system ‘sees’ it. There are also linux commands you can use to get the -by-id’ path for oyur USB stick.

Nope. Just change the reference and try again if it doesnt work. Worst case you’d have to change entity IDs but if you come back to the same HA install with the same restored network - it should ‘just work.’

Nathan,
You are a wealth of information. I really appreciate your help. Thank you.

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