This is a real z-wave head scratcher,… and what fixed it

This evening, after getting home from work, I realized none of my automations were working, so I started to investigate. I quickly determined the automations are fine, but my Z-wave devices weren't reporting nor responding status changes. I quickly brought my Zniffer online, and lo and behold, I find one device that is flooding my Z-wave network with messages. The odd thing is it is transmitting the correct Home ID, but the Source ID does not exist on my hub.

I have searched for over three hours for this device to no avail. I have turned off individual circuit breakers to try to isolate it. It keeps blasting out messages every 3-6 ms. I finally turned off the main circuit breaker to the house. It didn't even slow down.

Now I am thinking it is a battery device that has become a revolutionary and is commandeering my Z-wave network. I have gone to each and every battery device and removed its battery. The offender just keeps on trucking.

I have a C-7 hub that all of my Z-wave and Zigbee devices are attached to. I have 106 Z-wave devices. I also have a C-5 hub I use for WiFi devices and another C-7 i use for development and testing. It has one Z-wave device attached, and it has a different Z-wave Home ID.

Any ideas of how to ferret this gremlin out of my agony?? Thanks.

Well if it's flooding your z-wave network, it has to be attached to it. I mean it's not going to interfere with your existing mesh unless it's attached to the same z-wave controller as the devices being affected. Does the zniffer display in hex or dec? Could it be possible you're conflating the 2 so aren't seeing it in your head properly when looking at the hub? (I've done this on occasion when using the silabs software to remove ghosts and it's like, whoops!) Just a thought.

Thanks @rlithgow1. Good thoughts on being attentive to hex vs dec. Zniffer displays the source and destination in decimal notation, but I checked both just to be sure.

I figured out the source of the problem this morning. It was the hub. What puzzled me about this is that a reboot did not clear the problem. The Z-wave radio kept transmitting during the entire reboot process.

I found the source by using the receive strength information (RS column) in the Zniffer. There wasn’t a lot of change in signal strength, but enough to show the strongest signal when I got the Zniffer close to the hub,

With this truth in hand, I completely shutdown the hub and powered it off. I have in-line power switches on my hubs to make this very easy. All of the transmissions stopped. I also failed to mention every one of these transmissions had a CRC Error.

On restarting the hub, all was well again.

I asked my wife, she works at home, if she had seen any power fluctuations. There were storms in the area yesterday. She hadn’t. Couple that with my hub being on a UPS, and I can’t figure out how the hub got in that condition. At least I did get everything running properly again.


So corrupt radio. Reboot doesn't reboot the z-wave radio, powering down and disconnecting power for a min or so clears it.

What was the source ID?
The hub creates 4 additional helper nodes that are hidden from the zwave details page. Typically they are 2-4 but can be other node numbers for various reasons. You can see them with a secondary controller USB stick.

Also, any time there are issues with Z-wave, step 1 should be power off hub for 10 seconds and reboot it. Then go from there if issues continue.

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Thanks @rlithgow1 and @jtp10181. :+1:t2:

That had never crystallized in my mind until now. It was painful enough I won’t easily forget the lesson. :face_with_head_bandage:

Edit: @jtp10181 the node ID was 0x22 (dec 34). I have seen some of the helper node IDs when watching normal traffic. Those IDs were around 0x7D (dec 125). This was crazy It was like the hub couldn’t transmit fast enough.