Signal strength with Razberry + Zwave

  • Platform information:
    • Hardware: Raspberry Pi 3b + Razberry
    • OS: Raspbian lite (Jessie)
    • Java Runtime Environment: Zulu Embedded
    • openHAB version: 2.3.0-Snapshot

Hello everybody !
My config works like a charm now, but I would like to check my signal strength between the Razberry and my devices. Everything’s paired and I can read the values. What can I do ? Does it exist a configuration for openhab where I can read it in dBm? Maybe with the REST API ? I could not find it… I looked for that in the command class reference too.

Thank you for your time and keep up the amazing work.

There’s no such capability inside openHAB. You could check out the Z-Way software (but I’m not saying it’s there, just guessing).

Given that zwave is a mesh network what information do you hope to gain by getting at the dBm? The fact that a device has a low or zero signal with a device does not mean the controller cannot talk with that device. Zwave supports up to four hops (I believe) and message traffic is routed through the mesh.

In short:

  • The signal between the controller and the devices is only a small part of the picture. You would also need the signals between each node and its neighbors.

  • The signal between any two devices doesn’t tell you much as messages are routed across the mesh. You would need to figure out the strongest paths between a device and the controller to know anything about the quality of your zwave mesh network (i.e. there is a strong path to get a message from each device to the controller and back).

  • Even if you had the signal strength, I’m not convinced it would provide any additional useful information over the neighbor diagram you will hind in HABMin that shows what each node reports as its neighbors. From here you can see if you have any choke points and see how many hops you have between a device and the controller.

Thank you for your answers.

What I want is a tool to check if the planned network would work before definitively fixing Things, and where were the best spots for that.

The mesh network is certainly great, but not really usable with my house : one temperature sensor in the living room, one on the water boiler and one on the electric box, separated with at least 10 meters and through different walls.

There are chances I will invest in a more powerful antenna than Razberry, maybe UZB ? (

Take care

Try it out first. If it works, then it works.
If not, I suggest you change the locations or get a range extender.… 10m is nothing. I have devices further apart than that and they work flawlessly.

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Doesn’t make sense because 10m and a wall or two are absolutely no problem to zwave. And that tool won’t work out IMHO.
Dunno why you’re so afraid of this but ZWave isn’t EnOcean or Insteon or any of those unreliable technologies.
Just start and should you REALLY happen to encounter a problem then simply add or move a zwave socket plug close to your problematic sensor.

Just to elaborate on Lucky and Markus’s responses. The key to a reliable zwave network is not the signal strength between each node and the controller. The key is having more than one reliable path from each node to the controller. And you can discover that easily using the Habmin neighbors tool. And if you have a node that is hanging off to the side with no direct path to the controller or only one neighbor then you solve the problem by getting another mains powered device to place somewhere inbetween to give the device another path to the controller.

10m, even with walls between, is typically not a problem for zwave.

So, don’t worry about this until you actually see problems. If you do see problems there are three approaches that will likely work much better than worrying about signal strength:

  1. Move the controller to a more central location: Share Z-wave dongle over IP (USB over IP using ser2net / socat ) guide

  2. Add more mains powered Zwave devices like the repeater Lucky identified or a Zwave appliance or Light control switch and locate them between your controller and the problem devices.

  3. Add a second controller in the middle of the problem devices; works best when needing to extend the zwave network to an outbuilding. This can be combined with 1.