Reading state NULL from zwave hardware

  • Platform information: RasPi3/OpenHabian
    • Hardware: Rapsberry Pi3
    • OS: OpenHabian
    • openHAB version: 2.4.0-1
  • Issue of the topic: I am getting Null for several states but can control the hardware

I am using an Z-Wave USB Stick and 7 SPIRIT ZWAVE Plus smart radiator thermostats. I did my automation and anything looked OK. Now after a few weeks, I noticed that sometimes I get NULL values, when I read the states. Last night it was very bad and I was only controlling 2 of the 7 thermostats but all 7 were shown as online. After a reboot of the PI I saw a third ones Temperature and was able to control it. After removing batteries and installing them again I was able to set the temperature of all thermostats and saw the actual temperature of the forth. Two hours later I also see the actual temperatures of the missing ones. Still I cannot see the Dimmer values of two of them. It does not seem to be a distance problem since the thermostat closest to the USB stick has the most problems.
(Paper UI > Control shows NaNs when I read NULL in my rules and HABPanel)
Did anyone experience similar behavior? What is the reason that states change to NULL and back? What can be done to prevent it?

Thanks for you help,

Have you followed the instructions in the binding documentation for when things do not work as expected?
Post the unfiltered log.

If there was previously data available, then I don’t think the binding will set it back to NaN or NULL or UNDEF. If you are seeing this, then probably something in the system is restarting. As suggested by @Bruce_Osborne I would check the logs.

This feels like other reports involving unexpected Thing changes (not status changes)

Actually I can see that some Temperatures have not gotten any updated temperature for a very long time. I need to investigate that further.
Does anybody have any idea why this happens?

Probably it’s not updating! Sorry for the silly answer, but there are any number of reasons that a value doesn’t update, and a question like this is very open ended. You should look through your logs to try and understand what is happening, and when you have some information on what’s going on, then provide that so we can provide a more specific answer.

@Bruce_Osborne has already provide you some good advice above -:

1 Like

I am looking into event.log and can see no errors at all. The values go to NULL at restart and when I updated them (I was adding them to new groups). The number of ActTemp changes I see is very different for the different thermostats. One wasn’t changed in 7 days, but I cannot see what happened before it stopped sending changes.
Are there any other log files, which could give me more information? The only other one I know is openhab.log, which only shows the prints from my rules.

That’s normal events, then? What would be abnormal is simple absence of updating from zwave?

I’m not surprised to see it going to NULL at these events. Actually I even did expect it to do it at the reboot, since I’m not archiving these data. Is it abnormal? It is not that I don’t get any updates. I do get updates from some thermostats and I always get these messages from the USB stick:
2020-01-15 17:36:47.718 [vent.ItemStateChangedEvent] - zwave_serial_zstick_17c301d8_serial_ack changed from 603530 to 603531
2020-01-15 17:36:49.624 [vent.ItemStateChangedEvent] - zwave_serial_zstick_17c301d8_serial_sof changed from 1519689 to 1519690
2020-01-15 17:36:49.642 [vent.ItemStateChangedEvent] - zwave_serial_zstick_17c301d8_serial_ack changed from 603531 to 603532
2020-01-15 17:36:49.659 [vent.ItemStateChangedEvent] - zwave_serial_zstick_17c301d8_serial_sof changed from 1519690 to 1519691
2020-01-15 17:36:50.875 [vent.ItemStateChangedEvent] - zwave_serial_zstick_17c301d8_serial_sof changed from 1519691 to 1519692