WB-MSW v.3 motion sensor: high noise + periodic peaks

Good morning!

Problem:
One of my WB-MSW v.3 sensors appears to produce very noisy motion readings with large peaks approximately every 15 minutes as per the following graph:

Similarities:

  • Both sensors are WB-MSW v.3,
  • both are connected to the same RS485 port (the problematic one is closer to the controller),
  • both run the latest stable firmware 4.31.6,
  • both were left in a dark room without any motion for prolonged testing over multiple days and there seem to be no issues with e.g. temperature and humidity readings (both are highly correlated and without any unexpected noise or peaks).

I’m using Wiren Board 7.2.1, wb-2401.

Differences:

  • The problematic sensor includes the CO2 and VOC sensors whereas the other one does not.

The serial number of the problematic sensor is 4264819157.


I’ve done some searching and found this thread which looks relevant at first glance but the cause appears to be unrelated. So far, I haven’t been able to identify any correlate to those peaks.

Could you please help me understand the nature of this issue and resolve it?

Thank you!

Good day.
Highly likely this WB-MSW v.3: Errata — Wiren Board

Device number 4264819157 - from batch 4.19a
It was manufactured in 2021 and the warranty period has expired.

I advise you to use a higher motion threshold for it than for the second sensor.

Thank you for the quick reply!

I believe the CO2 and VOC sensors are mounted to the PCB through connectors. Would it be possible to transplant them into another WB-MSW v.3 (or potentially even v.4) from a batch which doesn’t suffer from this issue, please?

Also, just as a side note: your publicly available documentation is incredible! :star_struck:

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