Sporadic mismeasurement from SenseCAP S2105 Soil Moisture, Temperature and EC Sensor

Products & Technology SenseCAP
1

Dear forum,
I own some S2105 Soil Moisture, Temperature and EC sensors and deployed the first one recently.
All works fine with a ChirpStack LoRaWAN Server.
But from time to time the sensor sends completely wrong values.
It happened 11 times in the last 7 days, but at completely random points in time.
I would place a screenshot about the distribution in time, but I’m not allowed to paste images, maybe because I’m new to the forum.

The wrong values are always the same: 2.000.001.000 as raw vale or (divided by 1000) 2.000.001 for temperature, soil moisture and conductivity.
I looked into the actual payload and decoded it manually according to the “2SenseCAP S210X LoRaWAN Sensor User Guide.pdf”. The sensor really sends this strange values.

Any idea? Do I have to assume that the sensor is defect? Or could there be any other reason for this behavior?

Christian

2

Hi.

I don’t know if you’ve solved your problem yet, but if you can, can you just send a copy of the data message with the ‘strange value’ in it?

3

Hi thank you for asking.
Following an advice form the Seeed Studio support, I opened the sensor and found that the sensor wires are inserted into the terminal block, but the screws are not tightened at all!
I fixed the screws. But the sensor still sends the obviously wrong values from time to time. But - it seems to stop doing that since Jan 6th, without me doing anything!
Here is a graphical representation of soil moisture. You can easily see the wrong values. It’s always the value of 2.000.001 % soil moisture.
Higher values in the graph are due to averaging over a longer time.
[Image I noticed, for reasons I don’t know, I can not include images in my post. So unfortunately you have to come a long with text only].
But you can also see, that these values are no longer sent since about 2 weeks. It has never been “good” for such a long time. But since I haven’t done anything I wouldn’t be surprised if wrong values will be send again in the future. I will continue to monitor the sensor.

4

Deploy another S2105 sensor in the same location or swap this sensor with one from a different location to see if the issue persists. * If the problem is consistent across multiple S2105 sensors or under similar environmental conditions, it’s more likely an external factor or firmware issue.