Author Topic: Strange SolidWatch 10 behavior  (Read 12358 times)

ilan_sw

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Strange SolidWatch 10 behavior
« on: May 07, 2019, 02:28:19 PM »
Hello,
We are conducting experiments with the SolidWatch 10 (1.5 meter version) for our product.
The setup is:
- Arduino + Ethernet shield
- 4 SolidWatch sensors, each 2 sharing a power line (1&2, 3&4), the inputs are fed back to ADC on Arduino
- each sensor is burried at different depth

We ran a night long experiment, where the sensor readings were logged every 5 seconds.
We are experiencing a strange behavior with one of the sensors - its value plummets to zero for some time, then goes back.
This happened with several Testing kits, always with 1 sensor out of several, with no apparent pattern.

Attached are 3 graphs:
The first graph is the overall samples. You can see the The Column F (yellow) sensor plummeting and then restoring, plummeting again and restoring.
The second graph is a zoom on the first plummet
The third graph is the soom after it restores.
The other sensors are stable.
It was burried, so the system was not touched or otherwise disturbed.
If it was a power problem, then another sensor, sharing power with it, would exhibit similar behavior.
What might cause this behavior?
How can this be fixed? Thanks!

« Last Edit: May 07, 2019, 02:36:39 PM by ilan_sw »

pinolec

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Re: Strange SolidWatch 10 behavior
« Reply #1 on: May 07, 2019, 06:39:09 PM »
Hi,

It looks to me like there may be some connection issues. How do you connect sensors to your board? Do you use a breadboard?
You mentioned it happened with several testing kits. Can you trace it to a single sensor or maybe single ADC pin?

Breadboards are notorious for bad connections and intermittent faults. I'm not sure if this is how you connect your sensors. If you do use a breadboard, then this is your main suspect.

This looks similar to this issue: https://pino-tech.eu/forum/soilwatch-10/soilwatch-10-erratic-readings/

Regards,
Piotr