Checking a temperature probe is functional

#1

1) Give a description of the problem

I have a central heating system reliant on DS18b20 sensors connected through a fibaro UBS. Everything is controlled through webcore.

If a sensor (for whatever reason) becomes unavailable, or stops updating, or reads an odd temperature, I need to flag a fault.

2) What is the expected behaviour?

Need a way of checking the sensor is working. Initially the potential solutions seemed to suggest pistons checking on the ACTIVE states and going from there. But…

3) What is happening/not happening?

…it seems it’s possible for the sensors to still show as ACTIVE/ONLINE etc even if no changes have been received for anything between seconds or hours. So I’m struggling to find a way of determining whether it’s ok, or whether (I suspect) the temp has remained unchanged for a while.

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4) Post a Green Snapshot of the pistonimage
(UPLOAD YOUR IMAGE HERE)

5) Attach logs after turning logging level to Full
(PASTE YOUR LOGS HERE THEN HIGHLIGHT ALL OF THE LOGS AND CLICK ON THE </> ICON TO FORMAT THEM CORRECTLY)

REMOVE BELOW AFTER READING
If a solution is found for your question then please mark the post as the solution.

#2

I just happened to have a device with a dead battery, so I ran this test.

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It was successful at the right delay after pressing Test.

The question is, will it fire 2 hours after your device goes offline?

#3

Thanks for that. But the other problem would be that if say, the probe was monitoring a freezer which always stayed at - 21, then there’d be no changes anyway so this approach would assume it was broken.

#4

Honestly, I’d be afraid to place a sensor inside my freezer…
(that level of humidity & freezing temp can not be good for the electronics)

#5

Agreed, bad example. I find that temperatures sometimes stay fairly stable. So smartthings / webcore don’t see any activity for sometimes hours. The sensor could have dropped out and I’d never know.

Cjcharles adapted his dth for the fibaro ubs to allow successive checks to falsely adjust the temp by 0.1degrees if there was, in fact, no change. The following check then alters the reported temp back to actual temp if there’s still no change. And so on.

This way I should be able to knock up a diagnostic check based on activity.or lack of.

=)

#6

I would use this to your advantage. Instead of using 2 hours in my previous example, raise it to 5 or 8… Heck, even 12 hours will still tell you shortly after a device “dies”.

(don’t worry, your steaks will still be frozen solid :grin:)

Very creative workaround…

*tips his hat*