Derivative sensor doesnt update when no value change

David_Sedlacek · December 25, 2022, 11:31am

Hi,
I created a derivative sensor which derives my water counter sensor to see immediate water consumption in m3/hour.

It works,except one significant detail. Derivative sensor doesnt update when there is no update in the source sensor (which is expected behavior).
The result is the derivative never shows zero value. And this is a problem.

So my problem is that I need to update the source sensor periodically to trigger derivative sensor recalculation. I tried the trick with adding an attribute to the source/template sensor, but it does not trigger update.

Any suggestions appreciated, David

seanomat · December 26, 2022, 7:10am

Your attribute template only generates values between 0 and 5 so might this be the problem? I do know this works as I’m using this successfully in several places (not with derivative but with integration though).

Why not just use “{{ now() }}”?

Edit: wait! Do you have a trigger on your template-sensor? Won’t update otherwise. You should be able to see the result of you efforts in the “last_updated” attribute of your template-sensor in devtools.

sushant-verma · January 21, 2024, 10:35pm

I am having a similar issue with the derivative sensor that i have for my gas meter. Keen to know how to resolve this.

WoLpH · February 16, 2024, 2:35am

There has been a change to this. I’ve had my gas consumption meter set up like this for a few years and it broke some time ago:

- platform: derivative
  name: Hourly Gas Consumption
  source: sensor.gas_consumption
  time_window: '1:00:00'

mekaneck · February 16, 2024, 2:47am

This is either a known issue or an intended behavior, depending on your perspective.

github.com/home-assistant/core

Derivative integration gives incorrect values when source does not change

opened 08:29PM - 07 Dec 22 UTC

EDelsman

integration: derivative

### The problem The derivative of a constant value is 0: https://owlcation.com…/stem/The-Derivative-of-a-Constant-With-Examples However, the derivative integration only updates if the source value changes. Therefore, the derivative integration is never 0, even if the source stays the same for a very long time. This makes it impossible to see when the source is unchanging. Instead the derivative indicates a constant rising or falling value, which isn't true. In other words: the progressing of time, without changes to the source, should be considered as a possible change of the derivative too. The derivative should change towards zero while time progresses without changes to the source. ### What version of Home Assistant Core has the issue? 2022.11.5 ### What was the last working version of Home Assistant Core? _No response_ ### What type of installation are you running? Home Assistant OS ### Integration causing the issue derivative ### Link to integration documentation on our website https://www.home-assistant.io/integrations/derivative/ ### Diagnostics information _No response_ ### Example YAML snippet _No response_ ### Anything in the logs that might be useful for us? _No response_ ### Additional information _No response_

gapple · July 8, 2024, 10:57pm

There was a PR that looks like it would resolve this issue, but was closed as stale for sitting too long without attention: Fix derivative integration sample leave time window by FlorianOosterhof · Pull Request #110689 · home-assistant/core · GitHub

finity · July 13, 2024, 8:09am

of course…

stylobille · July 20, 2024, 11:53am

Hello, I’m also having this issue and it is really annoying to have a false instant consumption value when the indexes from which this is calculated do not increase (which means instant consumption should be 0)

FlorianOosterhof apparently you made some work on this in your commit that was closed, could you resubmit it if it works ?

finity · July 20, 2024, 2:18pm

Or if it works we could use it as a custom integration to replace the faulty built-in integration.

I’m amazed that this is still an issue after all this time. And apparently if someone submitted a fix for it.

mekaneck · July 20, 2024, 9:28pm

There was an architecture change to add a last_reported property and state_reported event, and so the devs are likely waiting for a PR which utilizes that property. It would be essentially identical to the PR that was just merged in 2024.7 to do the same thing for the Riemann Sum integration.

I think Florian’s PR may have addressed some other issues also, so he’d have to modify that PR to utilize the new event while keeping his other improvements.

Edit: there was also another PR merged in 2024.7 for the Riemann sum integration to add the max_sub_interval configuration option. We need that change as well for the derivative integration.