Action to be triggered when the power consumption is decreasing?

General
1

Hello Fellow Node Red users,

I got a 3D Printer for Xmas, all works fine. I would like to get a notification when the printing is done.
For sure, the straight way with Octoprint and the Home assistant it's easy, did a testing with Octo4a works great, but at this moment I don't have any device which could permanentlly run Octoprint and don't want to invest.

What I have, is a Shelly 1PM which is concted to the printer, so I can see the consumption.

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I would like to get an action triggered, when the power consumption drops.
I found some examples used for the Washingmachine, but all of them are considering as start of the power monitoring the start of the Shelly/Smart plug. I don't want to start the Shelly, the Shelly is doing only powermonitoring, it's allways on.

I have tried to use an RBE node, but because the power is fluctuating, not just increasing, it's not working.

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Do you have any other sugestion?

Thanks,

2

A filter node can be set to "block unless value change is greater than" a set amount, which seems like it should work.

Otherwise a switch node can only pass messages when the payload is below a certain level.

You might need a second filter node to block repeated messages.

3

Thanks Jbudd, but how to avoid messages when the Printer is idle? The consumption will be bellow the set value, and I will get by each polling the action triggered.

4

Like this?

5

So, finally I have found what I needed, straight out of the box.

node-red-contrib-edge-trigger

The Failing edge Node is doing exactlly what I need. Thanks J budd for supporting.

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6

My preference in this case would be to use core nodes rather than a contrib node. With contrib nodes you can be sure it will keep working into the future, with contrib nodes you do not know whether it will continue to be maintained.

7

Colin, you are right, but I have no ideea how to create this manually with standard nodes. And writing a function, is to far from my knowledge. Thanks,

8

Yes you do, @jbudd suggested how to do it earlier. A switch node and a filter node. Did you try that method? If it didn't work show us what you tried and what the problem was.

9

Our maybe a switch followed by a trigger.

10

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