Ahaa, so now I get a ‘True’ in the sensor, I guess I could change it to a binary sensor instead?
I couldn’t test it in the developer tools but it looks like it works IRL.
And then I can give it a class of some sort, maybe power, there is not really one for a monitor currently
Yes, that’s how I would implement this. Even without a proper device class, you at least get a green tick icon if the monitor is on.
Well, that’s because value_json is only defined by the rest sensor.
As a workaround for testing you can add an expression like this to the template editor: