Semantic Class and Semantic Property confusion

I just upgraded to OpenHab 3.0.1 and am somwhat confused about which Semantic Class and which Semantic Property I should assign to my items.

Is there a descriptions somewhere, when to use what?

For example I have some Smart Plugs that can just turn On/Off, no measuring of the electricity or any fancy stuff.
I have assigned the “Semantic Class” Switch, but no idea about which “Semantic Property” to assign.
Energy, Power or something else?

Same thing for my light sensors, that report illuminance in lux.
The are currently “Semantic Class” Point and “Semantic Property” None


HI Bernd,

this discussion might help you a bit:

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The tl;dr of the post Jan linked to is it doesn’t really matter. Use what tags make sense to you and make the Item appear in the auto generated tabs of the overview pages where and how you want it to.

For the smart plug, what is that smart plug controlling? Maybe you can ignore the fact that it’s a smart plug and tag it based on what it controls (e.g. if it’s a lamp tag the equipment as a LightBulb and the switch itself as Switch/Light). The model is there for your benefit. It should reflect how your home automation appears in the real world to the people in your home. They probably don’t care that the lamp is controlled by a smart plug. They just want to turn on the lamp.

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Well, it seems to matter for my light sensor.
It has “Semantic Class” Point and “Semantic Property” None:

When I change that to “Semantic Class” Measurment and “Semantic Property” Light, it shows “Err”:

I believe this is more like a bug or has a technical neccessity, i discovered that items turns Err or NULL every time you edit an Item, regardless what you change. They come back with a status once updated. Has nothing to do with the semantic classification from what i have seen. Try it.

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Oh you are right. It recovered:

After changing the light sensor to “measurment” and “light”, my location “house” does now show an illuminance:

But I have several light sensors on the outside of the house.
Which value does it show here? The average?

The values don’t match…

doing the math on those two values, it is the average.

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Is there a way to make it show both values at the location?

these are the default badge options in the UI. Just averages but i am sure the cracks in this board will guide to a workaround.

Where can I find this settings for “enabled badges”?

goto the overview page, there is a pen in the top right corner. click on the pen. now go to a location card and click to edit. in the edit Location Card you will find on the very bottom “enable badges”. open it and you will find the list. I hope i explains well.

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No, not as badges. It shows both as List Items inside the card but the badges can only show the average.

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