Set a group item state from one member state within the group

Setup, Configuration and Use Items & Sitemaps
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1

Hi there,

I am using openHAB 3 and was wondering if it is possible to set a state of a group item by the state of one concrete member of this group.

In my use case I have multi-sensors from different vendors. Mainly I am interested in the temperature values, but the sensors often also provide e.g. humidity, battery level, …
My strategy is always to create a group item for a sensor, that is tagged for the semantic model. Than I can access all values from the sensor via the group item within the pages by clicking on the group item. The group item itself has also a state, normally “NULL” or “UNDEF”. Now I wanted to route only the temperature value to the group, so that this value is shown on top level. I tried different things, but I was not able to get this running.
I am using textual definitions for my items.

Here is an example:

Group:Number:Temperature gAqaraSensor4 "Aqara Sensor Gefrierschrank" <temperature> (gAbstellkammer) ["Sensor"]
Number:Temperature aqaraSensor4Temperatur "Temperatur Gefrierschrank [%s °C]" <temperature> (gAqaraSensor4) {channel="deconz:temperaturesensor:zbaqsens4temp:temperature"}
Number:Pressure aqaraSensor4Luftdruck "Luftdruck Gefrierschrank" (gAqaraSensor4) {channel="deconz:pressuresensor:zbaqsens4press:pressure"}
Number:Dimensionless aqaraSensor4Luftfeuchtigkeit "Luftfeuchtigkeit Gefrierschrank" <humidity> (gAqaraSensor4) {channel="deconz:humiditysensor:zbaqsens4hum:humidity"}
Number aqaraSensor4Batterie "Batterie Gefrierschrank" <battery> (gAqaraSensor4) {channel="deconz:pressuresensor:zbaqsens4press:battery_level"}
Switch aqaraSensor4Alarm "Niedriger Batteriestatus Gefrierschrank" <alarm> (gAqaraSensor4, gWarnung) {channel="deconz:pressuresensor:zbaqsens4press:battery_low"}

This is what it looks like in the UI:
OH

Is there a way to do this?

Cheers,
fresch7

2

No.
Group Item state can be derived from member states by choice of aggregation function. There isn’t one to do that.

The use case is really about presentation - you already know the temperature and are not processing or “adding value” in any way.

One circumvention for your use case would be a custom widget that looks like a group but shows your given Item state.
I don’t know how you’d make that in MainUI. Someone may have something similar to represent a Thermostat made of a small collection of individual Items.

2 Likes
3

Thanks for your answer.

The proposed workaround sounds very laborious especially, when you never implemented a custom widget before. :frowning:
I was hoping there is an more easy solution for this, because I can imagine I am not the only one, who has this use case. :slight_smile: