Number:Illuminance got unit °C?

Setup, Configuration and Use Migration
1

Hey everyone!

After migrating from 3.4.5 to 4.0.2 I get the following warning in the logs:

2023-09-06 22:02:23.335 [WARN ] [penhab.core.library.items.NumberItem] - Failed to update item ‘PrasenzmelderGastebad_PMGastebadHelligkeit’ because ‘0 °C’ could not be converted to the item unit ‘lx’

Converting °C to Lux is indeed quite a task.

If I have a look at the item, it looks like this:

grafik
grafik718×447 7.49 KB

Should “Type” = Number:Illuminance set the item’s unit to lx instead of °C?

The item does have a state description:

grafik
grafik724×940 21.2 KB

grafik
grafik739×708 8.46 KB

If I remove the state description the warning is gone but the item does only show the number and not “Lux” anymore.

Where does the °C come from?
How can I get the “Lux” after the number if not by using the state description?

2

Please don’t post screen shots where a code tab is available. Click to edit the Item and you’ll see a code tab. Paste the YAML you find there. Use code fences.

```
code goes here
```

Yes, that tells OH that the units that Item accepts are those that represent illuminance which, in that specific case is only Lux. Note, the actual unit is lx not Lux.

The state description only changes how the Item is shown. The actual Item’s unit is controlled by the unit metadata (see the breaking changes for OH 4) or, if not defined at all, the system default which depends on your locale. Given illuminance only has one unit, lx should be the unit assumed.

What is updating this Item? Does it include °C as the unit? If an Item with a unit gets updated with a state with a unit, OH will try to convert from the sent unit to the unit carried by the Item.

3

I found the “reason”.

The item is updated by a channel (knx binding). The knx device is set to the correct DPT, i.e. 9.004

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grafik1362×18 2.78 KB

However, if the knx device within openhab is not explicitely set to 9.001 as well, it will interpret the received value as °C, which is 9.001 within KNX.



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Präsenzmelder Gästebad
1

UID: knx:device:e016ef5bd9:c74c558dda

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label: Präsenzmelder Gästebad

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thingTypeUID: knx:device

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configuration:

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  pingInterval: 600

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  address: 1.0.90

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  readInterval: 0

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  fetch: true

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bridgeUID: knx:ip:e016ef5bd9

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location: Gästebad

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channels:

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  - id: PMGaestebadPraesenz1

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    channelTypeUID: knx:switch

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    label: Präsenz Gästebad 1

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    description: ""

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    configuration:

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      ga: 6/0/0

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  - id: PMGaestebadPraesenz3

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    channelTypeUID: knx:switch

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    label: Präsenz Gästebad 3

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    description: ""

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    configuration:

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      ga: 6/0/2

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  - id: PMGaestebadAlarm

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    channelTypeUID: knx:switch

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    label: PM Gästebad Alarm

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    description: ""

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    configuration:

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      ga: 6/0/3

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  - id: PMGaestebadTemperatur

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    channelTypeUID: knx:number

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    label: PM Gästebad Temperatur

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    description: ""

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    configuration:

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      ga: 3/1/20

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  - id: PMGaestebadHelligkeit

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    channelTypeUID: knx:number

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    label: PM Gästebad Helligkeit

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    description: ""

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    configuration:

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      ga: 9.004:6/1/0

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​

That means that I have to set an explicit DPT for all KNX channels to make sure nothing weird happens.

1 Like