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[feature suggestion] Add transform on value of item to apply a bias [message #1761021]

Fri, 05 May 2017 11:10

jerome duquennoy

Messages: 2
Registered: May 2017

Junior Member

Hi Eclipse smartHome community,

I am a user of SmartHome through the OpenHAB project.
Here is the situation I am facing :
- I have a device that provides measures
- One of the measure is biased : the reported temperature is 2.5°c lower that it really is
- The device cannot fix that problem (no configuration parameter notably)

After asking on the OpenHAB forum, it seems there is no way to apply a bias on the value of an item. I was suggested some workaround, but that will make the configuration more complexe.

So I would like to discuss with you the possibility to add a "transform" feature to items configuration in SmartHome, with at least a bias capability.
I am willing to work on that and submit a pull request, but your opinion and advices would be more than welcome, as I have never submitted to this project, and thus am not very familiar with its architecture Smile

.

What do you think of that idea ?
Would a simple bias value be enough, or would a more more capable transform feature be more interesting ?

Jerome

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Re: [feature suggestion] Add transform on value of item to apply a bias [message #1761159 is a reply to message #1761021]

Mon, 08 May 2017 11:29

Stefan Triller

Messages: 29
Registered: April 2017

Junior Member

Hello Jerome,

thank your for your input to the ESH/openHAB community. Indeed in some cases it would be useful to adjust the raw values send by things before they are processed by ESH.

Your bias capability could be implemented via a "profile" that "sits on" a channel between a thing and an item. In this profile you would specify that every value gets adjusted by some offset. Such "profiles" are currently being discussed in this issue: https://github.com/eclipse/smarthome/issues/2226

As far as I know there is also ongoing work to implement these profiles..

I have linked this post from you in the issue as an example on how such "profiles" can be used.

Stefan

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