Transform scale range to other range

Setup, Configuration and Use Items & Sitemaps
1

Hi Guys,
I have an OH2.5 on RPi

I purchased a Tuya WIFI dimmer what I could connect to OH via Tuya_Mqtt and Mosquito.
Issue is that the Tuya dimmer brightness is adjustable in a range of 1-1000. Dimmer Things / Items in OH can play in scale 0-100 range so I could play with the brightness in 0-10% range.

Is there a way to extend it?
(if I initiate the Item as Number than it works well of course)

Thanks

2

Sure. The whole idea of Items is to represent many and various devices as idealized standard models. Leave the Dimmer Item alone, and instead do a transformation scaling in the binding channel.

3

Great. But what transformation service do you advise? I cannot find any which can tranform a range to another.
This is my Chanel definition:

Type dimmer : PowerDimmer   "Fényerő"     [ stateTopic="tuya/tuyadimmer_01/dps/2/state", commandTopic="tuya/tuyadimmer_01/dps/2/command" ]
4

That’s just maths. (As you point out, although this is “scaling”, the SCALE transform is not the one for this job.)
We can do any maths in a javascript transform.

I think you’d need two JS scripts here,one to multiply by 10 on the way out, one to divide by ten on the way in.
Similar examples in modbus binding docs -

In the MQTT channel, you’d be looking to use transformationPattern (for inbound) and transformationPatternOut

5

Thanks, it is working well.
Chanel:

Type dimmer : PowerDimmer "Fényerő"  [ stateTopic="tuya/tuyadimmer_01/dps/2/state", transformationPattern="JS:divide10.js", commandTopic="tuya/tuyadimmer_01/dps/2/command", transformationPatternOut="JS:multiply10.js" ]

Item:

Dimmer  MQTT_TuyaDimmer01_PowerDimmer  "Nappali Fényerő"  {channel="mqtt:topic:MQTT_Tuya_DIM_01:PowerDimmer"}

and the JS transformation (multiply10 is the same):
divide10.js

(function(inputData) {
    // on read: the polled number as string
    // on write: openHAB command as string
    var DIVIDE_BY = 10;
    return Math.round(parseFloat(inputData) / DIVIDE_BY);
})(input)