Multi channel calculation

With OH4, what’s the recommended way of doing calculations against two or more things to produce an item?

I’ve got a few places I’d like to do this, but the obvious one is to use humidity and temperature data to calculate dew-point. These are separate channels (for me, this is separate topics from MQTT). I’d like to do a transformation, but this works on a single channel input.


You will have to use a separate Item for the dewpoint, use a rule to calculate the value and update the Item from there.

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As you have both, temperature and humidity information, available in the same mqtt thing, you can calculate the drew point in a script transformation and add it as a channel to your mqtt thing.

The script transformation will receive the entire mqtt message, needs to extract temperature and humidity and then calculate the drew point

If needed I can share an example tomorrow