How to multiply a number by 1000

Setup, Configuration and Use Items & Sitemaps
1

My object gives me a number in kW, but I would like to show it in W. So I have to multiply it by 1000. Unfortunately just changing the item format from [%.2f kW] to [%.2f W] doesn’t help - it just changes the unit, not the number.
I tried to do this with Java Formatter language but didn’t find a way. Surely I could do this with a transformation (as a rule or so), but I think there should be an easier way to solve this simple problem, maybe with the support of the OpenHab Types. Any idea?

2

Please post your item,
There are different solutions to your problem

3

OK.
This is what gives me the kW number:
Number:Power seCaliaro_Live_Production "PV Produktion [%.2f] kW" {channel="solaredge:generic:seCaliaro:live#production"}
This results eg in 1,0 kW. But what I want is 1000 W.

4

In your sitemap:
We are using the Unit of Measurement system
Your item definition instructs OH to treat the incoming value as a POWER value with a UNIT of kW
We can ask OH to display the value a W in the sitemap by doing:
Sitemap

Text item=seCaliaro_Live_Production label="PV Produktion [%d] W"

On the other hand,
If you want an item with a value stored multiplied by a 1000 then you will need a proxy item:

Number:Power seCalario_Live_Production_W "PV Produktion [%.2f] W"

And a rule:

rule "Kw into W"
when
    seCaliaro_Live_Production changed
then
    val production = triggeringItem.state as Number
    seCalario_Live_Production_W.postUpdate(production * 1000)
end
2 Likes
5

Thank you @vzorglub!
I thought of something like that - you gave me the solution, but not not as I had thought: I am handing the item values over to a database (persistence), and would have liked to have the item value multiplied, not only the appearance in the Sitemap. The Unit of Measurement system only works on Sitemaps then?
However I will do this with a rule then with the proxy item you have described. Thank you for this also.