I have made a test run of the latest beta (2.12.04). I tried making a rule in order to link the alarm system’s in_alarm state to a siren (Heiman WarningDevice-EF-3.0, which is a light in deconz REST API) with no success. Apparently rules do not yet support alarm systems - is this true? If yes how do you link a siren (which appears as a light) to an alarm system?
Oh damn, sorry I forgot to enable rules engine for the alarm system resources 
Triggering the siren via rules will work then and is the right approach.
I’ll update the PR to add this, it will be available in the next v2.13.0-beta version after the stable stable.
Great, thanks. I’ll cherry-pick until the next beta cycles pushed a binary to support this.
Any update in this regard - i am more than thankful for the PR itself as currently the alarm system is kind of useless. I can do a manual build, anything to have it up and running and ditch more complex/stupid solutions i currently employ.
I plan to put up the PR by the end of this week, would be cool if you can test that it works in your setup.
The PR is up now, I don’t have a siren to test but could verify that it works to turn on a light.
I’ve successfully tested the rules and they work as expected (one rule turn the siren on and the second turns it off after some time). I just have a question though - is there an operator like “not in” available? In order to turn off the siren it would be nice/practical to have a rule like “if the alarmsystem/1 is not in_alarm turn off the siren”. Or maybe I got it wrong and the approach to binding a siren to the alarm system is different…