Thanks for the help Jos! I assumed as much, thanks for pointing me towards an alternative trigger mechanism. Did the event system of Domoticz change over time, thereby invalidating the example provided in the Alarm Setup Guide (wiki). I like the guide it helped me getting my alarm system up ...

I followed the Alarm Setup guide from https://www.domoticz.com/wiki/Alarm_Setup, but blockly is not triggered. Basically on a device change (a PIR sensor) a user variable AlarmDetected is set to 1. Blockly should handle this and perform an action. I assume this does not work to prevent event loops ...