Installing smoke detectors is mandatory

Yes, of course, but it is not possible for everyone.

In a new building, I would definitely integrate that in this way.

Everyone must decide for themselves what and how much they want to integrate. I just wanted to show that even a very simple part can be used with a bit more experience and functions.

Just for those who are interested... a clean KNX solution: We installed 9 pcs Gira Dual Q including KNX module. So all are networked. Software-wise, I solved it as follows: If a detector goes off, of course all others alarm as well. However, the detector in the garage only triggers the one in the central hallway (not bedroom, child's room, etc.). Background: I rather suspect false alarms in the garage since I sometimes do construction work there causing corresponding strain. However, the garage is fire and smoke proof separated from the house. In case of a fire alarm, all blinds on the ground floor immediately go up and the lights in the entire house turn on. My wife and I receive an SMS on our phones. All detectors monitor themselves and report low battery, sensor errors, etc. on the BUS or on the visualization. I am still considering whether the detector in the garage (when someone is home) directly opens the garage door. So far I have had no false alarms.

Regards, Steffen

That's a great solution . Tell us roughly how much you spent on it. In my opinion, a lot of overhead for little real added value, but that's KNX anyway.

That's a great solution .
Give us a rough estimate of what you spent on it.
In my opinion, a lot of overhead for little real added value, but that's KNX anyway.

A KNX module for a Gira smoke detector costs around €40-50.
I did it like Steffen, but "light". I networked the smoke detectors with cables and gave one RM the KNX module. That way I get the info on the bus when smoke is detected, if there are errors, and I can trigger alarms. But only for the complete smoke detector ring and not per smoke detector.
Costs, as said, €50 for the module. The rest is "already there".
Of course, the light also turns on here (and at full blast, where normally it is only dimmed up) and the blinds go up.
Furthermore, a motorized top light closes, if open, in the guest bathroom.