What is the common way to include central functions via the knx binding?
I want to set the group address “Day/Night” in my KNX network with openHAB. But unlike to actuators or sensors, I don’t have a specific knx device address (e.g. 1.1.12) to create in the Things section.
Shoud I create a “virtual” device with an fictive address (if this is possible) and insert there the channel “Tag_Nacht”, or is it better to create a new chanel at a n existing device?
What sort of “central functions” do you mean?
A scene is usually implemented with a rule, if triggered it just sends each device an individual command, no matter if KNX or any other technology.
In my KNX network I have a group address “Day_Night”. A couple of knx devices listen to this GA.
I want to set this GA to day or night via openHAB. But for this I have to create a channel with this address.
My question is now, at which “Thing” (KNX Binding) should I add this channel.
Then why didn’t you tell and ask that. You asked for the “common way” to have central functions, and the common way is NOT to do this inside any of the slave technologies but on the OH level.
You will not be able to add anything non-KNX to your scene that way such as a Hue bulb for example.
Puh, many bad vibes here…
I will try to break the ice with my simple solution to your problem.
(At least i think i am trying to achieve the same as you. 
)
For central (i would call it generic) functions i have one thing that collects all channels that i can’t sort to one specific device.
This holds all generic channels i want to use from openHAB or get the status back:
In my case i have 3 channels with corresponding group adresses
I do this because i like to have those channels separated, but they would be fine in any device thing.
Basically with the knx binding you would only need one thing with many channels, but that would be a hard to maintain mess in bigger systems of course.
In fact I tend to call Confectricians solution “the common way” for such GA, as most users will do it this way.
Please be aware of the fact, that it is not allowed to set non-real individual addresses. Fortunately it is not necessary either.
The individual address has (in general) no effect for devices, it’s more a “nice-to-have” feature. So for a virtual device (i.e. there is no real device for this part of configuration) just leave the individual address empty.
@mstormi Please be aware that there are good reasons to leave some simple functions in a “slave” system. If openHAB fails, I have a wall switch to control all rollershutters at once (I have 19 of them… hate to walk through the whole house just to open or close them).
And in knx a central GA has nothing in common with a scene, but is meant as a GA used by more than one device (or one actuator channel if a device has more than one channel). It could be the time/date information, outdoor temperature or some main “OFF” switches, and there is nothing wrong with those central GA even in combination with openHAB, as it’s simple to use them also in openHAB, in both directions.
Thank you guys,
that helped me a lot and was exactly what I was looking for.
Next time I’ll try to formulate my question a little better.
Sure there are. However the OP is apparently coming from a KNX only solution and wants to apply KNX(-only) concepts to openHAB, possibly without even being aware.
The bottom line here is that in an openHAB controlled system “central” functions as he called them apply to potentially every device not just KNX ones and therefore should not (or to be more precise, not only) be implemented in slave technologies (KNX that is here).
Nothing wrong with using GAs or with implementing simple functions like a direct switch-light communication or alarm broadcasting in there only, several other technologies like ZigBee, ZWave offer this as well and as you correctly mentioned this is good to have as a fallback
But I would not implement group functions there (call them “scenes” or whatever). Probably many beginners do it like that so yes you may call it the “common way”, however this IMHO is more due to lack of overview and knowledge of alternative ways to accomplish your goals at this stage of your home automation journey rather than because it is the natural or best solution.
Distributing logic across multiple systems greatly complicates overall maintenance and programming in the long run (using multiple tools/programming languages/… to maintain). A lot harder to debug.
IMHO particularly KNX users that are new to openHAB and who are used to do everything in “the server” (in GAs, that is) should be made aware of that and shift mindset here, and the sooner they do the better.
