Is it possible to take control of old KNX system without any documentation/config files?

Hi all,
Greetings from KNX n00b, but experienced system engineer, linux enthusiast…

Let me summarise my question as short as possible:
Recently I purchased “smart home” apartment which is 7 years old, I can see 3 KNX related modules in the electrical cabinet: Merten instabus EIB universal dimmer REG-K/4x230/250W, switch actuator REG-K/8x230/10 with man.mode and power supply 160mA.
(houses in this community come with some sort of central server device as GIRA or similar, and control the home via tablet, but apartments do not have it)

I was thinking of low cost solution such as KNX USB interface with raspberry pi with openHAB, knxd for binding.
Is it possible to connect knx usb device to this existing KNX components (mentioned above)?

Now, I would manage to setup these components, but then what? Since I don’t have any documentation, don’t know any physical address…how to configure knx.things and other files…

The apartment has 10 wall units to control AC + lights.
3 of them have screen to control AC temperature, set Auto mode, read the current room temperature + lights and dimmer.
7 of them are just light control.

What do you recommend, what is your opinion, should I try to locate the company that did the KNX installation or is there any hope for DIY project in this situation?

thanks in advance!

Well, at least it will be difficult…

One option is to install knxd, connect to the knx bus and then group-monitor the bus. switch every light and every set temperature, read actual temperature from display and compare to the output of the group monitor. It will be a pain in the ass to get all group addresses, and maybe there will be some addresses you can’t say what they are for, but at least you will get the essential group addresses.
another option would be to get ETS and read every device to get most of the configuration. although you won’t see any labels, you will be able to get all information needed.

It’s unlikely to get a complete documentation (not even the owner of a building gets this information…) although this is essential.

Thank you so much for the reply Udo! Sounds like a fun summer DIY project then :slight_smile:
I will try to get some config from the technicians of the maintenance company that takes care of the building, but I doubt it will be a success…

Can I ask for a recommendation of the USB KNX device to use?
Will this do the job?
Or please recommend any other device that is working nicely for community here with openhab + rpi combination


Perfect choice. Cheap and reliable

unfortunately they don’t ship to Croatia…found another cheap one

98 euro
It’s also good?