[KNX] How to setup a Dummy App in ETS and use it in OH


I finally completed a working setup of OpenHAB 2.4 with the KNX2 Binding. Yet, in order to actually get access to my KNX installation I had to open up my KNX-IP Router to forward all Groups and Physical adresses.

From what I learned by researching in this forum - mainly the comments from @Udo_Hartmann & @Dim, the reason appears to be that OpenHAB is not a known Device/App for the KNX Bus, yet it communicates with the Bus.

But that’s where I start to struggle.
It appears that I need to introduce a so called Dummy App (available e.g. from Gira) to mimik OH as device and thus allow ETS to create the filter tables that would allow for the GAs to be passed through to OH.

Unfortunately I have no clue on how this setup would work - could anyone help me with this?

  • Which Dummy App would you suggest
  • Do I need to assign all GA’s to this dummy app
  • How will I make use of this Dummy app in OH, do I need to add a Thing, or change the Binding Config

As for my Installation - here’s a few screenshots & documentation:

KNX Binding Configuration (knx.things)

Bridge knx:ip:bridge  [ 

The ETS Topology looks as follows:
I also had once a “Dummy App from Gira” introduced, but not configured - would this be the starting point?
Also I have all Devices in the “1 Hauptlinie Haus” no additional lines

Do you use a “firewall” in your knx installation (in german: linienkoppler)?

I don´t need any dummy app inside my ets. You can assign a knx-channel to a device by simply writing it inside the ets, not combine the two things with the mouse pointer.

I have a presence sensor (non-knx) and this sensor gives a signal to openhab, when movement is recognized. Then openhab sends a “on” message to the knx-adress maybe 5/1/1. I combined my knx-actuator for my lights with this adress inside the ETS and so the light goes on, when there is any movement.

No need for dummy apps.


Thanks for your quick reply- unfortunately I seem to not really understand?!
Are you using router or tunnel mode?

From what you are writing it appears we are doing the same - I setup all my KNX aktuators as Things in the OpenHab.things file.

So whenever the KNX bus gets any GA updates this is also available for OH and I can send GAs to KNX.
Yet - in order for this to work I had to forward al Physical Ardesses and GAs through the KNX router.
From what I understand this is required since ets generates filter tables for the router?!

I´m using the KNX1-binding. And i use tunnel mode.

In my configuration, i don´t need any dummy devices, because ALL KNX-messages will be sent to the KNX. There is no filtering. And when the KNX-bus is sending a message, openhab will see it too. It doesn´t matter, if the knx-message is for a knx-device or for openhab. Openhab will only do somoething, if the KNX-adress is known (configured in my items-file).

I had no time yet, to change my knx1-configuration to the new knx v2 binding.

It depends wether all KNX devices are in the same line (which might be extended by amplifiers) or if the devices are in different lines, connected by line couplers with activated filter functionality.

In the first case all KNX telegrams will be visible to all devices. In the second case you will need the dummy device.

To use it, you place the device in the line where openhab us connected. The dummy device has to be connected to all GAs from devices outside that line, that should be visible to openhab. This allows the ETS to calculate the filter tables of the couplers. After that the couplers have to be reprogrammed.

In a one family home (what is the correct english term for the german „Einfamilienhaus“) I would personally use the line couplers in amplifier mode, so that all devices can see each other. In this case I would use couplers with filtering only for security reasons, e.g. for devices outside the house or where others have access to.