Connecting OpenHAB to KNX directly via USB without knxd

Hello Community,
I’ve really done a lot of research but unfortunately I can’t find any hint to solve my problem.
I set up a Raspberry PI 3 with OpenHabian to control my KNX House System. So far I could establish a connection to the bus using the knxd interface. Unfortunately the connection seems not to be that reliable since from time to time commands are not properly sent to the bus. Therefore I looked for posts descibing similar problems and I found a post saying, that OpenHAB does not neccesarily need knxd to establish a connection to knx via USB interface.

Can someone confirm this and if so how do I have to configure the knx.cfg file.

Thanks a lot in advance.


Hi @Dr_Drube, did you manage to run configuration of OH2 + KNX-USB without knxd? What was your configuration?

No, unfortunately not yet. But to be honest I am quite busy at the moment so I did not put so much attention to this topic.
But anyway, with knxd it works quite well now.

I have never seen this scenario working.
In theory… it is supported by the underlying library (calimero).
From what I have read (but never tested it): You could connect using the FT1.2 protocol over the serial port /dev/ttyS0 or /dev/ttyUSB0.

In KNX1, there was an option to configure the serial port: serialPort=
In KNX2, I see that you can configure only IP connections (in Tunneling or Routing mode).

Anyway: with knxd you can make it work for sure with the USB interface

I’ve made some research. Indeed Calimero supports 4 types of connections: FT1.2, IP, TPUART and USB (see different classes KNXNetworkLink*:

However, OpenHAB2 KNX addon supports only two of them: FT1.2 and IP: see createThing() method of KNXHandlerFactory (

The other two (USB and TPUART) seem to be not implemented - which is sad, because Calimari itself works very well with USB connection (I have been able to run Calimari-tools network monitor with USB very easily).

Can we expect the other two connections types to be implemented in near future?

You would have to raise a PR on Github with such a feature request. Most users go with IP connectivity.