Hello,
i have two RPIs running, each with KNXD (Tunnel mode). I can toggle Lamps by “knxtool groupswrite…” on each of them. Switching Lamps by openhab (via KNXD) is only working, when one of the RPI is shut down. I noticed that by accident, because I thought it is normal that only one RPI has to run, because if KNXD is running it will block the ethernet-KNX-Interface.
Has anybody a reason for that behavior?
Thanks, Ingo
What’s the exact configuration? 2 Raspberry Pi, 2 knx interfaces, 2 knx busses? openHAB is capable to use one knx bus only (and this should fit anyway 
)
exact config:
1 Ethernet - KNX - Inteface
1 RPI, OH1, KNXD
1 RPI, fhem, KNXD
1 EibPC
It was used, so that the EibPC and fhem are using the KNXD on the RPI (with fhem) to communicate with the KNX devices.
Now I try to migrate from EibPB and fhem to OH. So I set up a new RPI with KNXD and OH1 (I don’t get OH2 configured and gave up)
With all my tryings, it was always, that only one KNXD had to run to get connection to KNX-devices. I thought, that’s the law. I allways had to shut down one of the RPI to get the other KNXD working.
Now I discovered, that I can have both KNXDs running and user both via KNXTOOL from any of the RPIs as well as any other computer on the Ethernet. But ether fhem or OH1 are working at a time. If the fhem and the OHI RPI are on, only th one which bootet first has contact via it’s KNXD to the KNX devices.
ah, I see… did you set up different bus addresses for the two knxd?
As you are using an ethernet interface, which one do you use? I’m using a weinzierl 730 which has the ability to make up to 5 connections knx<->ethernet simultaneous.
But even, if your ethernet interface does only allow one connection, you could use knxd to split up, so either configure
openHAB to use knxd from fhem or configure fhem to use knxd from openHAB installation.
At first, the two KNXDs had the same Bus addresses. I changed it, but with same result.
But I think, that can’t be the reason, because if I use knxtools both are working at the same time. And knxtools are using KNXD. So, where is the difference when knxtools switches and when OH or fhem switches (allways by using KNXD)??
The Interface is a:
Hersteller: EIBMARKT GmbH
Name: KNX / EIB IP Interface
Bestellnummer: N000401
BAU-Typ: BIM M112
There is definitely a difference in how the data is sent to knxd (web socket, unix socket, dbus, whatever).
Regarding to https://www.eibmarkt.com/cgi-bin/eibmarkt.storefront/57a7786c008cf6ee27604debae50071e/Ext/Custom/Search?query=N000401 this interface is capable to use up to 5 connections, so simply omit knxd completely 
I was quite sue, that it can handle only one connection. Don’t know why. Would be nice if OH and fhem could use their KNXDs as knxtool can. But I don’t know where to look for it. Till I know, I will have to shut down the fhem RPI while testing the OH one.