KNX - updated item is always triggering additional telegrams

Hi there,

with the help of @Dim (big thx again) i have got my knx binding (1.11) within an OH 2.2 running.
OH2 is running on a PineA64 2 GByte, Binding is connected in ROUTER-Mode with an PA of
a dummy Application in ETS for correct filtering.

Everything seems fine, got all telegrams, which had to be routed and being able to send read and write telegrams to knx.


Every change of an bound Item (eg a Number for temperature) results in an additional write- or/and read-telegrams.

This possibly relevant config-option:


has already been set.


Light Switch

Switch  FF_Office_Light  "Licht"  <light>  (FF_Office, gLight)  ["Lighting"]  { knx="1.001:1/1/16+<1/4/16" }
system start

i would expect, that there is 1 read action on system start, which sets the initial state, but there are always to two reads:

update item over basic ui

if i’ll be sending an update (for example via basic ui, this has happened:

update external

if an update on the item occurs, caused by an external switch (eg my rtr)

As u can see, there is an additional write or read on each update on the item.
While not having much updates / second and so, the knx bus is not becoming overflooded, this is not a big problem at this moment, but this couldn’t be the right behavior, right?


    Number  FF_Office_Temperature_actual  "Ist Temperatur [%.1f °C]"  <temperature>  (FF_Office, gTemperature)  { knx="<9.001:2/0/5", autoupdate="true" }
    Number  FF_Office_Temperature_set  "Soll Temperatur [%.1f °C]"  <temperature>  (FF_Office, gTemperature_set)  { knx="2/5/5+<2/6/5", autoupdate="true"}
    String  FF_Office_Temperature_mixed  "Temperatur (ist/soll) [%s]"  <temperature>
rule "FF_Office_Temperature_mixed_update"
    Item FF_Office_Temperature_actual changed or
    Item FF_Office_Temperature_set changed or
    System started
    FF_Office_Temperature_mixed.postUpdate(FF_Office_Temperature_actual.state.format("%.1f")+" °C / "+FF_Office_Temperature_set.state.format("%.1f")+" °C")
system start

i would expect here, 2 single read actions on start

but as u can see, there happens a write back action of the actial temperatur.

the item for the actual temp. has only one GA, the other Item two. afaik the knx binding is using the first ga for write-actions, but for the actual-temp-item, there is no need for that, should be readonly.

if thats the problem, not bound dummy ga could help? (had been testing it, yes, dummy ga fixes this problem, but this could not be the right / only solution, right?)

update of “temperature to set” through basic ui

the same strange (imho) behavior as before (switch). had changed the target temperature from 22 *C to 22.5 *C, but OH is writing 2 telegrams with the same content.


OH2 is sending additional telegrams all the time. i had been researching for a solution lots of hours, but now,
I’m inclined to give up. But before that, i’m hoping to get some help from u.



See this issue.

Hi Andreas,

Unfortunately, this issue has not been resolved yet…

According to my understanding: No one has been able to debug it, find the root-cause and fix it :frowning:

Check also:


I have the same setup as you (with dummy App) and I don’t experience echos in my deployment…