[OH3] KNX Binding - Dimmer Position command written to KNX Bus but no update on openHAB

Hi everybody!
Most of my KNX things/items work as expected, but i have some trouble with my dimmers: when i send a value (position) to the item, the postition is written to the KNX bus (and i can see with my own eyes that the lights react…) but openHAB doesn’t update the position-value. when i change the position value with my “old” openHAB2 setup the item DOES get the new position value. (the problems already exists on my OH2 setup but i just figured it out now…)

here’s my things:

Bridge knx:ip:bridge [  
] {
    Thing device generic [a
    ]  {
        Type dimmer        : Licht_Wohnzimmer      "Licht Wohnzimmer"          [switch="2/1/8+<2/1/108", position="2/1/15+<2/1/112", increaseDecrease="2/1/14" ]


Dimmer          Licht_Wohnzimmer       "Licht Wohnzimmer [%d%%]"    (gLichter_EG, Group_HabPanel_Dashboard)                            ["Switch"]                                              {channel="knx:device:bridge:generic:Licht_Wohnzimmer", autoupdate="false" }

debug log if i send a value command to the item:

==> /var/log/openhab/openhab.log <==
2021-09-25 22:10:49.186 [DEBUG] [nx.internal.client.AbstractKNXClient] - Wrote value '50' to datapoint 'command DP 2/1/15 'knx:ip:bridge', DPT id 5.001, low priority' (0. attempt).
==> /var/log/openhab/events.log <==
2021-09-25 22:10:49.164 [INFO ] [openhab.event.ItemCommandEvent      ] - Item 'Licht_Wohnzimmer' received command 50

no further entries.

this is debug log when i send the command on my other setup:

==> /var/log/openhab/openhab.log <==
2021-09-25 22:11:55.670 [DEBUG] [.internal.handler.DeviceThingHandler] - onGroupWrite Thing 'knx:device:bridge:generic' received a GroupValueWrite telegram from '15.15.241' for destination '2/1/15'
==> /var/log/openhab/events.log <==
2021-09-25 22:11:55.678 [INFO ] [openhab.event.ItemStateChangedEvent ] - Item 'Licht_Wohnzimmer' changed from 20 to 75

you can see in this entry that openHAB3 didn’t have the “old” value (which should be 50, not 20).
i have also tried to turn off my openHAB2 system and restart the KNX Binding on the openHAB3 binding but the problem persists.

is my configuration wrong or am i missing something else?
best regards,

Hi Peter,
do you see in the ETS Group monitor that 2/1/112 gets updated?

1 Like

no, i don’t :frowning:
so basically “system a” sees the bus message when “system b” writes a value and updates, but “system b” doesn’t see anything else after writing the value and doesn’t autoupdate because of autoupdate="false"

i guess i’ll have to talk to my electrician.

Is it a DALI Gateway by coincidence? Per default the status objects are passive. They need to be set in the ETS to active to put state changes on the bus.

no, it’s a “MDT KNX IP Interface”, i hope my technician can solve the problem (for he got paid for it :open_mouth: ).
i’ll keep you posted!

meh, in the end there was the “send dimmer value on change” flag missing. works now. obviously not openHAB related.
thanks for the hint @marco_hoefle !