KNX: Dimmer state changes to 100% and then back with every cyclic telegrams

Every time, my dimmer lights are not a 0% or 100%, they’re changing with every cyclic state telegrams from the bus.

item thing:

  - id: ArbeitenDL
    channelTypeUID: knx:dimmer
    label: Arbeiten Licht
    description: Kanal 2
    configuration:
      increaseDecrease: 1/2/1
      position: 1/2/2+<1/2/4
      switch: 1/2/0+<1/2/3

Bus:

Time	                 Source Address	  Source Name	    GA 	    Destination Name	        Type	              DPT	                    Info
27.10.2022 16:43:15,429	 1.1.251	      -	                1/2/2	Arbeiten DL HellWert	    GroupValueWrite	     5.001 Prozent (0..100%)	$66 | 40 %
27.10.2022 16:43:16,040	 1.1.5	          Dimmaktor 4fach	1/2/3	Arbeiten DL RückSchalt	    GroupValueWrite	     1.001 Schalten	            $01 | Ein
27.10.2022 16:43:46,198	 1.1.5	          Dimmaktor 4fach	1/2/4	Arbeiten DL RückHellWert	GroupValueResponse	 5.001 Prozent (0..100%)	$66 | 40 %
27.10.2022 16:43:17,065	 1.1.5	          Dimmaktor 4fach	1/2/4	Arbeiten DL RückHellWert	GroupValueWrite	     5.001 Prozent (0..100%)	$66 | 40 %

which results to this (KNX - TRACE) log

2022-10-27 16:43:15.430 [TRACE] [.internal.handler.DeviceThingHandler] - Handling command '40' for channel 'knx:device:local:1_1_5-Dimmaktor4:ArbeitenDL'
2022-10-27 16:43:15.432 [TRACE] [.knx.internal.channel.KNXChannelType] - getCommandSpec testing Keys '[increaseDecrease, position, switch]' for command '40'
2022-10-27 16:43:15.434 [TRACE] [.knx.internal.channel.KNXChannelType] - getCommandSpec key 'position' uses expectedTypeClass 'class org.openhab.core.library.types.PercentType' which isInstance for command '40' and dpt '5.001'
2022-10-27 16:43:15.436 [TRACE] [nx.internal.client.AbstractKNXClient] - writeToKNX groupAddress '1/2/2', commandSpec 'org.openhab.binding.knx.internal.channel.WriteSpecImpl@b5595f'
2022-10-27 16:43:15.438 [TRACE] [nx.internal.client.AbstractKNXClient] - sendToKNX mappedValue: '40' groupAddress: '1/2/2'
2022-10-27 16:43:15.462 [DEBUG] [nx.internal.client.AbstractKNXClient] - Wrote value '40' to datapoint 'command DP 1/2/2 'knx:ip:local', DPT 5.001, low priority' (0. attempt).
==> /var/log/openhab/events.log <==
2022-10-27 16:43:15.410 [INFO ] [openhab.event.ItemCommandEvent      ] - Item 'KNX_OfficeLight' received command 40
2022-10-27 16:43:15.417 [INFO ] [penhab.event.ItemStatePredictedEvent] - Item 'KNX_OfficeLight' predicted to become 40
2022-10-27 16:43:15.421 [INFO ] [openhab.event.ItemStateChangedEvent ] - Item 'KNX_OfficeLight' changed from 0 to 40
==> /var/log/openhab/openhab.log <==
2022-10-27 16:43:16.056 [TRACE] [nx.internal.client.AbstractKNXClient] - Received a Group Write telegram from '1.1.5' to '1/2/3' with value '[1]'
2022-10-27 16:43:16.058 [DEBUG] [.internal.handler.DeviceThingHandler] - onGroupWrite Thing 'knx:device:local:1_1_5-Dimmaktor4' received a GroupValueWrite telegram from '1.1.5' for destination '1/2/3'
2022-10-27 16:43:16.061 [TRACE] [.internal.handler.DeviceThingHandler] - onGroupWrite Thing 'knx:device:local:1_1_5-Dimmaktor4' processes a GroupValueWrite telegram for destination '1/2/3' for channel 'knx:device:local:1_1_5-Dimmaktor4:ArbeitenDL'
2022-10-27 16:43:16.063 [TRACE] [g.knx.internal.dpt.KNXCoreTypeMapper] - toType datapoint DPT = 1.001
==> /var/log/openhab/events.log <==
2022-10-27 16:43:16.068 [INFO ] [openhab.event.ItemStateChangedEvent ] - Item 'KNX_OfficeLight' changed from 40 to 100
==> /var/log/openhab/openhab.log <==
2022-10-27 16:43:17.081 [TRACE] [nx.internal.client.AbstractKNXClient] - Received a Group Write telegram from '1.1.5' to '1/2/4' with value '[102]'
2022-10-27 16:43:17.083 [DEBUG] [.internal.handler.DeviceThingHandler] - onGroupWrite Thing 'knx:device:local:1_1_5-Dimmaktor4' received a GroupValueWrite telegram from '1.1.5' for destination '1/2/4'
2022-10-27 16:43:17.086 [TRACE] [.internal.handler.DeviceThingHandler] - onGroupWrite Thing 'knx:device:local:1_1_5-Dimmaktor4' processes a GroupValueWrite telegram for destination '1/2/4' for channel 'knx:device:local:1_1_5-Dimmaktor4:ArbeitenDL'
2022-10-27 16:43:17.088 [TRACE] [g.knx.internal.dpt.KNXCoreTypeMapper] - toType datapoint DPT = 5.001
==> /var/log/openhab/events.log <==
2022-10-27 16:43:17.092 [INFO ] [openhab.event.ItemStateChangedEvent ] - Item 'KNX_OfficeLight' changed from 100 to 40
...

This behaviour is on everytime the GA 1/2/3 “Switch Feedback OfficeLights” sends his boolean “1” to signal, the lights are switched on. => then automatically the Dimmer Item springs to 100%. But in an instant the GA 1/2/4 “Brightness Feedback OfficeLights” sends its “40”, the Dimmer item springs to 40%.
So, my Dimmer actuator sends the state every 5mins or so - and then I’ll get that spike and log entries.

Is there a best practise configuration for openHAB, which prevents this oscillating dimmer item for every light? We set all our lights to a switch-on brightness of 40% to safe energy, so there’s a lot of changing in the logs - and of course there’s a lot of hopping around in charts and persistence for that also…

Sounds like a version of -

1 Like

yeah, it’s exaclty this. I’ll hop over for my 2 cents on this then! :wink:
I’ll close this here.