[SOLVED] Can't control a Group Item via MQTT

  • Platform information:
    • Hardware: QNAP NAS /Docker Image
    • OS: Docker
    • Java Runtime Environment: Latest Docker Image
    • openHAB version: 2.3.0:Latest
  • Issue of the topic: I try to control my Tado Heating through a node-red Dashboard. But i can’t figure out how to send the value via mqtt to a whole group

Hello Community,

i have the following problem:

I’ve added my Tado Heating to Openhab and so far the control of the individual Thermostat is working fine. Even when i control a “HeatingGroup”, for examples all Thermostat in my House via Sitemap and BasicUI.

My Main Dashboard runs on Node-Red connected via MQTT. I can control a single item via MQTT without a problem. The problem is that i can’t send a command or state to a group. I’ll always get the following error in the openhab.log:
2018-10-07 12:16:43.293 [WARN ] [b.core.events.EventPublisherDelegate] - given new state is NULL, couldn’t post update for ‘gHeizungTest’

Node-Red send the new State of the Group to gHeizungTest. The Payload or MQTT Value is OFF or HEAT.

A single Item looks like this: (Here i can send OFF or HEAT without a problem and the item gets the new state)

String      Wohnzimmer_Heizung_HVACModus                    "HVAC Modus"                    (gTado, gWohnzimmer, gHeizungTest)                { channel="tado:zone:dbd1315d:1:hvacMode", mqtt=">[openhabmqtt:wohnung/wohnzimmer/heizung/get/hvacMode:state:*:DEFAULT]" }

My Group Items looks like

Group:String      gHeizungTest                                                       (gTado)                             { mqtt=">[openhabmqtt:wohnung/alleraeume/heizung/get/hvacMode:state:*:DEFAULT],<[openhabmqtt:wohnung/alleraeume/heizung/set/hvacMode:state:DEFAULT]"}

I can control the Group via Sitemap and Basic UI without a Problem and set the Group to OFF or Heat. But i can’t do it via MQTT. I have the some Problem with other Groups.

Any Tipps to solve that Problem?


Groups are not intended to be directly controlled via a binding. Though it’s not explicitly forbidden, I doubt that this is a correct Group item definition, see https://www.openhab.org/docs/configuration/items.html#groups for details.
So, if you want to control the group item directly by a mqtt command, I think you have to use a rule and an additional item.

Thanks for the confirmation. I almost thought that it was because of the Group and not designed to be controlled via a binding. I’ve no created a additional switch with a rule to control the group.

Interestingly, when i change the Group via BasicUI or the rule it will publish its new status via MQTT.