You might be like me, after all those years being happy on KNX you decided to add some non-KNX lights to the home and can't turn them off with your magic bedside “All-Off” button.

Preparation

Create two new GA for this new function, one for switching and one for status. I'll use 8/2/1 and 8/2/2 in the automation below. Create a group in HASS with all the light you'd like to turn off. I'll use “Vraies lumieres”.

Automation

To be copy-pasted into a blank automation and edited to your used case.

alias: "[Light] All-Off  Parents"
description: ""
trigger:
  - platform: homeassistant
    event: start
  - platform: event
    event_type: automation_reloaded
  - platform: event
    event_type: knx_event
    event_data:
      destination: 8/2/1
action:
  - choose:
      - conditions:
          - condition: template
            value_template: >-
              {{ trigger is defined and trigger.platform == "event" and
              trigger.event.event_type == "knx_event" }}
        sequence:
          - choose:
              - conditions:
                  - condition: template
                    value_template: >-
                      {{ trigger.event.data.destination == 8/2/1 and
                      trigger.event.data.data == 1 }}
                    enabled: true
                sequence:
                  - service: light.turn_on
                    data:
                      entity_id: light.vraies_lumieres
                    enabled: false
              - conditions:
                  - condition: template
                    value_template: >-
                      {{ trigger.event.data.destination == "8/2/1" and
                      trigger.event.data.data == 0 }}
                sequence:
                  - service: light.turn_off
                    data:
                      entity_id: light.vraies_lumieres
                  - service: knx.send
                    data:
                      address: 8/2/2
                      payload: 0
      - conditions:
          condition: or
          conditions:
            - condition: template
              value_template: "{{ trigger is not defined }}"
            - condition: template
              value_template: "{{ trigger.platform == \"homeassistant\" }}"
            - condition: template
              value_template: >-
                {{ trigger.platform == "event" and trigger.event.event_type ==
                "automation_reloaded" }}
        sequence:
          - service: knx.event_register
            data:
              address: 8/2/1
          - service: knx.exposure_register
            data:
              address: 8/2/2
              type: binary
              entity_id: light.vraies_lumieres

How it works

This is based on the great examples found on the xknx discord.

Upon homeassitant start it checks that knx integration is loaded then registers a listener for the switching GA with the knx.event_register service and exposes the state of the lights group to the other GA with knx.exposure_register.

Conditional block ensures that we ask for Off ( payload = 0 ) before calling light light.turn_off.

I've left the turn_on part as disabled if you have any use for it.

Have fun !