Register knx_event

The Register knx_event action adds or removes group addresses in the knx_event filter. When a group address is registered, telegrams sent to that address fire a knx_event on the Home Assistant event bus, which you can use as an automation trigger.

This is useful when you want to react to KNX addresses that are not modeled as entities, and to do so only at certain times by registering and unregistering them on the fly.

Group addresses configured through the event key in your configuration.yamlThe configuration.yaml file is the main configuration file for Home Assistant. It lists the integrations to be loaded and their specific configurations. In some cases, the configuration needs to be edited manually directly in the configuration.yaml file. Most integrations can be configured in the UI. [Learn more] are always active and cannot be removed with this action. For more details, see the Events section.

Using this action from the user interface

If you prefer building automations and scripts visually, Home Assistant walks you through this action step by step. You pick what to target, tweak a few options, and save. No YAML knowledge required.

To register a group address from an automation or a script:

1. Go to Settings > Automations & scenes.
2. Open an existing automation or script, or select Create automation > Create new automation.
3. If you’re setting up a new automation, add a trigger in the When section. Scripts don’t need a trigger. They run when something else calls them.
4. In the Then do section, select Add action.
5. From the search box, search for and select KNX: Register knx_event.
6. Enter the Group address to register. Optionally, set a Value type to decode the payload, or turn on Remove event registration to remove the address.
7. Select Save.

This action does not support targets. In the UI, you are not prompted to choose an area, device, entity, or label. Only users with administrator rights can run this action.

Options in the UI

Using this action in YAML

If you work directly in YAML, or you want to know exactly what Home Assistant does under the hood, this section has the technical reference. It lists the field names you use in YAML, their types, and which ones are required.

In YAML, refer to this action as knx.event_register. A basic example looks like this:

action: knx.event_register
data:
  address: "0/4/20"

This registers group address 0/4/20 so that telegrams sent to it fire a knx_event.

Options in YAML

Try it yourself

Ready to test this? Open Developer tools > Actions, search for this action, fill in the fields, and select Perform action. You see what happens on your actual entitiesAn entity represents a sensor, actor, or function in Home Assistant. Entities are used to monitor physical properties or to control other entities. An entity is usually part of a device or a service. [Learn more] without writing a line of YAML.

More examples

Real scenarios where this action shows up in automations and scripts. Copy any example and adapt it to your setup.

Automation: register a group address on startup

This automation registers a cover-move group address when Home Assistant starts, so that its telegrams fire a knx_event you can act on.

alias: "Register KNX event on startup"
triggers:
  - trigger: homeassistant
    event: start
actions:
  - action: knx.event_register
    data:
      # Cover move trigger
      address: "0/4/20"

Still stuck?

The Home Assistant community is quick to help: join Discord for real-time chat, post on the community forum with the action you’re calling and what you expected to happen, or share on our subreddit /r/homeassistant.

Related actions

These actions work well alongside this one:

• Send to KNX bus: Sends arbitrary data directly to the KNX bus.

• Read from KNX bus: Sends GroupValueRead requests to the KNX bus.

• Expose to KNX bus: Adds or removes exposures to the KNX bus.