Read from KNX bus

The Read from KNX bus action sends a GroupValueRead request to one or more KNX group addresses. The response can be used in automations through the KNX telegram trigger, and it is processed in KNX entities.

This is useful when you want to actively ask a KNX device for its current value, for example to refresh a cover position after it has been moving for a while, instead of waiting for the device to report on its own.

To issue GroupValueRead requests for all state addresses of an entity at once, you can use the Home Assistant: Update entity action instead.

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 read from the KNX bus in 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: Read from KNX bus.
6. Enter the Group address to read from.
7. Select Save.

This action does not support targets. In the UI, you are not prompted to choose an area, device, entity, or label.

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.read. A basic example looks like this:

action: knx.read
data:
  address: "1/0/15"

This sends a GroupValueRead request to group address 1/0/15.

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: update a cover position after movement

This automation reacts to a cover-move telegram and, after a short delay, reads the cover position address so Home Assistant stays in sync.

alias: "Update cover position"
triggers:
  - trigger: knx.telegram
    # Cover move trigger
    destination: "0/4/20"
actions:
  - delay: "0:0:10"
  - action: knx.read
    data:
      # Cover position address
      address: "0/4/21"

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.

• Register knx_event: Adds or removes group addresses in the knx_event filter.

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