Send to KNX bus

The Send to KNX bus action writes data directly to one or more KNX group addresses. You can send a raw payload or have Home Assistant encode a value using a KNX datapoint type (DPT).

This is useful when you want to control a KNX device or update a value on the bus from an automation or script, without modeling that device as a separate entityAn 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] in Home Assistant.

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 send data to the KNX bus 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: Send to KNX bus.
6. Enter the Group address and the Payload to send. Optionally, set a Value type to encode the payload as a DPT.
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.send. A basic example looks like this:

action: knx.send
data:
  address: "1/1/1"
  type: percent
  payload: 50

This sends the value 50 to group address 1/1/1, encoded as a percentage.

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.

Script: send a fixed value and an entity state

This script sends a value to the bus in three different ways: encoded as a DPT, as a raw byte value, and from a Home Assistant entity state.

alias: "Send values to KNX"
sequence:
  - action: knx.send
    data:
      address: "1/1/1"
      type: percent
      payload: 50
  - action: knx.send
    data:
      # 50% as a 1-byte raw value
      address: "1/1/1"
      payload: [128]
  - action: knx.send
    data:
      address: "3/3/3"
      type: temperature
      payload: "{{ states('sensor.dew_point') }}"

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:

• Read from KNX bus: Sends GroupValueRead requests 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.