2026.6.4
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Set absolute variable

This action sets a variable or setpoint on an LCN module to a fixed value. Use it to write a known value, for example a target temperature, to a regulator setpoint.

Important

Ensure that the LCN module is configured properly to provide access to the defined variable. Otherwise the module might show unexpected behavior or return error messages.

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 set the absolute value of a variable 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 LCN: Set absolute variable.
  6. Select the LCN module or group in the Device field, and then choose the Variable.
  7. Optional: In Value, enter the variable or setpoint value.
  8. Select Save.

This action does not support targets. Instead, you select the LCN module or group through the Device field.

Options in the UI

Device (Required)

The LCN module or group to send the command to.
Variable (Required)

The variable or setpoint name.
Value (Optional)

The value to set.
Unit of measurement (Optional)

The unit of the value. Defaults to native.

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 lcn.var_abs. A basic example looks like this:

ActionActions are used in several places in Home Assistant. As part of a script or automation, actions define what is going to happen once a trigger is activated. In scripts, an action is called *sequence*. [Learn more] 
action: lcn.var_abs
data:
  device_id: 91aa039a2fb6e0b9f9ec7eb219a6b7d2
  variable: var1
  value: 75
  unit_of_measurement: "%"

This sets variable 1 of the selected module to 75%.

Options in YAML

device_id string Required

The device ID of the LCN module or group.

variable string Required

The variable or setpoint name. See Variables and units.

value integer

The value to set. If not provided, it is assumed to be 0.

unit_of_measurement string

The unit of the value. See Variables and units. If not provided, it is assumed to be native.

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.

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.

Tip

AI assistants like ChatGPT or Claude can also explain actions or suggest the right one when you describe what you want in plain language.

Related actions

These actions work well alongside this one: