---
title: Configure parameters
slug: litmusedge/product-features/digital-twins/configure-parameters
docTags: 
createdAt: 2026-08-14T13:04:23.577Z
---

A parameter is a named variable that you define in a Litmus Edge (LE) model and set separately in each instance. Parameters let one topic expression resolve to a different topic for every instance built from the model, which saves you from defining a topic per attribute per asset.

This topic shows you how to create a parameter, use it in a topic expression, and set its value for an instance. For the rest of the model, see [Create and configure a model](docId\:zPaDX1lMmE0F44V7r6v6Q).

## Before you begin

Before you configure parameters, ensure you have:

- A model with at least one dynamic attribute.

:::hint{type="info"}
**Note:** Also see [Digital Twins](docId\:xlj3gvOZyg_52Ue4pB5u7) for overview and background information.
:::

## How a parameter resolves

Define a parameter named `device`, then use it in a dynamic attribute's topic expression:

`devicehub.alias.{device}.Temperature`

Each instance sets its own value for `device`, so the expression resolves to the tag that belongs to that machine. One expression in the model serves every instance.

:::hint{type="info"}
**Note:** Parameter names and values are case-sensitive and cannot contain spaces. Allowed characters are uppercase and lowercase letters (A–Z), digits (0–9), hyphens (`-`), and underscores (`_`).
:::

## Create a parameter

**To create a parameter in the model:**

1. Open the **Parameters** tab and then click **Add Item**.
2. Enter a parameter name and a placeholder value.
3. Click **Save Row**.

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### Use a parameter in a topic expression

A parameter takes effect only when a dynamic attribute references it.

**To reference a parameter:**

1. Open the **Dynamic Attributes** tab.
2. Click the **Edit** icon for the attribute.
3. Enter a topic expression that combines static text with the parameter name in curly brackets, for example `devicehub.alias.{device}.Temperature`.
4. Click **Save Instance**.

:::hint{type="info"}
**Note:** When a dynamic attribute has a topic expression, its topic is read-only in the instance. To change the topic, edit the expression here or change the instance's parameter value.
:::



### Set the value for an instance

Each instance supplies its own value for every parameter the model defines.

**To set the values:**

1. Select the instance and then click **Open Parameters**.
   The *Instance Parameters* dialog appears.
2. Set the value of each parameter for this instance.
3. Navigate to the **Instance Dynamic Attributes** page and confirm that each topic expression resolved to the topic you expect.

## Verify the parameter resolves

**To confirm a parameter is working:**

1. Open the instance's **Dynamic Attributes** tab and check that the topic shows the resolved value rather than the `{parameter}` placeholder.
2. Open the **Data Access** tab and subscribe to the instance topic.
3. Confirm that the attribute carries data from the asset the parameter points at.

## Related topics

- [Digital Twins](docId\:xlj3gvOZyg_52Ue4pB5u7)
- [Create and configure a model](docId\:zPaDX1lMmE0F44V7r6v6Q)
- [Configure transformations](docId\:tbKP-rLU3oCBdJCnjy4lq)
- [Add an instance](docId\:jzOth4T0hCrTRauUSdRyK)
- [Model and instance actions](docId\:HK0IDxlg7ZCoetaJWcoBO)