---
title: "Creating a REST Tag"
description: "Configure a CAREL BOSS variable as a tag"
source_url: https://ai-ops.com/docs/tags/creating-rest
---

# Creating a REST Tag

After [creating a tag](https://ai-ops.com/docs/tags/creating-getting-started.md) on a REST (CAREL BOSS) device, you need to tell Koios which BOSS variable to read or write. You can configure these fields during creation or afterwards on the tag's **Configuration** tab.

> [!TIP] Use the BOSS browser to discover variables
> On the Configuration tab, click **Browse** to connect to the BOSS controller and explore its devices and variables. Select a variable to auto-populate all three fields below.

## Protocol Fields

### Device Address

The address of the device within the BOSS system. BOSS controllers can manage multiple downstream devices, and this field identifies which one to communicate with.

- Each device in the BOSS system has a unique address
- Example: `1`, `LOC001`

### Variable Code

The code that identifies the specific variable (data point) on the BOSS device.

- Each variable on a BOSS device has a unique code
- Example: `B0`, `A15`

### Variable Type

The data type of the BOSS variable.

| Type | Description |
|------|-------------|
| **Analog** | A numeric value — temperatures, pressures, setpoints |
| **Digital** | A binary on/off state — relays, switches, alarms |
| **Integer** | A whole number value — counters, mode selections |
| **Alarm** | An alarm state from the controller's alarm system |

## Using the BOSS Browser

The BOSS browser connects to the controller and lets you explore its device and variable hierarchy.

1. Open the tag's **Configuration** tab and click **Browse**
2. The browser lists all devices registered in the BOSS controller
3. Expand a device to see its available variables
4. Select the variable you want — the **Device Address**, **Variable Code**, and **Variable Type** are auto-populated
5. Click **Apply** to save the selection

> [!NOTE] The device must be reachable to browse
> The browser connects to the BOSS controller via its REST API. The device must be powered on, reachable on the network, and the REST credentials configured on the device must be valid.

## After Configuration

1. **Save** the tag configuration
2. **Test the tag** — click `Test` to verify Koios can read the variable's value (see [Testing a Tag](https://ai-ops.com/docs/tags/troubleshooting.md#testing-a-tag))
3. **Enable the tag** — flip the enable switch to start collecting data

> [!TIP] Enable the device first
> Tags only collect data when their parent device is also enabled and running.