Device Inactivity Alarm

Monitor device connectivity and automatically create or clear an alarm when a device stops sending data.

Use Case

Thermometer A1 (thermostat profile) sends temperature telemetry to ThingsBoard. When it stops reporting data, ThingsBoard marks it inactive and raises a Device inactive alarm. When the device reconnects, the alarm clears automatically.

Two approaches are covered:

Option 1: Alarm Rule — no-code, scoped to a device profile. Best for standard inactivity monitoring.
Option 2: Rule Engine — rule chain configuration, supports custom logic such as notifications or external forwarding.

Prerequisites

Create a device:

Name: Thermometer A1
Device profile: thermostat

Devices list showing Thermometer A1 with Inactive state badge

ThingsBoard’s Device State service automatically maintains two server attributes on every device:

active — true when the device is active, false when inactive
inactivityAlarmTime — timestamp of the last inactivity event

Option 1. Alarm Rule

You can import a ready-made alarm rule or build it manually.

Option 1. Import alarm rule

Download the Device Active/Inactive alarm rule as JSON file and import it into your instance.

When importing, set the thermostat as the target device profile.

Option 2. Create manually

Go to Alarms ⇾ Alarm rules and click + Add alarm rule ⇾ Create new alarm rule.

Step 1. Configure General Settings

In the Alarm rule dialog, set:

Alarm type: Device inactive
Entity type: Device profile
Device profile: thermostat (here specify the device type of your device)

Step 2. Add Argument

Click Add argument and configure it to read the active server attribute:

Entity type: Current entity
Argument type: Attribute
Attribute scope: Server attributes
Attribute key: active
Argument name: active

Argument settings dialog with active server attribute configured

Step 3. Add Trigger Condition

In the Trigger conditions section, set Severity to Critical, then click Add condition and configure:

Mode: Script
Script:
```
return active == false;
```

Trigger conditions section with Critical severity and Add condition button

Alarm condition dialog in Script mode with return active == false

Select Script mode and enter return active == false;. The alarm is created when the device becomes inactive.

Step 4. Add Clear Condition

Scroll down to Clear condition, click Add condition, and configure:

Mode: Script
Script:
```
return active == true;
```

Clear condition section with Add condition button

Alarm condition dialog in Script mode with return active == true

Select Script mode and enter return active == true;. The alarm clears when the device becomes active again.

Completed alarm rule with clear condition showing function expression

Click Add to save the alarm rule.

Step 5. Verify

Open Thermometer A1 ⇾ Attributes ⇾ Server attributes. ThingsBoard writes active and inactivityAlarmTime automatically.

To simulate inactivity, edit the active attribute and set it to false:

Thermometer A1 server attributes showing active attribute

ThingsBoard writes the active server attribute automatically. It is updated by the Device State service whenever the device connectivity state changes.

Editing active attribute with Boolean toggle set to False

Edit the active attribute and set it to False to simulate a device going offline.

Open Thermometer A1 ⇾ Alarms. A Device inactive Critical alarm appears:

Thermometer A1 Alarms tab showing Device inactive Critical alarm

Set active back to true to clear the alarm:

Editing active attribute with Boolean toggle set to True

Set the active attribute back to True to simulate the device reconnecting.

Thermometer A1 Alarms tab empty after alarm is cleared

Option 2. Rule Engine

Use this approach when you need custom processing alongside the alarm — for example, sending a notification email, forwarding data to an external system, or chaining conditional logic.

The Rule Engine processes device connectivity events as special message types:

INACTIVITY_EVENT — fired when the device exceeds the inactivity timeout
ACTIVITY_EVENT — fired when the device resumes activity

Step 1. Set Inactivity Timeout (Optional)

The global default timeout is 600 seconds (state.defaultInactivityTimeoutInSec in thingsboard.yml).

To override it particular device, add an inactivityTimeout server attribute (value in milliseconds):

Key: inactivityTimeout
Type: Integer
Value: 60000 (60 seconds)

Thermometer A1 server attributes configuration

Step 2. Configure the Rule Chain

Open your Root Rule Chain and create two nodes:

Create Alarm node:

Name: Create Inactivity Alarm
Alarm type: Inactivity Timeout

Clear Alarm node:

Name: Clear Inactivity Alarm
Alarm type: Inactivity Timeout

Connect these two nodes to the existing Message Type Switch node:

Message Type Switch ⇾ Inactivity Event ⇾ Create Inactivity Alarm
Message Type Switch ⇾ Activity Event ⇾ Clear Inactivity Alarm