Device Inactivity Alarm

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

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.

Create a device:

• Name: Thermometer A1
• Device profile: thermostat

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

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.

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)

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

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

• Mode: Script
• Script:

  return active == false;

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

• Mode: Script
• Script:

  return active == true;

Click Add to save the alarm rule.

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

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

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

Set active back to true to clear the alarm:

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

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)

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

• Device connectivity status — how ThingsBoard tracks device state
• Alarm rules — full alarm rule reference
• Create & clear alarms — threshold-based alarm recipe