An offline alarm tells you that a device has stopped talking. It is a separate alarm rule on the device profile, the Device offline rule, with the fixed type device_offline. Whether a device counts as online is decided by the profile’s online rule; the alarm only reacts to it.
Add the rule
- Open Device Profiles, open the profile, then the Alarm rules tab.
- Click Add rule > Device offline rule.
- Set Open after (seconds offline) (10 to 604,800; default 600), the Severity (default Warning), the Alarm title (default
{{device.name}} is offline) and a Runbook. - Click Add to list, then Save rules.
A profile has at most one Device offline rule.
{
"type": "device_offline",
"title": "{{device.name}} is offline",
"inactivity": { "afterSec": 900, "severity": "MAJOR" },
"notify": { "recipients": [ { "kind": "role", "role": "ADMIN" } ] },
"runbook": "Check power and the network at the site. The device's Log tab shows the last disconnect reason.",
"enabled": true
}The title may use {{device.name}}, {{severity}} and {{type}}.
When it opens
Two events open the alarm:
| Event | When the alarm opens |
|---|---|
| The device goes offline under the profile’s online rule (a disconnect, a keepalive timeout, or the end of the Recent message window) | Open after (seconds offline) later, if the device has not come back meanwhile. |
| The device goes quiet: it sent nothing for the profile’s Inactivity timeout (seconds) | At once. The inactivity timeout has already waited. |
The delay is checked every few seconds, so the alarm opens within about 5 seconds of its due time. The quiet check runs once a minute.
When it clears
The alarm clears automatically when the device comes online again (connects) or becomes active again after a quiet spell (sends something). Its pending check is cancelled at the same moment.
How it fits with the online rule
| Profile setting (tab Online status) | Effect on the offline alarm |
|---|---|
| Live connection | Offline when the MQTT session ends. The alarm opens afterSec later. Short reconnects shorter than afterSec never open it. |
| Recent message | Offline when nothing arrived for Expected interval × Factor. The alarm opens afterSec after that, so the total silence before the alarm is interval × factor + afterSec. |
| Last seen only | Never offline. Only the quiet check (inactivity timeout) can open the alarm. |
| Inactivity timeout (seconds) | Default 600 (10 to 604,800). When it passes without activity, the alarm opens at once. |
See Connection status and activity and Device profiles.
Choosing the times
- For a device on Live connection that may drop its session briefly (mobile networks), set afterSec longer than a normal reconnect, for example 300 to 900.
- For a device that reports every hour on Recent message, interval 3,600 × factor 2 plus afterSec 600 means the alarm opens 2 hours 10 minutes after the last message.
- If you want the alarm exactly when a device misses its reports, keep the Inactivity timeout a little longer than the reporting interval: the quiet check opens the alarm at once.
What it does not do
- It does not look at telemetry content. A device that stays connected but sends only empty or wrong data is not offline. Use a threshold rule or a flow watchdog for that.
- A disconnect or quiet message that arrives late (after an outage of the platform’s processing) is not evaluated; the check counts from now.
- Muting the device stops the notifications, not the alarm. See Muting a device for maintenance.
Notifications
The offline rule has the same notify block as threshold rules: recipients, channels, minimum severity and reminders. See Alarm notifications in depth.
Offline alarms from the Rules card
The Rules card has its own trigger A device connects or disconnects with goes offline and goes quiet. Use it when you want to do something (send a command to a backup unit, tell a team) rather than open an alarm. The ready rule Tell people when a device stays offline waits 10 minutes and tells the administrators only if the device is still offline. See Rules card cookbook.