ThingsBoard provides the ability to create and manage alarms related to your entities: devices, assets, customers, etc. For example, you may configure ThingsBoard to automatically create an alarm when the temperature sensor reading is above a certain threshold. Of course, this is a very simplified case, and real scenarios can be much more complex.
Let’s review the main concepts of the alarm below:
Alarm originator is an entity that causes the alarm. For instance, Device A is an originator of the alarm if ThingsBoard receives a temperature reading from it and raise the “HighTemperature” alarm because the reading exceeds the threshold.
Alarm type helps to identify the root cause of the alarm. For example, “HighTemperature” and “LowHumidity” are two different alarms.
Each alarm has severity which is either Critical, Major, Minor, Warning, or Indeterminate (sorted by priority in descending order).
Alarm may be active or cleared. When ThingsBoard creates an alarm it persists the start and end time of the alarm. By default, the start time and the end time are the same. If the alarm trigger condition repeats, the platform updates the end time. ThingsBoard can automatically clear the alarm when an event occurs that matches an alarm clearing condition. Alarm clear condition is optional. A user can clear the alarm manually.
Besides active and cleared alarm state, ThingsBoard also keeps track of whether someone has acknowledged the alarm. Alarm acknowledgment is possible via the dashboard widget, or an entity details tab.
To summarize, there are 4 possible values of the “status” field:
ThingsBoard identifies alarm using a combination of originator, type, and start time. Thus, at a single point in time, there is only one active alarm with the same originator, type, and start time.
Let’s assume you have provisioned alarm rules to create a “HighTemperature” alarm when the temperature is greater than 20. And you also provisioned alarm rules to clear the “HighTemperature” alarm when the temperature is less than or equal to 20.
Assuming the following sequence of events:
Hence, you should create a single “HighTemperature” alarm with start time = 12:30 and end time = 13:00.
Suppose you have a topology where one Tenant has 1000 Customers and each Customer has 1000 Devices. Thus, you have 1M Devices in your server installation. You may want to design a dashboard that displays all active alarms on the Tenant and Customer level. To simplify the database queries and improve load time, ThingsBoard supports the propagation of the alarm. When the alarm is created, we can specify whether it should be visible for parent entities or not. We can also optionally specify the relations that should be present between the parent entities and the originator for the alarm to propagate.
Now, when you know the theory, let’s proceed to practical tutorials.
The easiest way is to use the Alarm Rules.
The alternative option is to configure your custom logic in the Rule Engine and use Create Alarm and Clear Alarm rule nodes. You can find a corresponding example here.
To find alarms for a specific device or asset you should:
See this doc to add an alarm widget to the dashboard.
You can also explore datasource settings and advanced settings of the widget.
The Datasource setting allows you to:
To send notification when alarm is created or cleared, please check this doc.
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