Trigger Calculated Fields

The node is called calculated fields and alarm rules in the rule chain editor. Use it to trigger calculated field and alarm rule evaluation against incoming telemetry or attribute data without persisting that data to the database — for example, computing a derived metric such as a heat index from incoming temperature and humidity values and publishing the result to the rule chain, while keeping the raw values out of the time-series storage.

This node has no configuration options.

1. Check that the incoming message type is POST_TELEMETRY_REQUEST or POST_ATTRIBUTES_REQUEST. Any other type routes via Failure.
2. Parse the time-series or attribute data from the message body (including attribute scope from metadata scope key when applicable).
3. Trigger evaluation of all calculated fields configured for the message originator that reference the incoming data keys. The raw data is not written to the database.
4. For each calculated field whose state is updated, generate a new message with the originator and push it to the originator’s root rule chain.
5. Forward the original message unchanged via Success.

Type: POST_TELEMETRY_REQUEST | Originator: DEVICE with calculated field heatIndex = temperature + 0.5 * humidity.

{
  "temperature": 25.5,
  "humidity": 60
}

Result: heatIndex is evaluated (25.5 + 0.5 × 60 = 55.5). A new message containing the calculated value is pushed to the root rule chain. The original temperature and humidity values are not stored. Routes via Success.

Type: POST_ATTRIBUTES_REQUEST | Metadata: { "scope": "SERVER_SCOPE" } | Calculated field: speedPercentage = (currentSpeed / maxSpeed) * 100.

{
  "maxSpeed": 100,
  "currentSpeed": 75
}

Result: speedPercentage = 75%. New message pushed to root rule chain; attributes not persisted. Routes via Success.

Type: ENTITY_CREATED → routes via Failure. Only POST_TELEMETRY_REQUEST and POST_ATTRIBUTES_REQUEST are supported.

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  "$schema": "https://json-schema.org/draft/2020-12/schema",
  "title": "EmptyNodeConfiguration",
  "type": "object",
  "properties": {},
  "additionalProperties": false
}