Propagation Calculated Field

Propagation automatically transfers data from the current entity to one or more related entities resolved through entity relations. It can copy values as-is or compute a new value before sending — ideal for synchronizing telemetry and attributes across entity hierarchies.

Use Propagation when you need to:

• Mirror device telemetry to a parent asset (battery level, signal quality, last status)
• Push configuration attributes from an asset to child devices (HVAC mode, setpoints)
• Compute a derived value on a device and store it on the related asset (e.g., dew point → greenhouse)
• Propagate to multiple entities at once (all devices under a building or fleet)

1. Open the Calculated fields page.
2. Click the + Add calculated field ⇾ Create new calculated field in the top-right corner.
3. In General, enter a title, specify the entity the field applies to, and select the Propagation type.
4. Configure the Propagation path, Data to propagate, and Output.
5. Click Add to save.

Defines the path from the current entity to the target entity.

Calculated field runs on the child, writes to its parents.

Calculated field runs on the parents, writes to all matching children.

Two modes are available:

Arguments only — direct copy. Reads attribute or latest telemetry from the current entity and writes it to the related entity. Optionally rename the key before storing (via Output key).

Calculation result — compute and propagate. Reads data from multiple entities (current entity, devices, assets, customer, tenant), applies a TBEL script, then propagates the computed result to the related entity.

Script function (Calculation result mode):

function calculate(ctx, arg1, arg2, ...) {
  var result = arg1 + arg2;   // variable name becomes the output key
  return result;
}

For the ctx object and rolling argument methods, see Script — Script Function.

Data is stored on each related entity as either time series or attributes.

For output strategy options, see Calculated Fields — Output Strategy.

Problem: After editing Relation direction or Relation type, the field continues using the original path.

Cause: The propagation path is cached at creation. Updating only the relation settings does not trigger re-initialization.

Solution: Modify any argument (e.g., change the Default value) to force re-initialization. If arguments must remain unchanged, delete and recreate the field.

A Tracker A device sends batteryLevel as telemetry.
Goal: propagate batteryLevel to the related Truck 1 asset as a server-side attribute deviceBatteryLevel.

Setup: Create a Contains relation from Truck 1 to Tracker A (direction: From).

1. Apply the Propagation calculated field to the tracker device profile.
2. Select propagation path: Up to parent, relation type: Contains.
3. Mode: Arguments only. Add argument:
   • Entity type: Current entity
   • Argument type: Latest telemetry
   • Time series key: batteryLevel
   • Output key: deviceBatteryLevel
4. Output type: Attribute (Server).
5. Click Add.

Result: deviceBatteryLevel is stored on the Truck 1 asset as a server-side attribute.

A Smart Device sends temperature and humidity. It is linked to Greenhouse A via Contains. Goal: compute dew point and store it as dewPoint telemetry on the greenhouse asset.

1. Apply the Propagation calculated field to the smart-device device profile.
2. Propagation path: Up to parent, relation type: Contains.
3. Mode: Calculation result. Add two arguments:
   • humidity — Latest telemetry from current entity
   • temperature — Latest telemetry from current entity
4. Write the script:

   function calculate(ctx, temperature, humidity) {
     var a = 17.625;
     var b = 243.04;
     var alpha = ((a * temperature) / (b + temperature)) + Math.log(humidity / 100.0);
     var dewPoint = toFixed((b * alpha) / (a - alpha), 1);
     return { "dewPoint": dewPoint };
   }

5. Output type: Time series.
6. Click Add.

Result: dewPoint is stored as telemetry on Greenhouse A.

Building A asset manages multiple HVAC devices via a Manages relation. The asset has hvacMode as a server-side attribute. Goal: propagate hvacMode from Building A down to all managed HVAC devices.

1. Apply the Propagation calculated field to the building asset profile.
2. Propagation path: Down to child, relation type: Manages.
3. Mode: Arguments only. Add argument:
   • Entity type: Current entity
   • Argument type: Attribute (Server)
   • Attribute key: hvacMode
   • Output key: hvacMode
4. Output type: Attribute (Server).
5. Click Add.

Result: Each HVAC device receives the hvacMode attribute with the current value (e.g., cooling).