Bounds Rule

Type: bounds — Built-in check; no custom expression.

What the rules engine does

The bounds rule flags sensor values that fall outside a valid range. For each input, you define [low, high] bounds (optionally different for imperial vs metric). The engine evaluates (value < low) | (value > high) — when True, a fault is flagged. This catches bad data, sensor drift, or physically impossible readings (e.g., SAT at 200°F when the coil can’t produce that). Inspired by SkySpark/Axon-style badSensorCheck.

Use params={"units": "metric"} at runtime to switch to metric bounds when your data is in °C, Pa, etc.

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bad_sensor_check (bounds)

Sensor out of range. Pass params={"units": "metric"} for metric bounds.

name: bad_sensor_check
description: Returns fault if sensor is out of range (inspired by SkySpark badSensorCheck)
type: bounds
flag: bad_sensor_flag

params:
  units: imperial

inputs:
  Supply_Air_Temperature_Sensor:
    brick: Supply_Air_Temperature_Sensor
    column: sat
    bounds:
      imperial: [40, 150]
      metric: [4, 66]
  Return_Air_Temperature_Sensor:
    brick: Return_Air_Temperature_Sensor
    column: rat
    bounds:
      imperial: [40, 100]
      metric: [4, 38]
  Mixed_Air_Temperature_Sensor:
    brick: Mixed_Air_Temperature_Sensor
    column: mat
    bounds:
      imperial: [40, 100]
      metric: [4, 38]
  Outside_Air_Temperature_Sensor:
    brick: Outside_Air_Temperature_Sensor
    column: oat
    bounds:
      imperial: [-40, 120]
      metric: [-40, 49]
  Discharge_Air_Static_Pressure_Sensor:
    brick: Discharge_Air_Static_Pressure_Sensor
    column: ap
    bounds:
      imperial: [-5, 10]
      metric: [-1244, 2488]

Full rule with additional sensors in open_fdd/rules/sensor_bounds.yaml.

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Next: Flatline Rule