This OPC UA Variable, of DataType Float, represents the BACnet property Controlled_Variable_Value. The OPC UA EngineeringUnits Property of the Variable represents the BACnet property Controlled_Variable_Units.
This property indicates the value of the property (and its engineering units) of the object that is referenced by the Controlled_Variable_Reference property. The control loop compares this value with the Setpoint to calculate the error.