This OPC UA Variable, of DataType Float, represents the BACnet property Present_Value. The OPC UA EngineeringUnits Property of the Variable represents the BACnet property Output_Units.

The Present_Value of the BACnetLoopType indicates the current output value of the loop algorithm and describes the engineering units of the value. If the object supports event reporting, then the Present_Value is the monitored value for the object’s event algorithm. See the BACnet specification for information on the BACnet event enrolment model.

This OPC UA AnalogItemType Variable represents the BACnet properties Present_Value, Minimum_Output, Maximum_Output, Output_Units and Update_Interval. The OPC UA VariableType AnalogItemType is defined in OPC 10000-8. It defines the OPC UA Properties EURange, EngineeringUnits and InstrumentRange.

The following list provides the BACnet property and the mapping to the corresponding data member in the OPC UA AnalogItem.

• Present_Value represented by Value Attribute of the Variable.
• Minimum_Output represented by Low part of EURange Property of the Variable. If the optional BACnet property Minimum_Output is not present, the EURange Property should not be provided.
• Maximum_Output represented by the High part of EURange Property of the Variable. If the optional BACnet property Maximum_Output is not present, the EURange Property should not be provided.
• Output_Units represented by the EngineeringUnits Property of the Variable. The mapping of BACnet units to OPC UA units is defined in 11.
• Update_Interval represented by MinSamplingInterval Attribute of the Variable.