5.2 Model Overview

Figure 8 depicts the main ObjectTypes of the OPC UA for BACnet information model and their relationship. The drawing is not intended to be complete.

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Figure 8 – BACnet OPC UA Model Overview

The boxes in this drawing show the ObjectTypes used in this specification as well as some elements from other specifications. The upper grey box shows the OPC UA core ObjectType from which the OPC UA for BACnet information model ObjectTypes are derived and some VariableTypes used in the BACnet ObjectTypes.

The left grey box in the second level shows the main ObjectTypes that this specification introduces. They represent corresponding BACnet object types. A type hierarchy is used whenever identical components are used in different BACnet object types.

The right grey box in the second level shows the ObjectTypes used for grouping of BACnet features. These groupings are used in the OPC UA for BACnet information model ObjectTypes shown in the left grey box.

Figure 9 provides an example for the mapping of a BACnet Analog Input object type to an OPC UA ObjectType.

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Figure 9 – BACnet mapping example

The left grey box shows the list of BACnet properties of the BACnet Analog Input object type.

The middle grey box shows an instance of an OPC UA BACnetAnalogInput ObjectType.

The right grey box shows the OPC UA ObjectTypes used to represent a BACnet Analog Input object type.

Most of the BACnet properties are mapped to OPC UA Properties using the BACnet property name as OPC UA BrowseName. They are either Properties of the Object directly or Properties of the EventReporting Object.

The following BACnet properties are mapped to existing OPC UA information.