Annex D (informative) Mapping from OPC A&E to OPC UA A&C ToC Previous Next

D.2 Alarms and Events COM UA wrapper ToC Previous Next

D.2.1 Event areas ToC Previous Next

Event Areas in the A&E COM Server are represented in the A&E COM UA Wrapper as Objects with a TypeDefinition of BaseObjectType. The EventNotifier Attribute for these Objects always has the SubscribeToEvents flag set to True.

The root Area is represented by an Object with a BrowseName that depends on the UA Server. It is always the target of a HasNotifier Reference from the Server Node. The root Area allows multiple A&E COM Servers to be wrapped within a single UA Server.

The Area hierarchy is discovered with the BrowseOPCAreas and the GetQualifiedAreaName Methods. The Area name returned by BrowseOPCAreas is used as the BrowseName and DisplayName for each Area Node. The QualifiedAreaName is used to construct the NodeId. The NamespaceURI qualifying the NodeId and BrowseName is a unique URI assigned to the combination of machine and COM Server.

Each Area is the target of HasNotifier Reference from its parent Area. It may be the source of one or more HasNotifier References to its child Areas. It may also be a source of a HasEventSource Reference to any sources in the Area.

The A&E COM Server may not support filtering by Areas. If this is the case then no Area Nodes are shown in the UA Server address space. Some implementations could use the AREAS Attribute to provide filtering by Areas within the A&E COM UA Wrapper.

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