OPC UA Instance Nodes shall map to AutomationML InternalElements in an AutomationML InstanceHierarchy, as shown in Figure A.18.

Figure A.18 – OPC UA InstanceHierarchy

Note that the example hierarchy shown in Figure A.18 was created using the OPC2AML Conversion Tool that mimics the full OPC UA instance tree as specified in the NodeSet files, minus the standard OPC UA Types folder since the equivalent type objects are contained in the AutomationML Libraries. Engineering tools may organize instance elements in alternate hierarchies (utilizing AutomationML MirrorElements) in addition to the way they would appear in an OPC UA Server.

When SUCs are instantiated in the AutomationML InstanceHierarchy, care must be given to setting the URIs properly to reflect the correct NamespaceURI for both the BrowseName and the Node. In the InstanceHierarchy, an empty or missing NamespaceURI (of the BrowseName) or UaNodeNamespaceUri shall imply the default NamespaceURI of the OPC UA Server (i.e. Namespace index 1). In all other cases, the URI attributes shall contain valid URIs that reflect the correct Node and BrowseName URIs.