Namespaces are used by OPC UA to create unique identifiers across different naming authorities. The Attributes NodeId and BrowseName are identifiers. A Node in the UA AddressSpace is unambiguously identified using a NodeId. Unlike NodeIds, the BrowseName cannot be used to unambiguously identify a Node. Different Nodes may have the same BrowseName. They are used to build a browse path between two Nodes or to define a standard Property.
Servers may often choose to use the same Namespace for the NodeId and the BrowseName. However, if they want to provide a standard Property, its BrowseName shall have the Namespace of the standard’s body even though the Namespace of the NodeId reflects something else, such as the EngineeringUnits Property. All NodeIds of Nodes not defined in this document shall not use the standard Namespaces.
Table 146 provides a list of Namespaces typically used in a LADS OPC UA Server.
Table 146 – Namespaces used in a LADS Server
|
NamespaceURI |
Description |
|
Namespace for NodeIds and BrowseNames defined in the OPC UA specification. This Namespace shall have Namespace index 0. |
|
|
Local Server URI |
Namespace for Nodes defined in the local Server. This Namespace shall have Namespace index 1. |
|
Namespace for NodeIds and BrowseNames defined in OPC 10000-100. The Namespace index is Server specific. |
|
|
Namespace for NodeIds and BrowseNames defined in OPC UA for Machinery (OPC 40001-1). The Namespace index is Server specific. |
|
|
Namespace for NodeIds and BrowseNames defined in Asset Management Base. The Namespace index is Server specific. |
|
|
Namespace for NodeIds and BrowseNames defined in this document. The Namespace index is Server specific. |
|
|
Vendor-specific types |
A Server may provide vendor-specific types in a vendor-specific Namespace, such as types derived from ObjectTypes defined in this document. |
|
Vendor-specific instances |
A Server provides vendor-specific instances of the standard types or vendor-specific instances of vendor-specific types in a vendor-specific Namespace. It is recommended to separate vendor-specific types and vendor-specific instances into two or more Namespaces. |
Table 147 provides a list of Namespaces and their indices used for BrowseNames in this document.
The default Namespace of this document is not listed since all BrowseNames without prefix use this default Namespace.
Table 147 – Namespaces used in this document
|
NamespaceURI |
Namespace Index |
Example |
|
0 |
0:EngineeringUnits |
|
|
2 |
2:DeviceFeatures |
|
|
3 |
3:MaintenanceMethodEnum |
|
|
4 |
4:Machines |