Namespaces are used by OPC UA to create unique identifiers across different naming authorities. The Attributes NodeIdand BrowseNameare identifiers. A Nodein the UA AddressSpaceis unambiguously identified using a NodeId. Unlike NodeIds, the BrowseNamecannot be used to unambiguously identify a Node. Different Nodesmay have the same BrowseName. They are used to build a browse path between two Nodesor to define a standard Property.

Serversmay often choose to use the same namespace for the NodeIdand the BrowseName. However, if they want to provide a standard Property, its BrowseNameshall have the namespace of the standards body although the namespace of the NodeIdreflects something else, for example the EngineeringUnits Property. All NodeIdsof Nodesnot defined in this document shall not use the standard namespaces.

Table 166provides a list of mandatory and optional namespaces used in an OPC 40083 OPC UAServer.

Table 166– Namespaces used in an OPC 40083 Server

NamespaceURI

Description

Use

http://opcfoundation.org/UA/

Namespace for NodeIdsand BrowseNamesdefined in the OPC UA specification. This namespace shall have namespace index 0.

Mandatory

Local Server URI

Namespace for nodes defined in the local server. This may include types and instances used in an AutoID Device represented by the Server. This namespace shall have namespace index 1.

Mandatory

http://opcfoundation.org/UA/DI/

Namespace for NodeIdsand BrowseNamesdefined in OPC 10000-100. The namespace index is Serverspecific.

Mandatory

http://opcfoundation.org/UA/PlasticsRubber/

GeneralTypes/

Namespace for NodeIdsand BrowseNamesdefined in this document. The namespace index is Serverspecific.

Mandatory

Vendor specific types

A Servermay provide vendor-specific types like types derived from ObjectTypes defined in this document in a vendor-specific namespace.

Optional

Vendor specific instances

A Serverprovides 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.

Mandatory

Table 167provides a list of namespaces and their index used for BrowseNamesin this document. The default namespace of this document is not listed since all BrowseNameswithout prefix use this default namespace.

Table 167– Namespaces used in this document

NamespaceURI

Namespace Index

Example

http://opcfoundation.org/UA/

0

0:NodeVersion

http://opcfoundation.org/UA/DI/

2

2:DeviceClass