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 8provides a list of mandatory and optional namespaces used in an OPC 40084-12 OPC UAServer.

Table 8– Namespaces used in an OPC 40084-12 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 a 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 server specific.

Mandatory

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

GeneralTypes/

Namespace for NodeIdsand BrowseNamesdefined in OPC 40083. The namespace index is server specific.

Mandatory

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

Extrusion/GeneralTypes/

Namespace for NodeIdsand BrowseNamesdefined in OPC 40084-1. The namespace index is server specific.

Mandatory

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

Extrusion/Calender/

Namespace for NodeIdsand BrowseNamesdefined in this specification. The namespace index is server specific.

Mandatory

Vendor specific types and instances

A server may provide vendor specific types like types derived from MachineTypeor MachineStatusTypeor vendor specific instances of devices in a vendor specific namespace.

Optional

Table 9provides 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 9– Namespaces used in this document

NamespaceURI

Namespace Index

Example

http://opcfoundation.org/UA/

0

0:NodeVersion

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

2

2:DeviceClass

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

3

3:MachineInformationType

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

4

4:ExtrusionDeviceType