The Attributesof Nodes, their DataTypesand descriptions are defined in OPC 10000-3. Attributes not marked as optional are mandatory and shall be provided by a Server. The following tables define if the Attributevalue is defined by this specification or if they vendor specific.
For all Nodesspecified in this specification, the Attributesnamed in Table 3shall be set as specified in the table.
Table 3– Common Node Attributes
|
Attribute |
Value |
|
DisplayName |
The DisplayNameis a LocalizedText. Each server shall provide the DisplayNameidentical to the BrowseNameof the Nodefor the LocaleId “en”. Whether the server provides translated names for other LocaleIds is vendor specific. |
|
Description |
Optionally a vendor specific description is provided |
|
NodeClass |
|
|
NodeId |
The NodeIdis described by BrowseNamesas defined in 3.4.2.1and defined in Annex A. |
|
WriteMask |
Optionally the WriteMask Attributecan be provided. If the WriteMask Attributeis provided, it shall set all Attributesto not writeable that are not said to be vendor-specific like Description, EventNotifier or DisplayName with a LocaleId other than ‘en’. For example, the Description Attributemay be set to writeable since a Server may provide a server-specific description for the Node. The Attributes NodeId, BrowseName andNodeClass and DataTypeshall not be writeable, because they are defined for each Nodein this specification. The WriteMask Attribute does not take any user access rights into account, that is, although an Attribute is writeable this may be restricted to a certain user / user group. |
|
UserWriteMask |
Optionally the UserWriteMask Attributecan be provided. It takes the user access rights for the Sessionuser into account. |
For all Objectsspecified in this specification, the Attributesnamed in Table 4shall be set as specified in the table. The definitions for the Attributescan be found in OPC 10000-3.
Table 4– Common Object Attributes
|
Attribute |
Value |
|
EventNotifier |
Indicates whether the Nodecan be used to subscribe to Eventsor not. The value of the Attributeis vendor specific. |
For all Variablesspecified in this specification, the Attributesnamed in Table 5shall be set as specified in the table. The definitions for the Attributescan be found in OPC 10000-3.
Table 5– Common Variable Attributes
|
Attribute |
Value |
|
MinimumSamplingInterval |
Optionally, a vendor-specific minimum sampling interval is provided |
|
AccessLevel |
The access level for Variablesused for type definitions is vendor-specific, for all other Variablesdefined in this specification, the access level shall allow a current read; other settings are vendor specific. |
|
UserAccessLevel |
The value for the UserAccessLevel Attributeis vendor-specific. It is assumed that all Variablescan be accessed by at least one user. |
|
Value |
For Variablesused as InstanceDeclarations,the value is vendor-specific; otherwise it shall represent the value described in the text. |
|
ArrayDimensions |
If the ValueRankdoes not identify an array of a specific dimension (i.e. ValueRank<= 0) the ArrayDimensionscan either be set to null or the Attributeis missing. This behaviour is vendor-specific. If the ValueRankspecifies an array of a specific dimension (i.e. ValueRank> 0) then the ArrayDimensions Attributeshall be specified in the table defining the Variable. The concrete array length is contained in the delivered Value. Therefore this information is only relevant for write access to the Variable Valueif the array has a fixed length. |
For all VariableTypesspecified in this specification, the Attributesnamed in Table 6shall be set as specified in the table. The definitions for the Attributescan be found in OPC 10000-3.
Table 6– Common VariableType Attributes
|
Attributes |
Value |
|
Value |
Optionally a vendor-specific default value can be provided |
|
ArrayDimensions |
If the ValueRankdoes not identify an array of a specific dimension (i.e. ValueRank<= 0) the ArrayDimensionscan either be set to null or the Attributeis missing. This behaviour is vendor-specific. If the ValueRankspecifies an array of a specific dimension (i.e. ValueRank> 0) then the ArrayDimensions Attributeshall be specified in the table defining the VariableType. The concrete array length is contained in the delivered Value. Therefore this information is only relevant for write access to the VariableType Valueif the array has a fixed length. |