3 Terms, definitions and conventions ToC Previous Next

3.4 Conventions used in this document ToC Previous Next

3.4.3 Common Attributes ToC Previous Next

3.4.3.1 General ToC

The Attributes of Nodes, their DataTypes and 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 Attribute value is defined by this specification or if it is server-specific.

For all Nodes specified in this specification, the Attributes named in Table 4 shall be set as specified in the table.

Table 4 – Common Node Attributes

Attribute Value
DisplayName The DisplayName is a LocalizedText. Each server shall provide the DisplayName identical to the BrowseName of the Node for the LocaleId “en”. Whether the server provides translated names for other LocaleIds is server-specific.
Description Optionally a server-specific description is provided.
NodeClass Shall reflect the NodeClass of the Node.
NodeId The NodeId is described by BrowseNames as defined in 3.4.2.1.
WriteMask Optionally the WriteMask Attribute can be provided. If the WriteMask Attribute is provided, it shall set all non-server-specific Attributes to not writable. For example, the Description Attribute may be set to writable since a Server may provide a server-specific description for the Node. The NodeId shall not be writable, because it is defined for each Node in this specification.
UserWriteMask Optionally the UserWriteMask Attribute can be provided. The same rules as for the WriteMask Attribute apply.
RolePermissions Optionally server-specific role permissions can be provided.
UserRolePermissions Optionally the role permissions of the current Session can be provided. The value is server-specific and depend on the RolePermissions Attribute (if provided) and the current Session.
AccessRestrictions Optionally server-specific access restrictions can be provided.

3.4.3.2 Objects ToC

For all Objects specified in this specification, the Attributes named in Table 5 shall be set as specified in the table. The definitions for the Attributes can be found in OPC 10000-3.

Table 5 – Common Object Attributes

Attribute Value
EventNotifier Whether the Node can be used to subscribe to Events or not is server-specific.

3.4.3.3 Variables ToC

For all Variables specified in this specification, the Attributes named in Table 6 shall be set as specified in the table. The definitions for the Attributes can be found in OPC 10000-3.

Table 6 – Common Variable Attributes

Attribute Value
MinimumSamplingInterval Optionally, a server-specific minimum sampling interval is provided.
AccessLevel The access level for Variables used for type definitions is server-specific, for all other Variables defined in this specification, the access level shall allow reading; other settings are server-specific.
UserAccessLevel The value for the UserAccessLevel Attribute is server-specific. It is assumed that all Variables can be accessed by at least one user.
Value For Variables used as InstanceDeclarations, the value is server-specific; otherwise it shall represent the value described in the text.
ArrayDimensions If the ValueRank does not identify an array of a specific dimension (i.e. ValueRank <= 0) the ArrayDimensions can either be set to null or the Attribute is missing. This behaviour is server-specific.
If the ValueRank specifies an array of a specific dimension (i.e. ValueRank > 0) then the ArrayDimensions Attribute shall be specified in the table defining the Variable.
Historizing The value for the Historizing Attribute is server-specific.
AccessLevelEx If the AccessLevelEx Attribute is provided, it shall have the bits 8, 9, and 10 set to 0, meaning that read and write operations on an individual Variable are atomic, and arrays can be partly written.

3.4.3.4 VariableTypes ToC

For all VariableTypes specified in this specification, the Attributes named in Table 7 shall be set as specified in the table. The definitions for the Attributes can be found in OPC 10000-3.

Table 7 – Common VariableType Attributes

Attributes Value
Value Optionally a server-specific default value can be provided.
ArrayDimensions If the ValueRank does not identify an array of a specific dimension (i.e. ValueRank <= 0) the ArrayDimensions can either be set to null or the Attribute is missing. This behaviour is server-specific.
If the ValueRank specifies an array of a specific dimension (i.e. ValueRank > 0) then the ArrayDimensions Attribute shall be specified in the table defining the VariableType.

3.4.3.5 Methods ToC

For all Methods specified in this specification, the Attributes named in Table 8 shall be set as specified in the table. The definitions for the Attributes can be found in OPC 10000-3.

Table 8 – Common Method Attributes

Attributes Value
Executable All Methods defined in this specification shall be executable (Executable Attribute set to “True”), unless it is defined differently in the Method definition.
UserExecutable The value of the UserExecutable Attribute is server-specific. It is assumed that all Methods can be executed by at least one user.

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