The ExtensionFieldsTypeis formally defined in Table 106. It allows the configuration of fields with values to be included in the DataSetin case the existing AddressSpaceof the Publisherdoes not provide the necessary information.
Table 106– ExtensionFieldsType Definition
|
Attribute |
Value |
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|
BrowseName |
ExtensionFieldsType |
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|
IsAbstract |
False |
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|
References |
Node Class |
BrowseName |
DataType |
TypeDefinition |
Modelling Rule |
|
Subtype of BaseObjectType defined in OPC 10000-5. |
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|
|
|
|
|
|
|
|
HasProperty |
Variable |
<ExtensionFieldName> |
BaseDataType |
PropertyType |
OptionalPlaceholder |
|
HasComponent |
Method |
AddExtensionField |
Defined in 9.1.4.2.3. |
Mandatory |
|
|
HasComponent |
Method |
RemoveExtensionField |
Defined in 9.1.4.2.4. |
Mandatory |
|
The ExtensionFieldsType ObjectTypeis a concrete type and can be used directly.
The configured list of extension fields is exposed through Propertiesand managed through the Methods AddExtensionFieldand RemoveExtensionField. An ExtensionFieldis not automatically included in the DataSet. The ExtensionFieldmust be added to the DataSetafter creation.
Metadata that normally appear in message headers can be included to the body by adding extension fields with well-known QualifiedNames. These well-known QualifiedNamesare shown in Table 107. The qualifying namespace is the OPC UA namespace.
Table 107– Well-Known Extension Field Names
|
Name |
Type |
Description |
|
PublisherId |
BaseDataType |
The PublisherIdfrom the Connection Object. |
|
DataSetName |
String |
The Namefrom the DataSetMetaData. |
|
DataSetClassId |
Guid |
The DataSetClassIdfrom the DataSetMetaData. |
|
MajorVersion |
UInt32 |
The MajorVersion from the ConfigurationVersion |
|
MinorVersion |
UInt32 |
The MinorVersion from the ConfigurationVersion |
|
DataSetWriterId |
BaseDataType |
The DataSetWriterIdfrom the DataSetWriterTransport Object. |
|
MessageSequenceNumber |
UInt16 |
The sequence number from the DataSetMessage. |
If a well-known name is used the value placed in the message body is dynamically generated from the current settings. The value set in the AddExtensionField Methodis ignored. Subtypes of DataSetWriterTransportTypemay extend this list.