The HistoryRead Service returns different types of data depending on whether the request asked for the value Attribute of a Node or the history Events of a Node. The historyData is an Extensible Parameter whose structure depends on the functions to perform for the HistoryReadDetails parameter. See OPC 10000-4 for details on Extensible Parameters.

Table 41 defines the structure of the HistoryData used for the data to return in a HistoryRead.

Table 41 – HistoryData structure

Name

Type

Description

HistoryData

Structure

This structured datatype is a subtype of Structure defined in OPC 10000-3

dataValues[]

DataValue

An array of values of history data for the Node. The size of the array depends on the requested data parameters.

Its representation in the AddressSpace is defined in Table 30.

Table 42 – HistoryData definition

Attribute

Value

BrowseName

HistoryData

IsAbstract

False

References

NodeClass

BrowseName

DataType

TypeDefinition

Other

Subtype of the Structure defined in OPC 10000-3

Conformance Units

Historical Access Aggregates

Historical Access Time Instance

Historical Access Read Raw

Table 43 defines the structure of the HistoryModifiedData used for the data to return in a HistoryRead when IsReadModified = True. This DataType is a subtype of HistoryData.

Table 43 – HistoryModifiedData structure

Name

Type

Description

HistoryModifiedData

Structure

This structured datatype is a subtype of HistoryData (see 6.6.2)

modificationInfos[]

ModificationInfo

modificationTime

UtcTime

The time the modification was made. Support for this field is optional. A null shall be returned if it is not defined.

updateType

HistoryUpdateType

The modification type for the item.

userName

String

The name of the user that made the modification. Support for this field is optional. A null shall be returned if it is not defined.

Its representation in the AddressSpace is defined in Table 44

Table 44 – HistoryModifiedData definition

Attribute

Value

BrowseName

HistoryModifiedData

IsAbstract

False

References

NodeClass

BrowseName

DataType

TypeDefinition

Other

Subtype of the HistoryData defined in OPC 10000-3

Conformance Units

Historical Access Modified Values

Historical Access Annotations

Table 45 defines the HistoryEvent parameter used for Historical Event reads.

The HistoryEvent defines a table structure that is used to return Event fields to a Historical Read. The structure is in the form of a table consisting of one or more Events, each containing an array of one or more fields. The selection and order of the fields returned for each Event are identical to the selected parameter of the EventFilter.

Table 45 – HistoryEvent structure

Name

Type

Description

HistoryEvent

Structure

This structured datatype is a subtype of Structure defined in OPC 10000-3

Events []

HistoryEventFieldList

The list of Events being delivered.

eventFields []

BaseDataType

List of selected Event fields. This will be a one-to-one match with the fields selected in the EventFilter.

Its representation in the AddressSpace is defined in Table 46.

Table 46 – HistoryEvent definition

Attribute

Value

BrowseName

HistoryEvent

IsAbstract

False

References

NodeClass

BrowseName

DataType

TypeDefinition

Other

Subtype of the Structure defined in OPC 10000-3

Conformance Units

Historical Access Events

Historical Access Modified Events

Table 43 defines the structure of the HistoryEvent parameter used for Historical event reads when the readModified = True.

The HistoryModifyEvent defines a table structure that is used to return Event fields along with modification information to a Historical Read. The structure is in the form of a table consisting of one or more Events, each containing an array of one or more fields. The selection and order of the fields returned for each Event are identical to the selected parameter of the EventFilter. For each Event a modificationInfo record is also returned.

Table 47 – HistoryModifiedEvent structure

Name

Type

Description

HistoryModifiedEvent

Structure

This structured datatype is a subtype of HistoryEvent

modificationInfos[]

ModificationInfo

List of modifications (one record for each Event)

modificationTime

UtcTime

The time the modification was made. Support for this field is optional. A null shall be returned if it is not defined.

updateType

HistoryUpdateType

The modification type for the item.

userName

String

The name of the user that made the modification. Support for this field is optional. A null shall be returned if it is not defined.

Its representation in the AddressSpace is defined in Table 48.

Table 48 – HistoryModifiedEvent definition

Attribute

Value

BrowseName

HistoryModifiedEvent

IsAbstract

False

References

NodeClass

BrowseName

DataType

TypeDefinition

Other

Subtype of the HistoryEvent

Conformance Units

Historical Access Modified Events

Table 41 defines the structure of the Annotation used for the data to return in a HistoryRead.

This DataType describes Annotation structure information for the history data items. Its elements are defined in Table 49.

Table 49 – Annotation Structure

Name

Type

Description

Annotation

Structure

message

String

Annotation message or text.

userName

String

The user that added the Annotation, as supplied by the underlying system.

annotationTime

UtcTime

The time the Annotation was added. This will probably be different than the SourceTimestamp.

Its representation in the AddressSpace is defined in Table 50.

Table 50 Annotation definition

Attribute

Value

BrowseName

Annotation

IsAbstract

False

References

NodeClass

BrowseName

DataType

TypeDefinition

Other

Subtype of the Structure defined in OPC 10000-3

Conformance Units

Historical Access Annotations