The HistoryReadservice defined in OPC 10000-4can perform several different functions. The historyReadDetailsparameter is an Extensible Parameterthat specifies which function to perform.The ReadProcessedDetailsstructure is used to read aggregated data for HistoricalDataNodes.

The CreateMonitoredItems Serviceallows specifying a filter for each MonitoredItem. The MonitoringFilteris an extensible parameter whose structure depends on the type of item being monitored. The AggregateFilterstructure is used to obtain aggregated data for a subscription.

ReadProcessedDetails structure is formally detailed in OPC 10000-11. Table 6outlines the components of the ReadProcessedDetails structure for the purposes of discussion in this document.

Table 6– ReadProcessedDetails

Name

Description

ReadProcessedDetails

Specifies the details used to perform a “processed” history read.

startTime

Beginning of period to read.

endTime

End of period to read.

processingInterval

Interval between returned Aggregatevalues.

aggregateType[]

The NodeIdsof the AggregateFunction Objects. AggregateFunction Objectsindicate the list of Aggregates to be used when retrieving processed history.

aggregateConfiguration

Aggregateconfiguration structure.

useServerDefaults

If True the Server’s default values are used and any values specified for the other parameters are ignored.

treatUncertainAsBad

See 4.2.1.2.

percentDataBad

See 4.2.1.2.

percentDataGood

See 4.2.1.2.

useSlopedExtrapolation

See 4.2.1.2.

The AggregateFilterdefines the Aggregatefunction that should be used to calculate the values to be returned.The AggregateFilter is formally defined in OPC 10000-4. Table 7outlines the components of the AggregateFilterstructure for the purposes of discussion in this document.

Table 7– AggregateFilter structure

Name

Description

AggregateFilter

startTime

Beginning of period to calculate the Aggregatethe first time.

aggregateType

The NodeIdsof the AggregateFunction Objectsthat indicates the list of Aggregatesto be used when retrieving processed data.

processingInterval

The period to be used to compute the Aggregate.

aggregateConfiguration

This parameter allows Clientsto override the Aggregateconfiguration settings supplied by an AggregateConfiguration Objecton a per monitored item basis.

useServerDefaults

If True the Server’s default values are used and any values specified for the other parameters are ignored.

treatUncertainAsBad

See 4.2.1.2.

percentDataBad

See 4.2.1.2.

percentDataGood

See 4.2.1.2.

useSlopedExtrapolation

See 4.2.1.2.