Table 29 defines the ReadEventDetails structure. This parameter is only valid for Objects that have the EventNotifier Attribute set to TRUE (see OPC 10000-3). At least two of the three parameters, numValuesPerNode, startTime, and endTime shall be specified.

Table 29 – ReadEventDetails Structure

Name

Type

Description

ReadEventDetails

Structure

Specifies the details used to perform an Event history read.

numValuesPerNode

Counter

The maximum number of Events returned for any Node over the time range. If only one time is specified, the time range shall extend to return this number of Events. The default value of 0 indicates that there is no maximum.

startTime

UtcTime

Beginning of period to read. The default value of DateTime.MinValue indicates that the startTime is unspecified.

endTime

UtcTime

End of period to read. The default value of DateTime.MinValue indicates that the endTime is unspecified.

Filter

EventFilter

A filter used by the Server to determine which HistoricalEventNode should be included. This parameter shall be specified and at least one EventField is required. The EventFilter parameter type is an Extensible parameter type. It is defined and used in the same manner as defined for monitored data items which are specified in OPC 10000-4. This filter also specifies the EventFields that are to be returned as part of the request.

Its representation in the AddressSpace is defined in Table 30.

Table 30 – ReadEventDetails definition

Attribute

Value

BrowseName

ReadEventDetails

IsAbstract

False

References

NodeClass

BrowseName

DataType

TypeDefinition

Other

Subtype of the HistoryReadDetails defined in Table 28

Conformance Units

Historical Access Events