UA Part 13: Aggregates - 4.2.2 AggregateFunction Object

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This Object is used as the browse entry point for information about the Aggregates supported by a Server. The content of this Object is already defined by its type definition. All Instances of the FolderType use the standard BrowseName of ‘AggregateFunctions’. The HasComponent Reference is used to relate a ServerCapabilities Object and/or any HistoricalServerCapabilities Object to an AggregateFunction Object. AggregateFunctions is formally defined in Table 3.

Table 3 – Aggregate Functions Definition

Attribute	Value
BrowseName	AggregateFunctions
References		Node Class	BrowseName	DataType	TypeDefinition	ModellingRule
HasTypeDefinition		Object Type	FolderType	Defined in OPC 10000-5

Each ServerCapabilities and HistoricalServerCapabilities Object shall reference an AggregateFunction Object. In addition, each HistoricalConfiguration Object belonging to a HistoricalDataNode may reference an AggregateFunction Object using the HasComponent Reference.

4.2.2.2 AggregateFunctionType

This ObjectType defines an Aggregate supported by a UA Server. This Object is formally defined in Table 4.

Table 4 – AggregateFunctionType Definition

Attribute	Value
BrowseName	AggregateFunctionType
IsAbstract	False
References	Node Class	BrowseName	DataType	TypeDefinition	Mod.Rule
Subtype of the BaseObjectType defined in OPC 10000-5

For the AggregateFunctionType, the Description Attribute (inherited from the Base NodeClass), is mandatory. The Description Attribute provides a localized description of the Aggregate.

Table 5 specifies the BrowseName and Description Attributes for the standard Aggregate Objects. The description is the localized “en” text. For other locales it shall be translated.

Table 5 – Standard AggregateType Nodes

BrowseName	Description
	Interpolation Aggregate
Interpolative	At the beginning of each interval, retrieve the calculated value from the data points on either side of the requested timestamp.
Average	Retrieve the average value of the data over the interval.
TimeAverage	Retrieve the time weighted average data over the interval using Interpolated Bounding Values.
TimeAverage2	Retrieve the time weighted average data over the interval using Simple Bounding Values.
Total	Retrieve the total (time integral) of the data over the interval using Interpolated Bounding Values.
Total2	Retrieve the total (time integral) of the data over the interval using Simple Bounding Values.
Minimum	Retrieve the minimum raw value in the interval with the timestamp of the start of the interval.
Maximum	Retrieve the maximum raw value in the interval with the timestamp of the start of the interval.
MinimumActualTime	Retrieve the minimum value in the interval and the timestamp of the minimum value.
MaximumActualTime	Retrieve the maximum value in the interval and the timestamp of the maximum value.
Range	Retrieve the difference between the minimum and maximum value over the interval.
Minimum2	Retrieve the minimum value in the interval including the Simple Bounding Values.
Maximum2	Retrieve the maximum value in the interval including the Simple Bounding Values.
MinimumActualTime2	Retrieve the minimum value with the actual timestamp including the Simple Bounding Values.
MaximumActualTime2	Retrieve the maximum value with the actual timestamp including the Simple Bounding Values.
Range2	Retrieve the difference between the Minimum2 and Maximum2 value over the interval.
Count	Retrieve the number of raw values over the interval.
DurationInStateZero	Retrieve the time a Boolean or numeric was in a zero state using Simple Bounding Values.
DurationInStateNonZero	Retrieve the time a Boolean or numeric was in a non-zero state using Simple Bounding Values.
NumberOfTransitions	Retrieve the number of changes between zero and non-zero that a Boolean or numeric value experienced in the interval.
Start	Retrieve the value at the beginning of the interval.
End	Retrieve the value at the end of the interval.
Delta	Retrieve the difference between the Start and End value in the interval.
StartBound	Retrieve the value at the beginning of the interval using Simple Bounding Values.
EndBound	Retrieve the value at the end of the interval using Simple Bounding Values.
DeltaBounds	Retrieve the difference between the StartBound and EndBound value in the interval using Simple Bounding Values.
DurationGood	Retrieve the total duration of time in the interval during which the data is Good.
DurationBad	Retrieve the total duration of time in the interval during which the data is Bad.
PercentGood	Retrieve the percentage of data (0 to 100) in the interval which has Good StatusCode.
PercentBad	Retrieve the percentage of data (0 to 100) in the interval which has Bad StatusCode.
WorstQuality	Retrieve the worst StatusCode of data in the interval.
WorstQuality2	Retrieve the worst StatusCode of data in the interval including the Simple Bounding Values.
AnnotationCount	Retrieve the number of Annotations in the interval (applies to Historical Aggregates only).
StandardDeviationSample	Retrieve the standard deviation for the interval for a sample of the population (n-1).
VarianceSample	Retrieve the variance for the interval as calculated by the StandardDeviationSample.
StandardDeviation Population	Retrieve the standard deviation for the interval for a complete population (n) which includes Simple Bounding Values.
VariancePopulation	Retrieve the variance for the interval as calculated by the StandardDeviationPopulation which includes Simple Bounding Values.