IEC 62541-13:2015

IEC 62541-13 ®
Edition 1.0 2015-03
INTERNATIONAL
STANDARD
NORME
INTERNATIONALE
colour
inside
OPC unified architecture –
Part 13: Aggregates
Architecture unifiée OPC –
Partie 13: Agrégats
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IEC 62541-13 ®
Edition 1.0 2015-03
INTERNATIONAL
STANDARD
NORME
INTERNATIONALE
colour
inside
OPC unified architecture –
Part 13: Aggregates
Architecture unifiée OPC –
Partie 13: Agrégats
INTERNATIONAL
ELECTROTECHNICAL
COMMISSION
COMMISSION
ELECTROTECHNIQUE
INTERNATIONALE
ICS 25.040.40; 35.100 ISBN 978-2-8322-2365-9

– 2 – IEC 62541-13:2015  IEC 2015

CONTENTS
FOREWORD . 7
1 Scope . 9
2 Normative references. 9
3 Terms, definitions, and abbreviations . 9
3.1 Terms and definitions . 9
3.2 Abbreviations . 12
4 Aggregate Information Model . 12
4.1 General . 12
4.2 Aggregate Objects . 12
4.2.1 General . 12
4.2.2 AggregateFunction Object . 13
4.3 MonitoredItem AggregateFilter. 16
4.3.1 MonitoredItem AggregateFilter Defaults . 16
4.3.2 MonitoredItem Aggregates and Bounding Values . 16
4.4 Exposing Supported Functions and Capabilities . 16
5 Aggregate specific usage of Services . 17
5.1 General . 17
5.2 Aggregate data handling . 18
5.2.1 Overview . 18
5.2.2 ReadProcessedDetails structure overview . 18
5.2.3 AggregateFilter structure overview . 18
5.3 Aggregates StatusCodes . 19
5.3.1 Overview . 19
5.3.2 Operation level result codes . 19
5.3.3 Aggregate Information Bits . 19
5.4 Aggregate details . 20
5.4.1 General . 20
5.4.2 Common characteristics . 21
5.4.3 Specific Aggregated data handling . 24
Annex A (informative) Aggregate specific examples – Historical access . 56
A.1 Historical Aggregate specific characteristics . 56
A.1.1 Example Aggregate data – Historian 1 . 56
A.1.2 Example Aggregate data – Historian 2 . 57
A.1.3 Example Aggregate data – Historian 3 . 58
A.1.4 Example Aggregate data – Historian 4 . 59
A.2 Interpolative . 60
A.2.1 Description . 60
A.2.2 Interpolative data . 60
A.3 Average . 61
A.3.1 Description . 61
A.3.2 Average data . 62
A.4 TimeAverage . 63
A.4.1 Description . 63
A.4.2 TimeAverage data . 63
A.5 TimeAverage2 . 64
A.5.1 Description . 64

A.5.2 TimeAverage2 data . 64
A.6 Total . 65
A.6.1 Description . 65
A.6.2 Total data . 66
A.7 Total2 . 67
A.7.1 Description . 67
A.7.2 Total2 data . 67
A.8 Minimum . 68
A.8.1 Description . 68
A.8.2 Minimum data . 68
A.9 Maximum . 69
A.9.1 Description . 69
A.9.2 Maximum data . 69
A.10 MininumActualTime . 69
A.10.1 Description . 69
A.10.2 MinimumActualTime data . 69
A.11 MaximumActualTime . 70
A.11.1 Description . 70
A.11.2 MaximumActualTime data . 70
A.12 Range . 71
A.12.1 Description . 71
A.12.2 Range data . 71
A.13 Minimum2 . 71
A.13.1 Description . 71
A.13.2 Minimum2 data . 71
A.14 Maximum2 . 72
A.14.1 Description . 72
A.14.2 Maximum2 data . 72
A.15 MinimumActualTime2 . 73
A.15.1 Description . 73
A.15.2 MinimumActualTime2 data . 73
A.16 MaximumActualTime2 . 73
A.16.1 Description . 73
A.16.2 MaximumActualTime2 data . 73
A.17 Range2 . 74
A.17.1 Description . 74
A.17.2 Range2 data . 74
A.18 AnnotationCount . 75
A.18.1 Description . 75
A.18.2 AnnotationCount data . 75
A.19 Count . 75
A.19.1 Description . 75
A.19.2 Count data . 75
A.20 DurationInStateZero . 76
A.20.1 Description . 76
A.20.2 DurationInStateZero data . 76
A.21 DurationInStateNonZero . 76
A.21.1 Description . 76
A.21.2 DurationInStateNonZero data . 76

– 4 – IEC 62541-13:2015  IEC 2015
A.22 NumberOfTransitions . 76
A.22.1 Description . 76
A.22.2 NumberOfTransitions data . 77
A.23 Start . 77
A.23.1 Description . 77
A.23.2 Start data . 78
A.24 End . 78
A.24.1 Description . 78
A.24.2 End data . 78
A.25 StartBound . 79
A.25.1 Description . 79
A.25.2 StartBound data . 79
A.26 EndBound . 79
A.26.1 Description . 79
A.26.2 EndBound data . 80
A.27 Delta . 80
A.27.1 Description . 80
A.27.2 Delta data . 80
A.28 DeltaBounds . 81
A.28.1 Description . 81
A.28.2 DeltaBounds data . 81
A.29 DurationGood . 81
A.29.1 Description . 81
A.29.2 DurationGood data . 82
A.30 DurationBad . 82
A.30.1 Description . 82
A.30.2 DurationBad data . 82
A.31 PercentGood . 83
A.31.1 Description . 83
A.31.2 PercentGood data . 83
A.32 PercentBad . 84
A.32.1 Description . 84
A.32.2 PercentBad data . 84
A.33 WorstQuality . 85
A.33.1 Description . 85
A.33.2 WorstQuality data . 85
A.34 WorstQuality2 . 86
A.34.1 Description . 86
A.34.2 WorstQuality2 data . 86
A.35 StandardDeviationSample . 87
A.35.1 Description . 87
A.35.2 StandardDeviationSample data . 87
A.36 VarianceSample . 87
A.36.1 Description . 87
A.36.2 VarianceSample data . 87
A.37 StandardDeviationPopulation . 88
A.37.1 Description . 88
A.37.2 StandardDeviationPopulation data . 88
A.38 VariancePopulation . 88

A.38.1 Description . 88
A.38.2 VariancePopulation data . 89
Bibliography . 90

Figure 1 – Representation of Aggregate Configuration information in the AddressSpace . 17
Figure 2 – Variable with Stepped = False and Simple Bounding Values . 25
Figure 3 – Variable with Stepped = True and Interpolated Bounding Values . 26

Table 1 – Interpolation examples . 10
Table 2 – AggregateConfigurationType Definition . 13
Table 3 – Aggregate Functions Definition . 14
Table 4 – AggregateFunctionType Definition . 14
Table 5 – Standard AggregateType Nodes . 15
Table 6 – ReadProcessedDetails . 18
Table 7 – AggregateFilter structure . 18
Table 8 – Bad operation level result codes . 19
Table 9 – Uncertain operation level result codes . 19
Table 10 – Data location . 19
Table 11 – Additional information . 20
Table 12 – History Aggregate interval information . 22
Table 13 – Standard History Aggregate Data Type information . 23
Table 14 – Aggregate table description . 28
Table 15 – Interpolative Aggregate summary . 29
Table 16 – Average Aggregate summary . 30
Table 17 – TimeAverage Aggregate summary . 31
Table 18 – TimeAverage2 Aggregate summary . 32
Table 19 – Total Aggregate summary . 32
Table 20 – Total2 Aggregate summary . 33
Table 21 – Minimum Aggregate summary . 34
Table 22 – Maximum Aggregate summary . 35
Table 23 – MinimumActualTime Aggregate summary . 36
Table 24 – MaximumActualTime Aggregate summary . 37
Table 25 – Range Aggregate summary . 37
Table 26 – Minimum2 Aggregate summary . 38
Table 27 – Maximum2 Aggregate summary . 39
Table 28 – MinimumActualTime2 Aggregate summary . 40
Table 29 – MaximumActualTime2 Aggregate summary . 41
Table 30 – Range2 Aggregate summary . 41
Table 31 – AnnotationCount Aggregate summary . 42
Table 32 – Count Aggregate summary . 42
Table 33 – DurationInStateZero Aggregate summary . 43
Table 34 – DurationInStateNonZero Aggregate Summary . 44
Table 35 – NumberOfTransitions Aggregate summary . 44

– 6 – IEC 62541-13:2015  IEC 2015
Table 36 – Start Aggregate summary . 45
Table 37 – End Aggregate summary . 45
Table 38 – Delta Aggregate summary . 46
Table 39 – StartBound Aggregate summary . 46
Table 40 – EndBound Aggregate summary . 47
Table 41 – DeltaBounds Aggregate summary . 48
Table 42 – DurationGood Aggregate summary . 48
Table 43 – DurationBad Aggregate summary . 49
Table 44 – PercentGood Aggregate summary . 50
Table 45 – PercentBad Aggregate summary . 51
Table 46 – WorstQuality Aggregate summary . 51
Table 47 – WorstQuality2 Aggregate summary . 52
Table 48 – StandardDeviationSample Aggregate summary . 53
Table 49 – VarianceSample Aggregate summary . 53
Table 50 – StandardDeviationPopulation Aggregate summary . 54
Table 51 – VariancePopulation Aggregate summary . 55

INTERNATIONAL ELECTROTECHNICAL COMMISSION
____________
OPC UNIFIED ARCHITECTURE –
Part 13: Aggregates
FOREWORD
1) The International Electrotechnical Commission (IEC) is a worldwide organization for standardization comprising
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6) All users should ensure that they have the latest edition of this publication.
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8) Attention is drawn to the Normative references cited in this publication. Use of the referenced publications is
indispensable for the correct application of this publication.
9) Attention is drawn to the possibility that some of the elements of this IEC Publication may be the subject of
patent rights. IEC shall not be held responsible for identifying any or all such patent rights.
International Standard IEC 62541-13 has been prepared by subcommittee 65E: Devices and
integration in enterprise systems, of IEC technical committee 65: Industrial-process
measurement, control and automation.
The text of this standard is based on the following documents:
CDV Report on voting
65E/379/CDV 65E/411/RVC
Full information on the voting for the approval of this standard can be found in the report on
voting indicated in the above table.
This publication has been drafted in accordance with the ISO/IEC Directives, Part 2.

– 8 – IEC 62541-13:2015  IEC 2015
A list of all parts of the IEC 62541 series, published under the general title OPC Unified
Architecture, can be found on the IEC website.
The committee has decided that the contents of this publication will remain unchanged until
the stability date indicated on the IEC web site under "http://webstore.iec.ch" in the data
related to the specific publication. At this date, the publication will be
• reconfirmed,
• withdrawn,
• replaced by a revised edition, or
• amended.
IMPORTANT – The 'colour inside' logo on the cover page of this publication indicates
that it contains colours which are considered to be useful for the correct
understanding of its contents. Users should therefore print this document using a
colour printer.
OPC UNIFIED ARCHITECTURE –
Part 13: Aggregates
1 Scope
This part of IEC 62541 is part of the overall OPC Unified Architecture specification series and
defines the information model associated with Aggregates.
2 Normative references
The following documents, in whole or in part, are normatively referenced in this document and
are indispensable for its application. For dated references, only the edition cited applies. For
undated references, the latest edition of the referenced document (including any
amendments) applies.
IEC TR 62541-1, OPC Unified Architecture – Part 1: Overview and Concepts
IEC 62541-3, OPC Unified Architecture – Part 3: Address Space Model
IEC 62541-4, OPC Unified Architecture – Part 4: Services
IEC 62541-5, OPC Unified Architecture – Part 5: Information Model
IEC 62541-8, OPC Unified Architecture – Part 8: Data Access
IEC 62541-11, OPC Unified Architecture – Part 11: Historical Access
3 Terms, definitions, and abbreviations
3.1 Terms and definitions
For the purposes of this document, the terms and definitions given in IEC TR 62541-1,
IEC 62541-3, IEC 62541-4, and IEC 62541-11 as well as the following apply.
3.1.1
ProcessingInterval
timespan for which derived values are produced based on a specified Aggregate
Note 1 to entry: The total time domain specified for ReadProcessed is divided by the ProcessingInterval. For
example, performing a 10-minute Average over the time range 12:00 to 12:30 would result in a set of three
intervals of ProcessingInterval length, with each interval having a start time of 12:00, 12:10 and 12:20 respectively.
The rules used to determine the interval Bounds are discussed in 5.4.2.2.
3.1.2
interpolated
data that is calculated from data samples
Note 1 to entry: Data samples may be historical data or buffered real time data. An interpolated value is
calculated from the data points on either side of the requested timestamp.
3.1.3
EffectiveEndTime
time immediately before endTime

– 10 – IEC 62541-13:2015  IEC 2015
Note 1 to entry: All Aggregate calculations include the startTime but exclude the endTime. However, it is
sometimes necessary to return an Interpolated End Bound as the value for an Interval with a timestamp that is in
the interval. Servers are expected to use the time immediately before endTime where the time resolution of the
Server determines the exact value (do not confuse this with hardware or operating system time resolution). For
example, if the endTime is 12:01:00, the time resolution is 1 s, then the EffectiveEndTime is 12:00:59. See 0.
If time is flowing backwards, Servers are expected to use the time immediately after endTime where the time
resolution of the Server determines the exact value.
3.1.4
extrapolated
data constructed from a discrete data set but is outside of the discrete data set
Note 1 to entry: It is similar to the process of interpolation, which constructs new points between known points,
but its result is subject to greater uncertainty. Extrapolated data is used in cases where the requested time period
falls farther into the future than the data available in the underlying system. See example in Table 1.
3.1.5
SlopedInterpolation
simple linear interpolation
Note 1 to entry: Compare to curve fitting using linear polynomials. See example in Table 1.
3.1.6
SteppedInterpolation
holding the last data point constant or interpolating the value based on a horizontal line fit
Note 1 to entry: Consider the following Table 1 of raw and Interpolated/Extrapolated values:
Table 1 – Interpolation examples
Timestamp Raw Value Sloped Interpolation Stepped Interpolation
12:00:00 10
12:00:05 15 10
12:00:08 18 10
12:00:10 20
12:00:15 25 20
12:00:20 30
SlopedExtrapolation SteppedExtrapolation
12:00:25 35 30
12:00:27 37 30
3.1.7
bounding values
values at the startTime and endTime needed for Aggregates to compute the result
Note 1 to entry: If Raw data does not exist at the startTime and endTime a value shall be estimated. There are
two ways to determine Bounding Values for an interval. One way (called Interpolated Bounding Values) uses the
first non-Bad data points found before and after the timestamp to estimate the bound. The other (called Simple
Bounding Values) uses the data points immediately before and after the boundary timestamps to estimate the
bound even if these points are Bad. Subclauses 3.1.8 and 3.1.9 describe the two different approaches in more
detail.
In all cases the TreatUncertainAsBad (see 4.2.1.2) flag is used to determine whether Uncertain values are Bad or
non-Bad.
If a Raw value was not found and a non-Bad bounding value exists the Aggregate Bits (see 5.3.3) are set to
‘Interpolated’.
When calculating bounding values, the value portion of Raw data that has Bad status is set to null. This means the
value portion is not used in any calculation and a null is returned if the raw value is returned. The status portion is
determined by the rules specified by the bound or Aggregate.
The Interpolated Bounding Values approach (see 3.1.8) is the same as what is used in Classic OPC Historical Data
Access (HDA) and is important for applications such as advanced process control where having useful values at all
times is important. The Simple Bounding Values approach (see 3.1.9) is new in this standard and is important for
applications which shall produce regulatory reports and cannot use estimated values in place of Bad data.

3.1.8
interpolated bounding values
bounding values determined by a calculation using the nearest Good value
Note 1 to entry: Interpolated Bounding Values using SlopedInterpolation are calculated as follows:
• if a non-Bad Raw value exists at the timestamp then it is the bounding value;
• find the first non-Bad Raw value before the timestamp;
• find the first non-Bad Raw value after the timestamp;
• draw a line between before value and after value;
• use point where the line crosses the timestamp as an estimate of the bounding value.
The calculation can be expressed with the following formula:
V = (T – T )x( V – V )/( T – T ) + V
bound bound before after before after before before
where V is a value at ‘x’ and T is the timestamp associated with V .
x x x
If no non-Bad values exist before the timestamp the StatusCode is Bad_NoData. The StatusCode is
Uncertain_DataSubNormal if any Bad values exist between the before value and after value. If either the before
value or the after value are Uncertain the StatusCode is Uncertain_DataSubNormal. If the after value does not
exist the before value shall be extrapolated using SlopedExtrapolation or SteppedExtrapolation.
The period of time that is searched to discover the Good values before and after the timestamp is Server
dependent, but if a Good value is not found within some reasonable time range then the Server will assume it does
not exist. The Server as a minimum should search a time range which is at least the size of the ProcessingInterval.
Interpolated Bounding Values using SlopedExtrapolation are calculated as follows:
• find the first non-Bad Raw value before timestamp;
• find the second non-Bad Raw value before timestamp;
• draw a line between these two values;
• extend the line to where it crosses the timestamp;
• use the point where the line crosses the timestamp as an estimate of the bounding value.
The formula is the same as the one used for SlopedInterpolation.
The StatusCode is always Uncertain_DataSubNormal. If only one non-Bad raw value can be found before the
timestamp then SteppedExtrapolation is used to estimate the bounding value.
Interpolated Bounding Values using SteppedInterpolation are calculated as follows:
• if a non-Bad Raw value exists at the timestamp then it is the bounding value;
• find the first non-Bad Raw value before timestamp;
• use the value as an estimate of the bounding value.
The StatusCode is Uncertain_DataSubNormal if any Bad values exist between the before value and the timestamp.
If no non-Bad Raw data exists before the timestamp then the StatusCode is Bad_NoData. If the value before the
timestamp is Uncertain the StatusCode is Uncertain_DataSubNormal. The value after the timestamp is not needed
when using SteppedInterpolation; however, if the timestamp is after the end of the data then the bounding value is
treated as extrapolated and the StatusCode is Uncertain_DataSubNormal.
SteppedExtrapolation is a term that describes SteppedInterpolation when a timestamp is after the last value in the
history collection.
3.1.9
simple bounding values
bounding values determined by a calculation using the nearest value
Note 1 to entry: Simple Bounding Values using SlopedInterpolation are calculated as follows:
• if any Raw value exists at the timestamp then it is the bounding value;
• find the first Raw value before timestamp;
• find the first Raw value after timestamp
...