IEC 62541-13:2020

OPC Unified Architecture - Part 13: Aggregates

IEC 62541-13:2020 is part of the overall OPC Unified Architecture specification series and defines the information model associated with Aggregates. This second edition cancels and replaces the first edition of IEC 62541-13, published in 2015. No technical changes but numerous clarifications. Also some corrections to the examples.

Architecture unifiée OPC - Partie 13: Agrégats

L'IEC 62541-13:2020 fait partie de la série de spécifications générales sur l'Architecture unifiée OPC (OPC UA) globale. Elle définit le modèle d'information associé aux Agrégats. Cette deuxième édition annule et remplace la première édition parue en 2015. Aucune modification technique n'a été apportée, mais de nombreuses explications ont été introduites. Des corrections ont été apportées aux exemples.

General Information

• Status: Published
• Publication Date: 10-Jun-2020
• ICS: 25.040.40 - Industrial process measurement and control
• ICS: 35.100.05 - Multilayer applications
• Technical Committee: SC 65E - Devices and integration in enterprise systems
• Drafting Committee: WG 8 - TC 65/SC 65E/WG 8
• Current Stage: PPUB - Publication issued
• Start Date: 11-Jun-2020
• Completion Date: 22-May-2020

Relations

• Revises: IEC 62541-13:2015 - OPC Unified Architecture - Part 13: Aggregates
• Effective Date: 05-Sep-2023
• Revised: IEC 62541-13:2025 - OPC Unified Architecture - Part 13: Aggregates
• Effective Date: 05-Sep-2023

Overview

IEC 62541-13:2020 - OPC Unified Architecture, Part 13: Aggregates defines the OPC UA information model used to calculate and expose aggregated values (for example averages, minima, maxima, counts, totals and time‑based aggregates). This second edition replaces the 2015 edition with clarifications and corrected examples but no technical changes. The standard explains how servers and clients represent, request and return aggregated results for both current (processed) and historical data.

Key topics and technical requirements

• Aggregate information model - object types and structures used to describe aggregate functions and their metadata.
• AggregateFunction Object - representation of individual aggregate functions and their properties.
• MonitoredItem AggregateFilter - filter and default settings used when monitoring aggregated data for real‑time subscriptions.
• ReadProcessedDetails - details structure for requesting processed/historial aggregate reads (time windows, resolution, etc.).
• Aggregate data handling - rules for computing, combining and returning aggregate values and associated status/quality.
• Operation-level result codes and Aggregate Information Bits - standardized status reporting and quality information for aggregated results.
• Exposing supported functions & capabilities - mechanisms for servers to advertise which aggregates and behaviors they support.
• Annex with examples (Historical Access) - extensive, example‑driven guidance covering a wide range of aggregates (Average, TimeAverage, Total, Min/Max, Range, Count, DurationInState, PercentGood/Bad, StandardDeviationSample, etc.).

Practical applications and typical users

IEC 62541-13:2020 is intended for implementers and integrators who need reliable, interoperable aggregated data in industrial systems:

• IIoT and SCADA integrators using OPC UA to deliver time‑series summaries (e.g., hourly averages, daily totals).
• Historian and telemetry vendors implementing processed reads and historical aggregates for storage and reporting.
• Automation system developers implementing MonitoredItems and AggregateFilters for subscriptions that carry aggregated metrics.
• System architects and QA engineers who need consistent quality/status semantics and server capability discovery for aggregates.

Benefits include standardized aggregate semantics across vendors, clearer status reporting for processed values, and consistent historical-access examples to aid implementation and testing.

Related standards

• Part of the IEC 62541 (OPC UA) series - this part complements other OPC UA information model and services parts by specifying the aggregates model and how processed/aggregated reads and subscriptions behave.

Keywords: IEC 62541-13:2020, OPC Unified Architecture, OPC UA Aggregates, AggregateFunction, MonitoredItem AggregateFilter, ReadProcessedDetails, historical access, industrial automation, IIoT, telemetry.

Standards Content (Sample)

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OPC Unified Architecture –
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IEC 62541-13 ®
Edition 2.0 2020-06
REDLINE VERSION
INTERNATIONAL
STANDARD
colour
inside
OPC Unified Architecture –
Part 13: Aggregates
INTERNATIONAL
ELECTROTECHNICAL
COMMISSION
ICS 25.040.40; 35.100.05 ISBN 978-2-8322-8530-5

– 2 – IEC 62541-13:2020 RLV © IEC 2020
CONTENTS
FOREWORD . 7
1 Scope . 9
2 Normative references . 9
3 Terms, definitions, and abbreviated terms . 9
3.1 Terms and definitions . 9
3.2 Abbreviated terms . 12
4 Aggregate information model . 13
4.1 General . 13
4.2 Aggregate Objects . 13
4.2.1 General . 13
4.2.2 AggregateFunction Object . 14
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 . 20
5.4 Aggregate details . 21
5.4.1 General . 21
5.4.2 Common characteristics . 21
5.4.3 Specific aggregated data handling . 24
Annex A (informative) Aggregate Specific examples – Historical Access . 67
A.1 Historical Aggregate specific characteristics . 67
A.1.1 Example Aggregate data – Historian 1 . 67
A.1.2 Example Aggregate data – Historian 2 . 68
A.1.3 Example Aggregate data – Historian 3 . 69
A.1.4 Example Aggregate data – Historian 4 . 70
A.2 Interpolative . 71
A.2.1 Description . 71
A.2.2 Interpolative data . 71
A.3 Average . 73
A.3.1 Description . 73
A.3.2 Average data . 73
A.4 TimeAverage . 74
A.4.1 Description . 74
A.4.2 TimeAverage data . 75
A.5 TimeAverage2. 76
A.5.1 Description . 76

A.5.2 TimeAverage2 data . 76
A.6 Total . 78
A.6.1 Description . 78
A.6.2 Total data . 78
A.7 Total2 . 80
A.7.1 Description . 80
A.7.2 Total2 data . 80
A.8 Minimum . 81
A.8.1 Description . 81
A.8.2 Minimum data . 82
A.9 Maximum . 82
A.9.1 Description . 82
A.9.2 Maximum data . 83
A.10 MininumActualTime . 83
A.10.1 Description . 83
A.10.2 MinimumActualTime data . 84
A.11 MaximumActualTime . 84
A.11.1 Description . 84
A.11.2 MaximumActualTime data . 85
A.12 Range . 85
A.12.1 Description . 85
A.12.2 Range data . 86
A.13 Minimum2 . 86
A.13.1 Description . 86
A.13.2 Minimum2 data . 87
A.14 Maximum2 . 87
A.14.1 Description . 87
A.14.2 Maximum2 data . 88
A.15 MinimumActualTime2 . 88
A.15.1 Description . 88
A.15.2 MinimumActualTime2 data . 89
A.16 MaximumActualTime2 . 89
A.16.1 Description . 89
A.16.2 MaximumActualTime2 data . 90
A.17 Range2 . 90
A.17.1 Description . 90
A.17.2 Range2 data . 91
A.18 AnnotationCount . 91
A.18.1 Description . 91
A.18.2 AnnotationCount data . 91
A.19 Count . 92
A.19.1 Description . 92
A.19.2 Count data . 92
A.20 DurationInStateZero . 93
A.20.1 Description . 93
A.20.2 DurationInStateZero data . 93
A.21 DurationInStateNonZero . 93
A.21.1 Description . 93
A.21.2 DurationInStateNonZero data . 93

– 4 – IEC 62541-13:2020 RLV © IEC 2020
A.22 NumberOfTransitions . 94
A.22.1 Description . 94
A.22.2 NumberOfTransitions data . 94
A.23 Start . 95
A.23.1 Description . 95
A.23.2 Start data . 95
A.24 End . 95
A.24.1 Description . 95
A.24.2 End data . 96
A.25 StartBound . 96
A.25.1 Description . 96
A.25.2 StartBound data . 97
A.26 EndBound . 97
A.26.1 Description . 97
A.26.2 EndBound data . 98
A.27 Delta . 98
A.27.1 Description . 98
A.27.2 Delta data . 99
A.28 DeltaBounds . 99
A.28.1 Description . 99
A.28.2 DeltaBounds data . 100
A.29 DurationGood . 100
A.29.1 Description . 100
A.29.2 DurationGood data . 101
A.30 DurationBad . 102
A.30.1 Description . 102
A.30.2 DurationBad data . 102
A.31 PercentGood . 103
A.31.1 Description . 103
A.31.2 PercentGood data . 103
A.32 PercentBad . 104
A.32.1 Description . 104
A.32.2 PercentBad data . 104
A.33 WorstQuality . 105
A.33.1 Description . 105
A.33.2 WorstQuality data . 105
A.34 WorstQuality2 . 106
A.34.1 Description . 106
A.34.2 WorstQuality2 data . 106
A.35 StandardDeviationSample . 107
A.35.1 Description . 107
A.35.2 StandardDeviationSample data . 107
A.36 VarianceSample . 107
A.36.1 Description . 107
A.36.2 VarianceSample data . 108
A.37 StandardDeviationPopulation . 108
A.37.1 Description . 108
A.37.2 StandardDeviationPopulation data . 108
A.38 VariancePopulation . 109

A.38.1 Description . 109
A.38.2 VariancePopulation data . 109
Bibliography .

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
Figure A.1 – Historian 1 . 68
Figure A.2 – Historian 2 . 69
Figure A.3 – Historian 3 . 70

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 . 19
Table 8 – Bad operation level result codes . 19
Table 9 – Uncertain operation level result codes . 20
Table 10 – Data location . 20
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 . 27
Table 15 – Interpolative Aggregate summary . 30
Table 16 – Average Aggregate summary . 31
Table 17 – TimeAverage Aggregate summary . 32
Table 18 – TimeAverage2 Aggregate summary . 33
Table 19 – Total Aggregate summary . 34
Table 20 – Total2 Aggregate summary . 35
Table 21 – Minimum Aggregate summary . 36
Table 22 – Maximum Aggregate summary. 37
Table 23 – MinimumActualTime Aggregate summary . 38
Table 24 – MaximumActualTime Aggregate summary . 39
Table 25 – Range Aggregate summary . 40
Table 26 – Minimum2 Aggregate summary. 41
Table 27 – Maximum2 Aggregate summary . 42
Table 28 – MinimumActualTime2 Aggregate summary . 43
Table 29 – MaximumActualTime2 Aggregate summary . 44
Table 30 – Range2 Aggregate summary . 45
Table 31 – AnnotationCount Aggregate summary. 46
Table 32 – Count Aggregate summary . 47

– 6 – IEC 62541-13:2020 RLV © IEC 2020
Table 33 – DurationInStateZero Aggregate summary . 48
Table 34 – DurationInStateNonZero Aggregate Summary . 49
Table 35 – NumberOfTransitions Aggregate summary . 50
Table 36 – Start Aggregate summary . 51
Table 37 – End Aggregate summary . 52
Table 38 – Delta Aggregate summary . 53
Table 39 – StartBound Aggregate summary . 54
Table 40 – EndBound Aggregate summary . 55
Table 41 – DeltaBounds Aggregate summary . 56
Table 42 – DurationGood Aggregate summary . 57
Table 43 – DurationBad Aggregate summary . 58
Table 44 – PercentGood Aggregate summary . 59
Table 45 – PercentBad Aggregate summary . 60
Table 46 – WorstQuality Aggregate summary . 61
Table 47 – WorstQuality2 Aggregate summary. 62
Table 48 – StandardDeviationSample Aggregate summary . 63
Table 49 – VarianceSample Aggregate summary . 64
Table 50 – StandardDeviationPopulation Aggregate summary . 65
Table 51 – VariancePopulation Aggregate summary . 66

INTERNATIONAL ELECTROTECHNICAL COMMISSION
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OPC UNIFIED ARCHITECTURE –
Part 13: Aggregates
FOREWORD
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– 8 – IEC 62541-13:2020 RLV © IEC 2020
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.
This second edition cancels and replaces the first edition of IEC 62541-13, published in 2015.
This edition constitutes a technical revision.
This edition includes the following significant technical changes with respect to the previous
edition:
a) no technical changes but numerous clarifications. Also some corrections to the examples.
The text of this standard is based on the following documents:
FDIS Report on voting
65E/697/FDIS 65E/712/RVD
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.
Throughout this document and the other Parts of the series, certain document conventions
are used:
Italics are used to denote a defined term or definition that appears in the “Terms and
definition” clause in one of the parts of the series.
Italics are also used to denote the name of a service input or output parameter or the name of
a structure or element of a structure that are usually defined in tables.
The italicized terms and names are also often written in camel-case (the practice of writing
compound words or phrases in which the elements are joined without spaces, with each
element's initial letter capitalized within the compound). For example the defined term is
AddressSpace instead of Address Space. This makes it easier to understand that there is a
single definition for AddressSpace, not separate definitions for Address and Space.
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
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• amended.
IMPORTANT – The 'colour inside' logo on the cover page of this publication indicates
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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 are referred to in the text in such a way that some or all of their
content constitutes requirements of this document. 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 abbreviated terms
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 and the following apply.
ISO and IEC maintain terminological databases for use in standardization at the following
addresses:
• IEC Electropedia: available at http://www.electropedia.org/
• ISO Online browsing platform: available at http://www.iso.org/obp
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
data that is calculated from data samples

– 10 – IEC 62541-13:2020 RLV © IEC 2020
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
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 second, then the EffectiveEndTime is 12:00:59. See
5.4.2.4.
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
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
interpolation 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 ) × ( 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.

– 12 – IEC 62541-13:2020 RLV © IEC 2020
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;
• if the value after the timestamp is Bad then the before value is the bounding value;
• 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 formula is the same as the one used for SlopedInterpolation in Clause 3.1.5.
If a Raw value at the timestamp is Bad the StatusCode is Bad_NoData. If the value before the timestamp is Bad
the StatusCode is Bad_NoData. If the value before the timestamp is Uncertain the StatusCode is
Uncertain_DataSubNormal. If the value after the timestamp is Bad or Uncertain the StatusCode is
Uncertain_DataSubNormal.
Simple Bounding Values using SteppedInterpolation are calculated as follows:
• if any
...

IEC 62541-13 ®
Edition 2.0 2020-06
INTERNATIONAL
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IEC 62541-13 ®
Edition 2.0 2020-06
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; 35.100.05 ISBN 978-2-8322-8296-0

– 2 – IEC 62541-13:2020 © IEC 2020
CONTENTS
FOREWORD . 7
1 Scope . 9
2 Normative references . 9
3 Terms, definitions, and abbreviated terms . 9
3.1 Terms and definitions . 9
3.2 Abbreviated terms . 12
4 Aggregate information model . 13
4.1 General . 13
4.2 Aggregate Objects . 13
4.2.1 General . 13
4.2.2 AggregateFunction Object . 14
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 . 20
5.4 Aggregate details . 21
5.4.1 General . 21
5.4.2 Common characteristics . 21
5.4.3 Specific aggregated data handling . 24
Annex A (informative) Aggregate Specific examples – Historical Access . 67
A.1 Historical Aggregate specific characteristics . 67
A.1.1 Example Aggregate data – Historian 1 . 67
A.1.2 Example Aggregate data – Historian 2 . 68
A.1.3 Example Aggregate data – Historian 3 . 69
A.1.4 Example Aggregate data – Historian 4 . 70
A.2 Interpolative . 71
A.2.1 Description . 71
A.2.2 Interpolative data . 71
A.3 Average . 73
A.3.1 Description . 73
A.3.2 Average data . 73
A.4 TimeAverage . 74
A.4.1 Description . 74
A.4.2 TimeAverage data . 75
A.5 TimeAverage2. 76
A.5.1 Description . 76

A.5.2 TimeAverage2 data . 76
A.6 Total . 78
A.6.1 Description . 78
A.6.2 Total data . 78
A.7 Total2 . 80
A.7.1 Description . 80
A.7.2 Total2 data . 80
A.8 Minimum . 81
A.8.1 Description . 81
A.8.2 Minimum data . 82
A.9 Maximum . 82
A.9.1 Description . 82
A.9.2 Maximum data . 83
A.10 MininumActualTime . 83
A.10.1 Description . 83
A.10.2 MinimumActualTime data . 84
A.11 MaximumActualTime . 84
A.11.1 Description . 84
A.11.2 MaximumActualTime data . 85
A.12 Range . 85
A.12.1 Description . 85
A.12.2 Range data . 86
A.13 Minimum2 . 86
A.13.1 Description . 86
A.13.2 Minimum2 data . 87
A.14 Maximum2 . 87
A.14.1 Description . 87
A.14.2 Maximum2 data . 88
A.15 MinimumActualTime2 . 88
A.15.1 Description . 88
A.15.2 MinimumActualTime2 data . 89
A.16 MaximumActualTime2 . 89
A.16.1 Description . 89
A.16.2 MaximumActualTime2 data . 90
A.17 Range2 . 90
A.17.1 Description . 90
A.17.2 Range2 data . 91
A.18 AnnotationCount . 91
A.18.1 Description . 91
A.18.2 AnnotationCount data . 91
A.19 Count . 92
A.19.1 Description . 92
A.19.2 Count data . 92
A.20 DurationInStateZero . 93
A.20.1 Description . 93
A.20.2 DurationInStateZero data . 93
A.21 DurationInStateNonZero . 93
A.21.1 Description . 93
A.21.2 DurationInStateNonZero data . 93

– 4 – IEC 62541-13:2020 © IEC 2020
A.22 NumberOfTransitions . 94
A.22.1 Description . 94
A.22.2 NumberOfTransitions data . 94
A.23 Start . 95
A.23.1 Description . 95
A.23.2 Start data . 95
A.24 End . 95
A.24.1 Description . 95
A.24.2 End data . 96
A.25 StartBound . 96
A.25.1 Description . 96
A.25.2 StartBound data . 97
A.26 EndBound . 97
A.26.1 Description . 97
A.26.2 EndBound data . 98
A.27 Delta . 98
A.27.1 Description . 98
A.27.2 Delta data . 99
A.28 DeltaBounds . 99
A.28.1 Description . 99
A.28.2 DeltaBounds data . 100
A.29 DurationGood . 100
A.29.1 Description . 100
A.29.2 DurationGood data . 101
A.30 DurationBad . 102
A.30.1 Description . 102
A.30.2 DurationBad data . 102
A.31 PercentGood . 103
A.31.1 Description . 103
A.31.2 PercentGood data . 103
A.32 PercentBad . 104
A.32.1 Description . 104
A.32.2 PercentBad data . 104
A.33 WorstQuality . 105
A.33.1 Description . 105
A.33.2 WorstQuality data . 105
A.34 WorstQuality2 . 106
A.34.1 Description . 106
A.34.2 WorstQuality2 data . 106
A.35 StandardDeviationSample . 107
A.35.1 Description . 107
A.35.2 StandardDeviationSample data . 107
A.36 VarianceSample . 107
A.36.1 Description . 107
A.36.2 VarianceSample data . 108
A.37 StandardDeviationPopulation . 108
A.37.1 Description . 108
A.37.2 StandardDeviationPopulation data . 108
A.38 VariancePopulation . 109

A.38.1 Description . 109
A.38.2 VariancePopulation data . 109

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
Figure A.1 – Historian 1 . 68
Figure A.2 – Historian 2 . 69
Figure A.3 – Historian 3 . 70

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 . 19
Table 8 – Bad operation level result codes . 19
Table 9 – Uncertain operation level result codes . 20
Table 10 – Data location . 20
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 . 27
Table 15 – Interpolative Aggregate summary . 30
Table 16 – Average Aggregate summary . 31
Table 17 – TimeAverage Aggregate summary . 32
Table 18 – TimeAverage2 Aggregate summary . 33
Table 19 – Total Aggregate summary . 34
Table 20 – Total2 Aggregate summary . 35
Table 21 – Minimum Aggregate summary . 36
Table 22 – Maximum Aggregate summary. 37
Table 23 – MinimumActualTime Aggregate summary . 38
Table 24 – MaximumActualTime Aggregate summary . 39
Table 25 – Range Aggregate summary . 40
Table 26 – Minimum2 Aggregate summary. 41
Table 27 – Maximum2 Aggregate summary . 42
Table 28 – MinimumActualTime2 Aggregate summary . 43
Table 29 – MaximumActualTime2 Aggregate summary . 44
Table 30 – Range2 Aggregate summary . 45
Table 31 – AnnotationCount Aggregate summary. 46
Table 32 – Count Aggregate summary . 47
Table 33 – DurationInStateZero Aggregate summary . 48

– 6 – IEC 62541-13:2020 © IEC 2020
Table 34 – DurationInStateNonZero Aggregate Summary . 49
Table 35 – NumberOfTransitions Aggregate summary . 50
Table 36 – Start Aggregate summary . 51
Table 37 – End Aggregate summary . 52
Table 38 – Delta Aggregate summary . 53
Table 39 – StartBound Aggregate summary . 54
Table 40 – EndBound Aggregate summary . 55
Table 41 – DeltaBounds Aggregate summary . 56
Table 42 – DurationGood Aggregate summary . 57
Table 43 – DurationBad Aggregate summary . 58
Table 44 – PercentGood Aggregate summary . 59
Table 45 – PercentBad Aggregate summary . 60
Table 46 – WorstQuality Aggregate summary . 61
Table 47 – WorstQuality2 Aggregate summary. 62
Table 48 – StandardDeviationSample Aggregate summary . 63
Table 49 – VarianceSample Aggregate summary . 64
Table 50 – StandardDeviationPopulation Aggregate summary . 65
Table 51 – VariancePopulation Aggregate summary . 66

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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5) IEC itself does not provide any attestation of conformity. Independent certification bodies provide conformity
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6) All users should ensure that they have the latest edition of this publication.
7) No liability shall attach to IEC or its directors, employees, servants or agents including individual experts and
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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.
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.
This second edition cancels and replaces the first edition of IEC 62541-13, published in 2015.
This edition constitutes a technical revision.
This edition includes the following significant technical changes with respect to the previous
edition:
a) no technical changes but numerous clarifications. Also some corrections to the examples.

– 8 – IEC 62541-13:2020 © IEC 2020
The text of this standard is based on the following documents:
FDIS Report on voting
65E/697/FDIS 65E/712/RVD
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.
Throughout this document and the other Parts of the series, certain document conventions
are used:
Italics are used to denote a defined term or definition that appears in the “Terms and
definition” clause in one of the parts of the series.
Italics are also used to denote the name of a service input or output parameter or the name of
a structure or element of a structure that are usually defined in tables.
The italicized terms and names are also often written in camel-case (the practice of writing
compound words or phrases in which the elements are joined without spaces, with each
element's initial letter capitalized within the compound). For example the defined term is
AddressSpace instead of Address Space. This makes it easier to understand that there is a
single definition for AddressSpace, not separate definitions for Address and Space.
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 are referred to in the text in such a way that some or all of their
content constitutes requirements of this document. 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 abbreviated terms
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 and the following apply.
ISO and IEC maintain terminological databases for use in standardization at the following
addresses:
• IEC Electropedia: available at http://www.electropedia.org/
• ISO Online browsing platform: available at http://www.iso.org/obp
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
data that is calculated from data samples

– 10 – IEC 62541-13:2020 © IEC 2020
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
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 second, then the EffectiveEndTime is 12:00:59. See
5.4.2.4.
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
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
interpolation 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 ) × ( 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 r
...