IEC 62541-13-2020 OPC Unified Architecture – Part 13: Aggregates.
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 -1 1 , 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 -1 1 and the following apply.
ISO and IEC maintain terminological databases for use in standardization at the following addresses:
• IEC Electropedia: available at
• ISO Online browsing platform: available at
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 1 0-minute Average over the time range 1 2:00 to 1 2:30 would result in a set of three intervals of ProcessingInterval length, with each interval having a start time of 1 2:00, 1 2:1 0 and 1 2:20 respectively.
The rules used to determine the interval Bounds are discussed in
3.1.2 interpolated data
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
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 1 2:01 :00, the time resolution is 1 second, then the EffectiveEndTime is 1 2:00:59. See 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.IEC 62541-13 pdf download.