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.
