IEC 62541-13:2025

Overview - IEC 62541-13:2025 (OPC UA - Aggregates)

IEC 62541-13:2025 is the third edition of the OPC Unified Architecture (OPC UA) specification that defines the information model associated with Aggregates. It standardizes how aggregate values (for example averages, totals, minima/maxima, and time-weighted metrics) are computed, represented, and exposed by OPC UA servers and historical systems. This edition cancels and replaces IEC 62541-13:2020 and constitutes a technical revision with multiple computation and example fixes. Annex A contains programmatically produced aggregate examples (now provided as CSV).

Key topics and technical requirements

• Aggregate information model: Nodes and types to represent AggregateFunction objects, AggregateConfiguration and related AddressSpace structures.
• AggregateFilter and ReadProcessedDetails: Definitions for MonitoredItem aggregate filters and processed reads used by client requests.
• Standard aggregate functions: Definitions and semantics for aggregates such as TimeAverage, TimeAverage2, Total, Total2, Minimum/Maximum, Range, Count, DurationInState, Start/End/Delta, StandardDeviation/Variance, PercentGood/PercentBad, WorstQuality, etc.
• StatusCodes and information bits: Rules for computing StatusCodes (including Raw and Partial bits), handling uncertain data and bad statuses, and operation-level result codes.
• Interpolation and extrapolation: Clarifications on SlopedInterpolation vs SteppedInterpolation, use of sloped extrapolation, and how interpolation affects aggregate results.
• Uncertain and percent-good handling: PercentGood/PercentBad are now accounted for in calculations; TreatUncertainAsBad behavior clarified for many aggregates.
• Examples & certification alignment: Numerous corrections (rounding errors, data type corrections, removed incorrect zero values, updated Historian examples) to align with certification testing tools.

Practical applications

• Implementing consistent historian aggregation for SCADA, DCS and IIoT platforms.
• Building OPC UA servers/clients that provide certified aggregate metrics for analytics, reporting and KPI dashboards.
• Ensuring interoperability between process historians, analytics engines and OPC UA-aware applications when computing time-weighted averages, totals, and quality-aware aggregates.
• Supporting automated testing and certification by using the standardized example CSVs and clarified StatusCode rules.

Who should use this standard

• OPC UA server and historian implementers
• System integrators and automation vendors
• Industrial data platform and analytics developers
• Certification and test-tool authors working with OPC UA aggregates

Related standards

• Other parts of IEC 62541 (OPC UA core services, security and information models) - consult the IEC 62541 series for core OPC UA requirements and interoperability guidance.

Keywords: IEC 62541-13:2025, OPC Unified Architecture, Aggregates, aggregate functions, TimeAverage, PercentGood, TreatUncertainAsBad, interpolation, OPC UA historian.