IEC 62541-11:2020

Overview

IEC 62541-11:2020 - OPC Unified Architecture (OPC UA) Part 11: Historical Access specifies the information model extensions required for Historical Access (HA) in OPC UA. It defines the NodeClasses, Attributes, standard Properties and expected behaviour used to expose historical data and events from OPC UA servers. The document complements the core AddressSpace model (IEC 62541-3), the predefined Information Model (IEC 62541-5), and the historical Services (IEC 62541-4). Aggregate computation behaviour is covered by IEC 62541-13. The 2020 edition is a technical revision that adds a new method for determining the first historical point and clarifies how to add, insert, modify and delete annotations.

Key topics and technical requirements

• Historical Information Model: Extensions for HistoricalNodes, HistoricalDataNodes and HistoricalEventNodes including required Attributes and standard Properties (e.g., Annotations).
• History Services usage: How HistoryRead, HistoryUpdate and related service parameters must be used for raw, modified, processed and at-time reads (ReadRawModifiedDetails, ReadProcessedDetails, ReadAtTimeDetails, ReadEventDetails).
• Timestamps and time domains: Rules for timestamp semantics, bounding values, and determining first historical points.
• Aggregates support: Integration points for computing aggregates (min, max, average, etc.), with the concrete aggregate behaviour defined in IEC 62541-13.
• Annotations and audit events: Structure and lifecycle for annotations, audit event types for history updates and deletes, and clarified procedures to add/insert/modify/delete annotations.
• Server capabilities and configuration: How servers expose HistoryServerCapabilities, HistoricalDataConfiguration and continuation points for large result sets.
• Error semantics and StatusCodes: Operation-level result codes specific to historical access and semantics for continuity, modification and deletion operations.

Practical applications and who uses it

IEC 62541-11:2020 is essential for:

• OPC UA server and historian vendors implementing robust historical data/event storage and retrieval.
• System integrators and SCADA/IIoT engineers who design archival, trending and reporting solutions.
• Industrial automation architects needing standardized timestamping, annotations and auditability for regulatory or quality requirements.
• Plant analytics and MES/ERP integrators that rely on consistent historical reads and aggregate calculations across heterogeneous devices.

Practical benefits include interoperable historical reads/writes, standardized aggregate results, reliable annotation handling, and audit trails for history modifications-enabling consistent trending, reporting and analytics workflows.

Related standards

• IEC 62541-3: AddressSpace model
• IEC 62541-4: Services for historical data and events
• IEC 62541-5: Predefined Information Model
• IEC 62541-13: Aggregates (concrete definitions and computations)

Keywords: IEC 62541-11:2020, OPC UA Historical Access, HistoricalData, HistoricalEvent, HistoryRead, HistoryUpdate, Annotations, Aggregates, AddressSpace, HistoryServerCapabilities.