IEC 62541-5-2026 PDF

Full title and description

St IEC 62541-5:2026 — OPC unified architecture - Part 5: Information Model. Defines the OPC UA Information Model: the standardized Nodes, Types, DataTypes, ReferenceTypes, EventTypes and base Objects that form the AddressSpace of an OPC UA Server, including standard instances used for diagnostics and server entry-points.

Abstract

This fourth edition of IEC 62541-5 updates and extends the OPC UA Information Model. It consolidates changes from the previous edition, removes annexes that have been moved to other parts, and adds new DataTypes, ReferenceTypes and model elements to support currency, interfaces/add‑ins, method metadata, ordered lists, portability identifiers and improved server capability properties. The document specifies the structure, attributes and standard Nodes that OPC UA Servers and companion specifications can build upon.

General information

• Status: Published.
• Publication date: 6 January 2026.
• Publisher: International Electrotechnical Commission (IEC).
• ICS / categories: 25.040.40; 35.100.05.
• Edition / version: 4.0 (fourth edition).
• Number of pages: 189 pages.

Scope

Specifies the OPC UA Information Model — the normative definitions of Node classes, standard ObjectTypes, VariableTypes, Method signatures, EventTypes, ReferenceTypes and DataTypes required to model industrial information in an interoperable, extensible way. It defines the standard server Objects (for example the Server object and diagnostics objects), modelling rules, common Variable and DataType definitions and the standard Nodeset layout that companion specifications and implementations reuse. The part is foundational for OPC UA-based modelling and for other IEC/EN/ISO standards and companion specifications that map domain models into OPC UA.

Key topics and requirements

• New and revised Information Model elements added in the 2026 edition (high‑level): addition of a currency information model, Interfaces and AddIns model, and Method Metadata information model.
• Capability and limits extended: MaxSessions, MaxSubscriptions and MaxMonitoredItems added to Server capabilities.
• Portable identifiers and string types: PortableQualifiedName, PortableNodeId, UriString and SemanticVersionString DataTypes introduced to improve portability of models.
• Ordered and collection types: information model support for ordered lists of objects and related OrderedList/IOrderedObject types.
• New Reference and Event types: AssociatedWith ReferenceType and new AuditClientEventType/AuditClientUpdateMethodResultEventType.
• Model metadata: ConfigurationVersion and ModelVersion additions to NamespaceMetadataType and ModelVersion support to track model changes.
• Bit field support: BitFieldType and BitFieldDefinitionType added to represent compact flag/bitfield semantics.
• Annex restructuring: Annexes previously present have been split out into separate IEC deliverables (annex B/C moved to other IEC parts).

Typical use and users

The standard is used by OPC UA stack and SDK developers, industrial automation vendors, device manufacturers, system integrators, designers of companion specifications, QA/test laboratories and implementers who define or consume OPC UA AddressSpace models. It is applied when designing standardized device models, server capabilities, diagnostics, events, and for ensuring consistent NodeIds, DataTypes and modelling rules across products and systems.

Related standards

Part of the IEC 62541 (OPC UA) series. Closely related parts include: Part 1 (Overview & concepts), Part 2 (Security model), Part 3 (Address Space Model), Part 4 (Services), Part 6 (Mappings), Part 8 (Data Access), Part 9 (Alarms & Conditions), Part 11 (Historical Access), Part 12 (Discovery & Global Services), Part 13 (Aggregates) and Part 14 (Pub/Sub). Companion standards and domain-specific companion specifications commonly reference Part 5 for modelling rules and Nodeset definitions.

Keywords

OPC UA, Information Model, AddressSpace, Node, ObjectType, VariableType, DataType, ReferenceType, Nodeset, Server capabilities, NamespaceMetadata, PortableNodeId, PortableQualifiedName, SemanticVersion, BitField, Audit events.

FAQ

Q: What is this standard?

A: IEC 62541-5:2026 is the fourth edition of the OPC Unified Architecture Part 5 specification that defines the OPC UA Information Model — the standard Nodes, Types and DataTypes used to structure an OPC UA Server AddressSpace.

Q: What does it cover?

A: It covers normative definitions of ObjectTypes, VariableTypes, DataTypes, ReferenceTypes, EventTypes, standard server Objects and Methods, modelling rules and metadata for namespaces and models. The 2026 edition adds portability and metadata types, ordered-list support, currency and interface/add‑in models and other enhancements.

Q: Who typically uses it?

A: Implementers of OPC UA stacks and SDKs, device and equipment manufacturers, system integrators, authors of companion specifications, and test laboratories use this part to ensure interoperable AddressSpace modelling and to reference standardized Nodes and DataTypes.

Q: Is it current or superseded?

A: Current — the 2026 edition (published 6 January 2026) is the latest edition and cancels and replaces the third edition published in 2020.

Q: Is it part of a series?

A: Yes — IEC 62541 is the multi‑part OPC UA standard. Part 5 (Information Model) is one foundational part; other parts address services, mappings, profiles, data access, alarms, historical access, discovery and pub/sub, among others.

Q: What are the key keywords?

A: OPC UA, Information Model, AddressSpace, Nodeset, DataType, ObjectType, VariableType, ReferenceType, NamespaceMetadata, PortableNodeId, SemanticVersionString, BitField.