IEC 62541-6-2025 PDF

Full title and description

St IEC 62541-6-2025 — OPC unified architecture - Part 6: Mappings. Specifies the normative mappings that connect the OPC UA abstract service and information models and security model to concrete encodings and transport protocols (OPC UA Binary, XML, JSON encodings and network protocol mappings such as OPC UA TCP, HTTPS, WebSockets and related message/security behaviour).

Abstract

This fourth edition (2025) of IEC 62541-6 defines how the abstract OPC UA services, data structures and security model are represented on the wire and in interchange formats. It updates and extends the 2020 edition with technical revisions including ECC support for UA Secure Conversation, enhanced JSON mapping (including unions and string representations for NodeId/ExpandedNodeId/QualifiedName), Decimal data type encoding, certificate and CRL rules (AuthorityKeyIdentifier), rules for DateTime precision loss and handling of embedded nulls in strings, and additions to UANodeSet to support RolePermissions.

General information

• Status: Published / International Standard (current edition published).
• Publication date: 23 December 2025.
• Publisher: International Electrotechnical Commission (IEC).
• ICS / categories: 25.040.40, 35.100.05 (industrial automation systems; multilayer applications).
• Edition / version: 4.0 (fourth edition — cancels and replaces the 2020 edition).
• Number of pages: 138 (official IEC product listing). Note: some national bodies/resellers list different layout/page counts for their publication bundles (other listings have reported 288 pages); the IEC record is authoritative for the IEC publication details.

Scope

IEC 62541-6:2025 specifies the normative mappings between: the security model (IEC 62541-2), the abstract service definitions (IEC 62541-4), the data structures (IEC 62541-5) and the concrete network protocols and encodings used to implement OPC UA. The standard defines binary, XML and JSON encodings (including rules for built-in types, structures, unions, Variant and ExtensionObject), transport mappings (OPC UA TCP, HTTPS, WebSockets, SOAP/HTTP where applicable), and the security and certificate behaviours required for interoperable implementations.

Key topics and requirements

• Normative mappings for OPC UA encodings: OPC UA Binary, OPC UA XML and OPC UA JSON (including rules for Unions, Variant, ExtensionObject and string representations for NodeId, ExpandedNodeId and QualifiedName).
• Transport protocol mappings and behaviours: OPC UA TCP, HTTPS, WebSockets and related message framing, addressing and well-known addresses.
• Security and certificates: UA Secure Conversation enhancements with ECC support; certificate requirements for application, user and issuer certificates; CRL handling and use of AuthorityKeyIdentifier.
• Data type and encoding updates: Decimal data type encoding and rules for DateTime precision loss and conversion (TAI to UTC).
• Interchange and information model support: UANodeSet additions (including RolePermissions fields), Media types for UANodeSet, and normative XML/Schema/WSDL fragments for XML mapping.
• Robustness rules: handling/truncation of strings with embedded nulls and the possibility to omit Symbol in JSON when unknown.

Typical use and users

Implementers of OPC UA stacks, device and gateway vendors, system integrators, industrial automation software developers, security architects and testing labs use this part to ensure protocol interoperability and correct encoding/transport/security behaviour when building or evaluating OPC UA products and integration solutions. It is used during development, certification testing and integration of OPC UA-enabled systems.

Related standards

IEC 62541-6 is one part of the IEC 62541 (OPC UA) series. Closely related parts include IEC 62541-2 (Security model), IEC 62541-3 (Address space model), IEC 62541-4 (Services), IEC 62541-5 (Information model) and other parts covering Profiles, PubSub, Historical Access, Devices, Dictionaries and more. National/European adoptions (EN IEC) and translations exist for many parts.

Keywords

OPC UA, mappings, encodings, OPC UA Binary, OPC UA XML, OPC UA JSON, OPC UA TCP, WebSockets, HTTPS, UA Secure Conversation, ECC, certificates, CRL, AuthorityKeyIdentifier, UANodeSet, RolePermissions, Decimal, DateTime, NodeId, ExpandedNodeId, QualifiedName.

FAQ

Q: What is this standard?

A: IEC 62541-6:2025 is Part 6 of the OPC Unified Architecture series; it defines the normative mappings from OPC UA abstract models and security to concrete encodings and transport protocols. It is the fourth edition, published in December 2025.

Q: What does it cover?

A: It covers binary, XML and JSON encodings, transport protocol mappings (OPC UA TCP, HTTPS, WebSockets, etc.), message and security behaviours, certificate and CRL handling rules, encoding/representation rules for data types (including Decimal) and Information Model interchange details such as UANodeSet.

Q: Who typically uses it?

A: OPC UA stack and product implementers, automation equipment vendors, integrators, security engineers, and conformity testers use this part to implement, secure and validate OPC UA communication and interchange.

Q: Is it current or superseded?

A: This publication (IEC 62541-6:2025, edition 4.0) cancels and replaces the previous (2020) edition and is the current IEC edition as published on 23 December 2025; the IEC record indicates a stability date of 2028. Some resellers or national publications may show alternate page counts or local publication dates, but the IEC bibliographic entry is authoritative.

Q: Is it part of a series?

A: Yes — IEC 62541 is a multipart standard (OPC UA). Part 6 (Mappings) works together with Parts 2, 3, 4, 5 and the other parts in the series to define the complete OPC UA framework.

Q: What are the key keywords?

A: OPC UA, mappings, encodings (Binary/XML/JSON), transport (OPC UA TCP/HTTPS/WebSockets), UA Secure Conversation, certificates, UANodeSet, RolePermissions, Decimal, DateTime, NodeId.