IEC 62541-6:2020

Overview

IEC 62541-6:2020 - "OPC Unified Architecture – Part 6: Mappings" defines how the OPC UA abstract services, information model and security model are mapped to concrete encodings and network transports. This third edition (2020) is a technical revision of the 2015 edition and specifies binary, XML and JSON encodings, secure message protocols, and transport mappings (OPC UA TCP, HTTPS, WebSockets, etc.). It links the abstract definitions in IEC 62541-4 and data structures in IEC 62541-5 to implementable network and encoding choices while referencing the security model in IEC TR 62541-2.

Key topics and technical requirements

• Data encodings: OPC UA Binary, XML and added JSON encodings for both PubSub (non-reversible) and Client/Server (reversible). Support for optional fields, Unions, and multi-dimensional arrays outside of Variants.
• Transport mappings: Mappings for OPC UA TCP, WebSocket Secure (WSS), HTTPS (including session-less service invocation), and reverse connectivity mechanisms.
• Security and authentication: Message security protocols, application certificates, mapping for JSON Web Tokens (JWT), and added support for OAuth2 Authorization Framework.
• Deprecated transports: SOAP/HTTP with WS-SecureConversation is identified as deprecated due to limited platform support.
• NodeSet and schema updates: Support for Unions in NodeSet schema, batch operations for add/delete nodes, and binary representation for Decimal data types.
• Normative artifacts: WSDL/XML schema for XML mapping, OPC Binary schema, Information Model schema, and security settings management.

Practical applications and users

Who uses IEC 62541-6:2020:

• Industrial automation vendors implementing OPC UA stacks (device vendors, gateway makers)
• Systems integrators and SCADA/ICS architects designing secure field-to-cloud connectivity
• Software developers building OPC UA clients, servers, or PubSub components using Binary, XML or JSON
• Cybersecurity architects mapping authentication and token-based flows (JWT, OAuth2) into OPC UA deployments
• Standardization and compliance teams verifying interoperability against NodeSet schemas and transport mappings

Common applications:

• Secure IIoT and Industry 4.0 gateways connecting PLCs and edge devices to cloud services
• Real-time PubSub telemetry over WSS or UDP with JSON/Binary encodings
• Client/Server data exchange and historic/metadata services over HTTPS with session-less options
• Large-scale device provisioning and bulk NodeSet updates using batch add/delete operations

Related standards

• IEC TR 62541-2 (security model)
• IEC 62541-4 (abstract service definitions)
• IEC 62541-5 (data structures / information model)

Keywords: IEC 62541-6:2020, OPC UA mappings, OPC Unified Architecture, JSON encoding, WebSocket WSS, OAuth2, JWT, NodeSet schema, PubSub, client/server, transport mappings, industrial IoT.