IEC 62541-1:2025

Overview

IEC 62541-1:2025 - OPC Unified Architecture: Part 1: Overview and concepts introduces the foundational concepts, terminology and architecture of OPC UA (OPC Unified Architecture). This first edition replaces IEC TR 62541-1 (2020) and is intended as the entry point to the IEC 62541 series. It summarizes the structure of the series, explains the suggested reading order for subsequent parts, and defines the core goals and models that underpin OPC UA deployments.

Key topics and technical scope

The document covers high-level models and service sets used across OPC UA implementations, including:

• Design goals and general architecture of OPC UA
• Integrated models and services, such as the Security model, AddressSpace model, integrated object model and service interactions
• Terms and definitions (e.g., AddressSpace, Attribute, DataSet, Certificate, Client, Server, Aggregate, Alarm)
• Systems concepts: Client/Server overview, Server components (real objects, AddressSpace, subscriptions), Sessions and communication stacks
• Client/Server service sets (overview of Discovery, SecureChannel, Session, NodeManagement, View, Query, Attribute, Method, MonitoredItem and Subscription service sets)
• Publish–Subscribe and Redundancy models and Server-to-Server interactions
• Global services such as Discovery services, Certificate management, KeyCredential management, Authorization services, Device Onboarding, Alias names and the Security Key Service (SKS)

The standard is descriptive rather than normative for interfaces in later parts (it contains no normative references) and is primarily a conceptual guide to the rest of the IEC 62541 series.

Applications and practical value

IEC 62541-1:2025 is essential for anyone planning, designing or integrating OPC UA solutions in industrial automation and IIoT environments. Practical applications include:

• Defining secure device onboarding and certificate management flows
• Designing OPC UA servers with coherent AddressSpaces and object models
• Implementing client–server and publish–subscribe communication patterns
• Building interoperable SCADA, historian, MES and edge-device integrations
• Assessing security and lifecycle considerations for OPC UA deployments

Typical users:

• System architects and integration engineers
• OPC UA product developers and firmware engineers
• Cybersecurity specialists and compliance officers in industrial settings
• Automation vendors, device manufacturers, and solution integrators

Related standards

• This part is the introductory document to the IEC 62541 (OPC UA) series. For protocol specifics, data models, profiles and normative interfaces, consult the subsequent parts of the IEC 62541 series listed on the IEC website.

Keywords: IEC 62541-1:2025, OPC UA, OPC Unified Architecture, AddressSpace, Security model, Publish-Subscribe, Client/Server, Discovery services, Certificate management, industrial automation.