3 Structure of the OPC UA series

3.1 Specification organization

The OPC UA specification is organized as a multi-part series to provide a modular and extensible framework. This structure allows for focused development and maintenance of specific aspects of the technology, while ensuring overall coherence. The parts are broadly categorized into core concepts, information models, services, mappings, profiles, and domain-specific applications. Parts 1 through 5 describe core concepts of OPC UA, therefore, readers are encouraged to read Parts 1 through 5 of the specification before reading the other Parts.

3.2 Specification parts

At the time of publication of this document, the OPC 10000 series is composed of the following parts:

• Part 1 (OPC 10000-1) – Overview and Concepts

• Part 1 (this part) presents the concepts and overview of OPC UA.

• Part 2 (OPC 10000-2) – Security Model

• Part 2 describes the model for securing interactions between OPC UA Applications.

• Part 3 (OPC 10000-3) – Address Space Model

• Part 3 describes the contents and structure of the Server’s AddressSpace.

• Part 4 (OPC 10000-4) – Services

• Part 4 specifies the Services provided by Servers.

• Part 5 (OPC 10000-5) – Information Model

• Part 5 specifies the types and their relationships defined for Servers.

• Part 6 (OPC 10000-6) – Mappings

• Part 6 specifies the mappings to transport protocols and data encodings supported by OPC UA.

• Part 7 (OPC 10000-7) – Profiles

• Part 7 specifies the Profiles that are available for OPC UA Applications. These Profiles provide groupings of functionality that can be used for conformance level certification. OPC UA Applications will be tested against the Profiles.

• Part 8 (OPC 10000-8) – Data Access

• Part 8 specifies the use of OPC UA for data access.

• Part 9 (OPC 10000-9) – Alarms and Conditions

• Part 9 specifies use of OPC UA support for access to Alarms and Conditions. The base system includes support for simple Events; this specification extends that support to include support for Alarms and Conditions.

• Part 10 (OPC 10000-10) – Programs

• Part 10 specifies OPC UA support for access to Programs.

• Part 11 (OPC 10000-11) – Historical Access

• Part 11 specifies use of OPC UA for historical access. This access includes both historical data and historical Events.

• Part 12 (OPC 10000-12) – Discovery and Global Services

• Part 12 specifies how Discovery Servers operate in different scenarios and describes how UA Clients and Servers should interact with them. It also defines Information Models for Certificate management, key credential management, and authorization services.

• Part 13 (OPC 10000-13) – Aggregates

• Part 13 specifies how to compute and return aggregates like minimum, maximum, average etc. Aggregates can be used with current and historical data.

• Part 14 (OPC 10000-14) – PubSub

• Part 14 specifies the OPC Unified Architecture (OPC UA) PubSub communication model. The PubSub communication model defines an OPC UA publish subscribe pattern in addition to the ClientServer pattern defined by the Services in OPC 10000-4.

• Part 15 (OPC 10000-15) – Safety

• Part 15 extends OPC UA to fulfil the requirements of functional safety as defined in the IEC 61508 series of standards and in IEC 61784-3:2017.

• Part 16 (OPC 10000-16) – State Machines

• Part 16 specifies the basic infrastructure to model state machines.

• Part 17 (OPC 10000-17) – Alias Names

• Part 17 specifies a manner of configuring and exposing an alternate well-defined name for any OPC UA Node in a Server or system.

• Part 18 (OPC 10000-18) – Role-Based Security

• Part 18 specifies the basic infrastructure to model role-based access control (RBAC)

• Part 19 (OPC 10000-19) – Dictionary References

• Part 19 specifies the basic infrastructure to reference from an OPC UA Information Model to external dictionaries like IEC Common Data Dictionary or ECLASS.

• Part 20 (OPC 10000-20) – File Transfer

• Part 20 specifies the basic infrastructure to model file transfers and file systems.

• Part 21 (OPC 10000-21) – Device Onboarding

• Part 21 specifies the life cycle of Devices and Composites and mechanisms to verify their authenticity, set up their security and maintain their configuration.

• Part 22 (OPC 10000-22) – Base Network Model

• Part 22 specifies an OPC UA Information Model for a basic set of network related components to be used in more specific Information Models.

• Part 23 (OPC 10000-23) – Common ReferenceTypes

• Part 23 specifies common types of references between Nodes.

• Part 24 (OPC 10000-24) – Scheduler

• Part 24 specifies an OPC UA information model to expose and configure the dates and times specific actions are executed by the OPC UA Server.

• Part 25 (OPC 10000-25) – Object Serialization

• Part 25 specifies an OPC UA information model to configure and expose a merged compact representation of the selected subtree of a root Node.

• Part 26 (OPC 10000-26) – LogObject

• Part 26 specifies an OPC UA information model for a set of Objects and Events that can be used to collect diagnostic information in a system.