Errata exists for this version of the document.

This specification is organized as a multi-part specification, as illustrated in Figure 1.

Figure 1 – OPC UA Specification Organization

Parts 1 through 7 and Part 14 specify the core capabilities of OPC UA. These core capabilities define the structure of the OPC AddressSpace and the Services that operate on it. Part 14 defines an OPC UA publish subscribe pattern in addition to the Client Server pattern defined by the Services in Part 4. Parts 8 through 11 apply these core capabilities to specific types of access previously addressed by separate OPC COM specifications, such as Data Access (DA), Alarms and Events (A&E) and Historical Data Access (HDA). Part 12 describes Discovery mechanisms for OPC UA and Part 13 describes ways of aggregating data.

Readers are encouraged to read Parts 1 through 5 of the core specifications before reading Parts 8 through 14. For example, a reader interested in UA Data Access should read Parts 1 through 5 and 8. References in Part 8 may direct the reader to other parts of this specification.

Part 1 – Overview and Concepts

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

Part 2 – Security Model

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

Part 3 – Address Space Model

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

Part 4 – Services

Part 4 specifies the Services provided by Servers.

Part 5 – Information Model

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

Part 6 – Mappings

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

Part 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 – Data Access

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

Part 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 – Programs

Part 10 specifies OPC UA support for access to Programs.

Part 11 – Historical Access

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

Part 12 – Discovery

Part 12 specifies how Discovery Servers operate in different scenarios and describes how UA Clients and Servers should interact with them. It also defines how UA related information should be accessed using common directory service protocols such as LDAP.

Part 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 – 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 Client Server pattern defined by the Services in Part 4.