1 Scope

This part of IEC 62541 belongs to the OPC Unified Architecture standards series and defines the Information Model associated with Historical Access (HA). It particularly includes additional and complementary descriptions of the NodeClasses and Attributes needed for Historical Access, additional standard Properties, and other information and behaviour.

The complete AddressSpace Model including all NodeClasses and Attributes is specified in IEC 62541‑3. The predefined Information Model is defined in IEC 62541‑5. The Services to detect and access historical data and events, and description of the ExtensibleParameter types are specified in IEC 62541‑4.

This document includes functionality to compute and return Aggregates like minimum, maximum, average etc. The Information Model and the concrete working of Aggregates are defined in IEC 62541‑13.

Conventions for Historical Access Clients are informatively provided in Annex A.