return to the IEC Standards

Note: The following is an excerpt from the official IEC catalog. It is provided here as a convenience and is not authoritative. Refer to the original document as the authoritative reference.

IEC 62541-8:2020 is part of the overall OPC Unified Architecture (OPC UA) standard series and defines the information model associated with Data Access (DA). It particularly includes additional VariableTypes and complementary descriptions of the NodeClasses and Attributes needed for Data Access, additional Properties, and other information and behaviour.

The complete address space model, including all NodeClasses and Attributes is specified in IEC 62541-003 OPC Unified Architecture - Part 3: Address Space Model. The services to detect and access data are specified in IEC 62541-004 OPC Unified Architecture - Part 4: Services. This third edition cancels and replaces the second edition published in 2015. This edition constitutes a technical revision.

This edition includes the following significant technical changes with respect to the previous edition:

a) added new VariableTypes for AnalogItems;

b) added an Annex that specifies a recommended mapping of OPC UA Dataccess to OPC COM DataAccess;

c) changed the ambiguous description of “Bad_NotConnected”;

d) updated description for EUInformation to refer to latest revision of UNCEFACT units.