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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.

See also:

• IEC 62541-001 OPC Unified Architecture - Part 1: Overview and concepts
• IEC 62541-002 OPC Unified Architecture - Part 2: Security Model
• IEC 62541-003 OPC Unified Architecture - Part 3: Address Space Model
• IEC 62541-004 OPC Unified Architecture - Part 4: Services
• IEC 62541-005 OPC Unified Architecture - Part 5: Information Model
• IEC 62541-006 OPC Unified Architecture - Part 6: Mappings
• IEC 62541-007 OPC Unified Architecture - Part 7: Profiles
• IEC 62541-009 OPC Unified Architecture - Part 9: Alarms and Conditions
• IEC 62541-010 OPC Unified Architecture - Part 10: Programs
• IEC 62541-011 OPC Unified Architecture - Part 11: Historical Access
• IEC 62541-012 OPC Unified Architecture - Part 12: Discovery and global
• IEC 62541-013 OPC Unified Architecture - Part 13: Aggregates
• IEC 62541-014 OPC Unified Architecture - Part 14: PubSub
• IEC 62541-100 OPC Unified Architecture - Part 100: Device Interface