IEC 62541-3:2015 describes the OPC Unified Architecture (OPC UA) AddressSpace and its Objects. It is the OPC UA meta model on which OPC UA information models are based. This second edition cancels and replaces the first edition published in 2010 and constitutes a technical revision. It includes the following changes:
- Added rules for subtyping enumerations;
- Added Property EnumValues;
- Added Property ValueAsText;
- Added EventType SystemStatusChangeEventType;
- Added Properties MaxArrayLength and MaxStringLength;
- Removed the concept of ModelParent;
- Added EventType ProgressEventType;
- Stated that it is allowed to use TAI in all places where UTC time is used;
- Added Property EngineeringUnits;
- Added ModellingRules OptionalPlaceholder and MandatoryPlaceholder.