EN IEC 62541-12:2026

IEC 62541-12:2025 specifies how OPC Unified Architecture (OPC UA) Clients and Servers interact with DiscoveryServers when used in different scenarios. It specifies the requirements for the LocalDiscoveryServer, LocalDiscoveryServer-ME and GlobalDiscoveryServer. It also defines information models for Certificate management, KeyCredential management and AuthorizationServices.Annex A informatively discusses deployment and configuration aspects.Annex B defines NodeSet and numeric NodeIds.Annex F provides installation rules for the LDS.Annex H compares the Certificate management defined in this document with IETF RFC 7030.This second edition cancels and replaces the first edition published in 2020. This edition constitutes a technical revision.This edition includes the following significant technical changes with respect to the previous edition:a) addition of a "Quantity Model" which can be referenced from EngineeringUnit Properties. The model defines quantities and assigned units. In addition it provides alternative units and the conversion to them;b) addition of rules for ValuePrecision Property:• can also be used for other subtypes like Duration and Decimal.• additional rules when ValuePrecision has negative values.