IEC 62541-4 Ed. 4.0 en:2025

Full Description

This part of IEC 62541 defines the OPC Unified Architecture (OPC UA) Services. The Services
defined are the collection of abstract Remote Procedure Calls (RPC) that are implemented by
OPC UA Servers and called by OPC UA Clients. All interactions between OPC UA Clients and
Servers occur via these Services. The defined Services are considered abstract because no
particular RPC mechanism for implementation is defined in this document. IEC 62541-6
specifies one or more concrete mappings supported for implementation. For example, one
mapping in IEC 62541-6 is to UA-TCP UA-SC UA-Binary. In that case the Services described
in this document appear as OPC UA Binary encoded payload, secured with OPC UA Secure
Conversation and transported via OPC UA TCP.

Not all OPC UA Servers implement all of the defined Services. IEC 62541-7 defines the Profiles
that dictate which Services must be implemented in order to be compliant with a particular
Profile.

A BNF (Backus-Naur form) for browse path names is described in Annex A.