7.1 Overview Base Modelling Concepts

OPC UA provides various modelling concepts (see OPC 10000-3).

Objects structuring the AddressSpace

Variables providing Values

Methods that can be called by a Client and are executed by the Server

ObjectTypes defining the semantic and structure of Objects

VariableTypes defining the semantic and structure of Variables

DataTypes defining the semantic and structure of Values

Events generated by the Server that can be received by Clients

EventTypes describing the semantic and structure of Events

References defining relationships between Nodes

ReferenceTypes defining the semantic of References

Based on those fundamental concepts, additional base concepts are defined like

Conditions and Alarms as Events that are always in a state and can therefore be represented as Objects in the AddressSpace (OPC 10000-9)

State Machines (OPC 10000-16)

Interfaces and AddIns allowing extensibility into various ObjectType hierarchies (OPC 10000-3)

Alias Names as searchable entry points to Nodes (OPC 10000-17)

Dictionary References to reference external dictionaries (OPC 10000-19)

In OPC 10000-3 there is already an Annex describing how to use the modelling concepts in general, and in OPC 10000-5 there is an Annex, describing the design decisions for creating the server information (ServerType).