OPC UA Information Model Workbench

Browse nodes, follow references, read DataValues, create subscriptions, and call methods in an OPC UA address space

animation
opc-ua
industrial-iot
interoperability
protocols
Interactive OPC UA information model animation for learning address spaces, NodeIds, NodeClasses, references, Variables, Methods, DataValues, subscriptions, monitored items, and secure sessions.
Interactive animation OPC UA Information model

OPC UA Information Model Workbench

See how an industrial asset becomes a typed, browsable address space. Step through Browse, Read, Subscribe, Publish, and Call flows while watching the selected node, references, status code, timestamp, and diagnosis change together.

BrowseCurrent service
TemperatureSelected node
Model visibleClient result
Goal
Connect machine tags to OPC UA nodes, NodeIds, attributes, references, and services.
Try
Compare browsing, reading a DataValue, subscribing, method calls, and a weak flat tag model.
Watch
Use Step to see which service runs and what the client learns at each stage.
Check
Diagnose whether the issue is modeling, access rights, subscription timing, or method arguments.

Address Space and Service Flow

A SCADA client opens a secure channel and session, browses the server address space, follows references from a machine object to typed Variables and Methods, then reads or monitors selected nodes.

Ready: browse model loaded
Machine CellPLC tags and signals
OPC UA Serveraddress space
SCADA Clientbrowse/read/monitor
MES/Historiannotifications and context
Address Space
Service Trace
Start: the client must establish a secure channel and session before service calls reveal the modeled machine data.

Selected Node and Result

ns=2;s=Line1.Motor.TempNodeId
VariableNodeClass
68.4 deg CValue or result
GoodStatus or quality

Diagnosis

Step through the flow to see whether the client is discovering model structure, reading a DataValue, receiving notifications, or calling a modeled Method.

ServiceBrowse
Model clueFollow Organizes and HasComponent references before reading values.
RiskA client that only knows raw tag names cannot discover semantics, units, or relationships.
Quick Reference
  • Address Space: a graph of Nodes connected by References. Clients Browse this graph before selecting data or actions.
  • NodeId: stable identifier for a node. Human-readable BrowseName and DisplayName are attributes, not the only identity.
  • Variable/DataValue: a Variable holds data; a Read returns a DataValue with value, StatusCode, and timestamps.
  • Subscription: a client creates monitored items; the server samples and sends Publish notifications when reporting conditions are met.
How To Debug
  • If browsing is confusing, inspect NodeClass, BrowseName, TypeDefinition, and references such as Organizes and HasComponent.
  • If a value is missing, check the StatusCode, access level, user permissions, and whether the selected NodeId is a Variable.
  • If notifications are late, compare sampling interval, publishing interval, queue size, deadband, and network loss.
  • If a method call fails, check input arguments, executable flag, user authorization, and the current machine state.
Node Classes
ObjectRepresents an asset, folder, controller, or logical component.
VariableRepresents a readable or writable value with DataType, value rank, and access rules.
MethodRepresents a callable operation with input and output arguments.
ObjectTypeDefines reusable structure for Objects, such as a motor type.
ReferenceTypeDefines relationship meaning, such as Organizes or HasComponent.
DataTypeDefines the structure and meaning of values carried by Variables.
Technical Accuracy Notes
  • OPC UA is not just a tag transport. The address space model exposes typed Nodes, Attributes, and References.
  • Browse discovers structure. Read returns DataValues. Write changes writable Variables. Call invokes Methods.
  • Subscriptions contain monitored items. Sampling interval and publishing interval are related but not the same thing.
  • StatusCode must be treated as part of the value quality. A displayed number without its status can mislead operators.
  • Security mode "None" is included only as a lab comparison; production systems normally require application/user authentication and message protection appropriate to the risk.
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