medium OPC UA exam questions
OPC UA Knowledge mock exam questions selected at medium level. Ideal for consolidating what you've learned and gauging your real level.
Medium level questions
Q01
OPC UA supports two communication patterns: Client/Server (the classic Request/Response model) and Pub/Sub (publish/subscribe over MQTT or UDP multicast/unicast), the latter introduced in version 1.04 to address Industrie 4.0 use cases.TrueFalse1. Architecture· Client/Server vs. Pub/Sub· MediumCorrect answerTrueLearning tipOPC UA is dual-mode by design. Client/Server has been in the standard since version 1.0 and exposes bidirectional services such as Read, Write and Subscribe. Pub/Sub was added in 1.04 (2018) with transport bindings over MQTT, AMQP or UDP, which scales much better for IIoT and cloud telemetry. Both modes can coexist inside the same device, and the typical split is Client/Server for configuration and engineering access, Pub/Sub for high-volume telemetry.
Q02
The OPC UA Address Space is a hierarchical structure of Nodes linked by typed References (HasComponent, HasProperty, HasTypeDefinition, etc.), exposed as a graph that clients can walk through the Browse service.TrueFalse1. Architecture· Address Space· MediumCorrect answerTrueLearning tipThe Address Space is effectively the object filesystem of an OPC UA server. Nodes come in eight NodeClasses (Variable, Object, Method, ObjectType, VariableType, DataType, ReferenceType, View), each identified by a unique NodeId built from a namespace index and an identifier. Nodes are linked by typed References, and human-readable BrowseName/DisplayName attributes make navigation usable. The Browse service lets a client discover the structure dynamically without prior knowledge of the vendor model.
Q03
The main OPC UA Service Sets are: Discovery, SecureChannel, Session, NodeManagement, View, Query, Attribute (Read/Write), MonitoredItem, Subscription, and Method (Call).TrueFalse3. Services· Hauptsächliche Service Sets· MediumCorrect answerTrueLearning tipOPC UA Part 4 organises services into standardised sets. Discovery finds servers (FindServers, GetEndpoints). SecureChannel secures the transport. Session manages user authentication. View covers Address Space navigation (Browse, TranslateBrowsePathsToNodeIds). Attribute handles Read and Write of values and metadata. MonitoredItem and Subscription implement the change-notification mechanism (items grouped in subscriptions that publish periodically). Method exposes RPC-style calls. NodeManagement allows dynamic creation and deletion of nodes. Query supports filtered server-side queries on the Address Space.
Q04
OPC UA separates Application authentication (the client/server X.509 certificate) from User authentication (the actual end-user login), which can be Anonymous, Username/Password, or User Certificate.TrueFalse4. Security· User-Authentifizierung· MediumCorrect answerTrueLearning tipOPC UA security is layered on two axes. Application authentication answers "which software is connecting" via the X.509 Application Instance Certificate. User authentication answers "which human or service is operating that software" and is carried through the Session: it can be Anonymous, Username + Password, an X.509 user certificate, or a Kerberos/IssuedToken. This lets a single client application be used by ten different operators with different rights, and lets the server grant Anonymous read-only access while requiring Username/Password for write or Method calls.
Q05
UaExpert (Unified Automation) is the reference free OPC UA client for Windows, Linux and macOS: it browses the Address Space, reads and writes values, subscribes to changes, calls Methods and manages certificates, and is an indispensable tool for any OPC UA integrator.TrueFalse7. Tools· UaExpert· MediumCorrect answerTrueLearning tipUaExpert covers the full feature set an integrator needs day to day. It exposes the Address Space as a tree, offers type-aware Read/Write panels, plots subscribed values on real-time graphs, lets you call Methods through auto-generated input forms, and manages the trust and rejected certificate folders directly from the UI. Plug-ins extend it with a Performance Analyzer, a History Trend View and a Data Logger. It is free for commercial use and is downloaded from unified-automation.com. Common competitors are the Prosys OPC UA Browser, the OPC UA Foundation Sample Client and the Prosys OPC UA Modeler.
Q06
node-opcua is the most popular Node.js (JavaScript) OPC UA implementation, used for fast prototyping, audit scripts and Web/MQTT/REST-to-OPC-UA integrations, and it is embedded in Node-RED and in many IoT projects.TrueFalse7. Tools· node-opcua· MediumCorrect answerTrueLearning tipnode-opcua benefits from the native async model of Node.js, which keeps scripts short and responsive even when polling many servers in parallel. It is distributed as an NPM package, comes with extensive client and server examples, and delivers enough performance for 1 000 to 10 000 monitored items. In Python the competition is python-opcua / FreeOpcUa (deprecated) versus asyncua (the modern continuation), but the combination of Node.js with Node-RED remains one of the most productive IIoT prototyping environments available today.
Q07
Siemens S7-1500 (and S7-1200 V4.5+) PLCs embed a native OPC UA server that can be configured directly from TIA Portal: expose or restrict variables, set Security Mode and Policy, manage certificates, all without any additional hardware.TrueFalse11. Vendor implementations· Siemens TIA OPC UA· MediumCorrect answerTrueLearning tipThe TIA Portal workflow for OPC UA on an S7-1500 is straightforward. In CPU properties, the OPC UA section enables the server. The integrator then picks the endpoint Security Mode (None, Sign, SignAndEncrypt), imports or generates the CPU certificates, configures user authentication (Anonymous, Username/Password), and finally maps PLC tags to OPC UA nodes using a UserDefined Type in a custom namespace. After compile and download, a MES such as Inductive Ignition or Siemens WinCC can read PLC values directly through OPC UA, with no custom driver in between.
Q08
Ignition (Inductive Automation) is a modern SCADA/MES platform built around native OPC UA: it ships one integrated OPC UA Server plus drivers for 60+ protocols (BACnet, Modbus, KNX via gateway, Siemens S7, etc.), a web-based HMI and an MQTT IIoT Pub/Sub engine.TrueFalse11. Vendor implementations· Ignition (Inductive Automation)· MediumCorrect answerTrueLearning tipIgnition is structured around three components. The Gateway is a Java application that hosts the OPC UA Server and the protocol drivers. The Designer is a visual HMI builder. The runtime front-ends are Vision (legacy Java desktop client) and Perspective (modern responsive web and mobile client). An MQTT Engine module implements the Sparkplug B Pub/Sub specification for IIoT. The commercial model licences per module rather than per tag, which is a major difference from legacy SCADAs such as Wonderware: unlimited tags at no extra cost is a strong driver of the platform's fast growth since 2020.
Q09
OPC UA is codified by the IEC 62541 standard, divided into several parts (Part 1 Overview, Part 3 Address Space, Part 4 Services, Part 5 Information Model, Part 6 Mappings, Part 7 Profiles, etc.), and maintained jointly by the OPC Foundation and the IEC TC65 committee.TrueFalse14. Standards· IEC 62541· MediumCorrect answerTrueLearning tipIEC 62541 is the official multi-part standard for OPC UA. Part 1 covers Overview and Concepts. Part 3 specifies the Address Space Model. Part 4 defines the Services. Part 5 specifies the Information Model. Part 6 describes the Mappings (transport and encoding). Part 7 lists the Profiles used for conformity testing. Part 8 deals with Data Access, and Parts 9-14 address specific domains. Preview versions of the parts are available on the OPC Foundation site at no cost, while the official IEC publications are paid (the full set is on the order of EUR 3 000).