OPC UA in action: the SLX GridPilot industrial digital twin

Description and use

GridPilot showcases a complete OPC UA command‑to‑feedback loop in a simulated hydro plant, enabling users to validate data models, monitor quality, and handle faults within a single desktop application.

Problem

Industrial automation requires a clear link between OPC UA commands and observable plant behavior, but many systems lack a demonstrator that shows this end‑to‑end flow.

Outcome

GridPilot demonstrates a complete OPC UA command‑to‑feedback loop in a simulated hydro plant, enabling users to validate information models, monitor quality, inject faults, and observe recovery—all within a single desktop application.

Workflow

• 1. Start OPC UA Studio and connect to three local servers (127.0.0.1:4840‑4842).
• 2. Browse the server namespace (urn:siliconlogix:gridpilot:v1) and inspect node types, quality, timestamps, and engineering units.
• 3. Use the guided tour to request power via SetPower(1.2) on U1, observe the queued response, and monitor LastCommand, power, state, and actuator positions.
• 4. Stop the unit with Stop() and confirm zero speed and closed flow‑control devices through subscriptions.
• 5. Inject a sensor fault or communication loss to trigger OffNormalAlarmType conditions, acknowledge the alarm, and restore normal operation.
• 6. Use watchlists and Snapshot variables to view coherent plant state, source timestamps, and simulated time.
• 7. Export browsed instances as NodeSet2 XML, JSON, or CSV for documentation.
• 8. Replay recorded sequences in the Workbench to compare behavior and generate CSV exports.

Evidence

OPC UA becomes easier to understand when a command produces an observable response.

Source

Requesting power does not mean that power has already been delivered. Calling SetPower(1.2) on U1's endpoint requests 1.2 MW of generation.

Source

The servers expose standard OPC UA OffNormalAlarmType conditions with severity, message, active state and acknowledgement.

Source