# Test Infrastructure: OPC UA Server

## Overview

The test OPC UA server uses [Azure IoT OPC PLC](https://github.com/Azure-Samples/iot-edge-opc-plc), a simulated OPC UA server that generates realistic data. It is configured with custom nodes that match ScadaLink attribute patterns.

## Image & Ports

- **Image**: `mcr.microsoft.com/iotedge/opc-plc:latest`
- **OPC UA endpoint**: `opc.tcp://localhost:50000`
- **Web/config UI**: `http://localhost:8080`

## Startup Flags

```
--autoaccept            Accept all client certificates
--unsecuretransport     Enable plain (non-TLS) OPC UA connections for dev tools
--sph                   Show PLC heartbeat on console
--sn=5 --sr=10 --st=uint   5 slow-changing nodes (10s cycle, uint)
--fn=5 --fr=1 --ft=uint    5 fast-changing nodes (1s cycle, uint)
--gn=5                      5 stepping nodes
--nf=/app/config/nodes.json Custom node definitions
--pn=50000                  Listen port
```

## Custom Nodes

The file `infra/opcua/nodes.json` defines a single `ConfigFolder` object (not an array) with a root "ScadaLink" folder containing four equipment subfolders. Tags match typical ScadaLink instance attribute patterns:

| Folder | Tags | Types |
|--------|------|-------|
| Motor | Speed, Temperature, Current, Running, FaultCode | Double, Boolean, UInt32 |
| Pump | FlowRate, Pressure, Running | Double, Boolean |
| Tank | Level, Temperature, HighLevel, LowLevel | Double, Boolean |
| Valve | Position, Command | Double, UInt32 |

All custom nodes hold their initial/default values (0 for numerics, false for booleans) until written. OPC PLC's custom node format does not support random value generation for these nodes.

Custom nodes live in namespace 3 (`http://microsoft.com/Opc/OpcPlc/`). Node IDs follow the pattern `ns=3;s=<Folder>.<Tag>` (e.g., `ns=3;s=Motor.Speed`).

The browse path from the Objects root is: `OpcPlc > ScadaLink > Motor|Pump|Tank|Valve`.

## Verification

1. Check the container is running:

```bash
docker ps --filter name=scadalink-opcua
```

2. Verify the OPC UA endpoint using any OPC UA client (e.g., UaExpert, opcua-commander):

```bash
# Using opcua-commander (npm install -g opcua-commander)
opcua-commander -e opc.tcp://localhost:50000
```

3. Check the web UI at `http://localhost:8080` for server status and node listing.

## CLI Tool

The `infra/tools/opcua_tool.py` script provides a convenient CLI for interacting with the OPC UA server.

**Install dependencies** (one-time):
```bash
pip install -r infra/tools/requirements.txt
```

**Commands**:

```bash
# Check server status, namespaces, and endpoints
python infra/tools/opcua_tool.py check

# Browse the Objects folder (top-level)
python infra/tools/opcua_tool.py browse

# Browse a specific equipment folder
python infra/tools/opcua_tool.py browse --path "3:OpcPlc.3:ScadaLink.3:Motor"

# Read a tag value
python infra/tools/opcua_tool.py read --node "ns=3;s=Motor.Speed"

# Write a value to a tag
python infra/tools/opcua_tool.py write --node "ns=3;s=Motor.Running" --value true --type Boolean

# Monitor value changes for 15 seconds
python infra/tools/opcua_tool.py monitor --nodes "ns=3;s=Motor.Speed,ns=3;s=Pump.FlowRate" --duration 15
```

Use `--endpoint` to override the default endpoint (`opc.tcp://localhost:50000`). Run with `--help` for full usage.

## Relevance to ScadaLink Components

- **Data Connection Layer** — connect to this server to test OPC UA subscription, read/write, and reconnection behavior.
- **Site Runtime / Instance Actors** — deploy instances with tag mappings pointing at these nodes.
- **Template Engine** — design templates with attributes matching the Motor/Pump/Tank/Valve folder structure.