# DL205 Modbus Simulator

Wraps the `dl205.json` pymodbus profile as a standalone launcher and as an xUnit managed lifecycle.

## Manual launch

```powershell
pwsh tests/sim/run-dl205-sim.ps1 -Port 5020
```

On first run the script creates a Python venv at `tests/sim/.venv` and installs:

```
pymodbus==3.13.0
aiohttp
```

(`pymodbus 3.13.0` does not provide a `[server]` extra; the simulator is included in
the base package. `aiohttp` is required by the simulator's HTTP console.)

Re-runs detect the existing venv and skip provisioning (fast path, < 2 s to first packet).

Ctrl-C exits cleanly. The venv directory is gitignored.

## Requirements

- Python 3.10+ on `PATH` (tested with 3.13). The script also tries the Windows `py` launcher.
- Network access for first-run venv provisioning. Subsequent runs are fully offline.

## Parameters

| Parameter  | Default                        | Description                        |
|------------|--------------------------------|------------------------------------|
| `-Profile` | `dl205.json`                   | pymodbus JSON device profile       |
| `-Port`    | `5020`                         | TCP port the Modbus server binds   |

## xUnit integration

Test classes that need a live simulator declare:

```csharp
[Collection(nameof(DL205SimulatorCollection))]
```

The `DL205SimulatorFixture` (in `tests/Mbproxy.Tests/Sim/`) spawns `run-dl205-sim.ps1` via `pwsh -NoProfile -File`, polls for a TCP connection within 10 s, and exposes `Host`, `Port`, and `LogTail`. If Python is unavailable, `SkipReason` is populated and every test in the collection skips cleanly rather than failing.

## Version pin

`pymodbus[server]==3.13.0` — update this README and `run-dl205-sim.ps1` together when re-pinning.