Drag-Drop SLD Data Visualizer

### Core Architecture
- **Frontend (Desktop or Web)**
- **Drag‑and‑Drop Canvas**: Users place electrical components (breakers, transformers, meters, etc.) on an SLD canvas.
- **Data Binding**: Each component can be linked to a data source (RS485 register or TCP/IP stream).
- **Visualization**: Real‑time values (voltage, current, power, status) displayed as overlays, gauges, or color changes.

- **Backend**
- **Communication Layer**:
- RS485 → handled via USB‑RS485 converter + Python libraries (`pyserial`, `minimalmodbus`).
- TCP/IP → handled via sockets or REST/MQTT depending on the server.
- **Data Normalization**: Convert raw Modbus/TCP data into a unified JSON structure.
- **Database (optional)**: Time‑series storage (InfluxDB, TimescaleDB) for historical trends.

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### Technology Options
| Platform | Frameworks | Notes |
|----------|------------|-------|
| **Desktop** | Python + PyQt / Tkinter | Easier hardware integration, standalone executable |
| **Web** | React.js + D3.js / SVG | Rich drag‑and‑drop UI, scalable, accessible remotely |
| **Hybrid** | Electron.js + Node.js | Web‑like UI packaged as desktop app |

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### Data Flow Example
1. RS485 device → USB converter → `pyserial` reads Modbus registers.
2. TCP/IP server → Socket connection → JSON payloads.
3. Backend normalizes → Publishes via WebSocket/MQTT.
4. Frontend subscribes → Updates SLD components in real time.

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### Implementation Steps
1. **Define SLD component library** (symbols for breakers, meters, transformers).
2. **Build drag‑and‑drop canvas** (React DnD or PyQt GraphicsView).
3. **Integrate RS485/TCP drivers** for live data acquisition.
4. **Bind components to data points** (mapping UI element → Modbus register/IP tag).
5. **Add visualization logic** (color changes, alarms, tooltips).
6. **Optional**: Historical logging + dashboards.

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