Modbus to MQTT Bridge Service

A Python service that reads temperature and humidity data from a Modbus TCP server and publishes the data to an MQTT broker.

📁 Project Structure

POE/
├── config.py           # Configuration constants
├── sensor_bridge.py    # Core logic for Modbus and MQTT operations
├── main.py            # Entry point
├── requirements.txt   # Python dependencies
├── README.md         # This file
├── poe.py            # Original single file (backup)
└── memory-bank/      # Memory bank directory

🚀 Quick Start

1. Install Dependencies

pip install -r requirements.txt

2. Configure Settings

Edit config.py to match your environment:

# Modbus configuration
MODBUS_HOST = "10.84.48.153"
MODBUS_PORT = 505

# MQTT configuration  
MQTT_BROKER = "mqtt.service.mesh"
MQTT_TOPIC = "Temperature_Humidity"

3. Run the Service

python main.py

📊 Features

• Modbus TCP Client: Reads data from Modbus holding registers
• MQTT Publisher: Publishes sensor data to MQTT broker
• Data Processing: Converts raw sensor values to calibrated readings
• Error Handling: Robust error handling and retry mechanisms
• Logging: Comprehensive logging for monitoring and debugging
• Health Check API: HTTP endpoints for system health monitoring
• Sensor Status Tracking: Real-time tracking of individual sensor health
• Alerting System: Automatic alerts for sensor failures and recovery
• Recovery Detection: Detects when failed sensors come back online

📈 Data Format

The service publishes JSON data to the MQTT topic:

{
  "time": "2024-01-15 10:30:25",
  "location": "Office",
  "temperature": 23.5,
  "humidity": 65.2
}

🔧 Configuration

All configuration is centralized in config.py:

Parameter	Description	Default
MODBUS_HOST	Modbus TCP server IP	"10.84.48.153"
MODBUS_PORT	Modbus TCP port	505
MQTT_BROKER	MQTT broker address	"mqtt.service.mesh"
MQTT_TOPIC	MQTT publish topic	"Temperature_Humidity"
PUBLISH_INTERVAL	Data publish interval (seconds)	10
LOCATION	Sensor location identifier	"Office"

📡 Sensor Mapping

• Register 0: Temperature (raw value × 0.1 - 40)
• Register 1: Humidity (raw value × 0.1)

🏥 Health Check & Monitoring

Health Check Endpoints

The service provides HTTP endpoints for monitoring:

• http://localhost:8080/health - Basic service health check
• http://localhost:8080/sensors - Detailed sensor status information

Alerting System

The system automatically sends MQTT alerts for:

• Sensor Failures: When a sensor fails 3 consecutive times
• Sensor Recovery: When a failed sensor comes back online

Alert topics:

• sensor-alerts - Failure and recovery alerts
• sensor-status/{location}/status - Individual sensor status updates

Demo Monitoring Script

Use the demo script to test monitoring features:

# Check health endpoint
python demo_monitoring.py health

# Check sensors status
python demo_monitoring.py sensors

# Monitor system for 5 minutes
python demo_monitoring.py monitor 300

Configuration Options

Parameter	Description	Default
HEALTH_CHECK_ENABLED	Enable/disable health check server	True
HEALTH_CHECK_PORT	HTTP server port	8080
ALERTING_ENABLED	Enable/disable MQTT alerts	True
SENSOR_TIMEOUT_THRESHOLD	Failures before alert	3
RECOVERY_CONFIRMATION_COUNT	Successes to confirm recovery	2

🛠️ Maintenance

Running as a Service

For production deployment, consider running as a system service:

# Example systemd service file
[Unit]
Description=Modbus MQTT Bridge
After=network.target

[Service]
Type=simple
User=pi
WorkingDirectory=/path/to/POE
ExecStart=/usr/bin/python3 main.py
Restart=always

[Install]
WantedBy=multi-user.target

Monitoring

The service provides comprehensive logging. Monitor the logs for:

• Connection status
• Data reading success/failure
• MQTT publish status
• Error conditions

🤝 Contributing

1. Fork the repository
2. Create a feature branch
3. Make your changes
4. Test thoroughly
5. Submit a pull request

📝 License

This project is licensed under the MIT License.