Modbus TCP/IP Device Data-logging to MySQL Database using Python

Modbus TCP/IP to MySQL Datalogger

This project logs Modbus TCP/IP device data into a MySQL database for historical storage and analysis. It uses pymodbus for Modbus communication and mysql-connector-python for MySQL operations.

Features

• Reads Modbus holding registers (default configuration)
• Per-address reading for flexibility (supports non-consecutive addresses)
• Logs only when values change
• Batch logging: all changed values in a cycle are inserted in one query for performance
• Each register/address is logged with timestamp, type, address, and value
• Configurable update interval
• Supports reading from a specific Modbus slave ID (see MODBUS_SLAVE_ID in config)
• Easy configuration via src/config.py

Project Structure

modbus-mysql-datalogger-01092025
├── src
│   ├── main.py               # Main application logic
│   ├── modbus_client.py      # Modbus TCP client wrapper
│   ├── mysql_logger.py       # MySQL logger for Modbus data
│   └── config.py             # User configuration for Modbus/database/interval
├── requirements.txt          # Python dependencies
├── README.md                 # Project documentation

Library Version Details

Installation

1. Clone the repository:

   git clone <repository-url>
   cd modbus-mysql-datalogger-01092025
   

2. Install dependencies:

   pip install -r requirements.txt
   

Configuration

Edit src/config.py to set:

• Modbus server IP and port
• MySQL database connection details
• Modbus slave ID (MODBUS_SLAVE_ID) to target a specific device
• Register types and addresses to read (currently only holding registers enabled)
• Update interval (in seconds)

Example (src/config.py):

MYSQL_DB_CONFIG = {
    'host': '127.0.0.1',
    'user': 'root',
    'password': 'toor',
    'database': 'test'
}
MODBUS_SERVER = '127.0.0.1'
MODBUS_PORT = 502
MODBUS_SLAVE_ID = 1  # Modbus slave ID to read from
MODBUS_READ_CONFIG = {
    "holding_registers": {
        "addresses": [0, 1, 2, 5, 6, 7]
    }
}
UPDATE_INTERVAL = 5  # seconds

To enable other data types (coils, discrete inputs, input registers), uncomment and configure them in MODBUS_READ_CONFIG.

Usage

Start the datalogger:

python src/main.py

• The app reads configured Modbus addresses at the set interval from the specified slave ID.
• Only changed values are logged to the MySQL database, using batch logging for efficiency.
• Each value is stored with timestamp, type, address, and value.

Testing

• Ensure your Modbus server is running and accessible.
• Use any MySQL client or tool to inspect the modbus_data table in the test database.
• Change Modbus register values to see new rows logged in the database.

Advanced

• Supports all Modbus data types (add to MODBUS_READ_CONFIG as needed).
• Easily extend for batch reads, custom logging, or data export.