ModbusIM - Modbus Device Simulator

A Python package for simulating Modbus RTU/ASCII/TCP devices for testing and development purposes.

[](https://opensource.org/licenses/Apache 2.0 )

Features

• Simulate Modbus RTU/ASCII/TCP devices
• Support for all standard Modbus function codes
• Easy-to-use CLI interface
• Programmatic API for integration with tests
• Configurable device behavior
• Docker support for easy deployment

Installation

Using pip

pip install modbusim

Using Poetry (for development)

git clone https://github.com/yourusername/modbusim.git
cd modbusim
poetry install

Using Docker

# Build the image
docker build -t modbusim .

# Run the Modbus TCP simulator
docker run -p 5020:5020 modbusim

Or using Docker Compose:

docker-compose up -d

Usage

Command Line Interface

Start a Modbus RTU simulator:

modbusim rtu --port /tmp/ptyp0 --baudrate 9600

Start a Modbus TCP simulator:

modbusim tcp --host 0.0.0.0 --port 5020

Python API

from modbusim import ModbusSimulator

# Create a simulator instance
simulator = ModbusSimulator(
    mode="rtu",  # or "tcp"
    port="/tmp/ptyp0",  # or host="0.0.0.0" for TCP
    baudrate=9600
)

# Start the simulator
simulator.start()

try:
    # Your test code here
    while True:
        # Keep the simulator running
        pass
except KeyboardInterrupt:
    # Stop the simulator
    simulator.stop()

Development

Running Tests

make test

Linting and Formatting

make lint    # Run linters
make format  # Format code

Building and Publishing

make build    # Build the package
make publish  # Publish to PyPI

Docker Development

Build the development image

docker-compose -f docker-compose.dev.yml build

Run tests in Docker

docker-compose -f docker-compose.dev.yml run --rm modbusim make test

Start a development shell

docker-compose -f docker-compose.dev.yml run --rm --service-ports modbusim bash

License

Apache 2.0 - See LICENSE for more information.