Python Modbus Libraries Comparison: The Complete 2025 Guide

When working with industrial automation, IoT sensors, or PLC communication, the Modbus protocol remains one of the most widely used standards for device interoperability. Python, with its rich ecosystem and simplicity, has become a go-to language for building Modbus clients, servers, and gateways.

But with multiple Python Modbus libraries available — PyModbus, MinimalModbus, pyModbusTCP, Modbus-tk, and others — it can be confusing to choose the right one.

This guide provides a comprehensive comparison of Python Modbus libraries to help you select the best fit for your project, whether you’re building a small data logger or a large-scale SCADA system.

What Is Modbus and Why Use It with Python?

Modbus is a master–slave (or client–server) communication protocol originally developed in 1979 by Modicon (now Schneider Electric). It’s commonly used for communication between:

• PLCs (Programmable Logic Controllers)
• RTUs (Remote Terminal Units)
• Sensors and meters
• SCADA systems

Why Python?

Python is popular in industrial automation for its:

• Rapid prototyping and readability
• Cross-platform deployment (Windows, Linux, Raspberry Pi)
• Integration with analytics, visualization, and IoT platforms
• Mature Modbus libraries with both TCP and serial (RTU/ASCII) support

Top Python Modbus Libraries

Here are the most popular and actively maintained libraries as of 2025:

Library	Protocols	Async Support	License	Use Case
PyModbus	RTU, TCP, UDP	Yes (asyncio)	BSD	Full-featured client & server applications
MinimalModbus	RTU, ASCII	No	MIT	Lightweight, simple serial clients
pyModbusTCP	TCP only	Partial (threaded)	MIT	Pure TCP client/server
Modbus-tk	RTU, TCP	No	LGPL	Educational and synchronous systems
uModbus	TCP, RTU	Yes (asyncio)	MIT	Async-friendly lightweight Modbus library

1. PyModbus

PyModbus is the most widely used and feature-rich Modbus library in Python. It supports Modbus RTU, ASCII, TCP, and UDP, and can function as both client and server.

Pros

• Active community and documentation
• Full client/server and sync/async API
• Works on Windows, Linux, and embedded systems
• Supports custom function codes

Cons

• Heavier dependency footprint
• Slower for ultra-lightweight devices

Best For: Industrial-grade applications, gateways, and complex Modbus topologies.

Install:

pip install pymodbus

2. MinimalModbus

MinimalModbus is a lightweight library for communicating with Modbus RTU/ASCII devices via serial ports. It focuses on simplicity and reliability.

Pros

• Very easy to use
• Minimal dependencies
• Great for Raspberry Pi and embedded projects

Cons

• No TCP support
• No async or server-side capabilities

Best For: Simple one-device serial communication projects.

Install:

pip install minimalmodbus

3. pyModbusTCP

As the name suggests, pyModbusTCP handles only the Modbus TCP protocol. It’s ideal for Ethernet-based industrial devices and test servers.

Pros

• Lightweight TCP implementation
• Simple server and client modes
• Thread-safe architecture

Cons

• TCP only (no RTU/ASCII)
• Not ideal for embedded serial projects

Best For: Ethernet-based systems or test simulators.

Install:

pip install pyModbusTCP

4. Modbus-tk

Modbus-tk is an older but still useful synchronous Modbus library supporting RTU, ASCII, and TCP. It’s educational and easy to extend.

Pros

• Simple synchronous API
• Multi-protocol support
• Easy debugging and logging

Cons

• No async support
• Slower than PyModbus for large systems

Best For: Educational or small-scale synchronous setups.

Install:

pip install modbus-tk

5. uModbus

uModbus is a lightweight and asynchronous Modbus client/server library built for speed and scalability, supporting both TCP and RTU.

Pros

• Asyncio-friendly
• Minimal overhead
• Modern Python design

Cons

• Smaller community than PyModbus
• Limited advanced examples

Best For: Modern async-based IoT or SCADA projects.

Install:

pip install uModbus

Feature-by-Feature Comparison

Feature	PyModbus	MinimalModbus	pyModbusTCP	Modbus-tk	uModbus
RTU Support	Yes	Yes	No	Yes	Yes
TCP Support	Yes	No	Yes	Yes	Yes
Async Support	Yes	No	Partial	No	Yes
Client Mode	Yes	Yes	Yes	Yes	Yes
Server Mode	Yes	No	Yes	Yes	Yes
Documentation	⭐⭐⭐⭐	⭐⭐⭐	⭐⭐⭐	⭐⭐	⭐⭐
Performance	⭐⭐⭐⭐	⭐⭐⭐⭐	⭐⭐⭐⭐	⭐⭐	⭐⭐⭐⭐
Ease of Use	⭐⭐	⭐⭐⭐⭐	⭐⭐⭐	⭐⭐⭐	⭐⭐⭐⭐

Choosing the Right Library for Your Project

Use Case	Recommended Library
Beginner, single serial device	MinimalModbus
Multi-slave network or async TCP	PyModbus
Ethernet-based test server	pyModbusTCP
Educational or lab environments	Modbus-tk
Asyncio SCADA integration	uModbus

Example: Reading a Modbus Register Using PyModbus

from pymodbus.client import ModbusTcpClient

client = ModbusTcpClient('192.168.1.100', port=502)
client.connect()

result = client.read_holding_registers(100, 2, unit=1)
print(result.registers)

client.close()

This snippet connects to a Modbus TCP device and reads two registers starting at address 100.

Conclusion

All Python Modbus libraries serve different purposes:

• PyModbus → Industrial-grade, async-capable, multi-protocol.
• MinimalModbus → Lightweight and beginner-friendly for serial RTU.
• pyModbusTCP → Simple, TCP-only applications.
• Modbus-tk → Educational and synchronous scenarios.
• uModbus → Modern, async, lightweight IoT integrations.

Choosing the right library depends on your device communication type (TCP vs RTU), project scale, and async needs.

Key Takeaways

• Python has robust support for Modbus across several libraries.
• PyModbus remains the most comprehensive and actively maintained option.
• For lightweight serial use, MinimalModbus is ideal.
• Asyncio-based applications benefit most from uModbus.
• Always consider protocol type (RTU or TCP) before selecting a library.