pymodbus-dev / pymodbus

A full modbus protocol written in python
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modbus modbus-library modbus-master modbus-protocol modbus-rtu modbus-serial modbus-slave modbus-tcp python

PyModbus - A Python Modbus Stack

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Pymodbus is a full Modbus protocol implementation offering client/server with synchronous/asynchronous API a well as simulators.

Current release is 3.6.9 <https://github.com/pymodbus-dev/pymodbus/releases/tag/v3.6.9>_.

Bleeding edge (not released) is dev <https://github.com/pymodbus-dev/pymodbus/tree/dev>_.

All changes are described in release notes <https://pymodbus.readthedocs.io/en/latest/source/changelog.html>_ and all API changes are documented <https://pymodbus.readthedocs.io/en/latest/source/api_changes.html>_

A big thanks to all the volunteers <https://pymodbus.readthedocs.io/en/latest/source/authors.html>_ that helps make pymodbus a great project.

Source code on github <https://github.com/pymodbus-dev/pymodbus>_

Pymodbus in a nutshell

Pymodbus consist of 5 parts:

Common features ^^^^^^^^^^^^^^^

The modbus protocol specification: Modbus_Application_Protocol_V11b3.pdf can be found on modbus org <https://modbus.org>

Client Features ^^^^^^^^^^^^^^^

Client documentation <https://pymodbus.readthedocs.io/en/latest/source/client.html>_

Server Features ^^^^^^^^^^^^^^^

Server documentation <https://pymodbus.readthedocs.io/en/latest/source/library/server.html>_

REPL Features ^^^^^^^^^^^^^

REPL documentation <https://github.com/pymodbus-dev/repl>_

Simulator Features ^^^^^^^^^^^^^^^^^^

Simulator documentation <https://pymodbus.readthedocs.io/en/dev/source/simulator.html>_

Use Cases

The client is the most typically used. It is embedded into applications, where it abstract the modbus protocol from the application by providing an easy to use API. The client is integrated into some well known projects like home-assistant <https://www.home-assistant.io>_.

Although most system administrators will find little need for a Modbus server, the server is handy to verify the functionality of an application.

The simulator and/or server is often used to simulate real life devices testing applications. The server is excellent to perform high volume testing (e.g. houndreds of devices connected to the application). The advantage of the server is that it runs not only a "normal" computers but also on small ones like Raspberry PI.

Since the library is written in python, it allows for easy scripting and/or integration into their existing solutions.

For more information please browse the project documentation:

https://readthedocs.org/docs/pymodbus/en/latest/index.html

Install

The library is available on pypi.org and github.com to install with

Be aware that there are a number of project, who have forked pymodbus and

The latter is not because we rejected the extra functionality (we welcome all changes), but because the codeowners made that decision.

In both cases, please understand, we cannot offer support to users of these projects as we do not known what have been changed nor what status the forked code have.

A growing number of Linux distributions include pymodbus in their standard installation.

You need to have python3 installed, preferable 3.11.

Install with pip ^^^^^^^^^^^^^^^^ You can install using pip by issuing the following commands in a terminal window::

pip install pymodbus

If you want to use the serial interface::

pip install pymodbus[serial]

This will install pymodbus with the pyserial dependency.

Pymodbus offers a number of extra options:

which can be installed as::

pip install pymodbus[

It is possible to install old releases if needed::

pip install pymodbus==3.5.4

Install with github ^^^^^^^^^^^^^^^^^^^ On github, fork https://github.com/pymodbus-dev/pymodbus.git

Clone the source, and make a virtual environment::

git clone git://github.com//pymodbus.git cd pymodbus python3 -m venv .venv

Activate the virtual environment, this command needs repeated in every new terminal::

source .venv/bin/activate

To get a specific release::

git checkout v3.5.2

or the bleeding edge::

git checkout dev

Some distributions have an old pip, which needs to be upgraded:

pip install --upgrade pip

Install required development tools::

pip install ".[development]"

Install all (allows creation of documentation etc):

pip install ".[all]"

Install git hooks, that helps control the commit and avoid errors when submitting a Pull Request:

cp githooks/* .git/hooks

This installs dependencies in your virtual environment with pointers directly to the pymodbus directory, so any change you make is immediately available as if installed.

The repository contains a number of important branches and tags.

Example Code

For those of you that just want to get started fast, here you go::

from pymodbus.client import ModbusTcpClient

client = ModbusTcpClient('MyDevice.lan')
client.connect()
client.write_coil(1, True)
result = client.read_coils(1,1)
print(result.bits[0])
client.close()

We provide a couple of simple ready to go clients:

For more advanced examples, check out Examples <https://pymodbus.readthedocs.io/en/dev/source/examples.html>_ included in the repository. If you have created any utilities that meet a specific need, feel free to submit them so others can benefit.

Also, if you have a question, please create a post in discussions q&a topic <https://github.com/pymodbus-dev/pymodbus/discussions/new?category=q-a>_, so that others can benefit from the results.

If you think, that something in the code is broken/not running well, please open an issue <https://github.com/pymodbus-dev/pymodbus/issues/new>_, read the Template-text first and then post your issue with your setup information.

Example documentation <https://pymodbus.readthedocs.io/en/dev/source/examples.html>_

Contributing

Just fork the repo and raise your Pull Request against :code:dev branch.

We always have more work than time, so feel free to open a discussion / issue on a theme you want to solve.

If your company would like your device tested or have a cloud based device simulation, feel free to contact us. We are happy to help your company solve your modbus challenges.

That said, the current work mainly involves polishing the library and solving issues:

There are 2 bigger projects ongoing:

Development instructions

The current code base is compatible with python >= 3.9.

Here are some of the common commands to perform a range of activities::

source .venv/bin/activate <-- Activate the virtual environment ./check_ci.sh <-- run the same checks as CI runs on a pull request.

Make a pull request::

git checkout dev <-- activate development branch git pull <-- update branch with newest changes git checkout -b feature <-- make new branch for pull request ... make source changes git commit <-- commit change to git git push <-- push to your account on github

on github open a pull request, check that CI turns green and then wait for review comments.

Test your changes::

cd test pytest

you can also do extended testing::

pytest --cov <-- Coverage html report in build/html pytest --profile <-- Call profile report in prof

Internals ^^^^^^^^^

There are no documentation of the architecture (help is welcome), but most classes and methods are documented:

Pymodbus internals <https://pymodbus.readthedocs.io/en/dev/source/internals.html>_

Generate documentation ^^^^^^^^^^^^^^^^^^^^^^

Remark Assumes that you have installed documentation tools:;

pip install ".[documentation]"

to build do::

cd doc ./build_html

The documentation is available in /build/html

Remark: this generates a new zip/tgz file of examples which are uploaded.

License Information

Released under the BSD License <https://github.com/pymodbus-dev/pymodbus/blob/dev/LICENSE>_