https://github.com/advancedclimatesystems/umodbus

Python implementation of the Modbus protocol.
https://github.com/advancedclimatesystems/umodbus

hacktoberfest modbus python

Last synced: 11 months ago
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Python implementation of the Modbus protocol.

• Host: GitHub
• URL: https://github.com/advancedclimatesystems/umodbus
• Owner: AdvancedClimateSystems
• License: mpl-2.0
• Created: 2015-10-13T20:46:19.000Z (over 10 years ago)
• Default Branch: master
• Last Pushed: 2024-04-17T07:45:43.000Z (almost 2 years ago)
• Last Synced: 2025-05-10T01:05:05.684Z (11 months ago)
• Topics: hacktoberfest, modbus, python
• Language: Python
• Homepage:
• Size: 264 KB
• Stars: 222
• Watchers: 25
• Forks: 86
• Open Issues: 41
• Metadata Files:
  • Readme: README.rst
  • License: LICENSE

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README

          
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uModbus

=======

uModbus or (μModbus) is a pure Python implementation of the Modbus protocol as

described in the `MODBUS Application Protocol Specification V1.1b3`_. uModbus

implements both a Modbus client (both TCP and RTU) and a Modbus server (both

TCP and RTU). The "u" or "μ" in the name comes from the the SI prefix "micro-".

uModbus is very small and lightweight. The source can be found on GitHub_.

Documentation is available at `Read the Docs`_.

Quickstart

----------

Creating a Modbus TCP server is easy:

..

    Because GitHub doesn't support the include directive the source of

    scripts/examples/simple_tcp_server.py has been copied to this file.

.. code:: python

    #!/usr/bin/env python

    # scripts/examples/simple_tcp_server.py

    import logging

    from socketserver import TCPServer

    from collections import defaultdict

    from argparse import ArgumentParser

    from umodbus import conf

    from umodbus.server.tcp import RequestHandler, get_server

    from umodbus.utils import log_to_stream

    # Add stream handler to logger 'uModbus'.

    log_to_stream(level=logging.DEBUG)

    # A very simple data store which maps addresses against their values.

    data_store = defaultdict(int)

    # Enable values to be signed (default is False).

    conf.SIGNED_VALUES = True

    # Parse command line arguments

    parser = ArgumentParser()

    parser.add_argument("-b", "--bind", default="localhost:502")

    args = parser.parse_args()

    if ":" not in args.bind:

        args.bind += ":502"

    host, port = args.bind.rsplit(":", 1)

    port = int(port)

    TCPServer.allow_reuse_address = True

    try:

        app = get_server(TCPServer, (host, port), RequestHandler)

    except PermissionError:

        print("You don't have permission to bind on {}".format(args.bind))

        print("Hint: try with a different port (ex: --bind localhost:50200)")

        exit(1)

    @app.route(slave_ids=[1], function_codes=[1, 2], addresses=list(range(0, 10)))

    def read_data_store(slave_id, function_code, address):

        """" Return value of address. """

        return data_store[address]

    @app.route(slave_ids=[1], function_codes=[5, 15], addresses=list(range(0, 10)))

    def write_data_store(slave_id, function_code, address, value):

        """" Set value for address. """

        data_store[address] = value

    if __name__ == '__main__':

        try:

            app.serve_forever()

        finally:

            app.shutdown()

            app.server_close()

Doing a Modbus request requires even less code:

..

    Because GitHub doesn't support the include directive the source of

    scripts/examples/simple_data_store.py has been copied to this file.

.. code:: python

    #!/usr/bin/env python

    # scripts/examples/simple_tcp_client.py

    from argparse import ArgumentParser

    from socket import create_connection

    from umodbus import conf

    from umodbus.client import tcp

    # Enable values to be signed (default is False).

    conf.SIGNED_VALUES = True

    # Parse command line arguments

    parser = ArgumentParser()

    parser.add_argument("-a", "--address", default="localhost:502")

    args = parser.parse_args()

    if ":" not in args.address:

        args.address += ":502"

    host, port = args.address.rsplit(":", 1)

    port = int(port)

    # Returns a message or Application Data Unit (ADU) specific for doing

    # Modbus TCP/IP.

    message = tcp.write_multiple_coils(slave_id=1, starting_address=1, values=[1, 0, 1, 1])

    with create_connection((host, port)) as sock:

        # Response depends on Modbus function code. This particular returns the

        # amount of coils written, in this case it is.

        response = tcp.send_message(message, sock)

Features

--------

The following functions have been implemented for Modbus TCP and Modbus RTU:

* 01: Read Coils

* 02: Read Discrete Inputs

* 03: Read Holding Registers

* 04: Read Input Registers

* 05: Write Single Coil

* 06: Write Single Register

* 15: Write Multiple Coils

* 16: Write Multiple Registers

Other featues:

* Support for signed and unsigned register values.

License

-------

uModbus software is licensed under `Mozilla Public License`_. © 2018 `Advanced

Climate Systems`_.

.. External References:

.. _Advanced Climate Systems: http://www.advancedclimate.nl/

.. _GitHub: https://github.com/AdvancedClimateSystems/uModbus/

.. _MODBUS Application Protocol Specification V1.1b3: http://modbus.org/docs/Modbus_Application_Protocol_V1_1b3.pdf

.. _Mozilla Public License: https://github.com/AdvancedClimateSystems/uModbus/blob/develop/LICENSE

.. _Read the Docs: http://umodbus.readthedocs.org/en/latest/