ottowayi / pycomm3

A Python Ethernet/IP library for communicating with Allen-Bradley PLCs.
MIT License
407 stars 89 forks source link
allen-bradley cip eip ethernet-ip hmi industrial-automation industrial-controllers plc programmable-logic-controller protocol python python3 rockwell rslinx scada

======= pycomm3

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Introduction

pycomm3 started as a Python 3 fork of pycomm, which is a Python 2 library for communicating with Allen-Bradley PLCs using Ethernet/IP. The initial Python 3 port was done in this fork and was used as the base for pycomm3. Since then, the library has been almost entirely rewritten and the API is no longer compatible with pycomm. Without the hard work done by the original pycomm developers, pycomm3 would not exist. This library seeks to expand upon their great work.

.. _pycomm: https://github.com/ruscito/pycomm

.. _fork: https://github.com/bpaterni/pycomm/tree/pycomm3

Drivers

pycomm3 includes 3 drivers:

.. _CIPDriver: https://docs.pycomm3.dev/en/latest/usage/cipdriver.html

.. _LogixDriver: https://docs.pycomm3.dev/en/latest/usage/logixdriver.html

.. _SLCDriver: https://docs.pycomm3.dev/en/latest/usage/slcdriver.html

Disclaimer

PLCs can be used to control heavy or dangerous equipment, this library is provided "as is" and makes no guarantees on its reliability in a production environment. This library makes no promises in the completeness or correctness of the protocol implementations and should not be solely relied upon for critical systems. The development for this library is aimed at providing quick and convenient access for reading/writing data inside Allen-Bradley PLCs.

Setup

The package can be installed from PyPI_ using pip: pip install pycomm3 or python -m pip install pycomm3.

.. _PyPI: https://pypi.org/project/pycomm3/

Optionally, you may configure logging using the Python standard logging library. A convenience method is provided to help configure basic logging, see the Logging Section in the docs for more information.

.. _logging: https://docs.python.org/3/library/logging.html

.. _Logging Section: https://docs.pycomm3.dev/en/latest/getting_started.html#logging

Python and OS Support

pycomm3 is a Python 3-only library and is supported on Python versions from 3.6.1 up to 3.10. There should be no OS-specific requirements and should be able to run on any OS that Python is supported on. Development and testing is done primarily on Windows 10. If you encounter an OS-related problem, please open an issue in the GitHub repository_ and it will be investigated.

.. attention::

Python 3.6.0 is not supported due to ``NamedTuple`` not supporting
`default values and methods <https://docs.python.org/3/library/typing.html#typing.NamedTuple>`_ until 3.6.1

.. _GitHub repository: https://github.com/ottowayi/pycomm3

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Documentation

This README covers a basic overview of the library, full documentation can be found on Read the Docs or by visiting https://pycomm3.dev <https://pycomm3.dev>.

.. _Read the Docs: https://pycomm3.readthedocs.io/en/latest/

Contributions

If you'd like to contribute or are having an issue, please read the Contributing_ guidelines.

.. _Contributing: CONTRIBUTING.md

Highlighted Features

LogixDriver

LogixDriver Overview

Creating a driver is simple, only a path argument is required. The path can be the IP address, IP and slot, or a full CIP route, refer to the documentation for more details. The example below shows how to create a simple driver and print some of the information collected about the device.

::

from pycomm3 import LogixDriver

with LogixDriver('10.20.30.100/1') as plc:
    print(plc)
    # OUTPUT:
    # Program Name: PLCA, Device: 1756-L83E/B, Revision: 28.13

    print(plc.info)
    # OUTPUT:
    # {'vendor': 'Rockwell Automation/Allen-Bradley', 'product_type': 'Programmable Logic Controller',
    #  'product_code': 166, 'version_major': 28, 'version_minor': 13, 'revision': '28.13', 'serial': 'FFFFFFFF',
    #  'device_type': '1756-L83E/B', 'keyswitch': 'REMOTE RUN', 'name': 'PLCA'}

Reading/Writing Tags

Reading or writing tags is as simple as calling the read and write methods. Both methods accept any number of tags, and will automatically pack multiple tags into a Multiple Service Packet Service (0x0A) while making sure to stay below the connection size. If there is a tag value that cannot fit within the request/reply packet, it will automatically handle that tag independently using the Read Tag Fragmented (0x52) or Write Tag Fragmented (0x53) requests.

Both methods will return Tag objects to reflect the success or failure of the operation.

::

class Tag(NamedTuple):
    tag: str  # the name of the tag, does not include ``{<# elements>}`` from request
    value: Any  # value read or written, may be ``None`` if an error occurred
    type: Optional[str] = None  # data type of tag, including ``[<# elements>]`` from request
    error: Optional[str] = None  # ``None`` if successful, else the CIP error or exception thrown

Tag objects are considered successful (truthy) if the value is not None and the error is None.

Examples::

with LogixDriver('10.20.30.100') as plc:
    plc.read('tag1', 'tag2', 'tag3')  # read multiple tags
    plc.read('array{10}') # read 10 elements starting at 0 from an array
    plc.read('array[5]{20}) # read 20 elements starting at elements 5 from an array
    plc.read('string_tag')  # read a string tag and get a string
    plc.read('a_udt_tag') # the response .value will be a dict like: {'attr1`: 1, 'attr2': 'a string', ...}

    # writes require a sequence of tuples of [(tag name, value), ... ]
    plc.write('tag1', 0)  # single writes do not need to be passed as a tuple
    plc.write(('tag1', 0), ('tag2', 1), ('tag3', 2))  # write multiple tags
    plc.write(('array{5}', [1, 2, 3, 4, 5]))  # write 5 elements to an array starting at the 0 element
    plc.write('array[10]{5}', [1, 2, 3, 4, 5])  # write 5 elements to an array starting at element 10
    plc.write('string_tag', 'Hello World!')  # write to a string tag with a string
    plc.write('string_array[2]{5}', 'Write an array of strings'.split())  # write an array of 5 strings starting at element 2
    plc.write('a_udt_tag', {'attr1': 1, 'attr2': 'a string', ...})  # can also use a dict to write a struct

    # Check the results
    results = plc.read('tag1', 'tag2', 'tag3')
    if all(results):
        print('They all worked!')
    else:
        for result in results:
            if not result:
                print(f'Reading tag {result.tag} failed with error: {result.error}')

.. Note::

Tag names for both ``read`` and ``write`` are case-sensitive and are required to be the same as they are named in
the controller.  This may change in the future.

Unit Testing

pytest is used for unit testing. The tests directory contains an L5X export of the testing program that contains all tags necessary for testing. The only requirement for testing (besides a running PLC with the testing program) is the environment variable PLCPATH for the PLC defined.

User Tests

These tests are for users to run. There are a few tests that are specific to a demo plc, those are excluded. To run them you have the following options:

with tox:

- modify the ``PLCPATH`` variable in ``tox.ini``
- then run this command: ``tox -e user``

or with pytest:

.. code-block::

set PLCPATH=192.168.1.100
pytest --ignore tests/online/test_demo_plc.py

(or the equivalent in your shell)

.. Note:: Test coverage is not complete, pull requests are welcome to help improve coverage.

License

pycomm3 is distributed under the MIT License