durand

================================================ Python Durand - CANopen Responder Device Library

CANopen library to implement responder nodes.

Backends:

• CAN interfaces via python-can_

.. header

Synopsis

• Pure python implementation
• Under MIT license (2021 Günther Jena)
• Source is hosted on GitHub.com_
• Tested on Python 3.7, 3.8, 3.9 and 3.10
• Unit tested with pytest_, coding style done with Black_, static type checked with mypy_, static code checked with Pylint_, documented with Sphinx_
• Supporting CiA301_ (EN 50325-4)

.. _pytest: https://docs.pytest.org/en/latest .. _Black: https://black.readthedocs.io/en/stable/ .. _mypy: http://mypy-lang.org/ .. _Pylint: https://www.pylint.org/ .. _Sphinx: http://www.sphinx-doc.org .. _GitHub.com: https://github.com/semiversus/python-durand .. _CiA301: http://can-cia.org/standardization/technical-documents

Feature List

• Object dictionary

  • provides callbacks for validation, update, download and read
  • supports records, arrays and variables

• EDS support

  • dynamically generation of EDS file
  • automatically provided via object 0x1021 ("Store EDS")

• up to 128 SDO servers

  • expetited, segmented and block transfer for up- and download
  • COB-IDs dynamically configurable
  • custom up- and download handlers supported

• up to 512 TPDOs and 512 RPDOs

  • dynamically configurable
  • transmission types: synchronous (acyclic and every nth sync) and event driven
  • inhibit time supported

• EMCY producer service

  • COB-ID dynamically configurable
  • inhibit time supported

• Heartbeat producer service

  • dynamically configurable

• NMT slave service

  • boot-up service
  • callback for state change provided

• SYNC consumer service

  • COB-ID dynamically configurable
  • callback for received sync provided

• CiA305 Layer Setting Service

  • fast scan supported
  • bitrate and node id configuring supported
  • identify remote responder supported

• CAN interface abstraction

  • python-can_ fully supported
  • automatic CAN id filtering by subscripted services

• Scheduling supporting threaded and async operation

TODO

• build object dictionary via reading an EDS file
• supporting MPDOs
• TIME consumer service
• Up- and download handler as io streams

Examples

Creating a node

.. code-block:: python

import can
from durand import CANBusNetwork, Node, Variable, Record, DatatypeEnum

bus = can.Bus(bustype='socketcan', channel='vcan0')
network = CANBusNetwork(bus)

node = Node(network, node_id=0x01)

Congratulations! You have a CiA-301 compliant node running. Layer Setting Service is also supported out of the box.

Adding objects

.. code-block:: python

od = node.object_dictionary

# add variable at index 0x2000
od[0x2000] = Variable(DatatypeEnum.UNSIGNED16, access='rw', value=10, name='Parameter 1')

# add record at index 0x2001
record = Record(name='Parameter Record')
record[1] = Variable(DatatypeEnum.UNSIGNED8, access='ro', value=0, name='Parameter 2a')
record[2] = Variable(DatatypeEnum.REAL32, access='rw', value=0, name='Parameter 2b')
od[0x2001] = record

Access values

The objects can be read and written directly by accessing the object dictionary:

.. code-block:: python

print(f'Value of Parameter 1: {od.read(0x2000, 0)}')
od.write(0x2001, 1, value=0xAA)

Add callbacks

A more event driven approach is using of callbacks. Following callbacks are available:

• validate_callbacks - called before a value in the object dictionary is going to be updated
• update_callbacks - called when the value has been changed (via od.write or via CAN bus)
• download_callbacks - called when the value has been changed via CAN bus
• read_callback - called when a object is read (return value is used )

.. code-block:: python

od.validate_callbacks[(0x2000, 0)].add(lambda v: v % 2 == 0)
od.update_callbacks[(0x2001, 2)].add(lambda v: print(f'Update for Parameter 2b: {v}'))
od.download_callbacks[(0x2000, 0)].add(lambda v: print(f'Download for Parmeter 1: {v}'))
od.set_read_callback(0x2001, 1, lambda: 17)

PDO mapping

PDOs can dynamically mapped via the SDO server or programmatically. The PDO indices start at 0.

.. code-block:: python

node.tpdo[0].mapping = [(0x2001, 1), (0x2001, 2)]
node.tpdo[0].transmission_type = 1  # transmit on every SYNC

node.rpdo[0].mapping = [(0x2000, 0)]
node.tpdo[0].transmission_type = 255  # event driven (processed when received)

Install

.. code-block:: bash

pip install durand

Credits

This library would not be possible without:

• python-canopen_: CANopen library (by Christian Sandberg)
• python-can_: CAN interface library (by Brian Thorne)

.. _python-canopen: https://github.com/christiansandberg/canopen .. _python-can: https://github.com/hardbyte/python-can