README.rst

CANopen for Python, asyncio port

A Python implementation of the CANopen standard. The aim of the project is to support the most common parts of the CiA 301 standard in a simple Pythonic interface. It is mainly targeted for testing and automation tasks rather than a standard compliant master implementation.

The library supports Python 3.8+.

This library is the asyncio port of CANopen. See below for code example.

Async status

The remaining work for feature complete async implementation:

• Implement ABlockUploadStream, ABlockDownloadStream and ATextIOWrapper for async in SdoClient
• Implement EcmyConsumer.wait() for async
• Implement async in LssMaster`
• Async implementation of BaseNode402
• Implement async variant of Network.add_node. This will probably also add need of async variant of input_from_node in eds.py
• Update unittests for async
• Update documentation and examples

Features

The library is mainly meant to be used as a master.

• NMT master
• SDO client
• PDO producer/consumer
• SYNC producer
• EMCY consumer
• TIME producer
• LSS master
• Object Dictionary from EDS
• 402 profile support

Incomplete support for creating slave nodes also exists.

• SDO server
• PDO producer/consumer
• NMT slave
• EMCY producer
• Object Dictionary from EDS

Installation

Install from PyPI using pip:

$ pip install canopen

Install from latest master on GitHub:

$ pip install https://github.com/christiansandberg/canopen/archive/master.zip

If you want to be able to change the code while using it, clone it then install it in develop mode:

$ git clone https://github.com/christiansandberg/canopen.git
$ cd canopen
$ pip install -e .

Unit tests can be run using the pytest framework:

$ pip install pytest
$ pytest -v

Documentation

Documentation can be found on Read the Docs:

http://canopen.readthedocs.io/en/latest/

It can also be generated from a local clone using Sphinx:

$ python setup.py build_sphinx

Hardware support

This library supports multiple hardware and drivers through the python-can package. See the list of supported devices.

It is also possible to integrate this library with a custom backend.

Quick start

Here are some quick examples of what you can do:

The PDOs can be access by three forms:

1st: node.tpdo[n] or node.rpdo[n]

2nd: node.pdo.tx[n] or node.pdo.rx[n]

3rd: node.pdo[0x1A00] or node.pdo[0x1600]

The n is the PDO index (normally 1 to 4). The second form of access is for backward compatibility.

import canopen

# Start with creating a network representing one CAN bus
network = canopen.Network()

# Add some nodes with corresponding Object Dictionaries
node = canopen.RemoteNode(6, '/path/to/object_dictionary.eds')
network.add_node(node)

# Connect to the CAN bus
# Arguments are passed to python-can's can.Bus() constructor
# (see https://python-can.readthedocs.io/en/latest/bus.html).
network.connect()
# network.connect(bustype='socketcan', channel='can0')
# network.connect(bustype='kvaser', channel=0, bitrate=250000)
# network.connect(bustype='pcan', channel='PCAN_USBBUS1', bitrate=250000)
# network.connect(bustype='ixxat', channel=0, bitrate=250000)
# network.connect(bustype='vector', app_name='CANalyzer', channel=0, bitrate=250000)
# network.connect(bustype='nican', channel='CAN0', bitrate=250000)

# Read a variable using SDO
device_name = node.sdo['Manufacturer device name'].raw
vendor_id = node.sdo[0x1018][1].raw

# Write a variable using SDO
node.sdo['Producer heartbeat time'].raw = 1000

# Read PDO configuration from node
node.tpdo.read()
node.rpdo.read()
# Re-map TPDO[1]
node.tpdo[1].clear()
node.tpdo[1].add_variable('Statusword')
node.tpdo[1].add_variable('Velocity actual value')
node.tpdo[1].add_variable('Some group', 'Some subindex')
node.tpdo[1].trans_type = 254
node.tpdo[1].event_timer = 10
node.tpdo[1].enabled = True
# Save new PDO configuration to node
node.tpdo[1].save()

# Transmit SYNC every 100 ms
network.sync.start(0.1)

# Change state to operational (NMT start)
node.nmt.state = 'OPERATIONAL'

# Read a value from TPDO[1]
node.tpdo[1].wait_for_reception()
speed = node.tpdo[1]['Velocity actual value'].phys
val = node.tpdo['Some group.Some subindex'].raw

# Disconnect from CAN bus
network.sync.stop()
network.disconnect()

Asyncio

This library can be used with asyncio.

import asyncio
import canopen
import can

async def my_node(network, nodeid, od):

    # Create the node object and load the OD
    node = network.add_node(nodeid, od)

    # Read the PDOs from the remote
    await node.tpdo.aread()
    await node.rpdo.aread()

    # Set the module state
    node.nmt.set_state('OPERATIONAL')

    # Set motor speed via SDO
    await node.sdo['MotorSpeed'].aset_raw(2)

    while True:

        # Wait for TPDO 1
        t = await node.tpdo[1].await_for_reception(1)
        if not t:
            continue

        # Get the TPDO 1 value
        rpm = node.tpdo[1]['MotorSpeed Actual'].get_raw()
        print(f'SPEED on motor {nodeid}:', rpm)

        # Sleep a little
        await asyncio.sleep(0.2)

        # Send RPDO 1 with some data
        node.rpdo[1]['Some variable'].set_phys(42)
        node.rpdo[1].transmit()

async def main():

    # Start with creating a network representing one CAN bus
    network = canopen.Network()

    # Connect to the CAN bus
    # Arguments are passed to python-can's can.Bus() constructor
    # (see https://python-can.readthedocs.io/en/latest/bus.html).
    # Note the loop parameter to enable asyncio operation
    loop = asyncio.get_event_loop()
    network.connect(interface='pcan', bitrate=1000000, loop=loop)

    # Create two independent tasks for two nodes 51 and 52 which will run concurrently
    task1 = asyncio.create_task(my_node(network, 51, '/path/to/object_dictionary.eds'))
    task2 = asyncio.create_task(my_node(network, 52, '/path/to/object_dictionary.eds'))

    # Wait for both to complete (which will never happen)
    await asyncio.gather((task1, task2))

asyncio.run(main())

Debugging

If you need to see what's going on in better detail, you can increase the logging level:

import logging
logging.basicConfig(level=logging.DEBUG)