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An implementation of the CAN SAE J1939 standard for Python. This is the first J1939-22 (J1939-FD) implementation!
If you experience a problem or think the stack would not behave properly, do not hesitate to open a ticket or write an email. Pullrequests are of course even more welcome!
The project uses the python-can_ package to support multiple hardware drivers. At the time of writing the supported interfaces are
An SAE J1939 CAN Network consists of multiple Electronic Control Units (ECUs). Each ECU can have one or more Controller Applications (CAs). Each CA has its own (unique) Address on the bus. This address is either acquired within the address claiming procedure or set to a fixed value. In the latter case, the CA has to announce its address to the bus to check whether it is free.
The CAN messages in a SAE J1939 network are called Protocol Data Units (PDUs). This definition is not completely correct, but close enough to think of PDUs as the CAN messages.
one ElectronicControlUnit (ECU) can hold multiple ControllerApplications (CA)
ECU (CA) Naming according SAE J1939/81
full featured address claiming procedure according SAE J1939/81
full support of transport protocol (up to 1785 bytes) according SAE J1939/21 for sending and receiving
support of Multi-PG according SAE J1939/22
full support of fd-transport protocol according SAE J1939/22 (J1939-FD) for sending and receiving
Requests (global and specific)
correct timeout and deadline handling
(under construction) almost complete testcoverage
diagnostic messages (see https://github.com/juergenH87/python-can-j1939/tree/master/examples/diagnostic_message.py)
Install can-j1939 with pip::
$ pip install can-j1939or do the trick with::
$ git clone https://github.com/juergenH87/can-j1939.git
$ cd j1939
$ pip install .Upgrade an already installed can-j1939 package::
$ pip install --upgrade can-j1939To simply receive all passing (public) messages on the bus you can subscribe to the ECU object.
.. code-block:: python
import logging
import time
import can
import j1939
logging.getLogger('j1939').setLevel(logging.DEBUG)
logging.getLogger('can').setLevel(logging.DEBUG)
def on_message(priority, pgn, sa, timestamp, data):
"""Receive incoming messages from the bus
:param int priority:
Priority of the message
:param int pgn:
Parameter Group Number of the message
:param int sa:
Source Address of the message
:param int timestamp:
Timestamp of the message
:param bytearray data:
Data of the PDU
"""
print("PGN {} length {}".format(pgn, len(data)))
def main():
print("Initializing")
# create the ElectronicControlUnit (one ECU can hold multiple ControllerApplications)
ecu = j1939.ElectronicControlUnit()
# Connect to the CAN bus
# Arguments are passed to python-can's can.interface.Bus() constructor
# (see https://python-can.readthedocs.io/en/stable/bus.html).
# ecu.connect(bustype='socketcan', channel='can0')
# ecu.connect(bustype='kvaser', channel=0, bitrate=250000)
ecu.connect(bustype='pcan', channel='PCAN_USBBUS1', bitrate=250000)
# ecu.connect(bustype='ixxat', channel=0, bitrate=250000)
# ecu.connect(bustype='vector', app_name='CANalyzer', channel=0, bitrate=250000)
# ecu.connect(bustype='nican', channel='CAN0', bitrate=250000)
# subscribe to all (global) messages on the bus
ecu.subscribe(on_message)
time.sleep(120)
print("Deinitializing")
ecu.disconnect()
if __name__ == '__main__':
main()A more sophisticated example in which the CA class was overloaded to include its own functionality:
.. code-block:: python
import logging
import time
import can
import j1939
logging.getLogger('j1939').setLevel(logging.DEBUG)
logging.getLogger('can').setLevel(logging.DEBUG)
# compose the name descriptor for the new ca
name = j1939.Name(
arbitrary_address_capable=0,
industry_group=j1939.Name.IndustryGroup.Industrial,
vehicle_system_instance=1,
vehicle_system=1,
function=1,
function_instance=1,
ecu_instance=1,
manufacturer_code=666,
identity_number=1234567
)
# create the ControllerApplications
ca = j1939.ControllerApplication(name, 128)
def ca_receive(priority, pgn, source, timestamp, data):
"""Feed incoming message to this CA.
(OVERLOADED function)
:param int priority:
Priority of the message
:param int pgn:
Parameter Group Number of the message
:param intsa:
Source Address of the message
:param int timestamp:
Timestamp of the message
:param bytearray data:
Data of the PDU
"""
print("PGN {} length {}".format(pgn, len(data)))
def ca_timer_callback1(cookie):
"""Callback for sending messages
This callback is registered at the ECU timer event mechanism to be
executed every 500ms.
:param cookie:
A cookie registered at 'add_timer'. May be None.
"""
# wait until we have our device_address
if ca.state != j1939.ControllerApplication.State.NORMAL:
# returning true keeps the timer event active
return True
# create data with 8 bytes
data = [j1939.ControllerApplication.FieldValue.NOT_AVAILABLE_8] * 8
# sending normal broadcast message
ca.send_pgn(0, 0xFD, 0xED, 6, data)
# sending normal peer-to-peer message, destintion address is 0x04
ca.send_pgn(0, 0xE0, 0x04, 6, data)
# returning true keeps the timer event active
return True
def ca_timer_callback2(cookie):
"""Callback for sending messages
This callback is registered at the ECU timer event mechanism to be
executed every 500ms.
:param cookie:
A cookie registered at 'add_timer'. May be None.
"""
# wait until we have our device_address
if ca.state != j1939.ControllerApplication.State.NORMAL:
# returning true keeps the timer event active
return True
# create data with 100 bytes
data = [j1939.ControllerApplication.FieldValue.NOT_AVAILABLE_8] * 100
# sending multipacket message with TP-BAM
ca.send_pgn(0, 0xFE, 0xF6, 6, data)
# sending multipacket message with TP-CMDT, destination address is 0x05
ca.send_pgn(0, 0xD0, 0x05, 6, data)
# returning true keeps the timer event active
return True
def main():
print("Initializing")
# create the ElectronicControlUnit (one ECU can hold multiple ControllerApplications)
ecu = j1939.ElectronicControlUnit()
# Connect to the CAN bus
# Arguments are passed to python-can's can.interface.Bus() constructor
# (see https://python-can.readthedocs.io/en/stable/bus.html).
# ecu.connect(bustype='socketcan', channel='can0')
# ecu.connect(bustype='kvaser', channel=0, bitrate=250000)
ecu.connect(bustype='pcan', channel='PCAN_USBBUS1', bitrate=250000)
# ecu.connect(bustype='ixxat', channel=0, bitrate=250000)
# ecu.connect(bustype='vector', app_name='CANalyzer', channel=0, bitrate=250000)
# ecu.connect(bustype='nican', channel='CAN0', bitrate=250000)
# ecu.connect('testchannel_1', bustype='virtual')
# add CA to the ECU
ecu.add_ca(controller_application=ca)
ca.subscribe(ca_receive)
# callback every 0.5s
ca.add_timer(0.500, ca_timer_callback1)
# callback every 5s
ca.add_timer(5, ca_timer_callback2)
# by starting the CA it starts the address claiming procedure on the bus
ca.start()
time.sleep(120)
print("Deinitializing")
ca.stop()
ecu.disconnect()
if __name__ == '__main__':
main()This implementation was taken from https://github.com/benkfra/j1939, as no further development took place.
Thanks for your great work!
.. _python-can: https://python-can.readthedocs.org/en/stable/ .. _Copperhill technologies: http://copperhilltech.com/a-brief-introduction-to-the-sae-j1939-protocol/