Python3 python CAN notifier - TypeError: 'NoneType' object is not callables

Question

I'm trying to implement a notifier for for the python-can (4.0.0) following the exact same approach as in here but I'm getting the following error:

Exception in thread can.notifier for bus "socketcan channel 'can0'":
Traceback (most recent call last):
  File "/usr/lib/python3.7/threading.py", line 917, in _bootstrap_inner
    self.run()
  File "/usr/lib/python3.7/threading.py", line 865, in run
    self._target(*self._args, **self._kwargs)
  File "/usr/local/lib/python3.7/dist-packages/can/notifier.py", line 121, in _rx_thread
    self._on_message_received(msg)
  File "/usr/local/lib/python3.7/dist-packages/can/notifier.py", line 143, in _on_message_received
    res = cast(Union[None, Optional[Awaitable[Any]]], callback(msg))
TypeError: 'NoneType' object is not callables

My code:

import os
import can

os.system('sudo ip link set can0 up type can bitrate 500000')

bus = can.interface.Bus(channel = 'can0', bustype = 'socketcan')

def parseData(can):
        SingleCanFrame = can.Message

notifier = can.Notifier(bus,[parseData(can)])

while(1):
        continue

os.system('sudo ifconfig can0 down')

I don't really understand what I'm doing wrong and the python-can documentation on the notifier is not very helpful either.

Answer 1

Like @TimRoberts said I was passing the function in the wrong way.

Here is a code that works and can be tested even without the CAN Hardware.

from time import sleep
import can

bus1 = can.interface.Bus(channel = 'test', bustype = 'virtual')
bus2 = can.interface.Bus('test', bustype='virtual')

msg = can.Message(arbitration_id=0x123, data=[0, 1, 2, 3, 4, 5, 6, 7])

def parseData(can):
        print( can.arbitration_id )

notifier = can.Notifier(bus2,[parseData])

while (1):
    bus1.send(msg)
    sleep(1)

Answer 2

I'm posting my contribution since we don't have many info regarding this subject on the internet, follow my script here to help the community. I'm using a industrial computer with a CAN driver to collet CAN J1939 data, these data are generated by a VECTOR device using the CANnalyzer SW. This code is working very well to me and collecting data in a good sample rate (ms).

import cantools
import can
from ctypes import *
import logging
import time

# Logger config
logger = logging.getLogger(__name__)

# CAN filter
can_filter = [
    {"can_id": 0xCF00400, "can_mask": 0xFFFFFFF, "extended": True},
    {"can_id": 0xCF00300, "can_mask": 0xFFFFFFF, "extended": True},
    {"can_id": 0x10FD5200, "can_mask": 0x1FFFFFFF, "extended": True},
    {"can_id": 0x1CFE8800, "can_mask": 0x1FFFFFFF, "extended": True},
]

def main():
    """main _summary_"""
    can_bus = can.interface.Bus(bustype="socketcan", channel="can1", bitrate=500000, can_filters=can_filter)  # type: ignore
    log_filename = time.strftime("%d-%m-%Y_%H-%M", time.localtime())
    listener = can.Logger(filename=f"can_listener_{log_filename}.log", mode="a")  # type: ignore
    notifier = can.Notifier(can_bus, [listener])  # type: ignore

    try:
        while True:
            continue
    except Exception as e:
        print(e)
    finally:
        notifier.stop()


if __name__ == "__main__":
    try:
        main()
    except KeyboardInterrupt:
        print("can reciever stopped")
    except Exception as e:
        print(e)