Communication through CAN-bus interface not working

Question

I have python code running on a linux based device which has the following OS specifications:

NAME=Buildroot
VERSION=2020.11.1

This device is connected to a PLC using a three wire interface (CAN_H,CAN_L,GND).

I have written a code that sends a message to the PLC using the CAN-bus protocol. This is being done with the python-can package.

I have the following code:

import can

def send():
    #USB interface
    #bus = can.interface.Bus(bustype='pcan', channel='PCAN_USBBUS1', bitrate=500000)
    #on linux
    bus = can.interface.Bus(bustype='socketcan', channel='vcan0', bitrate=500000)
    #on windows
    #bus = can.interface.Bus(bustype='serial', channel='COM1', bitrate=500000)
    msg = can.Message(arbitration_id=0x68005,data=[0x10,0x11,0x12],is_extended_id=True)
    try:
        bus.send(msg)
        print("Message sent on {}".format(bus.channel_info))
    except can.CanError:
        print("Message NOT sent")


if __name__ == '__main__':
     send()

The problem faced is that the device is not sending any data to the PLC. This is probably due to incorrect options set for bustype and channel .

Can anyone advise on what to provide for bustype and channel for this physical interface with three CAN wires?

Answer 1

WARNING : I'm not familiar with the python-can library, but I am with socketcan.

vcan0 is a virtual can channel that you can setup in order to enable virtual communication between applications (eg testing).

An actual CAN device (eg PCAN-USB) is listed as can0, can1, canX. Beware that on some embedded systems this may not hold true (eg it can start with can1).

EDIT : I have forgotten to mention that you can get a list of all network interfaces like so, thus including CAN interfaces:

$ ifconfig -a

Reference documentation: https://elinux.org/Bringing_CAN_interface_up