Python Can

Revision as of 01:36, 20 March 2013 by Yegorich (Talk | contribs) (initial article)

(diff) ← Older revision | Latest revision (diff) | Newer revision → (diff)
Jump to: navigation, search

Since version 3.3 Python provides support for SocketCAN. You can specify AF_CAN protocol family as you do in C. Below you’ll find slightly modified example provided in the original SocketCAN patch.

To get started just copy the code into and start it as follows provided your CAN interface is can0:

python can0

Use build_can_frame() and dissect_can_frame() to build/dissect CAN frames. Interface management like bitrate settings or getting statistics will be made as usual via iproute2 utility.

       import socket
       import struct
       import sys

       # CAN frame packing/unpacking (see `struct can_frame` in <linux/can.h>)
       can_frame_fmt = "=IB3x8s"

       def build_can_frame(can_id, data):
               can_dlc = len(data)
               data = data.ljust(8, b'\x00')
               return struct.pack(can_frame_fmt, can_id, can_dlc, data)

       def dissect_can_frame(frame):
               can_id, can_dlc, data = struct.unpack(can_frame_fmt, frame)
               return (can_id, can_dlc, data[:can_dlc])

       if len(sys.argv) != 2:
               print('Provide CAN device name (can0, slcan0 etc.)')

       # create a raw socket and bind it to the given CAN interface
       s = socket.socket(socket.AF_CAN, socket.SOCK_RAW, socket.CAN_RAW)

       while True:
               cf, addr = s.recvfrom(16)

               print('Received: can_id=%x, can_dlc=%x, data=%s' % dissect_can_frame(cf))

               except socket.error:
                       print('Error sending CAN frame')

                       s.send(build_can_frame(0x01, b'\x01\x02\x03'))
               except socket.error:
                       print('Error sending CAN frame')