Source code for can.interfaces.usb2can.usb2canInterface

This interface is for Windows only, otherwise use SocketCAN.

import logging
from ctypes import byref
from typing import Optional

from can import BusABC, Message, CanInitializationError, CanOperationError
from .usb2canabstractionlayer import Usb2CanAbstractionLayer, CanalMsg, CanalError
from .usb2canabstractionlayer import (
from .serial_selector import find_serial_devices

# Set up logging
log = logging.getLogger("can.usb2can")

def message_convert_tx(msg):
    message_tx = CanalMsg()

    length = msg.dlc
    message_tx.sizeData = length = msg.arbitration_id

    for i in range(length):[i] =[i]

    message_tx.flags = 0x80000000

    if msg.is_error_frame:
        message_tx.flags |= IS_ERROR_FRAME

    if msg.is_remote_frame:
        message_tx.flags |= IS_REMOTE_FRAME

    if msg.is_extended_id:
        message_tx.flags |= IS_ID_TYPE

    return message_tx

def message_convert_rx(message_rx):
    """convert the message from the CANAL type to pythoncan type"""
    is_extended_id = bool(message_rx.flags & IS_ID_TYPE)
    is_remote_frame = bool(message_rx.flags & IS_REMOTE_FRAME)
    is_error_frame = bool(message_rx.flags & IS_ERROR_FRAME)

    return Message(
        dlc=message_rx.sizeData,[: message_rx.sizeData],

[docs]class Usb2canBus(BusABC): """Interface to a USB2CAN Bus. This interface only works on Windows. Please use socketcan on Linux. :param channel: The device's serial number. If not provided, Windows Management Instrumentation will be used to identify the first such device. :param bitrate: Bitrate of channel in bit/s. Values will be limited to a maximum of 1000 Kb/s. Default is 500 Kbs :param flags: Flags to directly pass to open function of the usb2can abstraction layer. :param dll: Path to the DLL with the CANAL API to load Defaults to 'usb2can.dll' :param serial: Alias for `channel` that is provided for legacy reasons. If both `serial` and `channel` are set, `serial` will be used and channel will be ignored. """ def __init__( self, channel: Optional[str] = None, dll: str = "usb2can.dll", flags: int = 0x00000008, *_, bitrate: int = 500000, serial: Optional[str] = None, **kwargs, ): self.can = Usb2CanAbstractionLayer(dll) # get the serial number of the device device_id = serial or channel # search for a serial number if the device_id is None or empty if not device_id: devices = find_serial_devices() if not devices: raise CanInitializationError("could not automatically find any device") device_id = devices[0] # convert to kb/s and cap: max rate is 1000 kb/s baudrate = min(int(bitrate // 1000), 1000) self.channel_info = f"USB2CAN device {device_id}" connector = f"{device_id}; {baudrate}" self.handle =, flags) super().__init__(channel=channel, **kwargs) def send(self, msg, timeout=None): tx = message_convert_tx(msg) if timeout: status = self.can.blocking_send(self.handle, byref(tx), int(timeout * 1000)) else: status = self.can.send(self.handle, byref(tx)) if status != CanalError.SUCCESS: raise CanOperationError("could not send message", error_code=status) def _recv_internal(self, timeout): messagerx = CanalMsg() if timeout == 0: status = self.can.receive(self.handle, byref(messagerx)) else: time = 0 if timeout is None else int(timeout * 1000) status = self.can.blocking_receive(self.handle, byref(messagerx), time) if status == CanalError.SUCCESS: rx = message_convert_rx(messagerx) elif status in ( CanalError.RCV_EMPTY, CanalError.TIMEOUT, CanalError.FIFO_EMPTY, ): rx = None else: raise CanOperationError("could not receive message", error_code=status) return rx, False def shutdown(self): """ Shuts down connection to the device safely. :raise cam.CanOperationError: is closing the connection did not work """ super().shutdown() status = self.can.close(self.handle) if status != CanalError.SUCCESS: raise CanOperationError("could not shut down bus", error_code=status) @staticmethod def _detect_available_configs(): return Usb2canBus.detect_available_configs() @staticmethod def detect_available_configs(serial_matcher: Optional[str] = None): """ Uses the *Windows Management Instrumentation* to identify serial devices. :param serial_matcher: search string for automatic detection of the device serial """ if serial_matcher is None: channels = find_serial_devices() else: channels = find_serial_devices(serial_matcher) return [{"interface": "usb2can", "channel": c} for c in channels]