NameError: name 'UcanInitHardwareEx' is not defined

[Mango-kid]

This error is in the systec interface when initalizing the bus.

bus = can.interface.Bus(bustype='systec', channel='0', bitrate=500000)

[karlding]

Is this still occurring? If so, can you provide more information (python-can library version, Python version, whether you installed the SYS TEC drivers, etc.)?

python-can requires SYS TEC CAN device drivers and the usbcan32.dll (or usbcan64.dll for 64-bit).

[ryleymcc]

I'm getting this error. I am using python 3.9.2 on windows 10. I have downloaded and run the driver setup (driver support for obsolete version GW-001, GW-002) and I can see the driver in the the folder.

I do not have my SYS TEC USB-CAN plugged in. I will update this post when I try my code with the USB-CAN plugged in.

This is my source code:

import can

#create a bus instance
#many other interfaces are supported as well (see below)
bus = can.Bus(interface='systec',
              channel='vcan0',
              bitrate='500000',
              receive_own_messages=True)
#send a message
message = can.Message(arbitration_id=123, is_extended_id=True,
                      data=[0x11, 0x22, 0x33])
bus.send(message, timeout=0.2)

#iterate over received messages
for msg in bus:
    print("{X}: {}".format(msg.arbitration_id, msg.data))
#or use an asynchronous notifier
notifier = can.Notifier(bus, [can.Logger("recorded.log"), can.Printer()])

This is the error I get:

Cannot load SYSTEC ucan library: function 'UcanEnumerateHardware' not found.
Traceback (most recent call last):
  File "C:\Users\ryley\OneDrive\Desktop\test.py", line 5, in <module>
    bus = can.Bus(interface='systec',
  File "C:\Users\ryley\AppData\Local\Programs\Python\Python39\lib\site-packages\can\interface.py", line 127, in __new__
    return cls(channel, *args, **kwargs)
  File "C:\Users\ryley\AppData\Local\Programs\Python\Python39\lib\site-packages\can\interfaces\systec\ucanbus.py", line 98, in __init__
    self.channel = int(channel)
ValueError: invalid literal for int() with base 10: 'vcan0'

If I change channel='vcan0', to channel='0' I get the error:

Cannot load SYSTEC ucan library: function 'UcanEnumerateHardware' not found.
Traceback (most recent call last):
  File "C:\Users\ryley\OneDrive\Desktop\test.py", line 5, in <module>
    bus = can.Bus(interface='systec',
  File "C:\Users\ryley\AppData\Local\Programs\Python\Python39\lib\site-packages\can\interface.py", line 127, in __new__
    return cls(channel, *args, **kwargs)
  File "C:\Users\ryley\AppData\Local\Programs\Python\Python39\lib\site-packages\can\interfaces\systec\ucanbus.py", line 125, in __init__
    self._ucan.init_hardware(device_number=device_number)
  File "C:\Users\ryley\AppData\Local\Programs\Python\Python39\lib\site-packages\can\interfaces\systec\ucan.py", line 368, in init_hardware
    UcanInitHardwareEx(byref(self._handle), device_number, self._callback_ref, None)
NameError: name 'UcanInitHardwareEx' is not defined

[felixdivo]

Loading of the ucan DLL probably failed and got unnoticed. It is probably fixed by #1158, see this. If the problem persists, please reopen or comment.