unable to transmit more than 8bytes in DLC of data in can bus using python

Question

This is my code iam using cantools here ggg contains the converted integer values of hex id of message , dlcs contain the respective dlc value

 can_bus = can.interface.Bus(channel='0',bitrate=500000, bustype='vector' ,app_name='CANalyzer',data_bitrate=2000000)
  can_bus2 = can.interface.Bus(channel='0',bitrate=500000,bustype='vector',app_name='CANalyzer',data_bitrate=2000000)
 for i,j in zip(ggg,dlcs):
    example_messages = db.get_message_by_frame_id(i)
    message = can.Message(arbitration_id=example_messages.frame_id,is_rx=False,data=[1,2,3,4,5,6,7,8],is_extended_id = True,dlc=int(j),is_fd=True,bitrate_switch=True)
    
    #can_bus.send(message) ##send single messages
    can_bus.send_periodic(message,0.100,30,True) # /send periodic messages
    example_message = can_bus2.recv(3) #/recieve messages

getting these errors due to more dlc size in my messages a helping hand would be wonderful .

Traceback (most recent call last):
  File "C:\Users\AppData\Local\Programs\Python\Python310\lib\site-packages\can\broadcastmanager.py", line 281, in _run
    self.bus.send(self.messages[msg_index])
  File "C:\Users\AppData\Local\Programs\Python\Python310\lib\site-packages\can\interfaces\vector\canlib.py", line 536, in send
    self._send_sequence([msg])
  File "C:\Users\AppData\Local\Programs\Python\Python310\lib\site-packages\can\interfaces\vector\canlib.py", line 543, in _send_sequence
    return self._send_can_msg_sequence(msgs)
  File "C:\Users\AppData\Local\Programs\Python\Python310\lib\site-packages\can\interfaces\vector\canlib.py", line 560, in _send_can_msg_sequence
    self.xldriver.xlCanTransmit(
  File "C:\Users\AppData\Local\Programs\Python\Python310\lib\site-packages\can\interfaces\vector\xldriver.py", line 37, in check_status_operation
    raise VectorOperationError(
can.interfaces.vector.exceptions.VectorOperationError: xlCanTransmit failed (XL_ERR_INVALID_DLC) [Error Code 513]
xlCanTransmit failed (XL_ERR_INVALID_DLC) [Error Code 513]

Note : when i tried to change the data more than 8 bytes in can.message its throwing error


 "C:\Users\AppData\Local\Programs\Python\Python310\lib\site-packages\can\broadcastmanager.py", line 281, in _run
    self.bus.send(self.messages[msg_index])
  File "C:\Users\AppData\Local\Programs\Python\Python310\lib\site-packages\can\interfaces\vector\canlib.py", line 536, in send
    self._send_sequence([msg])
  File "C:\Users\AppData\Local\Programs\Python\Python310\lib\site-packages\can\interfaces\vector\canlib.py", line 543, in _send_sequence
    return self._send_can_msg_sequence(msgs)
  File "C:\Users\AppData\Local\Programs\Python\Python310\lib\site-packages\can\interfaces\vector\canlib.py", line 556, in _send_can_msg_sequence
    xl_event_array = (xlclass.XLevent * message_count.value)(
  File "C:\Users\AppData\Local\Programs\Python\Python310\lib\site-packages\can\interfaces\vector\canlib.py", line 580, in _build_xl_event
    xl_event.tagData.msg.data = tuple(msg.data)
RuntimeError: (c_ubyte_Array_8) <class 'IndexError'>: invalid index
(c_ubyte_Array_8) <class 'IndexError'>: invalid index

You are using classic CAN and not CAN FD, right? If so then why are you surprised that the DLC caps at 8 bytes... — Lundin, Sep 28 '22 at 07:47
Only setting `is_fd=True` on each message is not enough to enable CAN FD. You should also add `fd=True` when you create the `can_bus` object. — MSpiller, Sep 28 '22 at 08:27
hi @M.Spiller after making the changes you suggested iam getting a TxErr , not acknowledged error and dominant error , please give guidance as iam new to this subject — Lakshmi Srikanta, Sep 28 '22 at 13:23
Again, can you please clarify if you are using CAN or CAN FD. — Lundin, Sep 28 '22 at 14:26
@Lundin my application is meant to be used for CAN FD and CAN TP respectively and simulate the IG Block using python . my network hardware settings are 500 , 2000 — Lakshmi Srikanta, Sep 28 '22 at 15:36
_Not acknowledged error_ means that no other CAN node has acknowledged the message. Check the other nodes, cabling, termination, etc. — MSpiller, Sep 29 '22 at 09:20

score 0 · Answer 1 · answered Apr 30 '23 at 20:31

I was getting the same error as you have mentioned.

RuntimeError: (c_ubyte_Array_8) <class 'IndexError'>: invalid index

Following set of code helped me: Can bus obj initialization: set fd=True

self.bus = can.Bus(channel=net_channel,
                   interface='vector',
                   receive_own_messages=True,
                   app_name='CANoe',
                   fd=True,
                   bitrate=500000)

msg0 = can.Message(arbitration_id=0x580, dlc=15, is_fd=True,
                   is_extended_id=True, bitrate_switch=True,
                   data=[3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3])

you can look into my reported issue https://github.com/hardbyte/python-can/issues/1582

unable to transmit more than 8bytes in DLC of data in can bus using python

1 Answers1