Error in simple script

Hi guys,

With the following script

  # Hello World program in Python
import uavcan

# Instantiating an instance of standard service type uavcan.protocol.GetNodeInfo
# Here we need the response data structure, which is why we use the factory Response()
node_info = uavcan.protocol.GetNodeInfo.Response() = 'org.uavcan.pyuavcan_demo'
node_info.software_version.major = 1
node_info.hardware_version.unique_id = b'100' # Setting first 5 bytes; rest will be kept zero
# Fill other fields as necessary...

node = uavcan.make_node('can0',
                        node_id=100,          # Setting the node ID 123
                        node_info=node_info)  # Setting node info

def perform_other_tasks():
    handle = node.add_handler(uavcan.protocol.NodeStatus, node_status_callback)

def node_status_callback(event):
    print('NodeStatus message from node', event.transfer.source_node_id)
    print('Node uptime:', event.message.uptime_sec, 'seconds')
    # Messages, service requests, service responses, and entire events
    # can be converted into YAML formatted data structure using to_yaml():
while True:
        node.spin(1)            # Spin for 1 second or until an exception is thrown
        # time.sleep(0.1)       # Never do this!
    except UAVCANException as ex:
        print('Node error**********************************************:', ex)

I get the following error

Traceback (most recent call last):
File “”, line 29, in
node.spin(1) # Spin for 1 second or until an exception is thrown
File “/usr/local/lib/python3.7/dist-packages/uavcan/”, line 414, in spin
File “/usr/local/lib/python3.7/dist-packages/uavcan/”, line 410, in execute_once
File “/usr/local/lib/python3.7/dist-packages/uavcan/”, line 314, in _recv_frame
File “/usr/local/lib/python3.7/dist-packages/uavcan/”, line 781, in from_frames
raise TransferError(“Toggle bit value {0} incorrect on frame {1}”.format(tail & 0x20, idx))
uavcan.transport.TransferError: Toggle bit value 0 incorrect on frame 1

During handling of the above exception, another exception occurred:

Traceback (most recent call last):
File “”, line 32, in
except UAVCANException as ex:
NameError: name ‘UAVCANException’ is not defined

I have to admit that I’m a beginner, so any help is appreciated.
Any idea?

Best regards,


Replace UAVCANException with uavcan.UAVCANException.