Library API

The main objects are the BusABC and the Message. A form of CAN interface is also required.


Check the backend specific documentation for any implementation specific details.



The Notifier object is used as a message distributor for a bus.

class can.Notifier(bus, listeners, timeout=1.0, loop=None)[source]

Bases: object

Manages the distribution of can.Message instances to listeners.

Supports multiple buses and listeners.


Remember to call stop() after all messages are received as many listeners carry out flush operations to persist data.


Add a bus for notification.

Parameters:bus (can.BusABC) – CAN bus instance.

Add new Listener to the notification list. If it is already present, it will be called two times each time a message arrives.

Parameters:listener (can.Listener) – Listener to be added to the list to be notified
exception = None

Exception raised in thread


Remove a listener from the notification list. This method trows an exception if the given listener is not part of the stored listeners.

Parameters:listener (can.Listener) – Listener to be removed from the list to be notified
Raises:ValueError – if listener was never added to this notifier

Stop notifying Listeners when new Message objects arrive and call stop() on each Listener.

Parameters:timeout (float) – Max time in seconds to wait for receive threads to finish. Should be longer than timeout given at instantiation.


class can.CanError[source]

Bases: OSError

Indicates an error with the CAN network.