Canbus support has been greatly improved but not in the release version yet. You might try dev. If you use a slcan adapter like the Zubax Babel you can monitor the CANbus messages. If you use Mission Planner there are many more parameters with dev than release firmware for CANbus. Enable CAN and reboot for mission planner to show the new parameters.
I wrote this article for copter but it might help.
https://discuss.ardupilot.org/t/configuring-ardupilot-for-uavcan/23059/2