Some protocol content issues regarding the DroneCAN interface on PX4

Hello everyone, I would like to ask some questions about the DroneCAN protocol on PX4. I am currently trying to send CAN data packets through my MCU so that it can connect to PX4 and be properly parsed by PX4, including data from rangefinders and optical flow sensors. However, I don’t know what format I should use for sending the data. Can anyone tell me?