CAN XL, an extension of the CAN protocol outlined in ISO 11898-1, is developed by CAN in Automation (CiA). This enhancement targets an ambitious goal of increasing the bandwidth capabilities of CAN to over 10Mbit/s. This evolution in CAN addresses the growing demands of the electric vehicle and autonomous industries, opening up new possibilities for signal-based communication buses.

To mitigate potential challenges associated with higher bitrates, the Special Interest Group introduces the CAN XL Signal Improvement Capability (SIC) Transceiver. With this innovative solution, CAN XL introduces several advancements in communication. It supports larger payloads, enabling the tunneling of ethernet traffic, commonly referred to as “ethernet tunneling.” Additionally, CAN XL facilitates the mixing of multiple higher layer protocols on the same bus, all while maintaining the reliability for which CAN is renowned.

Much like its predecessor, CAN FD, CAN XL is designed with backward compatibility in mind, allowing seamless access to both CAN FD and Classical CAN protocols. While a CAN FD node cannot directly receive a CAN XL message, it will not register an error and will participate in arbitration on the subsequent frame. This dual usage of CAN FD and CAN XL on the same bus is made possible by leveraging CAN FD’s Protocol Exception State. This state is activated when the recessive XLF bit of a CAN XL message sets the CAN FD node into the Protocol Exception State, a safeguard introduced in the CAN FD specification (ISO 11898-1:2015) for future expansions.