Terminology » Other Wireless » CAN vs CAN-FD vs CAN-XL: Key Differences Explained

CAN vs CAN-FD vs CAN-XL: Key Differences Explained

can bus can fd can xl automotive network industrial communication

CAN (Controller Area Network), CAN-FD (Controller Area Network - Flexible Data-Rate), and CAN-XL (Controller Area Network - eXtra Large) are all based on CAN technology, sharing several similarities.

All versions are used in controller area networks, commonly found in automotive and industrial applications, where multiple electronic control units (ECUs) need to communicate and coordinate their activities within a network.

They differ in terms of implementation, data rate, and flexibility. Here are some common features and similarities among these versions:

  • All the CAN variants use NRZ (Non Return to Zero) encoding.
  • They use a daisy chain network topology where devices are connected to a central bus with varying length stubs.
  • All utilize message-based communication in which nodes communicate by sending and receiving messages or frames. The frames contain an identifier, data, and control bits.
  • They include error handling mechanisms such as error detection and error confinement.
  • They use a priority-based arbitration mechanism.
  • CAN-FD and CAN-XL are backward compatible with the original CAN protocol.
  • Support a multi-master communication scheme.
  • They use CSMA/CR for bus access.
  • Maintain deterministic communication with consistent and predictable timing.

Difference between CAN, CAN-FD, and CAN-XL

The following table highlights the differences between each of these CAN protocols.

These versions offer varying levels of data rate and payload capacity to meet the specific requirements of different applications, from traditional and reliable communication in CAN to the increased flexibility in CAN-FD and the high-performance capabilities of CAN-XL.

ParametersCANCAN-FDCAN-XL
Full formController Area NetworkController Area Network - Flexible Data RateController Area Network - eXtra Large
Data Field or Payload size per message or frame0 to 8 byte0 to 64 byte1 to 2048 byte
Identifier11 bits and 29 bits11 bits and 29 bits11 bits
Bit stuffingDynamicDynamic, Fixed in CRCDynamic in arbitration phase, Fixed in data phase
CRC15 bit17 or 21 bitPCRC : 13 bits, FCRC : 32 bits
Data rateMaximum of 1 Mbps speed at 40 meter bus lengthThe standard permits speeds up to 5 MbpsSpeeds up to 10 Mbps
InteroperabilityLimited to traditional CAN devicesInteroperable with both classic CAN and CAN-FD devicesInteroperable with classic CAN, CAN-FD, and CAN-XL devices
VersatilityFixed data rate may limit versatility in some applicationsOffers flexibility in adjusting data rate to suit specific needsDesigned for versatile and high-demand applications with large data volumes
Application focusTraditional automotive and industrial applications requiring reliable communicationApplications that need higher data rates and larger data payloadsAdvanced applications like ADAS and autonomous vehicles demanding very high data rates
ReferencesISO 11899, ISO 16845ISO 11898-1, ISO 11898-2, ISO 11898-5It is specified by CiA 610-1 (CAN in Automation). CAN XL is currently standardized as part of ISO11898-1.

Conclusion

While these versions share core characteristics, they also introduce enhancements and differences, primarily related to data rates, payload sizes, and application-specific requirements.

CAN-FD allows for more flexible data rates and larger payloads, and CAN-XL goes further by supporting very high data rates, exceeding CAN-FD. These differences make CAN-FD and CAN-XL suitable for applications with increased bandwidth and data capacity needs while retaining the reliability and robustness of the original CAN protocol.

Refer to the CAN-XL protocol for more information on CAN-XL and its advantages.