# CAN XL

Protocols · `CAN XL` · verification: source checked

CAN XL is the third generation of the CAN data link layer and supports CAN CC, CAN FD and CAN XL protocol types. It carries data fields from 1 byte to 2048 bytes and separates the CAN-ID into an 11-bit priority ID and a 32-bit acceptance field. CAN XL is intended for backbone and sub-backbone networks and for integration into TCP/IP systems.

## Specification

| Property | Value |
|---|---|
| Transports | other |
| Architecture | producer consumer |
| Encoding | binary |
| Standard body | ISO |
| Standard ref | ISO 11898-1:2024 |

## Safety

- Error signaling can be switched off by optional configuration.
- Long CAN XL frames can block the network; LLC frame fragmentation is under development to interrupt and resume long-frame transmission.

## Study notes

- CAN XL is standardized in ISO 11898-1:2024; CiA SIG CAN XL develops related specifications in CiA 610, CiA 611, CiA 612 and CiA 613.
- The data field length ranges from 1 byte to 2048 bytes and can change in one-byte steps.
- The 11-bit priority ID provides the frame priority; the 32-bit acceptance field is included in the 64-bit hardware acceptance filter and may contain node address or content-indicating information.
- Two cascaded CRC fields are used: a 13-bit preface CRC (PCRC) in the control field and a 32-bit frame CRC (FCRC) in the CRC field.
- The CRCs detect any five randomly distributed bit errors, corresponding to a Hamming distance of 6.
- The 8-bit SDT indicates the next OSI layer protocol; the 8-bit VCID allows up to 256 logical networks on one CAN XL physical network segment.
- CANsec is an optional DLL security add-on indicated by the SEC bit; it uses a 4-byte header and a 16-byte trailer with an authentication tag.
- LLC frame fragmentation is under development in CiA 613-3 for long frames from 128 bytes to 2048 bytes.
- Bit rate switches from nominal to XL data phase at the ADH/DH1 boundary and back at the FCP(0)/DAH boundary.
- CAN SIC XL transceivers have arbitration, data TX and data RX modes; PWM coding is an optional alternative to NRZ coding.

## Sources

1. [CAN XL](https://www.can-cia.org/can-knowledge/can-xl) (accessed 2026-10-25)

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JSON: https://machineschema.com/protocol/can-xl.json  
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