This document is based on Add a dissector for FlexRay ticket in WireShark.

There are two different types of FlexRay Packets: FlexRay Frame Data Packets and FlexRay Symbol Packets.

  • FlexRay Frame Data Packet

    Each of the FlexRay Frame Packet contains a Measurement Header (1 byte), Error Flags Information (1 byte) and a FlexRay Frame (5 bytes + 0…254 bytes). The Measurement Header and the Error Flags Information are generated by a measurement device and precede the FlexRay Frame, which is captured from the bus. The FlexRay Frame consists of a Frame Header and the Frame Payload. The frame payload has a variable length of 0 to 254 bytes.

    Measurement Header (1 byte) Error Flags (1 byte) FlexRay Frame (5 bytes + 0-254 bytes)
  • FlexRay Symbol Packet

    The FlexRay Symbol Packet consists of the Measurement Header (1 byte) and the Symbol Length (1 byte).

    Measurement Header (1 byte) Symbol length (1 byte)

Measurement Header (1 byte)

7 6 5 4 3 2 1 0
CH: Channel, indicates the Channel
	0: Channel A
	1: Channel B
TI[0..6]: Type Index
	0x01: FlexRay Frame
	0x02: FlexRay Symbol

FlexRay Frame Data Packet

Error Flags Information (1 byte)

7 6 5 4 3 2 1 0
FCRCERR: Frame CRC error
HCRCERR: Header CRC error
FESERR: Frame End Sequence error
CODERR: Coding error… indicates if a Frame Start Sequence Error (FSSERR)
        or a Byte Start Sequence error (BSSERR) occurred
TSSVIOL: TSS violation

FlexRay Frame (5 bytes + 0..254 bytes)

A FlexRay frame, as described by section 8 "Frame Format" of ISO 17458-2:2013. The Frame CRC is not included. If the Frame CRC is incorrect, the error bit FCRCERR in Error Flags shall be set.

Extra low-level bits (TSS, FSS, BSS, FES) are not included in the frame. But a measurement device may set according error bits in the Error Flags if an error occurred during decoding of these bits (Bits CODERR, TSSVIOL, FESERR in Error Flags).

Do not assume that only whole FlexRay Frames are contained in the log file—a measurement device may also produce truncated frames if errors occur. Truncation may happen at each byte boundary!

FlexRay Symbol Packet

Through the symbol length can be determined, which symbol was transmitted.

7 6 5 4 3 2 1 0
- SL6 SL5 SL4 SL3 SL2 SL1 SL0
SL[0..6]: Symbol length
	Values between 0 and 127
	Length of received symbol in bit