LINKTYPE_FLEXRAY
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 |
TI6 |
TI5 |
TI4 |
TI3 |
TI2 |
TI1 |
TI0 |
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 |
HCRCERR |
FESERR |
CODERR |
TSSVIOL |
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