Image Processing Reference
In-Depth Information
Listen timeout
Yes
Traffic
detected?
No
Listen to traffic
and gather time
and cycle
information
Send frames
and wait for
matching reply
FIGURE .
Start-up process.
Protocol flags
Header
CRC
Message ID
Da ta
Frame ID
Length
Cycle
Data
Data
CRC
CRC
CRC
Da ta
0
...
252 Bytes
40 bit
16 bit
24 bit
Header section
Body section
Trailer section
FlexRay frame 5 + (0
...
254) + 3 Bytes
FIGURE .
FlexRay frame format.
in relation to the internal slot counter. If there is a match, the controller enters the normal mode, in
which active transmission of frames is allowed.
16.3.4 Coding and Physical Layer
The frame format for data transmission contains three sections: the header section, the payload sec-
tion, and a trailer section (see Figure .). .).The header contains protocol control information like the
synchronization frame flag, the frame ID, a null frame indicator and the frame length, and a cycle
counter. he payload section contains up to bytes of data. In case the payload does not contain
any data, the null frame indicator is set. A null frame is thus a valid frame that does not contain
any payload data. It can, however, serve as an alive signal or can be used for clock synchronization
purposes.
Optionally, the data section can contain a message ID, which identifies the type of information
transported in the frame. he trailer section contains a bit CRC that protects the complete frame.
