Datasheet

Application Note
www.tektronix.com/oscilloscopes30
Header Segment Components:
Indicator Bits – the first five bits are called the indicator bits
and indicate the type of frame being transmitted. Choices
include Normal, Payload, Null, Sync, and Startup.
Frame ID – the frame ID defines the slot in which the frame
should be transmitted. Frame IDs range from 1 to 2047
with any individual frame ID being used no more than once
on each channel in a communication cycle.
Payload Length – the payload length field is used to
indicate how many words of data are in the payload
segment. Header
CRC – a cyclic redundancy check (CRC) code calculated
over the sync frame indicator, the startup frame indicator,
the frame ID and the payload length.
Cycle Count – the value of the current communication
cycle, ranging from 0-63.
Payload Segment Components:
Data – the data field contains up to 254 bytes of data.
For frames transmitted in the static segment the first 0 to
12 bytes of the payload segment may optionally be used
as a network management vector. The payload preamble
indicator in the frame header indicates whether the payload
segment contains the network management vector. For
frames transmitted in the dynamic segment the first two
bytes of the payload segment may optionally be used as
a message ID field, allowing receiving nodes to filter or
steer data based on the contents of this field. The payload
preamble indicator in the frame header indicates whether
the payload segment contains the message ID.
Trailer Segment Components:
CRC – a cyclic redundancy check (CRC) code calculated
over all of the components of the header segment and the
payload segment of the frame.
Dynamic frames have one additional component that follows
the Trailer CRC called the Dynamic Trailing Sequence (DTS)
that prevents premature channel idle detection by the bus
receivers.
Figure 42. Triggering on Frame ID and Cycle Count, Searching through acquired data
for Startup Frames.
Figure 41. FlexRay bus setup menu.