The Frame ID defines the slot in which the frame should be transmitted and is used for prioritizing event-triggered frames. The Payload Length contains the number of words which are transferred in the frame. The Header CRC is used to detect errors during the transfer. The Cycle Count contains the value of a counter that advances incrementally each time a Communication Cycle starts. The payload contains the actual data transferred by the frame. The length of the FlexRay payload or data frame is up to 127 words (254 bytes), which is over 30 times greater compared to CAN. [14][18]
The reserved bit is reserved for future protocol use. It shall not be used by the application.
• A transmitting node shall set the reserved bit to logical '0'.
• A receiving node shall ignore the reserved bit.
2. Payload preamble indicator (1 bit)
The payload preamble indicator indicates whether or not an optional vector is contained within the payload segment of the frame transmitted:
• If the frame is transmitted in the dynamic segment the payload preamble indicator indicates the presence of a message ID at the beginning of the payload.
3. Null frame indicator (1 bit)
The null frame indicator indicates whether or not the frame is a null frame, i.e. a frame that contains no useable data in the payload segment of the frame.
4. Sync frame indicator (1 bit)
The sync frame indicator indicates whether or not the frame is a sync frame, i.e. a frame that is utilized for system wide synchronization of communication (used in static segment only).
4. Startup frame indicator (1 bit)
The startup frame indicator indicates whether or not a frame is a startup frame. Startup frames serve a special role in the startup mechanism. Only ColdStart nodes are allowed to transmit startup frames.
• If the startup frame indicator is set to zero then the frame is not a startup frame.
• If the startup frame indicator is set to one then the frame is a startup frame.
D. MOST, Media Oriented Systems Transport, a communication system with a new, flexible architecture, used by many different manufacturers, was developed to meet these demands. It can transmit audio signals synchronously, as in telephones, and is the most widely used multimedia system in cars today. [15]