[2][3] FlexRay is a communication bus designed to ensure high data rates, fault tolerance, operating on a time cycle, split into static and dynamic segments for event-triggered and time-triggered communications.
FlexRay supports data rates up to 10 Mbit/s, explicitly supports both star and bus physical topologies, and can have two independent data channels for fault-tolerance (communication can continue with reduced bandwidth if one channel is inoperative).
The static segment is preallocated into slices for individual communication types, providing stronger determinism than its predecessor CAN.
The dynamic segment operates more like CAN, with nodes taking control of the bus as available, allowing event-triggered behavior.
The first series production vehicle with FlexRay was at the end of 2006 in the BMW X5 (E70),[5] enabling a new and fast adaptive damping system.
The FlexRay system consists of a bus and electronic control units (ECUs).
Each bit to be sent is held on the bus for 8 sample clock cycles.
The errors are moved to the extreme cycles, and the clock is synchronized frequently enough for the drift to be small.
Clocks are resynchronized when the voted signal changes from 1 to 0, if the receiver was in either idle state or expecting BSS1.
Small transmission errors during the receiving may affect only the boundary bits.
When developing and/or troubleshooting the FlexRay bus, examination of hardware signals can be very important.
Ethernet may replace FlexRay for bandwidth intensive, non-safety critical applications.