FlexRay supports power management wakeup using the wakeup symbol. This wakeup symbol is repeated a fixed number of times. The wakeup symbol only pulls the bus in one direction and this avoids a possible contention that could occur if another node sent the pattern at the same time.

The wakeup pulse is only one direction which allows possible collisions

The wakeup symbol is repeated a number of times as part of the FlexRay cluster configuration

Here the number of wakeup symbols is part of the FlexRay cluster configuration