FlexRay is a protocol, which is a joint development activity of, among others, General Motors, BMW, DaimlerChrysler, Motorola and Philips. They aim to develop a protocol that implements a more flexible approach to the time-triggered architecture.

The time of a message round is divided into static and a dynamic segmens. In the static segment only messages already scheduled can be sent. Messages where the time is crucial to the operation (such as orders to the braking system) is sent in this segment.

The dynamic segment is for occasional burst transmissions, diagnostic information and ad hoc messages in general. The dynamic part is limited both in time and bandwidth consumption. The FlexRay system has support for both synchronous and asynchronous frame transfer by dividing the time into these two segments.

Although FlexRay is a broadcast protocol, the all information is not important for each node. A node disregard every message that’s not addressed for them.

The time is externally synchronized using a fault tolerant time synchronization algorithm at every node.

There is guaranteed frame latency time and jitter during the static part of the communications cycle, by using the time triggered architecture for this segment.