Introduction

Motor vehicles are subject to a genuine electronification. The motivation for the massive use of electronics is diverse, ranging from the desire for more convenience and driving safety to concerns about fuel economy and reduced emissions. The migration of ABS, ESP and other innovative driver assistance functions is causing electronics to increasingly penetrate into safety-critical areas. This is in part based on efforts to approach the vision of a state of autonomous car driving.

Gradually, electronic interfaces to the chassis (x-by-wire) are merging with existing safety-critical and very dynamic control applications to create distributed electronic systems that must be up to the task of satisfying challenging requirements for reliability and real-time capability.



A key role is played by cross-ECU communications. Real-time capable, fault tolerant communication systems provide for smooth data exchange between the individual "Electronic Control Units or ECUs" in the system network.

In this context, increasing importance is being ascribed to time-triggered serial bus systems whose core properties include activation of static, predefined time-based actions in the distributed system, and facilitation of concepts such as fault tolerance by coupling of redundancies. The serial bus system fulfils these requirements excellent.

The communication in a flexray network is based on the TDMA (Time Division Multiple Access) method. The send times of all messages to be transmitted are predefined in a communication schedule (messages schedule). During active communication, the messages schedule – consisting of a number of so-called time slots – is repeated periodically in time, which results in communication based on communication cycles. Assigned to each time slot is a bus node with a very specific message. Collisions and overload situations are excluded – guaranteeing deterministic data transport.