Guaranteed Message Latencies For Distributed Safety-Critical Hard Real-Time Control Networks

Analysis is presented that enables the worst case latencies for Controller Area Network (CAN) messages to be predicted. The analysis is illustrated in terms of the Intel 82527 controller and applied to a SAE benchmark. This benchmark contains some 53 message types; all of which are analysed for various transmission rates. Techniques are presented that enables the temporal behaviour of a CAN system to be improved. In particular the impact of message "piggybacking" is assessed. The paper concludes by considering error recovery, and presents a framework into which different failure models can be incorporated and analysed (in terms of the impact failures have on message latencies). 1. INTRODUCTION A recent trend in many control systems is to connect distributed elements of a control system via a shared broadcast bus instead of using point-to-point links [1]. However, there are fundamental differences between a shared bus and point-to-point links. Firstly, because the bus is shared between..