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Reliable Real-Time Communication in CAN Networks Outdated
Ref: HURRAY-TR-0109       Publication Date: 1, Apr, 2001

Abstract:
Controller Area Network (CAN) is a fieldbus network suitable for small-scale Distributed Computer Controlled Systems (DCCS), being appropriated for sending and receiving short real-time messages at speeds up to 1Mbit/sec. Several studies are available on how to guarantee real-time requirements of CAN messages, thus providing pre-run-time schedulability conditions to guarantee the real-time requirements of DCCS traffic. Usually, it is considered that CAN guarantees atomic multicast properties, by means of its extensive error detection/signalling mechanisms. However, there are some error situations where messages can be delivered in duplicate or delivered only by a subset of the receivers, leading to inconsistencies in the supported applications. In order to prevent such inconsistencies, a middleware for reliable communication in CAN is proposed, taking advantage of CAN synchronous properties to minimise its run-time overhead. This paper presents the provided set of atomic multicast and consolidation protocols, upon which the CAN reliable real-time communication is guaranteed. The related timing analysis demonstrates that, in spite of the extra stack of protocols, the real-time capabilities of CAN are preserved, since the predictability of message transfer is guaranteed.

Luis Miguel Pinho

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Francisco Vasques