Rapita Director’s Controller Area Network research “most downloaded” in Real-Time Systems journal

York, UK, 15th November 2010 A paper by Robert Davis of Rapita Systems has become the most downloaded from the Real-Time Systems journal. “Controller Area Network (CAN) schedulability analysis: Refuted, revisited and revised” identified flaws in the original analysis from the 1990s and recommended ways to revise schedulability analysis tools. The paper was co-written with Alan Burns, Reinder J. Bril and Johan J. Lukkien. “I am delighted that this important work, with its high impact and relevance to the automotive industry, is receiving such wide attention from both industry and academia”, said Robert Davis. Here is the original Abstract: Controller Area Network (CAN) is used extensively in automotive applications, with in excess of 400 million CAN enabled microcontrollers manufactured each year. In 1994 schedulability analysis was developed for CAN, showing how worst-case response times of CAN messages could be calculated and hence guarantees provided that message response times would not exceed their deadlines. This seminal research has been cited in over 200 subsequent papers and transferred to industry in the form of commercial CAN schedulability analysis tools. These tools have been used by a large number of major automotive manufacturers in the design of in-vehicle networks for a wide range of cars, millions of which have been manufactured during the last decade. This paper shows that the original schedulability analysis given for CAN messages is flawed. It may provide guarantees for messages that will in fact miss their deadlines in the worst-case. This paper provides revised analysis resolving the problems with the original approach. Further, it highlights that the priority assignment policy, previously claimed to be optimal for CAN, is not in fact optimal and cites a method of obtaining an optimal priority ordering that is applicable to CAN. The paper discusses the possible impact on commercial CAN systems designed and developed using flawed schedulability analysis and makes recommendations for the revision of CAN schedulability analysis tools. Visit www.springerlink.com to download the paper in full.