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Timeliness in COTS Factory-Floor Distributed Systems: What Role for Simulation?
Ref: HURRAY-TR-0409       Publication Date: 1, Mar, 2004

Abstract:
Throughout the years, researchers have developed and applied a considerable range of theory to the validation of factory-floor distributed real-time systems. In the past few years, it is particularly significant the considerable amount of work that has been devoted to the timing analysis of Ethernet-based technologies. It happens, however, that the majority of those works are restricted to the analysis of sub-sets of the overall computing and communication system, thus without addressing timeliness at a holistic level. In this paper we describe a research framework that is being set-up to embrace this objective. It is known that analytical models to provide real-time guarantees for factory-floor distributed systems, such as those based on worst-case scenarios tend to be overwhelmed with simplifications that often lead to very pessimistic assumptions, and therefore very pessimistic results. In this paper we advocate that discrete event simulation models of a distributed system can be a powerful tool, not only for the timeliness evaluation of the overall system, but also to provide results enabling less pessimistic assumptions for the analytical response time approach. To this end, we address a few inter-linked research topics with the purpose of setting a framework for the development of tools suitable to extract temporal properties of Commercial-Off-The-Shelf (COTS) factory-floor communication systems. In order to consolidate some of the ideas and exemplify some of the concerns outlined throughout the paper, a specific COTS technology, Ethernet/IP, is brought into the discussions.

Nuno Pereira

,

Luis Miguel Pinho

,

Eduardo Tovar

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