Performance analysis of Profinet networks

Nowadays, Ethernet networks may be profitably employed also at the lowest levels of factory automation systems. Indeed, suitable application layer protocols for Ethernet have been recently developed in order to cope with the critical requirements imposed by the industrial applications. In this paper we focus on the protocols used by PROFINET, an emerging standard for industrial communications based on Ethernet, which is now available in two different versions, named CBA and IO. After a description of the protocols, we show the results of some tests aimed at evaluating the performances of such a network. In particular, we concentrate the attention on the times necessary to transfer limited amounts of data among stations. With regard to PROFINET CBA, the outcomes of an experimental set-up comprising several components, show, for the transfer times, highly variable values, dependent on the network load. Conversely, for PROFINET IO, the results of a set of numerical simulations we performed, allow to expect constant transfer times of some milliseconds, or even less, provided that an accurate time synchronization between stations is maintained.