Theoretical and Experimental Evaluation of Ethernet Powerlink PollResponse Chaining Mechanism

Ethernet Powerlink (EPL) is an industrial Ethernet networking solution commonly used as a communication network in distributed control and automation systems ranging from simple I/O to highly complex motion control applications. The PollResponse Chaining (PRC) mechanism is a new EPL standard feature aimed at increasing the network performance when nodes exchange small amount of data, especially if they are connected in line topology. In this paper, we present a theoretical model suitable for assessing the real-time performance of the EPL protocol operating in both the standard and PRC mode for two basic topologies commonly found in real installations, line, and star. Moreover, we carried out a series of experiments on prototype networks in order to acquire the relevant timing parameters of the EPL network components required for the development of an OMNeT++ simulation model, which can be further exploited to evaluate the EPL protocol in the case of more complex scenarios. Finally, we propose a modification of the original PRC solution to improve its flexibility while allowing the same (or even higher) performance level. The feasibility of the proposed approach was demonstrated on a real prototype, whereas a certain performance gain over the original PRC mechanism was proved through simulations conducted on a more complex network structure.