Network delay analysis of EtherCAT and PROFINET IRT protocols

Real-time protocols originated from standard Ethernet technology have been gradually developed over the last decade. Candidates of real-time Ethernet protocols are EtherCAT and PROFINET IRT from Beckhoff and Siemens, respectively. In contrast to standard Ethernet, data-link layers of both Ethernet-like networks are modified from IEEE 802.3 in order to improve real-time capabilities for critical communications. Network delay refers to data transfer time on a network. It is of great importance to assess this parameter for industrial networks as it can possibly make significant impact to the control system performance. This paper gives network delay analysis on EtherCAT and PROFINET IRT in the context of industrial applications. Delays are formulated and then evaluated under both synchronous and asynchronous system configurations. Simulation results demonstrate that both protocols are of realtime guarantees in data transfer. However, each protocol has its own characteristics and strong points due to different MAC layer design.