Microsecond-Accurate EtherCAT Transmission Scheme for Industrial Cyber–Physical Systems

EtherCAT, an industrial Ethernet standard, supports high transmission rates and clock synchronization, making it well-suited for measurement and control systems (MCSs). Industrial cyber–physical systems (CPSs) rely on MCSs for the seamless integration of computational and physical components. This article proposes the microsecond-accurate EtherCAT transmission scheme (METS), a software-based solution for real-time data exchange that enables consistent and coordinated sampling and actuation in industrial CPSs. METS minimizes master–slave synchronization errors through timebase offset adjustment and message delay compensation and reduces message jitter via heuristic frame transmission scheduling. To address task execution variability, METS supports two scheduling modes: extensive, which aligns transmission with the worst case execution time, and adaptive, which tracks the average of recent execution times. Experiments conducted on an MCS testbed demonstrate that METS achieves synchronization error within $\pm 1.0~\mu $ s, with variance below $0.3~\mu $ s, and ensures high-periodicity message delivery, reducing jitter to approximately $1~\mu $ s. The proposed scheduling mechanism introduces a tunable tradeoff between message delay and jitter, governed by a slack reduction parameter $\alpha $ . A multiobjective optimization study based on the 95th percentile of delay and jitter across workloads demonstrates how designers can tune $\alpha $ to meet specific operating conditions. By enabling robust and precise MCS purely through software on general-purpose computing platforms, METS offers a flexible and scalable solution for industrial CPS applications.