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Purpose This paper aims to analyze the key factors influencing the synchronization performance of distributed motion control system and to improve the synchronization performance for peripherals control of this system. Design/methodology/approach This paper deals with the software synchronization problems of distributed motion control system based on real-time Ethernet. First, combined with communication and control tasks, the key factors affecting synchronization performance of system are analyzed. Then, aiming at key factors and considering the synchronization of system bus, protocol conversion and task scheduling, a software synchronization method based on CANopen protocol and real-time Ethernet is proposed. Finally, the feasibility of this method is verified by establishing distributed motion control system and testing the synchronization performance of terminal control signals of slaves. Findings Based on this method, the results show that the synchronization accuracy for peripherals control of all slaves could be about 100 ns. Practical implications This research provides high-precision synchronization method, which could lay a foundation for the application of distributed motion control system in the field of assembly automation, such as multi-axis assembly robots control. Originality/value In distributed motion control system, many factors affect the synchronization performance. At present, there is no synchronization method that could comprehensively consider these factors. This paper not only analyzes the key factors influencing the synchronization performance of system but also proposes a synchronization method. Therefore, the method proposed in this paper has certain theoretical value and engineering significance.

With the penetration of real-time Ethernet in industry, the mechanism of CANopen protocol based on real-time Ethernet (COE) has been widely used in various distributed control systems. However, due to some defects of the existing COE mechanism, the functional integrity and security for communication could not be guaranteed. Thus, Safe-COE architecture is designed in this paper. First, safe communication problems in systems are analyzed. Then, based on the Security and Safety Modeling (SESAMO) method, safe building blocks for communication are designed and combining these building blocks with Safe-COE mechanism, a kind of Safe-COE communication architecture is proposed. Finally, communication performance is tested based on this architecture. The results show that based on the general Ethernet MII bus interface, the minimum communication cycle could reach 125 μs , and the minimum synchronization accuracy of peripherals control could be about 100 ns. Moreover, the formal modeling method is used to verify the safe integrity of this architecture. The results show that the architecture could meet related safe requirements of attack protection, data validation, disconnect monitoring, and state switching. Currently, there is no safe communication architecture for a distributed control system that could fully meet related standards and consider both functional safety and information security. It could provide a theoretical basis and solution for safe communication in the distributed control system.