Motion Control System using SERCOS over EtherCAT

Abstract

SERCOS interface (SErial Real time COmmunication Specification) is known as a universal ‘motion control’ interface, while EtherCAT (Ethernet for Control and Automation Technology) is a high-speed, real-time, topology-flexible industrial ethernet for data communication in process automation and factory automation control system. In order to implement the SERCOS interface on the EtherCAT network, a SERCOS over EtherCAT (SoE) model is used in this paper. By introducing statemachine mapping and data mapping method, the SERCOS statemachine, service channel, IDNs and all kinds of telegram can be supported by EtherCAT. Simultaneously, EtherCAT is accessible to the servo profiles and drive parameters defined by SERCOS. The SoE model ensures the transmission of real-time motion control data in a maximum speed. For illustration, a high speed multi-axis SoE motion control system is developped which operates the highly synchronized movement with multi-servo drivers. The system which combines SERCOS interface with the advantages of Ethernet structure shows the outstanding real-time behavior. This paper provides a kind of brand-new control plan for the numerical control equipment and industrial robots.