The EtherCAT real-time Ethernettechnology that proposed by Beckhoff Company, is now widely used in industrialautomation and in motion control fields. Inthis paper, a slave moduledesign adopted the backplane type iscarried out, based on in-depth study of the ET1200 chip and the Ebusprotocol, including a communication board EKM which regards PIC microcontrolleras microprocessor, a board EKS-IO which is used for digital IO expansion,and a stepping motor control boardEKS-S. Then the overall debuggingand application on a warehousedevice show that the EtherCAT slave controller meets the performance requirements of EtherCAT buscommunication, with better reliability and a certain practical value.