说明：  绍了西门子PLC对四相步进电机的控制方法和编程技术、控制系统的设计方案及其软 硬件的实现方法，实现了PLC对四相步进电机的转速控制、正反转控制以及步数控制。
(Siemens PLC introduce the four-phase stepper motor control methods and programming techniques, the control system hardware and software design and implementation of methods to achieve a PLC on the four-phase stepper motor speed control, reversing control, and the number of steps control.)