Abstract: This paper introduces a control system based on a PLC-controlled servo motor drive for regulating the capacitor of the EAST-ICRH antenna. The main hardware components and program control of the system are described. Keywords: Programmable Logic Controller; Servo Motor; Capacitor 1 Introduction EAST (Experimental Advanced Superconducting Tokamak) is a new generation experimental device for controlled nuclear fusion research in China. Ion cyclotron wave heating (ICRH) is one of the important methods for heating plasma in this device, mainly through the short-range electromagnetic radiation of a novel ICRH antenna. A vacuum tuning capacitor is installed between the antenna and the feed line to adjust the input impedance of the antenna to match the impedance of the feed line, thereby improving the antenna's radiation capability. During plasma discharge, experimental personnel cannot approach the fusion device, and the tuning capacitor is more than 100 meters away from the control room. Therefore, the matching adjustment of the antenna impedance must be remotely controlled. The capacitor has a plug-in structure, with one electrode being fixed and the other movable. A rotating screw is located outside the capacitor. Therefore, when the screw rotates under the drive of an external motor, the nut connected to it pushes and pulls the bellows, causing the moving electrode to move and changing the facing area between the two electrode plates, thereby changing the capacitance value. 2. Basic System Structure The combination of PLC and LabVIEW is a relatively ideal solution in industrial control systems. To achieve remote control of the true harmonic capacitor, this system uses LabVIEW-developed control system software for the host computer; the slave computer uses a PLC as the hardware core of the system to control the servo motor drive. This section mainly describes the main hardware components and program control of the slave system. A Programmable Logic Controller (PLC) is an industrial computer with strong anti-interference capabilities, wide adaptability, and a wide range of applications, capable of meeting the automation control needs of various equipment. For details, please click: EAST-ICRH Capacitor Control Based on PLC-Servo Motor