Abstract : This paper introduces a polyester staple fiber post-spinning stretching control system that uses PLC, frequency converter, and touch screen, and discusses the composition, working principle, and software design ideas of the control system. Key words : PLC Inverter Parallel DC Rink bus Drawatio Synchronization 1 Introduction As shown in Figure 1, the polyester staple fiber post-spinning stretching system mainly consists of a guide machine, a three-stage seven-roller system, and a crimping machine. A stable, adjustable, and accurate stretch ratio is required between the three-stage seven-roller system, and a certain tension is required between the guide machine and the seven-roller system, and between the seven-roller system and the crimping machine. Precise control of the stretch ratio is a crucial part of the entire stretching system, directly affecting the quality of the staple fiber product. Traditional synchronization and stretching ratio control methods generally employ a single motor drive with a long-side shaft connection, relying on a mechanical continuously variable transmission (CVT) for speed regulation to achieve stretching ratio control and system synchronization. This approach suffers from drawbacks such as difficulty in adjusting the stretching ratio, low accuracy, large variations, and a high failure rate of mechanical equipment. This article focuses on introducing a stretching synchronization control system that utilizes a PLC, frequency converter, and touchscreen, with each stretching unit driven independently. [b][align=center]For details, please click: Application of PLC-Controlled Frequency Converter in Short Fiber Stretching Systems[/align][/b]