Abstract: This paper uses Siemens S7-200 PLC to construct a temperature control system for an intermittent dyeing machine. The system allows for setting different dyeing temperature curves via a central control computer, and the temperature control process is implemented by a field controller. Keywords: PLC; dyeing machine; temperature control; field controller 1 Introduction Dyeing plays a crucial role in textile production. Dyeing quality directly determines the color and appearance of textiles, and even affects production costs. In the dyeing process, factors affecting dyeing mainly include dye concentration, temperature, and liquid level. Among these, temperature control is a very important and complex process. The dyeing process essentially executes a temperature curve designed by process engineers for different fabrics. Each process has strict requirements for dyeing temperature and the heating/cooling process; otherwise, defects such as color difference, batch difference, and streaks can easily occur, leading to increased re-dyeing rates and production costs. To address the complexity of temperature control, a PLC-based temperature control system for a dyeing machine was designed to control the temperature during the dyeing process, thereby reducing fabric defects, improving production efficiency, and lowering production costs. 2. System Control Requirements 1) Temperature Curve Storage Requirements: Different dyeing varieties have different temperature requirements, resulting in different temperature process curves. Storing all temperature process curves for all dyeing varieties in the field temperature controller would place extremely high demands on the controller's memory, leading to a bloated system. Therefore, this system design uses a central control unit. All inputs are entered by operators on the central control unit and then transmitted to the field controllers via the PROFIBUS DP fieldbus. The field controllers perform temperature control based on the received temperature process curves. Simultaneously, the field controllers can request modifications to the temperature process curve parameters from the central control unit at any time. In the event of a network interruption, the field controllers can save the current temperature process curve and have the function of permanently saving the current temperature curve even after a power outage. For details, please click: PLC-based Temperature Control System