Abstract : To improve the operational capability of metallurgical raw material cranes, this paper presents a frequency converter drive system based on Siemens PLC. The PLC and frequency converter are key components of this system, and the various units are interconnected via the PROFIBUS-DP fieldbus to form the control system for the metallurgical raw material crane. Operational results show that the system not only has fast response but also high reliability, high flexibility, and scalability. Keywords : Frequency converter, PROFIBUS-DP, control. Siemens frequency drive products include two main categories: MASTERDRIVES VC/M and MICRO MASTER. The former is an engineering-grade frequency converter, while the latter is a general-purpose frequency converter. In the newly installed 50T raw material AC crane at our plant, the hoisting mechanism uses a 6SE7031 series installed and cabinet-type engineering frequency converter, while the translation mechanism uses a 6SE6440 series general-purpose frequency converter. The system control equipment used in this AC crane is a Siemens S7-300 PLC with a CPU of 6ES7313-1AD03-0AB0, and the monitoring equipment is a Siemens TP17DA touch screen. In terms of technical configuration, this equipment is relatively advanced among similar equipment in the metallurgical industry. 1. Process Control Approach The main function of the metallurgical raw material crane is to transport raw materials for the smelting production process, occupying a crucial position in the process. Due to its importance in production, considering performance stability and operational safety, the design aims to maximize the performance of the control equipment and drive devices, ensuring safety, stability, reliability, and optimization to meet the requirements of the smelting production process and adapt to the fast-paced production of modern enterprises. To ensure the equipment's performance is fully utilized to meet the needs of fast-paced production, a fieldbus communication protocol is introduced into the control system. The system uses a PLC as the control center, the PROFIBUS-DP fieldbus communication protocol for data communication, and advanced control methods combined with a frequency converter drive to complete the entire system control process. To improve equipment uptime during maintenance and repair, reliability, safety, simplicity, and optimization are always key principles in electrical control system design. Considering the characteristics of metallurgical enterprise production and the operating environment, and leveraging the high reliability of control equipment, design efforts are strengthened to ensure stable equipment operation, allowing the advanced control functions of the equipment to be fully realized during production. [b][align=center]For details, please click: Application of Siemens PLC-Controlled Variable Frequency Drive System in Metallurgical Raw Material Cranes[/align][/b]