SIMATIC S7-300 programmable logic controller is a modular small and medium-sized PLC system that can meet the needs of medium-performance applications. It has a wide range of functional modules that can meet and adapt to automatic control tasks very well. The simple and practical distributed structure and multi-interface network capabilities make the application very flexible. It also has a user-friendly and simple fanless design, as well as the freedom to expand when the control task increases.