The special system refers to the places where some special projects are used, which are relatively simple and have specific needs. For example: The State Key Laboratory of Estuarine and Coastal Research at East China Normal University-the Hehai Sediment Sink Experiment Automatic Control System, this system was built specifically for an academic experiment. This system adopts a host computer to choose WINCC system, uses PLC as CPU315, uses Siemens frequency converter, and encoder positioning. Special cases and special cases, designed separately and programmed separately to complete academic functions.