PLC-controlled water tank level control system Abstract:In people's lives and many fields such as industrial production often involves the control of liquid level and flow problems, such as water supply for residents, beverages, food processing, solution filtration, chemical production and other sectors of the production process, often need to use the build liquid pool, build pool liquid level the need to maintain an appropriate height, overflow can not be too wasteful, nor too small and unable to meet the demand. Therefore, the process of industrial control surface height is an important parameter, especially in a dynamic state, the use of appropriate methods to detect liquid level control, to receive good results. Programmable Logic Controller (PLC) is a computer in a family is to design and manufacture of industrial control applications, mainly used to replace relay logic control to achieve. PID control (proportional, integral and differential control) is currently the most used control methods. This article is a water tank level control system design process, involving the dynamic control level, control system modeling, PLC control, PID algorithm, sensors and control valve and a series of knowledge. As a single-capacity water tank level control system, its model is one-order inertia function, the control mode of the PID algorithm is used to control the core for the S7-200 series, CPU222, and A / D, D / A converter module, the sensor for the proliferation of silicon-type pressure sensors, regulating valves for electric control valve. Use the above device equipment, the control program and algorithms, in order to be able to satisfy the system such as control precision, adjusting the time and the overshoot and other quality control requirements Key words: PLC PID level control
