摘要:水位的控制和监测在农业和工业生产中的应用越来越多。与此同时，生活中的水位控制也越来越重要。然而随着社会的不断发展，人们生活质量也随着不断提高，对用水的需求不断增长，传统的水位控制方法单纯依靠软件编程实现，能耗大、不方便维护、操作复杂等缺陷逐渐暴露，已经满足不了人们的实际需求。

　　　本文在传统的以西门子S7-200系列PLC为控制核心的基础上，加入PID闭环控制方法，对水塔水位实现综合控制。在传统控制系统中，加入液位传感器和控制模块。实现原理是液位传感器将测量的实际的液位高度传递给PLC，PLC通过A/D转换，将液位值转化为数字量与设定值进行比较，通过差值控制水泵和阀门，进行进水或出水，同时设有报警电路，当水位高于或低于某个设定值时，触动报警器，控制模块用来显示整个过程和整体控制。本文很好的将PLC控制与PID控制方法相结合，形成了一种更好的水位控制方案。

关键词 水位控制；西门子S7-200；液位传感器；控制模块；设定值

Abstract:Control and monitoring of water level is more and more applied in the agricultural and industrial production. At the same time, the water level control is becoming more and more important in life. However, with the fast development of society, the quality of people life rise ceaselessly, the demand for water is also constantly improve, the traditional method of water level control relying on software programming implementation start to show it’s shortage, large energy consumption and inconvenient maintenance, operating complex defects exposed gradually, people is not satisfied with it for the actual needs .

　　　Based on the traditional with the Siemens series S7-200 PLC as the core, on the basis of joining PID closed loop control method, the water tower water level to achieve integrated control. Adding sensors and control modules to traditional control system. Principle was A liquid level sensor to measure the actual level of transmitted to PLC, PLC through A/D conversion, liquid level value could be converted to digital quantity comparing with set point, through differential control pumps and valves, water or water, at the same time equipped with alarm circuit, when the water level above or below a set point, alarm, and control module used for displaying the was whole process and the overall control. It is very good in this paper that PLC control combined with PID control method has formed a better water level control scheme.

Keywords  Water level Control  Siemens S7-200  Sensor  Control Module  Set Point