基于 PLC 的水箱温度控制系统摘要本文研究的是可编程控制器在水箱恒温控制系统中的应用，水箱恒温控制装置主要用来完成对水箱中液体的液位和温度检测，并对温度参数进行调节。系统中温度控制是一个非常重要的部分。通过铂热电阻对温度进行测量，将测量到的温度传到 PLC 中。PLC 对采集到的温度值与给定值进行比较，经过 PID 运算后，调节双向晶闸管在设定周期内通断时间的比例，改变加热丝中电流大小及加热时间，以完成对温度的控制要求。本系统硬件部分主要由 CPU224、EM235、双向晶闸管等组成；软件部分主要由 PID 控制来完成。关键词：PLC CPU224 EM235 双向晶闸管 PID 控制IAbstractIn this paper, is the programmable controller in the water tank temperature control system application, water tank temperature control system is mainly used to complete the tank liquid level and temperature detection, and adjust the temperature parameters. System, temperature control is a very important part. By platinum RTD temperature measurement will be measured in the temperature reached the PLC. PLC on the collected temperature values compared with a given value, after a PID operation, the regulator Triac off the set period of time the ratio of change in heating wire in the current size and heating time to complete the right temperature control requirements.The system hardware mainly by the CPU224, EM235, bi-directional thyristor etc.; software, some of the major by the PID control to complete. Key words: PLC CPU224 EM235 Triac PID ControlII目录1.前言.........................................................................................................................................................................11.1 恒温系统应用..................................................................................................................................................11.2 PLC 的结构..........................................................................................
