基于PLC的混合液体温度控制系统的设计
摘要：在炼油、化工、制药等行业中，多种液体混合是必不可少的程序，而且也是其生产过程中十分重要的组成部分。但由于这些行业中多为易燃易爆、有毒有腐蚀性的介质，以致现场工作环境十分恶劣，不适合人工现场操作。另外，生产要求该系统要求对混合液体的温度控制是非常的重要的，这也是人工操作和半自动化控制所难以实现的。所以为了帮助相关行业，特别是其中的中小型企业实现多种液体控制温度的目的,液合液体温度控制程序就显得尤为重要。
本文通过对合液体温度控的系统进行设计能更好的应用在化工和制药的企业中去，plc功能是非常的重要的对于实现自动控制是非常的好的，所以对于混合液体的温度的控制非常的实用。
关键词:PLC;混合液；温度设计；控制系统
Design of hybrid liquid temperature control system based on PLC
Abstract: in the oil refining, chemical, pharmaceutical and other industries, a variety of liquid mixing is an essential procedure, but also a very important part of its production process. However, due to these industries are flammable and explosive, toxic corrosive medium, so that the working environment is very poor, is not suitable for manual operation. In addition, the production requirements of the system requirements for mixed liquid temperature control is very important, which is also difficult to achieve manual and semi-automatic control. Therefore, in order to help the relevant industries, especially small and medium enterprises to achieve a variety of liquid temperature control purposes, liquid liquid temperature control procedures are particularly important.
This application can design better in pharmaceutical and chemical enterprise to go through the system to control the temperature of the liquid, the PLC function is very important for the realization of automatic control is very good, so the control for the temperature of liquid mixture is very practical.
Key words: PLC; mixture; temperature control; control system
1绪论……………………………………………………………………………………………………… 1
1.1 概论…………………………………………………………………………………………… 1
1.2 设计的目的及意义……………………………………………………………………… 1
1.3 实验设计的内容…………………………………………………………………………. 1
2 系统总体方案设计……………………………………………………………………………….. 2
2.1 系统硬件配置及组成原理…………………………………………………………. 2
2.1.1 PLC型号的选择……………………………………………………………….. 2
2.1.2 PLC CPU的选择……………………………………………………………….. 2
2.1.3 EM235 模拟量输入/输出模块 ……………………………………….. 3
2.1.4 传感器……………………………………………………………………………… 3
2.1.5 可控硅加热装置 ……………………………………………………………. 4
2.1.6 系统组成原理图……………………………………………………………….. 4
2.3 系统接线图设计…………………………………………………………………………. 6
3 控制系统设计………………………………………………………………………………………. 6
3.1 控制程序流程图设计 ………………………………………………………………… 6
3.1.1 主程序……………………………………………………………………………… 7
3.1.2 子程序……………………………………………………………………………… 7
3.1.3 中断程序………………………………………………………………………….. 8
3.2 控制系统控制程序的开发…………………………………………………………… 8
3.2.1 温度设定………………………………………………………………………….. 9
3.2.2 A/D转换功能模块的控制程序…………………………………………… 9
3.2.3 标度变换程序…………………………………………………………………. 11
3.2.4 恒温控制程序（PID）设计…………………………………………….. 12
3.2.5 数字触发器程序设计………………………………………………………. 16
3.2.6 显示程序………………………………………………………………………… 19
3.2.7 恒温指示程序…………………………………………………………………. 20
3.2.8 报警程序………………………………………………………………………… 20
4 上位监控系统设计……………………………………………………………………………… 21
4.1 PLC与上位监控软件通讯…………………………………………………………. 21
4.1.1 串行数据传送和并行数据传送………………………………………. 21
4.1.2 异步方式与同步方式…………………………………………………….. 21
4.1.3 网络的通讯PPI协议 …………………………………………………… 22
4.2 上位监控系统组态设计…………………………………………………………….. 23
4.2.1 外部设备的定义 ………………………………………………………….. 23
4.4.2 定义数据变量 ……………………………………………………………… 23
4.2.3 数据类型………………………………………………………………………. 23
4.3 实现的效果………………………………………………………………………………. 24
4.3.1 初次上电………………………………………………………………………… 24
4.3.2启动………………………………………………………………………………… 24
4.3.3停止 …………………………………………………………………………….. 25
4.3.4报警 ………………………………………………………………………………. 25
结束语…………………………………………………………………………………………………… 26
参考文献……………………………………………………………………………………………….. 28
辞谢………………………………………………………………………………………………………. 30
附录………………………………………………………………………………………………………. 31
