基于Modbus通信协议的冷库连续除霜制冷系统的控制设计

Control design of continuous defrosting refrigeration system for cold storage based on Modbus protocol

针对部分小型冷库连续除霜制冷系统存在不能实现实时、稳定的通信以及采集有用信号,导致自动化程度低下、操作繁琐等问题,提出一种可靠的通信设计:以PC作为处理器,PLC作为主控制器,将电脑MCGS组态与PLC利用自身编程口协议进行通信,同时基于Modbus-RTU协议与温湿度采集模块、模拟量输入输出模块等多模块进行实时通信,采集相关数据。利用MCGS组态软件编写脚本程序,并创建通信状态查看、启停控制、实时/历史数据查看、数据曲线查看、故障报警、画面监控等用户窗口,可以实现高效的自动控制和良好的人机交互,提高系统的自动化水平和智能化程度。

Aiming at the problems of the continuous defrosting refrigeration system of some small cold storages that can not realize real-time and stable communication and collect useful signals,resulting in low automation and cumbersome operation,a reliable communication design is proposed:PC is as processing,and PLC(programmable logic controller)is as the main controller.The MCGS(monitor and control generated system)configuration and PLC communicate by own programming port protocol of PLC.At the same time,the real-time communication is achieved among the temperature and humidity acquisition module,analog input and output modules to collect relevant data based on Modbus-RTU protocol.The MCGS configuration software is used to write script programs and create user windows such as communication status viewing,start-stop control,real-time/historical data viewing,data curve view,error alarm,screen monitoring,etc.It can achieve efficient automatic control and good human-computer interaction,which greatly improves the level of automation and degree of intelligence of the system.