基于S7-200 PLC的某除湿机控制系统设计

Design of a Dehumidifier Control System Based on S7-200 PLC

采用西门子S7-200PLC为主控制器,配以人机界面TD400C和通信模块EM277,设计了某除湿机控制系统。温度、湿度的采集采用频率输出方式的传感器/变送器,将频率信号接入PLC集成的高速脉冲输入口,定时计数从而得到采样值。控制指令可以从数字输入接口、TD400C或上层计算机获得;系统运行状态也可在数字输出接口、TD400C上显示或传送至上层计算机。现场应用情况表明,系统运行可靠、使用方便,可以作为智能节点集成到现场总线控制系统中。

A dehumidifier control system based on S7-200 PLC, HMI TD400C and communication module EM277 is designed. Date acquisition of temperature and humidity sensors or transducers is by means of frequency-out. The frequency signals are connected to the high speed counter of PLC. To count the pulses in definite time so as to the sampling value can be obtained. The control instruction can be got from the digital input interface, TD400C and upper computer, and the running status can also displayed on digital output interface and TD400C or transfer to upper computer. Field application shows that the system runs reliably and it can be integrated into the field bus control system as intelligent node.