西門子公司的SIMATIC S7-200 系列是適應于中小型設備控制的微型PLC， 應用領域廣泛。無論是獨立運行或相連成網絡皆能在自動化系統中實現復雜的控制功能，強勁的通信能力使其在同類PLC 產品中獨具特色。本文以飛剪控制系統為例，介紹了S7-222 的通信方式，著重闡述了自由口通信的參數設定、協議規劃和通信程序設計 。
關鍵詞：PLC；S7-200；Win9x；自由口模式；串口
the Implement of Communication between PLC and PC Abstract：The PLC of SIEMENS SIMATIC S7-200 series is suit for small and middle controlling systems. It is widely used in many areas. It fulfills complicated controlling tasks whether individually or in networks. It’s powerful communication ability makes itself distinguished in PLC products. The article takes a flying shear system for example, introduces the communication method of S7-200, mainly discusses the parameters, protocols and programming in Freeport mode.
Key words: PLC;S7-200; Win9x;Free-Port;Serial Port