The advantages of communication mode based on PPI protocol between computer and S7-200 PLCs are analyzed.The approach to acquire PPI protocol by intercepting communication data is introduced.

• 分析了计算机与S7-200PLC间基于PPI协议通讯的优点,介绍了通过数据侦听方式获取PPI协议下的通讯数据并对其进行分析,从而解析出PPI协议的方法。