说明：  对西门子公司尚未公布的PPI 协议的通信过程、协议内容和功能实现等方面进行了详细的研究与分析,掌握了西门子PPI 通信协议的有关技术细节 给出了利用通信程序形成的报文数据,并对其进行测试与分析,能够用于PLC 的远程监控。
(This paper analyzes the content and implementation of Siemens PPI communication protocol yet to be released , and studies it s technical details. The datagrams are tested and analyzed , and proven to be applicabe to all the functions for PLC remote monitoring.)