1，How do you establish an open TCP/IP communication connection (without RFC1006), and exchange data, between a CPU 315-2PN/DP and a partner station (PC) via Ethernet?
http://support.automation.siemens.com/CN/news/en/19553230

2, How is an open TCP communication connection established between an S7-300 PN CPU and a CP343-1, and how is data exchanged?
http://support.automation.siemens.com/CN/news/en/25620930

3, How is an open TCP communication connection established between two S7-300 PN CPUs, and how is data exchanged?
http://support.automation.siemens.com/CN/news/en/25621631