Ethereal (Wireshark) is a popular network protocol analyzer and it is free software without licensing fees. Ethereal is used by network professionals around the world for troubleshooting, analysis, software and protocol development, and education. It has all of the standard features you would expect in a protocol analyzer, and several features not seen in any other product. It runs on all popular computing platforms, including Unix, Linux, and Windows.
Starting now Ethereal is able to decode the complete PROFINET protocol suite, including the application protocol for PROFINET. Also decoded are RT (Real Time Communication) and DCP (Discovery and Configuration Protocol). This tool enables the device developer to develop efficiently PROFINET devices.
Ethereal is now called "Wireshark" and available for download via internet under: