The Tao Of Fieldbus
The Zen way to dissect EtherCAT® protocol
Since 2012 they talk about us, the original and most imited :
"Understanding the bits and bytes of EtherCAT
I recently came across an interesting link regarding EtherCAT that provides the filters and some analysis of just how the EtherCAT packets are formed including full description of the registers for the EtherCAT Slave Controller and the text content of the individual registers/values. The download is available for free from http://www.thetaooffieldbus.com/ and uses Wireshark www.wireshark.org to capture the data. Because the analysis is based on Wireshark the tool can be used regardless of the operating system you are using.
There is also a link to an EtherCAT tutorial at the end of the above link that uses the developed tools to explain, in quite a level of detail the “workings” of this protocol by explaining how to identify lost frames"