https://infosys.beckhoff.com/english.php?content=../content/1033/tc3_io_intro/1258020619.html&id=2597873903779157582

https://infosys.beckhoff.com/english.php?content=../content/1033/tc3_io_intro/1257993099.html&id=

https://www.ethercat.org/en/technology.html

https://www.ethercat.org/en/downloads/downloads_7BA2567EB9F443219AD0014448F674F2.htm

https://sir.upc.edu/wikis/roblab/index.php/Development/Ethercat