The originator is mk6, and ARCnet is used on Mark V.
Your best bet would be to talk to Contemporary Controls; their website is http://www.arccontrol.com. They have some very intelligent and helpful people; if you explain your problem/situation, they might be able to help. They have some USB-to-ARCnet devices that might be what you're looking for.
But we don't know what you're trying to solve or accomplish, and it's still unclear about the whole mk6 and ARCnet thing.