As far as industrial motion control is concerned, Ethernet, field bus and PCI are all capable of carrying the ısame information between a high-level machine controller and a motion controller. Ethernet is a networking ıprotocol, PCI is a PC bus architecture and fieldbus is used in industrial control. These three technologies are ınow competing for the same users, and while the playing field may be level, the technologies offer their own ıhighs and lows.