When you buy a MC664-X, it comes with 2 EtherCAT axes enabled. You will only be able to go operational on an EtherCAT network with 2 axes. Either a dual axis drive or 2 individual one-axis drives.

To expand the capability of the MC664-X you need to buy enable codes that are effectively licenses to run more axes. The Trio part number for the enable codes is P914; MC664 Axis Upgrade x 2. Each P914 will multiply the axes by 2, so one P914 will give 4 axes, 2 x P914 will enable 8 axes and 3 x P914 will enable 16 axes.