The 425 oz-in motors that you currently have are possibly a little
underpowered for a 4' x 4' router depending on how fast and hard
you need to cut. Hopefully this is a gantry machine with a tandem
setup moving the gantry.
More powerful motors would require upgrading to a NEMA 34 or
to NEMA 23 oversize 60 mm motors which typically have a 3/8"
shaft instead of a 1/4" shaft. For this reason I would recommend
running your machine for a while before deciding to upgrade the
motors.
Likewise upgrading your driver box will not significantly change
things because it is already well matched to the motors and
delivers the full 4 amperes that the motors can take.
The PMDX-424 has a ribbon header that can be used to connect
the step and direction signals to the Xylotex box with the
PMDX-DB25Ribbon, PMDX-DB25Ribbon-18 cable, or equivalent.
The home and limit switches would connect to the PMDX-424 directly.
The PMDX-407 would supply signals to control a VFD inverter to
run a high speed spindle. If you are using a regular Bosch, Porter
Cable, or other manual style router then you do not need the
PMDX-407 since computer control of these routers is not typically
implemented.
The PMDX-179 is a nice touch, but it is optional.
If you decide that you later need to upgrade your motors and
drivers, the PMDX-424 can interface to many types of drivers
including the Geckos.
When you are unsure of how to wire things, we recommend
that you read and try to understand examples, then ask us
questions where you cannot find examples or data sheets.
Then try to draw your own wiring diagram and send it to us.
This will allow us to make sure that your wiring is valid and
more importantly, that you understand your wiring instead
of having us assume that you have followed a diagram that
was provided to you.