It's not FANUC. It's FUCAN!
FUCAN CNC is a collection of circuits designed to enable connection of an Arduino, probably running Grbl, to the "real world", that is, your stepper controllers, limit switches, push buttons and pendants (if applicable), and so on.
Developed by an impoverished university student, it is designed to be budget conscious, whilst minimising compromises on things that are nice to have. One example is that all logic components are in DIP form factor so they can be socketed and easily replaced in the event that the magic smoke escapes a component.
TRI-LIMIT-INTERFACE is a 3 axis limit switch debounce and logical OR board. Because we often have limit switches at each end of our axis limits, this handles debouncing both ends, and sending a single clean signal to the Arduino.
Grbl has some debounce routines in it, but having this board enables changing to other systems that may not have debouncing built in.
LIMIT-INTERFACE is a single axis, strip board version of the 3 axis board. Not everyone can fab a PCB, and not everyone can afford to have the large 3 axis board professionally fabbed. The strip board version can be easily made (and tripled) while getting started. Once you are up and running, you should be able to route the TRI version if you are so inclined.
PUSHBUTTON-DEBOUNCE is a board for debouncing pushbutton switches.
The Arduino Mini Pro is a really neat little board. It takes an Arduino and puts it into a wide DIP array.