It can either be done manually by homing the drivers through their external program, or I could get fancy and tap into their I/O and send a signal from the Duet to the drivers when I want them to home. I am leaning towards the second option, because that would allow me to simply tell the drivers to home, and then have the Duet wait for the "homed" or "at endstop" signal. The drivers come from the same company as the linear motors, and have their own built-in system for movement, homing and fault (over velocity/maximum position limiting) handling. I am simply trying to use the Duet and its integrated 3D printing capabilities to command the X/Y/Z axes of the machine as necessary for printing.
Again, I am not sure this is possible using the stock firmware on the Duet, as the physical limit switches are connected to the external drive system. I would be making my own "limit" or really "homing" digital outputs using the configurable I/O of the external drivers.
Thanks for the help. I understand this is an unconventional use of the Duet, but I have high hopes that I will be able to make it functional!