There is info ( schematics and installation and Mach configuration) for each of the boards and the drive.
Read and print them out.
So you will have inputs and outputs ( and note what range of pins can and can't be used for whatever) in Mach for the DB25 pin cable.
Start with the drives as if there were no other boards defining the pins to be used, add one board a time, that will help you define what
pin is assigned to what in Mach.
IE; If you assign a pin in Mach for say a probe, then that signal source comes from one of the boards and is used as an input. That
pin will not be used for anything else. The signal path could be probe signal from the probe connection, thru the break BOB, thru the DB25
connector board and then thru the cable connection to the PC.
So make an overall diagram so you see the signal paths / what connects to what and where.
You probably have options for some things. You decide what your going to use, but don't duplicate.
RICH