https://www.centroidcnc.com/dealersuppo ... 901.r3.pdf
If you want a "really solid system" I'd suggest you remove all that other stuff in the system as it overcomplicates everything and introduces many unknowns and failure points. Not to mention noise and circuits prone to interference. You only need ONE of the breakout boards mentioned by Marty. It plugs into the Acorn and allows you to terminate your step and direction wires from the drives to the Acorn. You could have cut one end off your existing DB25 cable but I'll save that option for another day.
I'd also recommend rewiring the power to your drives, the way they are daisy chained is not correct. Does it work? Sort of. Is it best practice? No.
Consider shielded wire for step and direction signals as well as your limit switches.
Study the diagram above and wire your drive exactly as shown. Do not wire up the enable or alarm outputs. Wire one drive at a time and get it working then add the second and then the third. Then add in the enable signal if it's even needed and then the alarm output to the Acorn.
I'm not sure why you don't have the Acorn control the VFD, it's designed to do this for you. It'll make you life easier.
![Very Happy :D](./images/smilies/icon_e_biggrin.gif)
Just my 2¢.....