Viper V60 troubles

I am building a mill using V60 drives and Bx7. They repeatedly send a reset to Mach3 but the drives show no fault led. Larken says I need an opto coupler in the fault cct to connect the two boards.
Which two boards? Why do the pdf manuals not show an opto coupler in their drawings? Any help available?

Its because you probably have noise between the drive and bob so try adding an RC filter in the connection. Try adding a 200 ohm resistor and a 100uf Cap. I'm helped you alot but when you start getting rude, im not interested.

Larry