Chinese 5 axis BoB wiring

Hi 

I'm trying to figure out how to wire my Chinese 5 axis BOB, specifically the home switches. (This is the generic blue BOB that is on sale everywhere)

At the moment I'm powering the BOB with 5V from a PSU. The stepper drivers are powered from a separate bridge rectifier/capacitor combo which produces about 30V DC. The step and direction pins from the BOB are connected to the drivers and all three axes drive fine. Now I have to get the home switches to work. 

I appreciate that I have to also supply the BOB with 12-24V DC which I plan to do from another PSU. My first question is: should this 12V DC share the same ground as the 5V DC? 

The home switches (and the ESTOP switch)  are normally closed.  My second question is Do I just connect one side of each switch to the 5V ground of the BOB and the other side to the input pins as specified in stepconf? (For this to work I presume that the BOB must have internal pull-up resistors which take the inputs high except when pulled low by the switch being close). 

Thanks! 
 

Your switches should connect to ground.

The 12v often on those boards is for the relay and the 0-10v spindle output. Used for vfd's
They can share a ground.

Thanks. All working now. It turns out that the 12V is needed for the switches to work, oddly enough, as well as for the VFD and relay