After being flat out making stuff with the cheezoid yoocnc setup I finally decided to get stuck in to building the 542 with bob box - the main reason being the yoocnc went tit's up (spindle won't stop spinning) so with that said I got the 542's wired to the bob, I can see where the e-stop, limit switches etc go, where the X,Y,Z wires go but what about the spindle and or spindle power? The only other free connection says 'relay' - or is the spindle powered by the 5v???

These are the bits I bought, gunna make use of my existing PSU which looks like the round jobby - 3X M542 CNC Stepper Driver FOR NEMA17 NEMA23 NEMA34 Motor 5 Axis Breakout Board | eBay

Looking at all that has me none the wiser so any help wiring it up would be much appreciated.