Click image for larger version.  Name: DSC01916.JPG  Views: 339  Size: 891.0 KB  ID: 19676Click image for larger version.  Name: DSC01917.JPG  Views: 327  Size: 827.8 KB  ID: 19677 I use P16 for coolant (just an air blower really) and P17 to turn the spindle on (Kress, not a three phase one with speed control)

You may like to play with active high / low and whether you connect to NO or NC on the relay as there can be some activity on the pins before Mach3 takes control.

Cheers,

Rob