The HP-UHU logic supply is 15VDC, I didn't find a suitable 15VDC DIN-rail mount supply so I went for a 24V supply and a 7815 for each drive - seems to work fine. (I wish the logic supply would've been 24V since that is more "standard" but this is fine too)
The limits aren't included in the block-diagram yet.... They are all wired in series with the E-stop, the power-supply is turned off and the bleeder resistor discharges the caps. With no load on the powersupply it discharges from 130 to <20V in ~1s. Mach3 is informed about the Limit-condition via the C11 breakoutboard and on the control-panel there's a pushbutton that bypasses the switches so the system can be enabled again. It also, via the PLC, signals a limit-override to Mach3 so recovery is possible.
The plan is to automatcailly set the jog-rate in Mach3 to a very low value when the Limit-override button is pressed, this will hopefully prevent damaging the machine when jogging off the limit. Not that I will ever hit a limit... ;-/