E-STOP Circuit - will this cause any problems?

[birchy]

I have a 3-axis CNC kit from Zapp which consists of 3Nm steppers, M542 drives, 50V PSU and a PCPPS V3 interface board. Bought it some time ago but only just getting on with it. You know what these projects are like...

For the E-Stop circuits, I'm going to use a Telemecanique contactor with a latching circuit and a reset button. Obviously all the stop buttons will be wired in series with dual N.C. contacts on each. I was planning to maintain a constant 24V DC supply for the safety circuit and then drop all remaining AC supplies which would be the Milling machine I'm converting, the 50V PSU and the PC. The PCPPS board would still be powered as it will be connected to the 24V DC supply. Will this setup cause any problems or risk buggering any of the components? I can probably cut the 24V to the PCPPS as well but may not have a N.O. aux available on the contactor.