New build – input/comments appreciated

[ngundtoft]

I have started looking at the electrical side of the project. I noticed that GTJim switched to the PMDX-126 BOB, and has a setup very similar to my own. Since the Pilz safety relay PNOZ X9 seems to be available from eBay for reasonable prices, and I do not have much experience with these relays, I have based my diagram on the very nice drawings that GTJim has made.
I have a few questions though:

• You can connect the stepper drivers to the BOB as open collector (common anode) or PNP (common cathode). Has anyone noticed any differences (with eg. noise) by using one or the other type?
• The stepper drivers have Enable signal terminals – which output terminals from PMDX-126 should you use?
• The stepper drivers also have alarm signal terminals – if you would like to use this function how should it be implemented? Should the relay cut power or activate the K pin (machine hold function) on the BOB?
• GTJim has implemented a limit override switch – what is the practical use for this?
• Can you use the K1 or K2 relay (in PMDX-126 for controlling a vacuum cleaner?
• I also noticed that GTJIm uses a separate time delay relay for the power supply (1 to 10s). But this is not really required. I noticed that the Pilz safety relay has an on-delay of approx. 150ms (PNOZ 10) which is perfect for this use. 1 to 10 s is way too long time and only results in heating up the resistor. I could not find a data sheet/wiring diagram for Pilz PNOZ X9. Does anyone have a link for this?
• I am not sure if I should use single or 3-phase connection to spindle motor. 3-phase operation can be implemented by using a contactor controlled from the Pilz safety relay.
• Mains power indicator – since the other power supplies have indicators I think that this one is not really required