Limit and Home Switch Choice

[Wobblycogs]

Thanks for the advice on home and limit switches. Hopefully I've now got a reasonable first stab at a circuit diagram for the machine.

The stuff on the left hand side such as the wiring of the steppers and the power supply control I'm fairly happy with (the power control is basically a copy of circuit Irving drew). I'm a less confident that the stuff on the right is correct.

I'm happy enough with the e-stop circuit as it's just a bunch of N.C. micro switches and a big red button.

The manual for the AM882 drivers seems a bit vague with exactly what happens when the alarm activates. As far as I can tell the alarm can be set to either active high or active low and I'll set it to active high. Since the fault pin on the PMDX is active low and pulled up I've put in a N.O. relay which gets closed in the case of an alarm (because one of the alarms goes high). If I understand correctly the relay is necessarily because the ground for the alarms is not necessarily the ground on the PMDX. I can see this isn't fail safe but I'm not sure it needs to be as a fault shouldn't be an immediately dangerous situation.

The PNP inductive home switches are wired as per the PMDX manual so I think they are correct but I don't understand what is stopping them dumping a ton of power into the PMDX when the sensor is triggered. Do I need a current limiting resistor in the circuit and if so what size? Actually the same question goes for the AM882 fault circuit.

The circuit diagram image is really big, you might be best off right clicking and opening it in a new window / tab.




Now to start reading up on the VFD wiring...