Limit and Home Switch Choice

[Wobblycogs]

As always Dean a couple of very good points. I knew as soon as I said I was happy with the e-stop circuit that there would be something wrong with it , it's my super power.

As you suggested I've put in a relay and run 24V through the switches. Can I just check that my understanding of how this works is correct. I think this is a suitable relay. Since the voltage is 24V and the coil resistance is 2.8k will this portion of the circuit draw 23/2800 = 8.6mA? It can handle 2A across the contacts which must be about 500* what the PMDX will put through it.

I was using PNP sensors because I had a 24V supply already in the system. That's a really stupid reason to make life difficult for myself though so I've switched them over to using NPN. I assume 12V is sufficiently noise immune for this to not be a problem?

Is the two e-stop button arrangement a good / bad idea? The one at the top left will completely kill everything by removing power. I only envisage using that in "hand-being-eaten-by-the-machine" emergency and it will be on the control box (probably). The e-stop button connected to the PMDX is for "uh-oh-that's-not-good" type emergencies and will be mounted on the machine.