Originally Posted by
doorknob
That should do the job for you.
Just to be sure that I understand you, you're talking about paralleling the AC inputs to the power supply, and by "positive mains" you mean "AC hot wire" and by "negative to negative" you mean "AC neutral", right? That's the way that I would describe it with US power wiring anyway, not sure about Australian power. If so, that should be fine, although you may want to get more sophisticated, for example with separate fuses in the 'hot' leads, one or more power contactor relays possibly controlled by an emergency power off switch, and the like (but that is all beyond the scope of the question that you are addressing now).
Yes that is correct. I have a emergency switch on the AC hot wire between the main on/off rocker switch and the AC input on 48v power supply. This would also cut power to the other power supply.
The G540 inputs 1-4 are taken from a terminal strip, and you will be wiring them directly to the DB9. According to my reading of the proximity switch hookup diagram, you do not need to hook any resistors to those terminals. The resistor shown in the diagram posted by john_100 is the same "pull-up" resistor internal to the G540 that I mentioned in my post above. That diagram shows the G540 inputs as optoisolated, and the resistor is in series with the LED of the optoisolator. You do not need an external resistor, because that one should be fine as it is.
Excellent. Less is better when you are new to the world of electronics.
Note that you will also need to wire a ground connection to the DB9 from the common power supply ground terminal of the G540 (because you will need to connect the -V terminal of each switch to ground). I would not trust the DB9 shell to be that ground, although you might consider connecting one end of the shield of the wire going to the the switch(es) to the DB9 shell (if you are using shielded cable and a metal connector shell and if the chassis mount DB9 is connected to a grounded metal chassis).