[LazyMan]

Is it possible to put 3 proximity switches on one input?

[Al_The_Man]

Usually possible In parallel if they are open collector, and depending somewhat on the nature of the input?
I believe the G540 is sourcing input so you would need O.C. NPN outputs on the Prox.
Al.

[LazyMan]

What is O.C? Do you mean normally open? I was thinking about using this ones New LJ12A3-4-Z/BX Inductive Proximity Sensor Switch NPN DC6-36V | eBay

[doorknob]

There are different styles of NPN output proximity sensors, and it is not clear to me which style is used by the eBay one (but the price is very tempting).

An OC or "open collector" NPN output would be like the one described here (open collector means that there is nothing connected to the collector of the output transistor other than the output terminal):

PMDX.COM - Products for CNC and motion control applications

From that page:

The normally open NPN output allows multiple sensors to be paralleled into one PMDX input. The output is "open collector" and pulls the signal to ground when active.

By connecting multiple sensor outputs in parallel you would be doing a "wired OR" connection (where the signal could come from any of the connected sensors).

Contrast that with the "loaded" NPN output transistor shown here (on page 2 and page 3):

http://www.redlion.net/Products/Grou...Docs/PSA-A.pdf

In that one, there is a built-in "pull-up" resistor to the 12 volt line connected to the NPN output transistor's collector, which would probably not be suitable for the application that you have in mind. However in that app note they claim that it can be used in place of an open collector type, with certain provisos:

Note: PSA-6A, 7A, and 8A outputs are NPN loaded collector outputs
which contain an internal load resistor that is returned to +VDC for
internal feedback purposes. This does not interfere with the ability to
use these sensors as conventional “Open Collector” outputs, as long as
the +VDC for the proximity sensor is supplied by the indicator or
control receiving its output signal. A PSA-6A, 7A, or 8A may be used
as an input to more than 1 indicator or control only if the respective
power supplies are “unregulated” and can load share. These supplies
may then be paralleled together as shown. An indicator or control with
a regulated power supply may not be paralleled.

[Al_The_Man]

I was thinking about using this ones

You could always send a question for more info on it.
As well as O.C. (open collector) you need to know if it is either N.O./N.C.
Normally open/closed.
For parallel operation you need N.O.
Al.

[anthropod]

I think I have my head wrapped around this G540 and proximity switches now.

I have:
(1) G540
(1) 48Volt Power Supply
(5) Inductive, Normally Open, NPN Three wire Proximity Switches. 10 to 30 Volt DC

On order I have (1) DC-to-DC regulator to bring down the voltage of my PS to below 30.

If I wire them in Parallel I should be able to only take up one input. (Although I may use three inputs, one for each axis.)

Does that sound correct?

[doorknob]

It sounds correct to me.

[sclelectronics]

Yes it will work if your sensors are capable of working in parallel!
I using NPN Open Collectors 3wire prox sensors...
I have three connected in parallel for my home switches.
I use a separate 24 vdc sensor/relay pwr supply for them......

Stuart