MESA 7i96S and Input config

Hi all,
So my issue is as follows: I want to know if I can use NO with NC switches at the same time easily on the inputs to the MESA card.

My understanding (which could be wrong) is that for switching you should "chose your poison" regarding if you want to use NO or NC switching and wire Ground or Power to common to accommodate. I have 6 NO switches that are configured and operating well (i.e. when switched they close and activate), however, I now want to wire in a Touch off sensor that has a tool touch point (2 wire), and a Master E-stop (2 wire) which are NC and so therefore are always on until switched to open. I am currently running 24V ground to common. IN addition, will be running a probe in separately, and believe this has a 24V input NO to NC (So I think that should be Ok). 

So I guess my question is, do I just wire the same and select "Invert" for the switches that are NC and this is just sorted, or should I re-wire all switches to be NC and run power to common.?

What is the best approach?

Thanks all.

It does not really matter. Each pin has a matching pin ending in -not that is always the inverse of the main pin.
so you can choose which pin you use to set the default position to be on or off.

Hi Rodw,

Sorry, did not quite understand.

So to clarify, you are saying just pin to input as per the others and set to Invert and this will take care of the "non-default (i.e. NO)" position of NC? IN other words, it will set its default position to ON, whereas all the others are set to OFF. Is this correct?

Separately, is there any need to put a resistor in line as I have seen elsewhere when talking about using a alternate.

Is there anything I have missed?

Yes, regardless of whether you use sinking inputs (Input common = GND, switch common = V+)
or sourcing inputs (input common = V+, switch common = GND), the switch "on" state will be the
high state of the input pin in hal.

That means for things like limit and home switches which are active high in LinuxCNC, you must use
the plain inputs pins for NO contacts and the -not pins for NC contacts.

You would only need external resistors if you needed to mix sourcing and sinking input devices.

Note that sinking inputs are generally preferred as they allow mixing of input voltages so for example
you could use a 24V switch voltage along with 5V MPG signals.

Also, NC contacts are preferred for limit/home switches as a broken wire will cause a fault rather than a crash.
 

Sorry, I'm a bit stupid today, but when you say "you must use
the plain inputs pins for NO contacts and the -not pins for NC contacts."

On the 7i96S there are only input pins with a common, not listed particularly as NO (normal pins ref:inputs) or NC (i.e. -not pins).

Do you mean that the NO are set as normal with Common Ground, and when set to NC then the Inversion sets the logical pin "type" to -NOT?

I know I am being a bit anal, but just want to be clear.

Thanks.

Yes, thanks, I understand NO and NC, my question is relating to the reference to the PINS.

There was a reference to use "different" pins. The 7i96S has a set of inputs.

I have it currently wired Ground Common.

So for simple answers:
Can i use mixed NO/NC switching (Common 24V) on the exiting 7i96S Input pins with Ground common?
Do I just use invert when using NC configuring for this to work as designed.

Thanks,