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Author Topic: Can I mix NC / NO limit switches? If yes, is my LPT1 broken?  (Read 2474 times)

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Can I mix NC / NO limit switches? If yes, is my LPT1 broken?
« on: January 27, 2014, 06:17:00 PM »
I'm updating the controls on an older router right now to use a Gecko G540 and Mach3, and I'm having trouble with the limit switches.

The manufacturer used NO for the Z axis and NC for the X & Y, and they're giving me fits.

Obviously I can't use NO & NC together when wired in series, so I've got each switch (all ++, used for both ++ and home on each axis) set up on a different input on my Gecko.  They're plugged into pins 1-3 on the Gecko, in order of X-Y-Z.  One wire goes to the Gecko, the other goes to the -48VDC pin on my power supply.

When I disconnect the switches and use a meter on them to check continuity, I get the expected behavior.  The Y-axis switch shows 0 ohms, and goes open when I press the button.  The Z, of course, does exactly the opposite.  When I wire them in, however, things start to go south.  The switches don't respond to anything anymore.  Automatic input setup doesn't recognize them as inputs.  I've even gone to the level of pulling the manufacturer's wiring harness and adding a new one of my own, so I know it's not the wiring.  I'm almost wondering if it's an issue at the Gecko, because even if I disconnect the switches and jumper the input to the -48VDC pin, nothing happens.  (It's unlikely to be a Gecko problem though - it's brand new.)

Anyway.  Next possible culprit is my parallel port.  If I'm not in the right mode (EPP vs ECP vs w/e), will I have LPT1 pins 11/12/13 as inputs still?  I know that pin 10 is still being used / recognized as an input.  Is there a way to tell if my LPT1 is set to the right mode?  (My BIOS doesn't show the info - my only options there are enable & disable.)  Computer is a Gateway E4300 running Windows XP SP3.


Thanks ...


Offline Hood

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Re: Can I mix NC / NO limit switches? If yes, is my LPT1 broken?
« Reply #1 on: January 29, 2014, 06:03:31 AM »
I do not know anything about the G540,it may be expecting the Input to be grounded or it may be expecting to be supplied with 5v, you would have to see what the manual says for that.
I can say however there is no problem with using either NC or N0, as long as they are not on the same pin of course. In Mach you would just need the active state for then set to opposites, one would be active High the other Low.
Hood

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Re: Can I mix NC / NO limit switches? If yes, is my LPT1 broken?
« Reply #2 on: January 29, 2014, 07:23:59 AM »
I do not know anything about the G540,it may be expecting the Input to be grounded or it may be expecting to be supplied with 5v, you would have to see what the manual says for that.
I can say however there is no problem with using either NC or N0, as long as they are not on the same pin of course. In Mach you would just need the active state for then set to opposites, one would be active High the other Low.
Hood
Well..... that depends on how you wire them  :P

Offline Hood

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Re: Can I mix NC / NO limit switches? If yes, is my LPT1 broken?
« Reply #3 on: January 29, 2014, 07:51:57 AM »
Please elaborate Ian :)
Hood

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Re: Can I mix NC / NO limit switches? If yes, is my LPT1 broken?
« Reply #4 on: January 29, 2014, 08:11:31 AM »
pullups or pulldowns

Offline Hood

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Re: Can I mix NC / NO limit switches? If yes, is my LPT1 broken?
« Reply #5 on: January 29, 2014, 08:23:28 AM »
Quote
They're plugged into pins 1-3 on the Gecko, in order of X-Y-Z.  One wire goes to the Gecko, the other goes to the -48VDC pin on my power supply.

My reply was in response to the OPs method ;)

Hood

Offline stirling

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Re: Can I mix NC / NO limit switches? If yes, is my LPT1 broken?
« Reply #6 on: January 29, 2014, 08:27:23 AM »
I'll get my coat  ;D