Home/Limit switch issue

[Mike Bailey]

Computer: Desktop PC
Operating System: Windows XP
CAM Software: Mach 3
CAM Software version: 3
I verified
Not motor issues so NA.
Description of the problem: I have two normally open switches connected between GND and pins 12 and 13. If I disconnect from pins 12 ad 13 and do a continuity check I get 0 ohms when I trigger each switch on the appropriate wire. If I connect a wire to pin 12 I get no continuity on the block when I trip the switch. If I connect a wire to pin 13 I have 880 ohms normally and 440 ohms when the switch is triggered.

I moved one of the switch wires to pin 11 and it worked as it should. I then moved the other switch wire to pin 15 and it killed my computer.
Was the issue with 12, 13 and 15 an issue with my computer?
Mike

[BrianV]

Something I’d fishy in Denmark. I’ll have to draw it out, but no way, no how can it cause any problems with the computer!

Till I can noodle on it, see if the resistor pack by those pins is in the correct orientation.

I’m going to assume an EZ board. Crude drawing attached.

There is nothing but a pull-up resistor.

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[BrianV]

Something I’d fishy in Denmark. I’ll have to draw it out, but no way, no how can it cause any problems with the computer!

Till I can noodle on it, see if the resistor pack by those pins is in the correct orientation.

I’m going to assume an EZ board. Crude drawing attached.

There is nothing but a pull-up resistor.

As a matter of personal preference, I use the NC side of limit/home switches. That way, any switch, wiring or connectors that fail usually will fail open (e.g. fail safe).

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