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Author Topic: RESET- E-stop & Limit switch's issue  (Read 10348 times)

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RESET- E-stop & Limit switch's issue
« on: January 12, 2011, 06:16:01 PM »
Hello to the Forum..
I am using a HobbyCNC driver and a X Y Z setup I built a long time ago and just got it all rewired and setup to test.

I have configured Mach3 port# and pin#'s for the motors and limit switch's  ok..yet I am having a problem
with Mach 3 recognizing that the E-stop switch and limit switch's are ok..

RESET keeps going active almost at random saying E-stop or limit switch's are active but using the diagnostic
screen I see the limits light glow yellow when I push an X or Y limit switch and the E-stop light will glow
red when I push the E-stop switch ( E-stop pin set for active low).
Measuring the pull-up voltage at the connector for the driver pcb I am measuring 4.43V(5V comes from the driver and measures 5.03V)..that should be high enough to
prevent false triggering.
So I am at a loss as to what else needs to be done..I would like to test out mach3 before purchasing but the way things are
working I may never get to that..so is this resetting issue a way to prevent full operation of this program until purchase?
Just curious about that..
Any ideas out there?

Offline ger21

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Re: RESET- E-stop & Limit switch's issue
« Reply #1 on: January 12, 2011, 06:22:04 PM »
You've got noise giving you false triggers on your switches. Do you have shielded wire on your switches?

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Re: RESET- E-stop & Limit switch's issue
« Reply #2 on: January 12, 2011, 07:36:21 PM »
Yes, the cable is shielded..but the motor wires run in the same cable for each axis too.
The shield is connected only on one end, kinda like a Faraday screen..
I will look at the inputs with a scope and see how much noise is there..I have a feeling separating the limits from the
motor wires is in order..however that doesn't fully explain the E-stop signal randomness unless I am dealing with a
nasty ground loop..:-(

Offline Tweakie.CNC

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Re: RESET- E-stop & Limit switch's issue
« Reply #3 on: January 13, 2011, 05:26:02 AM »

Sounds like you know what to look for, ground loops are so easy to create and cause so many problems. Noise spikes can be extremely narrow and although of high amplitude are still sometimes quite difficult to spot.

UPDATE:Re: RESET- E-stop & Limit switch's issue
« Reply #4 on: January 14, 2011, 08:34:47 AM »
Ok..I finally got the random limits and E-stop to stop triggering..temporarely..
I removed the limit switch wires from the driver pcb but left the E-stop switch, still random triggering going on.
I then went into the input config window and disabled the limit inputs and E-stop input..ahh, quiet now.
So I was able to play and adjust the motor tuning..
So I have purchased a opto isolated parallel port adapter to keep these ground loop/noise gremlins from coming back and next I will separate the limit switch wiring and use shielded cable on all runs to/from the driver pcb.
Thanks to all that helped with this issue and I hope this helps others that may run into this during their cnc builds.