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Homing failed
« on: April 05, 2015, 06:40:53 AM »
I got some inductive prox sensors hooked up and they light up nicely on the Diagnostic page when you hold metal over 'em.

So I hit the Ref Y and all that it did was twitch once and the axis turns green.  It's nowhere near the home.

I thought maybe I screwed up the level, changed to Active-High, and then it said "homing switch already active, fix this and try again".  OK so no it was right before, and I put it back.

Now before this, I had the pin set to the wrong port, and of course the Ref Y operation just drove past the homing switch and banged into the mechanical stops.  But that tells me Mach3 DOES know how to drive the axis.

Noise is on the list of suspects, but I didn't see the M2 Home light blink on the Diagnostics page when moving the axis.  Also it just twitched the motor once and stopped.  It didn't do the run-into-the-homing, back-off, reapproach-slowly-and-stop.


Any ideas?

Offline ger21

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Re: Homing failed
« Reply #1 on: April 05, 2015, 07:41:53 AM »
I'd say it's noise. To check, set the debounce in General Config to a very high number, like 10,000 or 20,000. If it works, it's noise.

You often won't see the LED light up if it's noise, as it happens much too fast.
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Offline stirling

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Re: Homing failed
« Reply #2 on: April 05, 2015, 09:13:47 AM »
other thing you could try is to temporarily configure your switches as limits. Does it trip when stationary? - (noise from somewhere) or does it only trip when you move? (noise from motors etc.)
Re: Homing failed
« Reply #3 on: April 05, 2015, 03:17:25 PM »
I'll try that.  The wires do run parallel to the stepper wires for a long distance, and it's open-collector with a pullup resistor, so noise could definitely be an issue.

But there is a shield around that cable.  Hmm wait though I may not have connected the drain to anything, I ran out of space to put wires.  Will check.
Re: Homing failed
« Reply #4 on: April 06, 2015, 01:04:58 AM »
IMPORTANT: I have a Warp9 Ethernet Smoothstepper.  That's important, sorry, I should have mentioned that.

I went at it again.  Actually made it all the way home once, other times it went a few inches and stopped, or only twitched.

I set Debounce higher, it didn't help.  I think I put in 100 which would be 4ms.

I changed the pin from Y Home to Y-- Limit.  Then, yes, it just randomly went into Reset "Limit Switch Triggered" after a moment.  Sometimes it wouldn't clear when Reset was clicked, other times it cleared for a few moments and reset.  So yeah it's false-triggering the input, even without moving the motors.  I changed the Y-- Limit pin to a pin used for another prox sensor that hasn't been config'ed in yet.  It also threw the "Limit Switch Triggered" error from there.

I checked, the shield's drain WAS connected on the board's ground.  On the sensor's side, the drain wasn't connected but usually that's not important.

I put a Fluke meter on that input and saw 4.92v DC with no twitching.  I switched to AC and it was 0.000v.  That's not entirely definitive but it looks unlikely to be cable noise.  Yeah I should have disconnected the wire totally, it's open-collector anyhow, but I didn't think of it at the time.
« Last Edit: April 06, 2015, 01:07:03 AM by MechanoMan »

Offline stirling

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Re: Homing failed
« Reply #5 on: April 06, 2015, 08:12:15 AM »
You won't register noise on a meter. Try turning your motor drivers off and see if you still get limit trips.