Messages

1

General Mach Discussion / Re: Newbee limit switch false trigger problem

« on: October 10, 2013, 05:29:37 PM »

Yes, both of you are right. And this is good learning experience for me.

The limit switch was triggered continuously and immediately after enabling the limits, without the yellow lights lighting up even once.
I was trusting the yellow light more than the ticker.

In hindsight since the ticker is sticky, its much more reliable than the flicker of the yellow light.


Iqbal

2

General Mach Discussion / Re: Newbee limit switch false trigger problem

« on: October 10, 2013, 04:21:47 PM »

The switches have mechanical hysteresis, they are certainly not bouncy.
They have contact noise, but once they change state they stay set.

The diagnostic page is limited as a visual guide. A trace file recording the events can also help. Especially if some event like that is triggered during a long job run.



Iqbal

3

General Mach Discussion / Re: Newbee limit switch false trigger problem

« on: October 10, 2013, 12:45:07 PM »

So finally
Removed the debounce from Mach3
Changed the debounce in SS from 500 us to 10 us.
Added four 0.1 uf caps to each of the inputs.

The system is able to home correctly on all 3 axis.


One small thing that would have really helped, if the limits lights on the diagnostic page were sticky. That is, once its set, it remains set until its cleared.
A small momentary noise spike will trigger the limit, but there is no visual indication on the panel that such an event has occurred . That kept me wondering as to what the problem could be.

4

General Mach Discussion / Re: Newbee limit switch false trigger problem

« on: October 09, 2013, 12:04:12 AM »

!!! SUCCESS !!!

SS settings for 500 us on each input works.
Strangely the debounce in Mach3 didn't do any good. I am going to remove those. Since they are driven by the SS i am sure the input to Mach3 is noise free. its the noise seen by the SS thats causing the problem.

The power to the entire drive is off, but it would still trigger the limits, so i cannot not understand where the noise is coming from.
I am going to bypass the input limit lines with a 1 uf capacitor, the pull up is 4k, so it should be fast enough. Would like your comment on the bypass cap.
 

5

General Mach Discussion / Re: Newbee limit switch false trigger problem

« on: October 08, 2013, 11:40:31 PM »

Didn't know about SS settings, will try that first.

6

General Mach Discussion / Re: Newbee limit switch false trigger problem

« on: October 08, 2013, 11:21:00 PM »

I am running Windows7 64 bit. No anti virus.
WARP3 USB smooth stepper.
The motor driver is opto isolated to the smooth stepper.

The wires are not shielded. But they are shorted to ground when they are inactive. So I didn't suspect any noise
I have a 300 MHz scope hooked on the input lines to watch for noise, I didn't see any.

I am going to use a shielded wire and try again.
If that works, I am going to kick myself for being a such smart ass.

Iqbal

7

General Mach Discussion / Newbee limit switch false trigger problem

« on: October 08, 2013, 10:21:56 PM »

I am having false triggers with the limit switches.

I have 6 switches, 2 on each axis wired in series. They are wired normally closed. So they are grounded when they are inactive.
Each of the switch functions normally when tested manually on the diagnostic page.
As soon as i enable the limit switches, the Mach3 flashes error "Limit switch triggered" and wont jog.
The diagnostic page has none of the limits lit.
The inputs are normally grounded, the motors are not running, the debounce is set to 1000x40us, i dont think there can be any noise.

What am i doing wrong ? i have attached the xml.
Please help i am stuck.