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Author Topic: Home Limit Switch problems Mach3 with HobbyCNC Pro  (Read 10449 times)

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Home Limit Switch problems Mach3 with HobbyCNC Pro
« on: October 20, 2007, 08:46:29 AM »
Hi everyone

This year I bought myself the HobbyCNCPro kit and a 3D milling machine.
As operating SW I decided to by Mach3 from Canada. A very useful
Software, off course!
Now everything went perfect until I wanted to set up the home/limit
switches. I'm using them as follows: Xhome/X-- and X++ in series as
well as Yhome/Y-- and y++ in series. At Z axis I'm using Zhome and Z++.
This means I have on X and Y 2 switches in series and in Z 1 switch.

Now according to the Mach3 manual I've set up and activated all inputs.
If I'm looking at the diagnostic page I see the LED lighting up but
nothing happens. Even more I get the message that a limit switch is
triggered. So I disabled all switches and operate the machine with soft
limits. That works but I would like to use those switches.

I use NC switches and all have the same ground at HobbyCNC Pro and I
use the pins 10 (X) 11(Y) 12(Z). At Mach3 active low is not activated.

I own an older version of the 4AUPC Choper Driver kit. If I connect the
same kind of switches there (with or without power on) Mach3 recognises
the switch an stops immediately. May there be a problem with the length
of the cablings. My Maschine has travel in X 950mm and in Y 650mm. The
longest cable may be (Z) over 2m. I'm using shielded cables with .14mm2.

Does anyone have an idea where I would have to look at. ??? ??? ???

I appreciate all your efforts.

Kindly
Martin Steiner

Offline Hood

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Re: Home Limit Switch problems Mach3 with HobbyCNC Pro
« Reply #1 on: October 20, 2007, 09:49:11 AM »
Try increasing the debounce on the General Configs page.
Hood
Re: Home Limit Switch problems Mach3 with HobbyCNC Pro
« Reply #2 on: October 20, 2007, 10:45:09 AM »
I run the same controller and had the same problem made worse by the fact that I shared the motor cable with the limit switches. You need to add some capacitors to the inputs at the control board between eash switch line & ground. I 'think' I used .1 or .01 caps on mine. It solved the problem with the induced noise on the lines and all is well.
Re: Home Limit Switch problems Mach3 with HobbyCNC Pro
« Reply #3 on: October 21, 2007, 05:41:27 AM »
Thanks Hood for your input. Yesterday evening I tried this but it didn't change anything. But as you may have seen rustyolddog runs the same driverboard and he might have the solution with the capacitors.
Anyway thank you for helping!
Re: Home Limit Switch problems Mach3 with HobbyCNC Pro
« Reply #4 on: October 21, 2007, 05:45:19 AM »
Hi rustyolldog I'm very happy having found someone who was facing the same problem. That's the reason for why I placed this message in this forum. Next week I will get me some capacitors and try all over again. The result I will report to the forum and as well to Dave Rigotti who supllies those driver boards.
Thanks a lot for your help so far and have a nice day.
Kind regards
Martin
Re: Home Limit Switch problems Mach3 with HobbyCNC Pro
« Reply #5 on: October 21, 2007, 07:43:09 AM »
Hey Martin, I went back and searched my old posts on another forum from where I was having the problem, note that 5v is all that is neccessary to change the state of the input:

H-CNC board is chopper drive, &
stepper motors are obviously pulse drive. Noisy, trashy stuff. I
included my limit switch wires in the same cable with the motors. I
put my scope on the limit swith leads at the controller board and I
found 3 Vpp of noise on the switch lines.
I put a .01 cap from the lines to ground and viola, noise was gone
and the home switchs worked as designed. I suspect shieled cable for
the home switches would be in order but I'd still use a cap across
any & all of the I/O lines to reduce the chance of a spike tripping
things.
Re: Home Limit Switch problems Mach3 with HobbyCNC Pro
« Reply #6 on: October 21, 2007, 08:14:12 AM »
Hi Rustyolddog as a matter of fact I'm using shielded cables separately for switches and motors. But still facing this certain problem. As mentioned before I will try with capacitors and see what happens (or not!?). But now as not an electronic specialist where exactely do you put the capacitors in? Ground is clear but than where would I have to hook up the other leg of capacitor. Maybe you can explaine oer send me a sketch by email! Thanks anyway
Re: Home Limit Switch problems Mach3 with HobbyCNC Pro
« Reply #7 on: October 21, 2007, 09:11:56 AM »
I put mine in right on the connector strip where the  wires from your switches go. I used the small monolythic (yellow rectangular kind) between the ground screw and  each switch input. Simple, no soldering required.
Re: Home Limit Switch problems Mach3 with HobbyCNC Pro
« Reply #8 on: October 21, 2007, 10:14:03 AM »
If you say 0,01, do you mean uF, pF or nF for the capacitors?
Re: Home Limit Switch problems Mach3 with HobbyCNC Pro
« Reply #9 on: October 21, 2007, 11:52:37 AM »
.01 uF