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Author Topic: Homing and limit problem  (Read 4433 times)

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Homing and limit problem
« on: May 06, 2009, 10:17:39 PM »
I am setting up the homing and limits on my CNC Router (Joe's 4x4 Hybrid).   I have wired my limits/home switches for XYZ axis to the same port/pin and and my A axis (which is slaved to the Y) switches wire to a different port/pin so I can do squaring.

The limits all work as expected and the homing all works as expected, however after homing ("Ref All") the limit switches are no longer working although I can still move all the axis and run g-code with the exception that the limit switches are inactive (although they are still working according to the diag screen in Mach 3 as I can see the LED go on if I press one).  If I press reset (Mach 3 is not asking me to do this) then the limits are reactivated and function fine unless for some reason I do another "Ref All".

Can anyone tell me what is happening here.


« Last Edit: May 06, 2009, 10:31:53 PM by dacostad »

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Re: Homing and limit problem
« Reply #1 on: May 07, 2009, 02:07:44 AM »
Please attach your xml and I will see if I can replicate.
Re: Homing and limit problem
« Reply #2 on: May 07, 2009, 09:56:51 AM »

It's amazing what a nights sleep does as I just figured out the problem and of course it's a stupid one!

I had not yet hooked up the A axis homing switch which will be used for squaring, but I had left the A axis limit/ homing enabled in Mach 3 and had also not yet turned of limit/ homing slave with Master under the general settings which you have to do for squaring.  So when I hit "Ref All" it was homing Z, X and Y but then continuing to look for A which never activated and therefore it really never finished homing and therefore the limit switches don't work.

Now the reason I did not spot this is because the A is slaved to Y, there is no DRO movement shown for A while it is homing which if there was I would have spotted it was still moving.  The reason I figured it out today was that I ref/homed each axis at a time and tested that after each axis (XYZ) had homed the limit switches still worked, which they did, then I homed A and of course it never finished homing as the switch is not yet connected (it is on a separate pin to the rest) and after that the limit did not function.

As soon as I disabled the limit/homing of A in Ports & Pins I could then do a "Ref All" and the limit switches afterwards still triggered and limit reached event.

Today's task - wire up the A axis switches :)

Thanks for all the help efforts and as is the case in most instances it was a stupid (user) error!