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Please help me remove the red lights!
« on: December 15, 2016, 07:00:38 AM »
Hi All

Newbie here.

Something has happened to our CNC machine and we cannot 'Ref All Home' successfully when using Mach3

We have 3 home switches and 2 remain lit.  See attached.

I have followed some instruction regarding 'Auto Setup of Input Signals' but no joy.

I have also attached a photo of our control panel and other info.

Any help would be appreciated!

Richard


Re: Please help me remove the red lights!
« Reply #1 on: December 23, 2016, 02:19:09 AM »
Hi,
not sure I can help but I can try.

How are your switches wired? The pic shows them at the very end of the table so I guess you're combining limit
and home switches. Also shown it the pic looks like the head of the screw is what actually is detected. Are you able
to shift it?

Can you post a screen shot of the Config/Ports and Pins/Input Signals page.

What I'm going to suggest it that you shift the head of the screw an inch or so back within the table travel area. Really helps to
have a little to play with while your experimenting and learning. Then I would suggest disabling the limit switches and use it
as a home switch only. I suspect what's happening is that the machine is stopping because a limit switch is triggered. Try in the
first instance to get it working as home switch then try to incorporate it as a limit switch as well once you've got homing sorted.

Craig
My wife left with my best friend...
     and I miss him!
Re: Please help me remove the red lights!
« Reply #2 on: December 23, 2016, 03:35:18 AM »
Craig

Thanks for the feedback.

Just to reply.

How are your switches wired? The pic shows them at the very end of the table so I guess you're combining limit
and home switches.

This is correct.

Also shown it the pic looks like the head of the screw is what actually is detected. Are you able
to shift it?

Yes but the machine has worked fine for a couple of years now.  When we switch it on, we ref all home, and all works ok.  I think (according to the user) it stopped when they were manually moving the XYZ to the start of a job.  Not sure that I need to move the screw.


Can you post a screen shot of the Config/Ports and Pins/Input Signals page.

Later, as I am some miles from the machine.

Then I would suggest disabling the limit switches and use it as a home switch only.

This would be good, not sure how to do this, as each time I reset, it comes on the screen, limits triggered.

I suspect what's happening is that the machine is stopping because a limit switch is triggered.

Yes

Try in the first instance to get it working as home switch then try to incorporate it as a limit switch as well once you've got homing sorted.

Ok, I can move the XYZ to the centre of table.  Then when ref all home, it moves all axis to stops short of the Z and Y as they have the red lights on the top of the switches.

Any help appreciated.

Thanks

Richard

Re: Please help me remove the red lights!
« Reply #3 on: December 23, 2016, 02:51:54 PM »
Hi Richard,
I'm not familiar with the logic and wiring of combined Home/Limit switches. I have three independent Home switches
on three input pins and all the six Limit switches in series on a separate pin.

The Home switches trigger a few mm inside the Limit and consequently the Limits are never triggered when I HomeAll
unless one of my Home switches is faulty.

In Mach3 there are buttons 'Auto LimitOveride' and 'OverideLimts', I've seen them on the Settings page but have never had
reason to use them but I believe their use is when you have Limits/Home combined. If you are homing then you must at least
temporarily tell Mach to ignore the limits otherwise it will 'stop on limit' and never get the chance to complete its homing
sequence. Does that sound like what's happening? In that case it may just be that a setting has changed and if you restore
it things will go back to normal.

Craig
My wife left with my best friend...
     and I miss him!
Re: Please help me remove the red lights!
« Reply #4 on: December 23, 2016, 03:15:09 PM »
Craig

Again, thanks for the feedback

You say, "If you are homing then you must at least temporarily tell Mach to ignore the limits otherwise it will 'stop on limit' and never get the chance to complete its homing sequence."

If I do this wont the motor want to run of the rails or is this just the 'limits' after you ref all home?

Cheers

Richard
Re: Please help me remove the red lights!
« Reply #5 on: December 23, 2016, 08:06:19 PM »
Hi Richard,
again I cannot be absolutely clear about this because my setup is different.

While 'Limit Overide' is in operation if you called either by jogging, MDI or faulty homing direction/logic yes indeed the machine
can run out of limits and crash. It is for this reason I suggested that the screw heads be shifted inboard a wee bit so that if
some fault of yours or your homing logic happens you will have time to Estop before the crash.

Unless you temporarily disable the limits then when homing and the switch is activated the machine stops. Imagine the situation
that your intended home position for X is at the far right of travel and prior to homing the table is several inches to the left
of that. When the axis homes it does so in the direction and speed that you nominate on the Config/Homing-Limits page.
Should you have the direction setting wrong then the table will travel to the left expecting to find a home switch to trigger
a stop. If it doesn't find one it may well keep on going and crash because the limits are disabled. Yet if the limits are not
disabled and the axis homed in the correct direction ie to the right then as soon as it triggers your home/limit switch the
machine will stop and you can't continue to home the remaining axes.

When I was setting up my machine all that logic baffled me and that's how it came to be that I have separate home switches,
one for each axis, it just made sense to me at the time. Later I realised that home and limits could be combined with possible
savings in switch numbers, wiring and input pins required I'd gotten so used to what I had that I never changed it. You
know what they say 'there's nothing so permanent as a temporary fix'.

Craig
My wife left with my best friend...
     and I miss him!