Moving from Soft limits to hard limit switches

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PeteJ
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Re: Moving from Soft limits to hard limit switches

Post by PeteJ »

tblough wrote: Tue Aug 12, 2025 10:16 pm Machine tool coordinate systems are based on spindle movement. Therefore X+ is actually the table moving LEFT, and Y+ is the table moving towards the operator.
I understand that and what I sent came direct from the Allin1DC manual (full page acreen shot attached). It was to clarify my intent and provide additional information that @cncsw was asking for.

Having a knee mill with a table that moves vs other types of machines where the tool moves is why I believe the direction reversal was set to "Y" for the specific Axis. Because the machine was configured with Soft limits for homing the machine prior to shutting it down, I am trying to understand what changes in the cnc12 software need to be adjusted now that I am installing hard limit switches for the home position.
Attachments
Screenshot_20250813_081312_Adobe Acrobat.jpg


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Re: Moving from Soft limits to hard limit switches

Post by PeteJ »

cncsnw wrote: Mon Aug 11, 2025 5:18 pm You do not need to disable soft limits while homing.

First, soft limits do not apply until after machine home has been set.
Second, soft limits never apply to M91 and M92 moves.

If you only have one switch per axis, then you will only connect to three inputs (either INP1 or INP2 for X; either INP3 or INP4 for Y; and either INP5 or INP6 for Z). Which one you use for a given axes depends on which direction you want that axis to home, and whether or not you needed to set Direction Reversal for that axis.

You will need to turn off (open) the limit defeater DIP switches for the three inputs you connect.
You will need to leave the limit defeater DIP switches for the other (unused) three limit inputs turned on (closed).
I'm getting very close here's how the machine is behaving now:

Z-axis executes homing cycle properly

For the x-axis I didn't need to tell it to not reverse the direction as shown in the picture attached. Once I did that it would properly home x in the correct direction but once it hits the limit I get the 410 error.

At this point the cycle stops.

I am also have a blinking light for the Y-. If I manually trip the limit switch the control responds properly so I know the limit switch is functioning.
Attachments
20250813_113008.jpg
20250813_112940.jpg


cncsnw
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Re: Moving from Soft limits to hard limit switches

Post by cncsnw »

If you have X axis Direction Reversal = "No", then you need to put the limit input numbers back:
X minus limit/home = INP1
X plus limit/home = INP2
Then, if your actual switch is the minus limit, you need to move the wire over to INP1; turn off the defeater for INP1 ("0-"); and turn on the defeater for INP2 ("0+").


cncsnw
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Re: Moving from Soft limits to hard limit switches

Post by cncsnw »

The green LEDs behind the limit defeater DIP switch block are MPU status LEDs. They are not related to limit switches.


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Re: Moving from Soft limits to hard limit switches

Post by PeteJ »

I am wondering if I have a wiring issue with the servo motors on this machine.

I reversed the Y limit and home settings (+ and -) and now it will execute a homing sequence if I run it manually.

I'm still running into the same issue I had when we did the upgrade. For the X and Y axis when it hits the limit switch it throws a 410 position error and will not back off of the limit switch. I was originally told it was because of the older style limit switches so I installed the new ones as recommended by the technician.


cncsnw
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Re: Moving from Soft limits to hard limit switches

Post by cncsnw »

What exactly do you mean when you refer to "running [the home sequence] manually"?

Note that there are important differences between F3/"Find Home" and F4/"Set Home" on the Machine Configuration menu.

Stalling with "410 ... position error" while trying to move back off of a tripped limit switch is characteristic of having the switches on the wrong inputs.


cncsnw
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Re: Moving from Soft limits to hard limit switches

Post by cncsnw »

Also, for what it's worth, it is still not clear to me in which directions you intend to home X and Y.
Regarding the mill itself, it is an ATrump K4V, the goal for the limit switches is to have both the X and Y home so that the table table to the left and back as shown in the picture and z fully retracted (X-, Y+, Z,+).
Table left and back (toward the column) would be X+ and Y-.

With your current direction-reversal settings (whatever they may be...), when you press the right-pointing "X+" jog button, in which direction does your mill table move? When you press the upward-pointing "Y+" jog button, in which direction does your mill saddle move?


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Re: Moving from Soft limits to hard limit switches

Post by PeteJ »

cncsnw wrote: Wed Aug 13, 2025 5:38 pm Also, for what it's worth, it is still not clear to me in which directions you intend to home X and Y.
Regarding the mill itself, it is an ATrump K4V, the goal for the limit switches is to have both the X and Y home so that the table table to the left and back as shown in the picture and z fully retracted (X-, Y+, Z,+).
Table left and back (toward the column) would be X+ and Y-.

With your current direction-reversal settings (whatever they may be...), when you press the right-pointing "X+" jog button, in which direction does your mill table move? When you press the upward-pointing "Y+" jog button, in which direction does your mill saddle move?
I think I have work myself into a full circle.

You are correct as far as my intentions I want the table to move to the left and back as the home position.

Regarding machine movements with settings as per the attached image:

When I jog X+ The table moves to the left
When I jog Y+ the tanle moves out (away from the knee)
When I try and home the machine it moves the the table "X" to the right.
Attachments
20250814_111143.jpg


PeteJ
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Re: Moving from Soft limits to hard limit switches

Post by PeteJ »

Looking at the behavior of the machine and what is configured in the setup, I believe I found my directional issue. Currently the CNCM.hom file is set to use m91/x and M92/y. If the machine configuration is correct based on what you see should I be using m92/x and m91/y?

If I manually execute m92/x and m91/y via MDI the machine does move in the correct direction but I get an error saying "switch fail to clear, homing cycle canceled"

Editing the above, I created a new cncm.hom file using m92/x and m91/Y and when I run the program it trips the x - limit (407 error) and the next line is "325 limit: job cancelled"


PeteJ
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Re: Moving from Soft limits to hard limit switches

Post by PeteJ »

Doing some additional digging i found this great explanation on limits and home. In my head I combined the function of the limit switch configuration and the homeing of the machine into one process.

I need to re run the process from a cold startup, boot the controller and verify what if any issues I am actually having.

viewtopic.php?p=4872&hilit=Soft+limit#p4872


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