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Author Topic: Can Home Switch be -- limit switch...  (Read 14921 times)

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Can Home Switch be -- limit switch...
« on: January 07, 2009, 05:01:33 PM »
Im currently setting up my limits, the previous control on the machine im retrofitting ran a single limit switch at each end of the machine travel. If i assign the same limit switch input to the Y home and to the Y--, when i home, the machine will shut down. I can run the machine with just a Y++ limit switch and make sure the soft limits are on, but if they're not on, you can crash the head at the Y-- limit.

Do I have to run a separate home switch from my limit or is there a way around? Say, the machine homes, then comes .5" off the home switch and once its homed it treats the switch as a limit?

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Re: Can Home Switch be -- limit switch...
« Reply #1 on: January 07, 2009, 05:08:34 PM »
You just set the pins for your limit and home as the same and when homing Mach will treat it as a home switch and once homed Mach will then treat it as a limit switch.
Hood
Re: Can Home Switch be -- limit switch...
« Reply #2 on: January 07, 2009, 05:39:10 PM »
When i tried this, the axis will home. Then it says "cannot jog when limit switch is active" and i have to disable the limit to jog off.

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Re: Can Home Switch be -- limit switch...
« Reply #3 on: January 07, 2009, 05:52:11 PM »
You mean the SoftLimit button you need to disable? If so then you have your softlimits set wrong.
If not then please try and explain a bit more as I dont think I have ever seen that, where do you see that message? Does your Reset  flash?

Hood
Re: Can Home Switch be -- limit switch...
« Reply #4 on: January 07, 2009, 06:12:29 PM »
The Y axis travels towards the home/limit switch.

It homes, but because its homed onto the limit switch, it resets and generates a limit switch error. I then go into ports and pins and disable the limit so i can jog off.  We build press brakes here, and when we calibrate our backgauges, it will home then come forward about an inch automatically and the home switch acts as a limit.  If the axis homes and sits on the switch, the limit is triggered.

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Re: Can Home Switch be -- limit switch...
« Reply #5 on: January 07, 2009, 06:15:59 PM »
OK then that is because you have noisy or bouncing switches, set the debounce interval to  2000 and see if that helps, if it does keep lowering until it starts again then notch up slightly again.
Hood

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Re: Can Home Switch be -- limit switch...
« Reply #6 on: January 07, 2009, 06:32:36 PM »
What happens when Mach homes it will move to the switch and open it, it will then reverse until the switch closes then it will stop and set that as your home position. If the switch has noise or is bouncy then Mach will see the switch closing before it actually does and will stop, problem is the switch in reality is still open and because Mach is now seeing it as a limit switch you get that error. Shielding your limits wiring properly and only grounding at the control end should help, if not then maybe the switch is just not very good.
 Setting the debounce interval higher makes Mach wait for a longer signal before it acts on it so noise is less likely to trigger the switch.

Oh and another thing just for your reference, you can set AutoLimits override which will allow you to jog off a limit after you have pressed the ReSet button. Its not a cure for your problem but may help in the future if you accidentally hit a limit and need to jog off.
Hood
Re: Can Home Switch be -- limit switch...
« Reply #7 on: January 07, 2009, 07:02:57 PM »
Ill try this tommorrow, thanks.
Re: Can Home Switch be -- limit switch...
« Reply #8 on: January 08, 2009, 11:29:10 AM »
Where do I adjust debounce intervals?

I finally finished setting up all my limits, the X axis will home and bounce back, but still when I set up the home to the same as the -- limit switch, it shuts down the second it touches the limit.

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Re: Can Home Switch be -- limit switch...
« Reply #9 on: January 08, 2009, 11:38:07 AM »
Config menu then General config, its top right of that page.
Hood