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Author Topic: homing/limit setup  (Read 4512 times)

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homing/limit setup
« on: December 24, 2009, 03:10:07 PM »
Hey,

I'm trying to get my machine setup with homing and limit switches. I have the hardware setup- one switch per axis to control +,-, and home, wired closed until tripped.

The problem I am having is that when I home the machine, it jogs until it hits the switch, backs off it but stops prematurely. It doesn't go far enough to untrip the switch.

What can I do to remedy my problem?

 Thanks!
Thorp

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Re: homing/limit setup
« Reply #1 on: December 24, 2009, 03:45:48 PM »
Increase the debounce interval to 2000 and see if that helps. If it does you either have noise issues or bouncy switches and its best to sort it out.
Hood

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Re: homing/limit setup
« Reply #2 on: December 24, 2009, 03:46:28 PM »
Oh the debounce Interval is on General Configs page BTW.
Hood
Re: homing/limit setup
« Reply #3 on: December 24, 2009, 04:15:20 PM »
That did it. It now functions fine.

The debounce was originally set to 0.

You say the cause could be a bouncy switch. What is the downside to a bouncy switch? Lack of repeatability?

I think the problem is less the switch and more the way I have them mounted. I created ramps to ride against the switch roller arm and actuate them. I think I may have made my ramps far too shallow.

I will check the repeatability.
Re: homing/limit setup
« Reply #4 on: December 24, 2009, 04:15:48 PM »
and thanks again Hood!
Re: homing/limit setup
« Reply #5 on: December 24, 2009, 04:22:11 PM »
if I enable the limit switches then they get triggered. .

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Re: homing/limit setup
« Reply #6 on: December 24, 2009, 04:41:15 PM »
Yes if your switches are not a positive clcik on/off type then you can get them fluttering when just on the point of opening/closing so probably a steeper slope will help.
Hood

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Re: homing/limit setup
« Reply #7 on: December 24, 2009, 04:43:52 PM »
Just noticed your last post, not sure what you are meaning but thinking maybe you are saying the homing works fine but if you enable the same switches as limits they trigger right away, if thats the case check you have the active state the same as you have for the home switch in ports and pins.
Hood
Re: homing/limit setup
« Reply #8 on: December 24, 2009, 04:58:22 PM »
That is what I meant.

Originally it was setup with the home set active low and the limit switches active high. I had the problem you described.

I set the limit switches active low and it seems to work, but this doesn't really make sense to me. The limit switches are wired so that the circuit is closed unless tripped.

How should I have it setup?

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Re: homing/limit setup
« Reply #9 on: December 24, 2009, 05:00:50 PM »
Sohould really be set active high if they are NC switches unless your board inverts them in some way.
When you have them set active low do they trip when you activate them?

Hood