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newbie - limit switches
« on: May 26, 2015, 12:52:00 PM »
Hi,

I have limit switches on boths ends of all my axis. In my config currently I just have home set for them.
They are all wired in a normally closed setup. When I check the diagnostic screen all of my home switches are lit, triggering it turns off the light.
So does this mean I need turn them to active low...watched the video on home limits and none seem to be set active low...i guess it depends on your setup?

Triggering the switch currently does not trigger on Estop.

also i would like to set them be limit switches as well.
« Last Edit: May 26, 2015, 12:57:42 PM by airbrush »
Re: newbie - limit switches
« Reply #1 on: May 27, 2015, 09:41:15 AM »
settings were wrong...they were already set active low...unchecked now.

So i check all of the axis ++ and -- limits as well as home.

When I hit a limit switch and trigger and Estop it does not back off of the switch...should it??

Offline ger21

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Re: newbie - limit switches
« Reply #2 on: May 27, 2015, 09:47:55 AM »
No, you have to jog it off the switch yourself. You need to turn on either manual override or automatic override before you can jog off the switch.
Gerry

2010 Screenset
http://www.thecncwoodworker.com/2010.html

JointCAM Dovetail and Box Joint software
http://www.g-forcecnc.com/jointcam.html
Re: newbie - limit switches
« Reply #3 on: May 27, 2015, 09:59:06 AM »
okay..right. I've done that.

Just confused reading/watching all of the home and limit stuff. As it mentioned when homing it hits a switch and then backs off, so i wasn't sure if this was expected behavior for limits as well.

Switches are all set up now, will have to try homing next.

thx
Re: newbie - limit switches
« Reply #4 on: May 27, 2015, 11:45:23 AM »
Hitting a limit during operation says something bad just happened, so don't try moving anything.  So you have to override the E-stop function and take responsibility for jogging in the correct way to clear the problem. Note that after an E-stop Mach 3 no longer knows where it is.  So you must reestablish your X0,Y0,Z0 positions.
Re: newbie - limit switches
« Reply #5 on: May 27, 2015, 11:49:30 AM »
got it...hitting limits is bad :)

so when you hit a limit mach gets rid of your zero you set?? why would it do that?
How would you restart your cut if you hit a limit??

Offline ger21

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Re: newbie - limit switches
« Reply #6 on: May 27, 2015, 11:56:12 AM »
Quote
so when you hit a limit mach gets rid of your zero you set?? why would it do that?

Because a limit switch is an emergency stop, and Mach3 will instantly stop sending steps, which causes the motor to lose position, as it doesn't decelerate properly.

How you restart depends on how you started in the first place.
Gerry

2010 Screenset
http://www.thecncwoodworker.com/2010.html

JointCAM Dovetail and Box Joint software
http://www.g-forcecnc.com/jointcam.html
Re: newbie - limit switches
« Reply #7 on: May 27, 2015, 11:57:36 AM »
okay..thx...one step at  time. I'm sure more will become clear later