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Author Topic: Homing and Limits  (Read 2688 times)

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Homing and Limits
« on: February 12, 2017, 11:00:07 AM »
There's a million hits when I search for this but not a simple answer! I have single inductive proximities on each axis. Told Mach3 to use each signal (each on separate pin) as a combination home, limit+ and limit- trigger. When I 'ref all' machine homes and backs-off in all axes as it should but if I inadvertently jog in the wrong direction the 'limit' switch is re-triggered and all stops...as it should...but then Mach won't let me reset as it 'sees' a limit switch STILL triggered??? I would have thought that it would allow you to manually 'back-off' the limit switch in the opposite direction but until 'reset' is hit (which it won't accept) you can't. I'm sure I have something not set right as each time this happens I have to go into Ports and Pins and disable the X++ and X-- detection just to allow me to move off the limit switch! What am I doing wrong!! This can't be the normal operation of any controller as it ends up in a logical lock-up situation...'Limit switch hit therefore NOTHING moves, reset needed...Oh...you can't reset while a limit switch is STILL hit' therefore solid lock-up??

Tim
Pacer Cadet, guts gone, new stuff installed, sounds like a full string quartet in motion...

Offline kolias

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Re: Homing and Limits
« Reply #1 on: February 12, 2017, 11:18:21 AM »
Did you check the box on the Settings Menu "Auto Limits Override" ?
Nicolas
Re: Homing and Limits
« Reply #2 on: February 12, 2017, 11:21:21 AM »
Hi Kolias..Not yet as I am trying to find a way where Mach allows you to move 'away' from the triggered limit but only stops you from barging any further 'into' the switch.
Tim
Pacer Cadet, guts gone, new stuff installed, sounds like a full string quartet in motion...

Offline ger21

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Re: Homing and Limits
« Reply #3 on: February 12, 2017, 12:47:05 PM »
Mach3 is not that smart. Since you're using a single switch, Mach3 has no idea which direction to move.
Gerry

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Re: Homing and Limits
« Reply #4 on: February 13, 2017, 06:03:09 AM »
Hi Ger,

Thing is there is a switch per axis and if Mach3 moves, say ++ and hits a limit switch then surely it is kids play in software for it to disallow further ++ movement and only allow -- movement??

Tim
Pacer Cadet, guts gone, new stuff installed, sounds like a full string quartet in motion...

Offline ger21

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Re: Homing and Limits
« Reply #5 on: February 13, 2017, 07:14:35 AM »
That's not how it works, and since development stopped 5 years ago, it's not going to change.
Gerry

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

JointCAM Dovetail and Box Joint software
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Re: Homing and Limits
« Reply #6 on: February 14, 2017, 03:45:54 AM »
 :-\ :-\...mmm..OK. Well I've changed a few things, set the soft limits before the physical switch limits, set the auto limits override and ditched having both + and - limits on the same input pin and although it's not perfect it doesn't get into the irreversible lock-up situation that it did before! Does Mach4 address the problem??
Pacer Cadet, guts gone, new stuff installed, sounds like a full string quartet in motion...

Offline Davek0974

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Re: Homing and Limits
« Reply #7 on: February 14, 2017, 10:51:46 AM »
I don't know about Mach4 but once setup and working, limits with soft-limits in Mach3 is pretty bullet proof, I have three machines here all setup the same and all work just fine - I can jog into any soft-limit and it still allows me to jog off ok.

It must be a setting or construction/wiring issue.
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Offline kolias

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Re: Homing and Limits
« Reply #8 on: February 14, 2017, 11:00:07 AM »
I set my limits in Ports & Pins/Input Signals, at the bottom right of the screen there is a button "Automated Setup of Inputs". Mach3 will do all the work for you
Nicolas
Re: Homing and Limits
« Reply #9 on: February 14, 2017, 11:26:14 AM »
Hi Guys,

Thanks for the replies but Dave...I can jog into and away from a soft limit like you can... but if I hit a full limit (as opposed to a soft limit) movement stops (correctly) but I can't reset to allow me to manually 'back-off' as the reset says 'no reset while a limit switch is active'.

I set all the pins manually with no issues but there does exist this anomaly in Mach3 that once on a full limit you can do nothing to get off it manually without going back into the program, altering a parameter, coming out the program, moving the axis OFF the limit, going back into the program, returning the parameters to normal and then carrying on! Mach3 is so comprehensive that I had imagined there would be a couple of lines of code that allowed you to jog AWAY from a hit limit switch with a jog button. I'm sure the coder had a reason to not include it...probably safety or something.

I'll live with it ;)

Pacer Cadet, guts gone, new stuff installed, sounds like a full string quartet in motion...