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HOLD machine via LPT pin?
« on: October 22, 2009, 12:13:37 PM »
Hi!
Tried to do search, but many possibilities to write the question gives none results.

So, in my design, tool is not always ready to do it's job. I know when it is ready or not and I have a swtich output (OC, relay doesn't matter in this case). How I can hold the machine in exactly current position until the tool be ready? I mean, not before next line, just right now. This should be done via input LPT pin. eStop doesn't suits of course.

Something ready for use?

Offline Hood

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Re: HOLD machine via LPT pin?
« Reply #1 on: October 22, 2009, 02:48:53 PM »
If your axis are in motion at the time then your only option is to feedhold which you can do via an input using an OEM trigger.
Hood
Re: HOLD machine via LPT pin?
« Reply #2 on: October 22, 2009, 03:22:58 PM »
Good afternoon,

in my experience, using the safety lockout should work fine. This input is normally used to stop the machine immediately if an external guard is triggered, and also inhibits re-start. (Of course, it is done by software, and thus not as reliable as an E-Stop, but works very well)


To enable the safety lockout, tick "program safety lockout " in "General Config".  (bottem left corner of the menu)
Also assign your input pin to "Input #1".


Have fun ;-)
Konrad

Offline Hood

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Re: HOLD machine via LPT pin?
« Reply #3 on: October 22, 2009, 03:26:50 PM »

in my experience, using the safety lockout should work fine.


That will lose position if an axis is in motion in motion.

Hood
Re: HOLD machine via LPT pin?
« Reply #4 on: October 22, 2009, 03:29:46 PM »
Thank you Konrad. This should do the job. Tomorrow will try it and write a report.
Software stop is enough if works as described. The tool will be "almost" ready for a small period of time until motion stops.


----

Oppps. Losing position is not good. Anyway, tomorrow will try and will ask about OEM trgiger how to if is necessary.

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Re: HOLD machine via LPT pin?
« Reply #5 on: October 22, 2009, 03:34:04 PM »
Can you tell us a bit more about the tool in the respect of why and how it becomes "not ready"

Hood
Re: HOLD machine via LPT pin?
« Reply #6 on: October 22, 2009, 03:40:02 PM »
Thanks Hood.
It's useful to learn that it works in my case, but not in all cases...


(I was writing about experience... In some cases, knowledge is actually better than experience ;-) )

Konrad

Offline Hood

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Re: HOLD machine via LPT pin?
« Reply #7 on: October 22, 2009, 03:45:15 PM »
I may be wrong, often am ;)

On My Lathe I use that as an error signal input from the servo drives so it will E-Stop at the same time due to that reason but if I did not have it set up as such it would possibly do as yours does. Do your motors decelerate to a stop and the DROs show that deceleration?

Hood
Re: HOLD machine via LPT pin?
« Reply #8 on: October 22, 2009, 03:55:12 PM »
Tool is profile molded hot wire, laser or something similar, which may be ready or not ready in exact time. If this is laser, only happens not cut or bad cut. Should revert the program, second time in the same way, worst cut and more and more. If this is molded hot wire and from some case it isn't enough "hot" the shape will be deformed and all next process will be for nothing. Material will be for garbage too.

With another words. Any pulse which comes from the mach3 to the drivers should be send after checking the tool situation. Situation is self recovered, so just is enough to await permission to move.

And one more modification in my post. Not necessary to decelerate the motors. In any case between two pulses software has no care about next step to limit current or something like this. I'm talking about steppers. So, inertia after the step will be cut from the stepper drivers. They are enabled and all is fine. Just to await some time and go again. Now, acceleration after this hold situation is discussable, but we talking about a level few higher which mach3 covers...
« Last Edit: October 22, 2009, 04:03:23 PM by Vaklin »
Re: HOLD machine via LPT pin?
« Reply #9 on: October 22, 2009, 04:12:04 PM »
Do your motors decelerate to a stop and the DROs show that deceleration?

Hood

This would have to be checked on the machine... Can report on Saturday, or Sunday. But I can state that I use a stepper motor drive and it doesn't lose steps at all when opening the protective window and the machine is forced to stop that way. - In E-Stop it definitely does.

But now, I am courious. Let's wait the weekend. :-)

Konrad