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Author Topic: Endstops and Torch Touch Off - 1 Input  (Read 649 times)

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Offline tjb1

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Endstops and Torch Touch Off - 1 Input
« on: June 20, 2018, 10:09:32 PM »
Is it possible to put X, Y, Z, and Torch Touch Off sensors all on 1 input?  If not, is there a breakout available that can work over USB for endstops and such?
Re: Endstops and Torch Touch Off - 1 Input
« Reply #1 on: June 21, 2018, 12:53:58 AM »
Hi,
yes you can combine all of those and have one input, it would stop Mach.
The only down side is that any of the conditions would always result in Mach stopping,
you couldn't have one input do one thing and another input, say TorchOff, do something
different.

In Control Engineering terms its called 'loss of discrimination'. Its not the end of the world and when
so many users only had one parallel port with only five inputs it was necessary to combine inputs.
In more recent years with external motion controllers falling in price its doubtful we really need to do it
anymore.

For instance the USB connected USS of Warp9's has the equivelant of three ports. If you arrange them suitably
you haven port 1 doing all the normal motor and spindle outputs but the other two ports can be  arranged as
26 inputs and 10 outputs.
The UC300 and UC400 of CNCdrives also have multiple ports which would offer you alot of flexibility.

If you were going for an external controller I would advise Ethernet connection, its more stable and resistant
to electrical noise.

External controllers such as those I've mentioned have a much faster pulse rate and very much more accurately
timed pulses which often results in smoother motion. One last advantage is that you are no longer required to
stick to Windows 7 32bit and earlier....you can use just about any PC and Windows OS you like and often without
interference if some other program is running at the same time as Mach.

Craig
My wife left with my best friend...
     and I miss him!

Offline tjb1

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Re: Endstops and Torch Touch Off - 1 Input
« Reply #2 on: June 21, 2018, 05:59:44 AM »
Well the X, Y, and Z endstops would only be used to home the machine. The touch off is used during the piece operation to find the top of the work piece.  The Z endstop is Z max while touch off would be Z min so none of them would ever activate at the same time. I'm fine with homing one axis at a time but still unsure if I can still use that input during a G92 (I think) routine that would offset Z. I just got a UC100 and have run out of inputs on the G540/UC100.

After reading http://www.machsupport.com/forum/index.php/topic,17132.msg116525.html#msg116525

It looks like I can use 1 stop on Z as home or a second on Z as a probe. I would prefer to go the probe route.  Will 3 home inputs and a probe input all work on 1 if they would never be active at the same time?
« Last Edit: June 21, 2018, 06:05:22 AM by tjb1 »
Re: Endstops and Torch Touch Off - 1 Input
« Reply #3 on: June 21, 2018, 06:24:44 AM »
Hi,

Quote
Will 3 home inputs and a probe input all work on 1 if they would never be active at the same time?
It might be possible but it would require that the one input be treated differently at different times during a session. When homing for instance
the input has to be treated as a home switch. While having all three axes on one input is likely to confuse you or Mach it could be done.
THEN you want that input to be treated as a probe input, ie different behavior. Unless you can reprogram your ports and pins on the fly
then its not compatible with homing as well.

I would recommend you consider the UC300 or UC400 instead.

Craig
My wife left with my best friend...
     and I miss him!

Offline tjb1

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Re: Endstops and Torch Touch Off - 1 Input
« Reply #4 on: June 21, 2018, 06:33:40 AM »
Will it work in the G28.1 scenario as it will be a homing switch then and not a probe?
Re: Endstops and Torch Touch Off - 1 Input
« Reply #5 on: June 21, 2018, 06:37:59 AM »
Hi,
it would seem more likely that it would work that way, at least the input has one consistent mode of behavior. Why don't you try it?
I think you are well down the  'loss of discrimination' track.

Craig
My wife left with my best friend...
     and I miss him!

Offline tjb1

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Re: Endstops and Torch Touch Off - 1 Input
« Reply #6 on: June 23, 2018, 11:08:07 PM »
Just to give an update to this, I have home switches for X, Y, and Z as well as a probe all on the same input and I'm able to home, use soft limits and use G31 with no issues.