Limit Switch Struggles Shopbot PRS

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acornKurt
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Limit Switch Struggles Shopbot PRS

Post by acornKurt »

I am attempting to get my limit switches working for simple safety tripping.

I have X and Y limit switches.
They are wired in series between common and Input 2 on the Acorn board.
Acorn configuration shown in below image.
If I set input 2 to NC I can move the machine, but limit switches do not trip.
If I set input 2 to NO machine says X/Y/Z is tripped and I can't move the machine.

I am not really sure what to do, I have watched Marty's video on this topic and not sure I am on track.

Also if a limit switch trips, how do I move the machine off the tripped switch? I tried reset, but no joy.
IMG_1084.jpeg
IMG_1083.jpeg
IMG_1081 (1).jpeg
Sword
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Re: Limit Switch Struggles Shopbot PRS

Post by Sword »

Kurt,

Are these mechanical switches or the SB 3 wire inductive? Assuming mechanical and with 3 tabs (com and NC or NO), are you sure that you have them wired in series properly? Check them for continuity when not tripped (closed). You can also use the I/O diagnostic screen to check the state of them (Ctrl+I), and to see if you possibly have INP2 forced on.

To get off a tripped limit, use "Limit Switch Defeat" for a one shot move to get off them.
Scott
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Re: Limit Switch Struggles Shopbot PRS

Post by acornKurt »

Sword wrote: Sun Dec 04, 2022 1:30 pm Kurt,

Are these mechanical switches or the SB 3 wire inductive? Assuming mechanical and with 3 tabs (com and NC or NO), are you sure that you have them wired in series properly? Check them for continuity when not tripped (closed). You can also use the I/O diagnostic screen to check the state of them (Ctrl+I), and to see if you possibly have INP2 forced on.

To get off a tripped limit, use "Limit Switch Defeat" for a one shot move to get off them.
I have tried limit switch defeat and no joy.

They are not mechanical, they are from automation direct I had them on my SB before Acorn and they were working as expected.

"Micro Detectors inductive proximity sensor, tubular, 8mm diameter x 29.4mm body, stainless steel housing, NPN, N.C. output, 2mm sensing distance, flush, 7 kHz switching frequency, IP67, 3-pin M8 quick-disconnect."

Below is wiring diagram provided by manufacturer.
limitSwitches.JPG
Gary Campbell
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Re: Limit Switch Struggles Shopbot PRS

Post by Gary Campbell »

Kurt...
Maybe not the instructions on how to fix what you are experiencing, but advice in a different direction. This will allow you to make your machine perform better than it ever could on the SB3 control software.

Use the sensors to home the machine, ON ALL 3 AXES, and use the built-in travel limits to keep the machine off the hard stops. There is no guarantee that prox sensors will work in series, you must connect and test one, then two, then 3 to ensure they will work properly.

Since I always use discreet pins for limit/homing sensors I am not sure that the SB positive end target bolts will work with the Acorn controller, especially in the multi axis, multi direction setup.

Some questions:
Can you trigger each of the sensors with a wrench and see the sensors indicator light change state? If yes, does the assigned input light on the Acorn board change state also? If no you have something wired wrong.

I still recommend adding a sensor to the Z and set up homing and travel limits on all 3 axes like the big boys do, not the "do it cheap and simple" way that SB does.
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Re: Limit Switch Struggles Shopbot PRS

Post by cnckeith »

Need support? READ THIS POST first. http://centroidcncforum.com/viewtopic.php?f=60&t=1043
All Acorn Documentation is located here: viewtopic.php?f=60&t=3397
Answers to common questions: viewforum.php?f=63
and here viewforum.php?f=61
Gear we use but don't sell. https://www.centroidcnc.com/centroid_di ... _gear.html
cncsnw
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Re: Limit Switch Struggles Shopbot PRS

Post by cncsnw »

When you had them working on the ShopBot, did you have them all wired together in series to a single input? Or did you have each sensor on a separate input?

How many sensors do you have connected together in series?

Can you sketch your wiring for how you have connected them together in series?
robtown
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Re: Limit Switch Struggles Shopbot PRS

Post by robtown »

I agree with Gary.

Use them to home your machine.

And set your travel limits in the software.

That’s how my PRT is setup, works a treat.
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Re: Limit Switch Struggles Shopbot PRS

Post by Sword »

Agreed as well, sensors on all three, each to their own input, and use software travel limits. Been working great on my PRS for 4 years.
Scott
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Re: Limit Switch Struggles Shopbot PRS

Post by acornKurt »

Gary Campbell wrote: Sun Dec 04, 2022 2:24 pm Kurt...
Maybe not the instructions on how to fix what you are experiencing, but advice in a different direction. This will allow you to make your machine perform better than it ever could on the SB3 control software.
....
Thanks Gary, and for everyone's information, I wired them in series because that is what my Acorn Wiring Diagram had on it. I am a newbie here and did not realize that I could wire them into different inputs.

For Gary Cambell, I did order a Z Axis probe as you suggested and will get that in place now rather than later.

For cnckeith, thanks so much for that diagram, with that and Gary's suggestions, I should be on track to make progress.

This has been a long journey for me trying to get my Acorn Upgrade done, but this forum has been a life saver for me.

Regards,
Kurt
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