Correct wiring of limit switches

[digdagdigedag]

Finally, the HW of my CNC monster(Acorn with 3 Leadshine Controllers and Nema 34 Servos) is ready and I have started the calibration.
First thing I noticed, I may have got the wiring of the limit switches wrong.
For each axis, I have two limit switches (NC) wired in one loop and connected to one of the Acorn inputs. I was assuming that for any given axis, the Acorn can detect the limit and then based on the last movement keep the reverse direction enabled so that the switch can be cleared.
Unfortunately, I seemed to be wrong and instead both directions are blocked.
It seems I will have to add one more wire to distinguish the plus and minus switch but having home and limit for each axis would require 6 inputs. Acorn only provides 4 inputs.
What would be the best way of wiring 6 switches for a 3 axis machine ?
Thanks
Uwe

[cnckeith]

you can use "homeAll" and "limitAll" and you'll only use up two inputs for 6 switches.
take a look at schematic S14902

[digdagdigedag]

Thanks for the advice !
as all cables meet inside teh control box i will have to install one more wire for each axis so that i can distingusih home and limit and recombine them accordingly. is there no simpler way by using some intelligent feature of the acorn ? anyway, I will try and keep you updated.
Thanks.

[digdagdigedag]

Just found a video on youtube.
This guy also used the same wiring as I did (i.e. both switches of one axis in one separate series circuit). Seems like his controller (Mach3) is able to handle that for homing and limit detection. As far as I understood one of martyscncgarage video, he also had home and limit in series.
There must be some hidden Acorn function (I hope).

[digdagdigedag]

Forgot to paste the link to that Video (https://www.youtube.com/watch?v=mbT9SSVoeZc&t=1284s)
Based on that video, I eventually kept my original wiring (both end switches in series for each axis) and configured limits for both - and + as well as home for one of the direction and luckily, it seems to work just as expected, i.e. controller can find the home position of each axis and then changes the switches to limit mode.

[markcadcam]

When I try to use Limit All with Home All I get an error message. See attached picture. Why is this?

Report

report_985DAD48D628-0929170130_2018-12-20_09-53-51.zip

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[cnckeith]

procedure.

1.) put input 2 to "unused"
2.) leave input one as "HomeAll"
3.) Wire Normally closed HOME switches in series into Input 1
4.) Set the homing direction
5.) Set the Travel limit of each axis (the distance from the home switch to just before the limit switch on the other side of the axis.) be sure to get the positive and or negative values correct.
6.) Set Homing to "Home to Switch"
7.) press "write settings to CNC control" follow instructions.

Now test the homing cycle and report back.

[markcadcam]

4) set Homing direction? How.
5) set travel limit of each axis? How?
6) set Homing it Home switch? How?

[cnckeith]

4) set Homing direction? How. tab #2 in wizard
5) set travel limit of each axis? How? tab #2 in wizard
6) set Homing it Home switch? How? tab #2 in wizard

viewtopic.php?f=61&t=1449

[martyscncgarage]

4) set Homing direction? How.
5) set travel limit of each axis? How?
6) set Homing it Home switch? How?

Mark, all of the above requires some description of your machine, where your home switches are, what the travels are.
Pictures and or video would be helpful.

Hopefully the videos Keith provided a link to help.