converting microswitches to prox sensors problem

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Thread: converting microswitches to prox sensors problem

  1. #1
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    Default converting microswitches to prox sensors problem

    Equipment:
    UC300ETH + EB1
    existing limit/home switches - N/O Microswitches, 5 of them all individually connected to X103-X107 (X-, X+, Y-, Y+, Z-)

    Works just fine, except the microswitches were an afterthought by previous owner and they are mounted on bit of scrap metal and wires are haphazard.

    I'm rebuilding the electronics (so far the UC300ETH/EB1 has replaced a USBCNC knockoff and I have sourced some proper equipment for safety circuit etc) and wanted to upgrade to prox sensors so I ordered a few NPN N/C 6-36V sensors as pictured in the 3d printed mount.



    I set this up on x109 and functionally the switch is working fine. LED is lit (both on sensor and the UB1) until some metals approaches, then the LEDs both go out. I switched the Y- limit to use x109 and tried homing, using a bit of metal to manually trigger it before the gantry got there and it all worked just fine.

    When I ran it for real however, the gantry approached, it DID detect and back off, but it doesn't back off far enough to untrigger (open in this case) the sensor, so after homing, the machine goes straight into limit stop. I have to override limits and jog off...

    I tried setting the offset but that just sets Y to -2 (for example) and the gantry stayed stuck at -2 in limit stop.

    I can't see anywhere to make UCCNC actually move back from the limit switch a set amount - surely there is an option and I'm just being blind? Oh, I am using Gerry's 2017 Screenset.

    Any advice appreciated.

    Oh, while I am here, since I have heaps of inputs, is there any benefit to running the X+ and X- (and Y+/Y-) in series, so there are only 3 ports used for limit/home switches? I was going to just connect 5 individually for the sake of simplicity.

    Regards
    N

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  2. #2
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    Default Re: converting microswitches to prox sensors problem

    There is a back off parameter, but only in their latest test releases which are not on their website yet, only posted on the cncdrive forum.
    You can try that version or try to higher the homing speed faster to make the axis move further off of the limit switch when deccelerating off the switch.



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    Default Re: converting microswitches to prox sensors problem

    Thankyou for that - great info. I'll check if the 2017 screenset works with the test release and if not will try the faster backoff.

    Cheers - N



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    Default Re: converting microswitches to prox sensors problem

    Dezsoe created a macro that will achieve the same and will work with your version with 2017 screenset.

    forum.cncdrive.com • View topic - Macro - SmartHome



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    Default Re: converting microswitches to prox sensors problem

    Thanks for the pointer to the test version. The homing backoff parameter there works perfectly.

    I had a quick look at that thread but the author says it's deprecated essentially by the feature being in the core code...

    I edited the parameters into the 2017 screenset and they worked, but if anything at all changes (perhaps only on the axis pages - haven't checked) then the backoff parameters are overwritten with zero values. The line is still there (and some others from the new version), but the value is changed to 0.

    I am sure that it can be easily fixed either in the screenset or even with an AWK or PERL script that runs before UCCNC to add the lines back to the file. I'm just happy that the hard stuff and the stuff I spent the money on (The prox switches etc) works as designed - I am in no huge hurry to fix this - I am waiting for lots of stuff to still arrive so I can rebuild the rest of the electronics.

    Cheers - N

    Oh, I tried speeding up the backoff speed as well, that didn't help.



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converting microswitches to prox sensors problem

converting microswitches to prox sensors problem