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NPN Normally Open Inductive Sensor - will signal fry blackbox

Discussion in 'Controller Boards' started by StuartD, Dec 31, 2020.

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  1. StuartD

    StuartD New
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    Hello, I intend to connect in a 6-36V NPN NO Inductive Sensor to the Blackbox. The vendor has provided the following wiring diagram:

    upload_2020-12-31_18-5-36.png
    I have tested the above wiring diagram using an LED as the load albeit with a low voltage (6V) to avoid frying the LED. This has proved the sensor works: the LED lights when a iron object (screwdriver) is placed close to the sensor.

    With respect to the Blackbox I am assuming that the load shown in the above diagram will be implemented as some sort of switch within the blackbox and as such I should be able to directly wire the sensor to one of the limit switch inputs, i.e. the sensor's brown wire to +VE, blue wire to ground and the black wire to signal without any further electronic components. I have set the Blackbox jumper to 24V and fully expect it to work, however, I have a nagging doubt that when the sensor fires it may fry the Blackbox. Please can you confirm whether my concerns are valid or will it just work?

    Many thanks,

    Stuart
     
    #1 StuartD, Dec 31, 2020
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  2. Peter Van Der Walt

    Peter Van Der Walt OpenBuilds Team
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    Blackbox's limit inputs are protected against high voltages, exactly to support inductives :)
    I run SN-04 Inductive switches on my Plasma for example

    Correct

    Correct as the switches themselves dont work on a 5v supply

    The only wiring mistake to watch out for is shorting V+ to GND.
     
    #2 Peter Van Der Walt, Dec 31, 2020
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  3. Rob Taylor

    Rob Taylor Master
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    Black to +, blue to -, 10k resistor between brown and black. That's how I'd do it anyway.
     
    #3 Rob Taylor, Dec 31, 2020
  4. Peter Van Der Walt

    Peter Van Der Walt OpenBuilds Team
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    Not needed!
     
    #4 Peter Van Der Walt, Dec 31, 2020
  5. Rob Taylor

    Rob Taylor Master
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    Oh, nice, well that's exciting. I generally just err on the side of "when in doubt, current limit".
     
    #5 Rob Taylor, Dec 31, 2020
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  6. StuartD

    StuartD New
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    Peter, thank you both for your reply and the promptness of your reply. It's exactly what I assumed; I just didn't want to gamble the Blackbox without asking first. Thank you again and have a very happy new year.
     
    #6 StuartD, Dec 31, 2020
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  7. JStewieDesigns

    JStewieDesigns New
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    So, I also had this question and they pointed me out to this thread. So should we use the NPN or is the PNP more suited for this?
     
    #7 JStewieDesigns, Jan 4, 2021
  8. Peter Van Der Walt

    Peter Van Der Walt OpenBuilds Team
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    I would go to NPN, as tested, known working.
     
    #8 Peter Van Der Walt, Jan 4, 2021
  9. JStewieDesigns

    JStewieDesigns New
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    So on the NPN NO inductive switch (black & brown) would go to V+ and (blue) to GND. Nothing on the Signal terminal?
     
    #9 JStewieDesigns, Jan 4, 2021
  10. JStewieDesigns

    JStewieDesigns New
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    Or am I just having a brain fart and it's still a 3 wire setup with 24v+ going to (brown), GND going to (blue), and (black) going to SIG like this inductive speed sensor I just put on my Grizzly metal lathe? Screenshot_20210104-085109_Amazon Shopping.jpg
     
    #10 JStewieDesigns, Jan 4, 2021
  11. StuartD

    StuartD New
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    Sorry for the late reply - work has recommenced and gotten in the way! The sensors I'm using are NPN normally open and I'm connecting them into an OpenBuilds BlackBox and so can take power from the box itself. That said I haven't got them working: I can see the light (on the sensor) go on when a screwdriver is placed in close proximity to a sensor but no alert is being seen by the software ($5 = 0).
     
    #11 StuartD, Jan 4, 2021
  12. Peter Van Der Walt

    Peter Van Der Walt OpenBuilds Team
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    Alerts (alarms) also relates to Hard Limits parameters etc. Rather, use the Troubleshooting tab in CONTROL to test Limits

    upload_2021-1-4_21-28-13.png
     
    #12 Peter Van Der Walt, Jan 4, 2021
  13. JStewieDesigns

    JStewieDesigns New
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    So my black box shipped out today. I'd like to start browsing for inductive switches. Nobody replied to my last comment with picture so, have we found out if the NPN NO is the way to go and are ya'll only using 2 wires at the BB or 3 wires?
    I know that previously when I had a Shapeoko XXL cnc router it just had locations for XYZ and Feed Hold which were a 2 pin header per axis that were just NO contacts. I don't believe there was any voltage on any of this pins. Using an 3 wire inductive switch is a little newer to me. I get needing voltage for the on board led for the switch and a ground, but then you have the signal wire. So is that the whole thing behind NPN or PNP that determines whether the signal wire becomes a ground or v+ when triggered?
     
    #13 JStewieDesigns, Jan 5, 2021
    Last edited by a moderator: Jan 5, 2021
  14. Peter Van Der Walt

    Peter Van Der Walt OpenBuilds Team
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    #14 Peter Van Der Walt, Jan 5, 2021
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  15. JStewieDesigns

    JStewieDesigns New
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    This will be going on my Onefinity cnc router. No v-rails. So I'll be making custom brackets. I'm not too fond of the controller it came with and I'm really liking all the features of the black box which is why I'm going that route.
     
    #15 JStewieDesigns, Jan 5, 2021
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  16. Glen.G

    Glen.G New
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    Good morning,

    I have sn04 pnp inductive sensors, and a BlackBox X32 can you tell me about the wiring because the one displayed in your documentation is not good, my sensors stay on and do not detect the axes...

    Thank you.
     
    #16 Glen.G, Mar 26, 2023
  17. Peter Van Der Walt

    Peter Van Der Walt OpenBuilds Team
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    Refer the documentation and note that we only support NPN type (yours is PNP)
     
    #17 Peter Van Der Walt, Mar 26, 2023
  18. Glen.G

    Glen.G New
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    yes sorry, I made a mistake my sensors are NPN .... I relied on the documentation but I have a problem my sensors stay on and I don't know if I should modify via the blackbox or if I should change the wiring as on the documentation it is well said to ask before anything, well I ask ;)
     

    Attached Files:

    #18 Glen.G, Mar 27, 2023
  19. Peter Van Der Walt

    Peter Van Der Walt OpenBuilds Team
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    If its NPN, it should work, provided you
    A) have the correct Grbl Settings ($5=? In your current Grbl Settings?)
    B) set the Limits V+ jumper to correct voltage for your sensors
    C) wiring correct (color coding may differ between vendors)
     
    #19 Peter Van Der Walt, Mar 27, 2023
  20. Glen.G

    Glen.G New
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    I don't understand the $5? Is this not noted in your documentation?
     
    #20 Glen.G, Mar 27, 2023
  21. Peter Van Der Walt

    Peter Van Der Walt OpenBuilds Team
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    See the Grbl/grblHAL wiki's for documentation on Firmware parameters

    As yours is NPN-NC (not just NPN) you may need either one of the following $5=0 or $5=7 (For BlackBox X32)
    Try each in turn until Troubleshooting tab says they all work as expected.

    CONTROL > Grbl Settings tab > Scroll down to $5 Limits Invert > If its currently 7, try 0. If its currently 0, try 7, etc. Save and Reset
     
    #21 Peter Van Der Walt, Mar 27, 2023
  22. Glen.G

    Glen.G New
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    Good morning,

    Here they work but I have a problem on the Z axis I get the message that the Z axis is stopped by the sensor but impossible to bring the axis back, the message is repeated all the time suddenly my axis Z is blocked... anyone have an idea???

    THANKS
     
    #22 Glen.G, Mar 29, 2023
  23. Peter Van Der Walt

    Peter Van Der Walt OpenBuilds Team
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    One of two possibilities, depending on the following question:

    1) If you turn off the machine, move it away from the switch manually, power up and reconnect, does it still go into an alarm loop? (before hitting the sensor)
    2) Or only right after hitting the sensor?
     
    #23 Peter Van Der Walt, Mar 29, 2023
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  24. Glen.G

    Glen.G New
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    the alarm stops after manual removal of the sensor
     
    #24 Glen.G, Mar 29, 2023
  25. Glen.G

    Glen.G New
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    Good morning

    Could you think about my problem?

    THANKS
     
    #25 Glen.G, Mar 30, 2023
  26. Peter Van Der Walt

    Peter Van Der Walt OpenBuilds Team
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    That points to the sensor itself.

    Would you consider our proven switches instead? Better repeatability, reliability, easier to use and would actually work :)

    Checkout Xtension Limit Switch Kit
     
    #26 Peter Van Der Walt, Mar 30, 2023
  27. Glen.G

    Glen.G New
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    I think that even if I would place your limit suitche the problem that the alarm does not stop will continue, and my budget is exploding with the purchase of the ratrig kit .... but in the future I think well ;-)
     
    #27 Glen.G, Mar 30, 2023
  28. Peter Van Der Walt

    Peter Van Der Walt OpenBuilds Team
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    But you report it does stop when you unplug your sensor.
     
    #28 Peter Van Der Walt, Mar 30, 2023
  29. Glen.G

    Glen.G New
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    yes if I unplug the sensor then it resumes, and therefore time for the sensor to detect the axis I no longer know how to move it so I would also always have to unplug the sensor ... because this is the kind of problem I don't think it's must come from the sensor itself?

    Is there a way to disable this type of alarm?
     
    #29 Glen.G, Mar 30, 2023
  30. Peter Van Der Walt

    Peter Van Der Walt OpenBuilds Team
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    Yes. Set Hard Limits to Disabled in Grbl Settings, but would have liked to work through it so we are sure its not hiding some other issue
     
    #30 Peter Van Der Walt, Mar 30, 2023
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