Questions regarding endstop voltages and Duex2/5



  • Hi everyone,

    I have a couple Duet Wifi (early production) but haven't put them to use yet (still designing mechanical hardware). The switches I want to use for endstops specify a minimum 5vdc for operation. AFAIK, the duet does not natively support this, but the duex2/5 expansion boards do. Is this correct? My printer design will need a duex espansion board anyway, so this makes for an easy solution. Presumably I would simply have to configure the use of the additional endstops rather than the typical ones.

    Basically, my question is regarding the base Duet board – it does not have the functionality to use a jumper to set 5vdc for endstops, correct?


  • administrators

    You haven't said what type of endstops they are. Some 5V endstops can be modified to work from 3.3V, and some can be powered from 5V while providing a 3.3V-compatible output. See https://duet3d.com/wiki/Connecting_endstop_switches.

    The firmware does not currently allow you to swap endstop connectors around.



  • This is the switch I would like to use:

    https://us.misumi-ec.com/vona2/detail/110302201870/?ProductCode=N-CMST

    Here is some info from the PDF linked in the "More Information" tab:

    Contact Rating DC5~24V 20mA (MAX) Resistive Load (10mA with LED)
    Dielectric
    Strength 100MΩ or More DC250V Megohm-meter
    Withstand
    Voltage AC500V 50/60Hz, 1 min. between Each Terminal and Case



  • I'm not sure by the description or on Misumis pages but I get the impression this is a mechanical switch with 2 wires. If so the led will be lit by 5-24V while switch circuit is not closed. You only need >= 5V if you want the LED to be lit.


  • administrators

    I suggest you get the version without the LED. The LED may stop the Duet recognising the difference between triggered and not triggered.



  • Thanks. for that suggestion. I was leaning that way, just because a constantly lit LED would be annoying. Do you think the switch will work with 3.3v? I'm not sure why it wouldn't, but I'm also not an electrical engineer.


  • administrators

    I can't see why the version without the LED wouldn't work on 3.3V.



  • Thanks, I'll give it a shot. I should have two IDEX printers to test the firmware on within 1-2 months. (This is the reason I want to use switches with such precision – aligning idex heads).


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