3+ Limit Switch Filament Run Out Detection



  • Hello all, I am planning on using multiple limit switches as filament run out detection for multiple tools. However, according to the documentation, the endstop connections on the DueX cannot be used for this purpose.

    On Duet electronics: 0=X endstop input, 1=Y endstop input, 2=Z endstop input, 3=E0 endstop input etc. If you have a Duex 2 or Duex 5 in your system, note that C5 thru C9 (the endstop inputs on the DueX) cannot be used for filament monitors, but C10 and C11 (the endstop inputs on the CONN_LCD connector) can.

    https://duet3d.dozuki.com/Wiki/Gcode#Section_M591_Configure_filament_sensing

    Does this mean I would need to reassign the end stop inputs on the Duet main board for filament detection, and then assign the endstop inputs on the DueX for my X, Y, and Z axes?



  • Also, on a side note, would it be possible to wire an LED in series with an appropriately sized resistor and either the NC or NO contacts of the limit switch so that if the filament runs out and the switch opens an LED would turn on or off? I'm not sure of the limit on current output of the endstop pins on either the DueX or Duet 2, and would like to know if this would be feasible.



  • @dc42 Would you have any info for me regarding my two questions? Thanks in advance!


  • administrators

    @red-sand-robot said in 3+ Limit Switch Filament Run Out Detection:

    Hello all, I am planning on using multiple limit switches as filament run out detection for multiple tools. However, according to the documentation, the endstop connections on the DueX cannot be used for this purpose.

    On Duet electronics: 0=X endstop input, 1=Y endstop input, 2=Z endstop input, 3=E0 endstop input etc. If you have a Duex 2 or Duex 5 in your system, note that C5 thru C9 (the endstop inputs on the DueX) cannot be used for filament monitors, but C10 and C11 (the endstop inputs on the CONN_LCD connector) can.

    https://duet3d.dozuki.com/Wiki/Gcode#Section_M591_Configure_filament_sensing

    Does this mean I would need to reassign the end stop inputs on the Duet main board for filament detection, and then assign the endstop inputs on the DueX for my X, Y, and Z axes?

    I think simple switch-type filament sensors should work even if connected to the endstop inputs on the DueX. Duet3D and pulse-type filament monitors won't work on those inputs, because the latency is too high.

    So if you are using Duet3D or pulse-type filament monitors, with RepRapFirmware 2.x on a printer with no additional axes, you are limited to 4 of them if you use a Z endstop switch for Z homing, or 5 of them if you use a Z probe for Z homing (because then the Z endstop input is free for a filament monitor). If you use stall detection instead of X and Y endstop switches, you can get 2 more.

    With RepRapFirmware 3 you can re-assign the XYZ endstop switches to inputs on the Due X, which allows you to use up to 7 filament monitors.

    HTH David



  • @dc42 Awesome, thank you! As for my additional question, do you think an LED wired in series with the switch (so it would turn on/off in the case of the switch being released) be too much for the endstop pins?

    Or is that something I would need to get off of the datasheet for the board?


  • administrators

    @red-sand-robot said in 3+ Limit Switch Filament Run Out Detection:

    As for my additional question, do you think an LED wired in series with the switch (so it would turn on/off in the case of the switch being released) be too much for the endstop pins?

    An LED wired in series with a filament monitor switch wouldn't work. An LED + series resistor wired between the +3.3V pin and the STP pin of the endstop connector would work - they would be in parallel with the ones on the Duet.


 

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