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Getting the digital step/dir signals on stepper X,Y, Z

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  • undefined
    educa
    last edited by 29 Nov 2019, 12:24

    Hi,

    I would like to use a duet 2 wifi for making a extremely precise (but ultraslow 😉 ) laser resin printer.

    The XY stage will be dome with THK linear rails using ballscrew with 1mm pitch and Z axis too.

    X, Y, Z is all very easy to setup because in that case it is just acting like a cartesian printer.

    I would however like to be able to sense the signals for step/dir on the X axis.
    Allow me to explain. The controller on the board sends step and dir signals to the trinamic drivers and those make sure the motor works.

    But is there a place where I can actually connecta dupont connector and read the real step/dir signal which will probably be 5/3.3vDC ?

    I searched on the 50 pin expansion connector, but there I think only the signals for the EXTRA duex channels can be found ?

    Also, it might seem a stupid question, but I'll ask it anyway.

    Is the Duet 2 wifi capable of driving 5 steppers totally independent of eachother with each their own accelerations etc..... .

    If you do it, do it good.

    undefined 1 Reply Last reply 29 Nov 2019, 14:17 Reply Quote 0
    • undefined
      dc42 administrators @educa
      last edited by dc42 29 Nov 2019, 14:17

      @educa said in Getting the digital step/dir signals on stepper X,Y, Z:

      Hi,

      I would like to use a duet 2 wifi for making a extremely precise (but ultraslow 😉 ) laser resin printer.

      The XY stage will be dome with THK linear rails using ballscrew with 1mm pitch and Z axis too.

      X, Y, Z is all very easy to setup because in that case it is just acting like a cartesian printer.

      I would however like to be able to sense the signals for step/dir on the X axis.
      Allow me to explain. The controller on the board sends step and dir signals to the trinamic drivers and those make sure the motor works.

      But is there a place where I can actually connecta dupont connector and read the real step/dir signal which will probably be 5/3.3vDC ?

      I searched on the 50 pin expansion connector, but there I think only the signals for the EXTRA duex channels can be found ?

      Two options:

      1. (recommended) Use the M584 command in config.g to assign both an internal driver and a driver on the expansion connector to each of X, Y and Z axes. Both drivers will receive step pulses at exactly the same time (within a few nanoseconds).

      2. There are test pads on the underside of the Duet where the step and direction signals for the internal drivers can be picked off.

      Also, it might seem a stupid question, but I'll ask it anyway.

      Is the Duet 2 wifi capable of driving 5 steppers totally independent of eachother with each their own accelerations etc..... .

      Yes, it can drive up to 12 steppers independently, of which up to 9 (or 10 in RRF3) can be axes (XYZUVWABCD)

      Duet WiFi hardware designer and firmware engineer
      Please do not ask me for Duet support via PM or email, use the forum
      http://www.escher3d.com, https://miscsolutions.wordpress.com

      1 Reply Last reply Reply Quote 0
      • undefined
        educa
        last edited by 29 Nov 2019, 15:13

        @dc42 said in Getting the digital step/dir signals on stepper X,Y, Z:

        command in config.g to assign both an internal driver and a driver on t

        ok thank you.

        You say drive up to 12 steppers of which 9 can be axes. Out of curiousity, but what are the other 3 then ?

        If you do it, do it good.

        undefined 1 Reply Last reply 29 Nov 2019, 16:16 Reply Quote 0
        • undefined
          deckingman @educa
          last edited by 29 Nov 2019, 16:16

          @educa said in Getting the digital step/dir signals on stepper X,Y, Z:

          @dc42 said in Getting the digital step/dir signals on stepper X,Y, Z:

          command in config.g to assign both an internal driver and a driver on t

          ok thank you.

          You say drive up to 12 steppers of which 9 can be axes. Out of curiousity, but what are the other 3 then ?

          Extruders for example

          Ian
          https://somei3deas.wordpress.com/
          https://www.youtube.com/@deckingman

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          • undefined
            dc42 administrators
            last edited by dc42 29 Nov 2019, 16:27

            Or additional motors for some of the axes. For example, using 3 Z motors drives connected to separate stepper drivers facilitates automatic true bed levelling. The motors are driven together most of the time, but independently when levelling the bed.

            Duet WiFi hardware designer and firmware engineer
            Please do not ask me for Duet support via PM or email, use the forum
            http://www.escher3d.com, https://miscsolutions.wordpress.com

            1 Reply Last reply Reply Quote 0
            • undefined
              educa
              last edited by 10 Dec 2019, 18:49

              Somehow I figured out I need M584 for what I want to do, but

              My machine will have 2 steppers on Y axis, 1 on Z and 1 on X.

              Can I somehow easily configure the duet so that my first Y stepper runs on the Y-driver and then the second Y stepper runs completely parallel in movement, but driven by the E1 driver?

              M584 X0 Y1:5 Z2

              But what with extruder 1 then which is probaly assigned by default to E1 ? Or should I use then

              M584 X0 Y1:5 Z2 E7

              My ultimate goes is this setup

              X axis on X driver
              Y axis on Y and E1 driver (2 motors with each a driver)
              Z axis on Z driver
              NO extruder needed, but I want 1 virtual axis (It might be E0 or E1) which sends its step and dir signals to the expansion header where I can grab them. They will NOT drive a stepper but give signals to some other piece of electronics.

              If you do it, do it good.

              undefined 1 Reply Last reply 10 Dec 2019, 19:31 Reply Quote 0
              • undefined
                dc42 administrators @educa
                last edited by 10 Dec 2019, 19:31

                @educa said in Getting the digital step/dir signals on stepper X,Y, Z:

                But what with extruder 1 then which is probaly assigned by default to E1 ? Or should I use then
                M584 X0 Y1:5 Z2 E7
                My ultimate goes is this setup
                X axis on X driver
                Y axis on Y and E1 driver (2 motors with each a driver)
                Z axis on Z driver
                NO extruder needed, but I want 1 virtual axis (It might be E0 or E1) which sends its step and dir signals to the expansion header where I can grab them. They will NOT drive a stepper but give signals to some other piece of electronics.

                Yes that M584 command will achieve that.

                Are you sure that you want to configure your "virtual axis" as an extruder, and not as an additional axis?

                Duet WiFi hardware designer and firmware engineer
                Please do not ask me for Duet support via PM or email, use the forum
                http://www.escher3d.com, https://miscsolutions.wordpress.com

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                • undefined
                  Danal
                  last edited by 10 Dec 2019, 19:34

                  Everything you are proposing is well within the capabilities of a Duet 2. It is mostly a matter of choosing the pins you wish to use, and configuring for them.

                  It can be slightly confusing that the drivers and/or pins have default labels that appear meaningful. In reality, they are fairly abstract (V2 firmware does have a few assumptions that are hard to abstract. For example. Heater 0 is intended to be the bed and it is fairly hard to move this around). So, yes, it is very possible to have logical X on the driver labeled X, logical Y on the drivers labeled Y and ____ (fill in the blank with almost anything you wish) and so on and so forth.

                  Delta / Kossel printer fanatic

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                  • undefined
                    educa
                    last edited by 10 Dec 2019, 20:15

                    dc42 what would be the difference between defining them as axis and extruder ? Don't they both react the same ?

                    If you do it, do it good.

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                    • undefined
                      Danal
                      last edited by 11 Dec 2019, 14:57

                      An axis will not move until it is homed (or the gcode to override "move without home" is issued). An extruder does not home.

                      An extruder will not move until its associated heater is above the configured temperature (unless the gcode to override "cold extrudes" is issued).

                      Both axis and extruder can be specified in G0 or G1, and if other axis/extruders are included in that same command, "coordinated linear motion" will occur (moving each at a speed that ensures they all reach their respective final points at the same instant in time.) So no difference there.

                      There are probably more differences and similarities. These are a few that came to mind.

                      Delta / Kossel printer fanatic

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