Going to plug external driver

  • Hi,
    I going to wire my next printer, a big 400400600 core XY and i try to figure out how to wire my external driver to the duet wifi expansion pin, my driver have DIR +, DIR - and STEP + , STEP -. On the wiring diagrams i just see one pin for each, does it mean that all - can be plug on GND ?
    Second question, can i use the 3.3V and 5V pin with a common GND to use my signal converter board ? (https://www.sparkfun.com/products/12009)

    Using same GND for signal converter and STEP/DIR sound not good to me, did i forget something ?

    This an old picture of the frame without linear rails, they are now fixed so it is the time to think about wiring !


  • administrators

    Can you send details of the driver soni can check. It may be that step+ is wired and Dir+ is wired the others are left floating.

    Depending on the driver you may not need a signal converter board, some 5V signals can work with 3.3V as logic 1. Just don't feed any 5V back to the Duet.

  • administrators

    That converter board is unlikely to work with external drivers. It uses 10K pullup resistors to provide the logic high signal and they won't supply enough current to drive the opto isolators in your external stepper drivers.

    [Edited the following]

    As Tony says, you can try connecting the driver inputs directly between the expansion connector pins and ground, because they may work with 3.3V inputs. If they don't, then I suggest you use 74HCT244 chips powered from +5V and GND. Each chip converts 8 signals.

    The Enable outputs from the Duet are active low by default, so to keep things simple it is best to wire them differently; either EN+ to +3.3V and EN- to the expansion connector, or EN+ to +5V and EN- to a 74HCT244 output.

    You can use 74HCT04 chips instead of 74HCT244 to do the conversion, giving you a smaller chip but only 6 level converters per chip, if you allow for the 74HCT04 inverting the level.

  • Thanks for this precious information, i agree to keep this simple.
    My driver are leadshine ESD 508 (http://www.leadshine.com/productdetail.aspx?type=products&category=easy-servo-products&productype=easy-servo-drives&series=ES-D&model=ES-D508)

    I will try to wire them directly otherwise will try the 74HCT244 chip.

  • What steppers are you going to use on this printer? Some 2A 1.8 Nema17's will work it fine and the onboard steppers will support them.

    Off topic i would suggest some 10MM belts if your going coreXY and smooth idlers as toothed idlers caused vibrations in the prints for me.

  • Stepper are 573hbm10-1000, 1.2° with a back encoder. They allow closeloop motion security and a full setup possibility by sofware when coupled to the driver.

    What's the advantage to go in 9mm belt ? is the rigidity better ?
    I'm still in smooth idler on my small printer and sure i'm really happy with them.

  • The wider belts dont seem to twist as much over a longer span. I've got a 500x500 bed so X & Y are around 700mm.

  • Ok, i will see if i can implement it easily, all parts are machined. Thanks for the advice !

    Back to the topic, an old duet 0.6 can be plug straight to the board without signal converter ! It's a good news !

    Motors are not sync, i just plugged wire as Tony and David recommended. Thanks a lot !

  • So will a stepper drive need to be wired common anode or common cathode with a Duet Wifi?

  • administrators

    Common cathode for the step inputs. For the enable inputs, common anode saves having to invert the enable signal polarity in the M569 command. For the direction inputs, it really doesn't matter but I suggest common cathode.

  • i have the same problem. I going to connect 2 nema 23 to Z and 2 nema23 to Y. which driver you recommend guys ?? please try to recommend something cheaper than the leadshine ESD 508... thanks !!!

  • administrators

    @pablo said in Going to plug external driver:

    i have the same problem. I going to connect 2 nema 23 to Z and 2 nema23 to Y. which driver you recommend guys ?? please try to recommend something cheaper than the leadshine ESD 508... thanks !!!

    If they are rated at no more than about 2.8A then one possibility is to use a Duet+DueX5 or DueX2. There is a wide choice of 2.8A Nema 23 motors here https://www.omc-stepperonline.com/nema-23-stepper-motor/filter/146-rated-current-a,2.8.

Log in to reply