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Having a bit of a problem getting it right. Smoothieboard & DQ542MA

Discussion in 'Controller Boards' started by Lasersc, Jun 29, 2018.

  1. Lasersc

    Lasersc Well-Known
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    EStopStep..jpg newdriver..jpg I feel I am getting really close but I am still having some issues. I have a Smoothie board, DQ542MA drivers and heavy duty NEMA 23 Steppers. All of which came from Openbuilds. I have two 24vdc power supplies for the drivers and the Smoothiboard is getting its power from the USB port connected to my computer. The Dipswitches are set as follows: #4 on, #5 off, #6 on, #7 off, #8 on. I have only had the board for a couple of months and all other components are new as well. That being said, I haven't upgraded my firmware to the CNC firmware but I have modified the original config file to only include CNC related settings. Here are a few Question and problems I am having:

    #1 Do I need to upgrade firmware? I can jog all three axis in certain situations
    #2 As soon as I supply power to the Enable connector on all drivers I get a fault on drivers. Nothing will move.
    #3 If I unplug the Enable connector the steppers appear to lock, fault goes away and I can jog the steppers
    when sending command. The steppers get really warm in this state as they sit idle.
    #4 I am attaching 2 illustrations of my wiring, do they appear to be correct? Do I need to add any
    special code such as adding the "o" or "!" to make thing work the way I have them wired?
    #5 My end stops do not appear to function, while jogging a stepper I can press the end stop switch
    and the steeper keeps running.

    Thank you for any help.
     
  2. Peter Van Der Walt

    Peter Van Der Walt OpenBuilds Team
    Staff Member Moderator Resident Builder Project Maker Builder

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    Enable pin = active LOW. If you add V+ to the ENable pin, it DISABLES the driver. Disabled state also shows as the fault LED. Its not a fault, its just disabled :)
    If you don't wire enable the driver is already enabled on power up.


    Check your smoothie config: you want:


    alpha_limit_enable true If set to true, the machine will stop if one of the alpha ( X axis or alpha tower ) endstops are hit
    beta_limit_enable true If set to true, the machine will stop if one of the beta ( Y axis or beta tower ) endstops are hit
    gamma_limit_enable true If set to true, the machine will stop if one of the gamma ( Z axis or gamma tower ) endstops are hit
    (from endstops [Smoothieware])
     
  3. Lasersc

    Lasersc Well-Known
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    Thank you so much for your help. I changed the settings in my config to enable the end stops and after doing so I couldn’t move any axis. So, a I am figuring I have the end stops wired wrong. Can you tell by the picture attached if they are in deed wired wrong?

    On the first issue if I leave the ENable unplugged everything works fine, it’s just if left powered up while not running they get very warm. Is there something else I can change in the config that would allow me to hook up the ENable and it will only engage the steppers when a command to move is given? Does that make sense?

    Thank you again, I appreciate any help I can get.
     

    Attached Files:

  4. Gary Caruso

    Gary Caruso OpenBuilds Team
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    Hi Lasersc,
    That would not be too good for the machine as ever time the drives disable there is a chance the position moves.. The drive does have a reduced power mode as set by switch #4
    Cooling fans are a good idea, the setting for current will make a difference in the heat as well.

    upload_2018-7-4_0-46-8.png
     
  5. Lasersc

    Lasersc Well-Known
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    Thank you Gary, I will switch #4 to half current and check into some fans. But I want to get it right. I should never wire the ENable connector as it only disables the steppers?
     
  6. Gary Caruso

    Gary Caruso OpenBuilds Team
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    You can use it to disable the drives if you wanted, but most people don't bother, it's not necessary and adds complexity.
    Cheers
    Gary
     
  7. Craig & Silas

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    I purchased the C-Beam XL bundle which came with everything that you are using except the second power supply. Why do you need a second power supply?
     
  8. Peter Van Der Walt

    Peter Van Der Walt OpenBuilds Team
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    If its one of our Meanwell LRS350-24 PSUs you can easily run 4x NEMA23s on it (even the High Torque motors, and even then still lots of power left over for accesories):


    FAQ: How many amps do you really need?

    The motors current ratings are done at the coil voltage (As stepper drivers are constant current switchmode choppers, they dont also output 24v when you power them off 24v. They lower the voltage, to attain the correct constant current) : ie 3A at the much lower Coil voltage of 3.6v. (Which can be calculated from the coil resistance and amperage rating on the datasheet, V=IR (Ohms Law)). So with the lower voltage in the current calculation, you'll see whether you are withing the limits of the PSU you selected

    From our NEMA23 High Torque motor's Datasheet as an example:
    Ohms law says V=I*R:

    R=1.2ohm (From datasheet)
    I=3.0A (From datasheet)
    V=3.6v (Calculated)

    Ohms law also says W=V*A
    3.6v * 3.0A = 10.8 watt. (Calculated) per coil x 2 coils = 21.6w per motor + 25% overhead for Peak draw = 27w per motor

    The stepper drivers are not 100% efficient either, so lets add 20-30% for it too (the VM voltage powers its internal circuitry, some losses in the switching mosfets burned off as heat, etc etc) - lets call it 35w per motor+driver...

    35w @24v = +-1.5A x 4 drivers = 6A @24v
     
    #8 Peter Van Der Walt, Aug 20, 2019 at 4:50 PM
    Last edited: Aug 20, 2019 at 4:56 PM
    Gary Caruso likes this.
  9. Craig & Silas

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    Thank you for the clear answer.
     

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