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Thread: Stepper driver, breakout board problems

  1. #1

    Default Stepper driver, breakout board problems

    Hi everyone

    I purchased some nema 34 stepper motors, drivers and breakout boards for use on a 4x4 cnc router from a chinese company. I have some serious problems in the setup if anybody can possibly help. Support is now non existent from them and im stuck!

    2 main problems, we cant get the e-stop and any limits to work,and the Z axis loses steps no matter what pulse setting I seem to try. Have got 2 identical breakout boards and they both act the same so maybe its something i have overlooked.

    The motors say 3.5amp on them but the motor drawing says 5.6A/phase? The drivers they say were matched and are model SD-2H086MB.

    Power supply is 48v, 10.4amp. The 2 Y axis motors are geared 1.5:1 and the Z axis motor is 1:1. The ballscrews are all 5mm pitch.

    All technical docs are attached. Would greatly appreciate some guidance to maybe sort one problem at a time. Possibly discover why no limits etc are working. Maybe someone has had this board.

    Thanks, Dougie

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    Attached Thumbnails Attached Thumbnails -wantai-002-jpg   -wantai-003-jpg   -wantai-006-jpg   -wantai-007-jpg  


  2. #2


    What software are you using this with? If it's Mach or EMC, perhaps we can help. If it's something else, it will be harder.

  3. #3


    Using mach3 software, set up according to their instructions. I am wondering if perhaps its wired incorectly or needs something to bring the limits on

  4. #4


    Okay, we can help with Mach.

    Does ANYTHING appear to work with the board? Trying to figure out if Mach is able to see the LPT port the board is on.

    If it doesn't, then you have an addressing problem = the board's address is not what Mach thinks it is.

    If something appears to work, then we need to figure out what is in your config that is wrong. You might go into the diagnostics panel. In the center right, you will see LEDs that show the state of the pins. Try hitting some of your limit/estop switches and see if any of the lights change. If they do, we can figure out what is happening.

    I assume that one side of the switch is connected to power supply ground. The other side would be connected to the BOB. Measure the voltage with a switch in both states, and tell us what the voltages are. One them should be zero volts.

  5. #5


    Yes I have the 4 motors working although Z stalls no matter what pulse setting I seem to use. The motor settings in mach all give the correct distance moves.

    When I press a limit switch if I put them on pins 10,11,12,13 it lights up an LED on the board to indicate it gets a signal but when I autodetect on mach it picks nothing up. However pin 10 works.

    Yes one side of the switches are to ground. If I put the e-stop in pin 10 it works 3.85v when pressed. If I put the limits in pins 11,12,13 I measure 0v normally and when pressed 2.6v, 3.7v and 3.5v but the status pins in mach dont change to indicate a response. I have tried a different cable and the other board but nothing.

  6. #6



    Looking at your photo's it looks like you have some "Daisy Chaining"
    of the cables going on can you confirm which wires are coming from what and going to


    PS where abouts in the UK are you?

  7. #7



    Let's make ONE thing work, and then go on to the next. How about E-Stop?
    You said pin 10 works. Make pin 10 E-Stop. Don't use autoscan, manually configure pin 10 to be E-Stop in pins and ports. Use the same port as the motors.

    You said you measure 3.84V when pressed. That sounds good. It means that the switch is normally low, and goes high to activate. It should measure close to zero when at rest.

    You should be able to get E-Stop to work with pin 10, and the right active setting. You can confirm it works easily enough, right?

  8. #8


    I just went through some of these problems. Even though I used shielded cables with proper grounding, I have a lot of electrical noise. I ended up with a .01 mfd capacitor (its all that I had) across the limit switch terminals on the breakout board. I also had to set the "debounce" value to around 7000, in the general config screen.


  9. #9


    Hi Guys

    The daisy chaining is the pulse and enable (+5v) between the drives which I assumed would be ok to do. I am in Lancashire UK, near Burnley.

    Brtech the E-stop on pin 10 works and if I put a limit switch on pin 10 it works but no other input pins work. Not sure what those little toggle switches on the breakout board do.

    Johnmac did the capacitor and debounce sort your problems? I am not sure its that as the limits do give a good reading when they change state, just nothing is being outputted through the 25 pin port.

    Its impossible to trace them.

  10. #10



    I would avoid any daisy chaining, not sure what you mean by the pulse being daisy chained.


  11. #11


    Yes, for me that combination fixed my problem. When I first started troubleshooting this problem, neither the limit or E-stop would reset.

    Even if you discover you have other problems, don't forget about the debounce setting.


  12. #12


    Okay, so E-stop works on pin 10.


    Put a limit switch on Pin 11. Manually configure it for the right axis in config.
    It should be provisioned identically to the E-Stop except for the pin number, assuming that for the limits the switch reads about 0 when at rest and +3. something when activated.

    I believe you said you could see the LEDs changing on the diagnostic screen when you activated the limit switch. If that is still working, then the configuration should work to detect the limit.

    Just get one to work first. If that works, try another.

    The capacitors aren't needed yet. You need them if your limit seems to be activated when it shouldn't be (like in the middle of a good move).

    Debounce may need to be set to something, but just to get the limit to activate it shouldn't matter. Debounce is needed because a mechanical switch may not cleanly go from off to on. It may bounce between off and on a bit (milliseconds) before settling down. Most microswitches, if that is what you are using, have very little bounce, but you may get some. For a limit switch, bounce doesn't matter, but the way the debounce function works, it also acts as a noise filter, and you may get noise. The capacitor is also a noise filter and you should not need both.

    If you can see the LEDs changing on the diagnostic screen when you activate a limit switch, then the BOB, the wiring and the limit switch is working: configuration is all that is needed. If you can't see the LEDs change, then we have an electrical problem of some sort.

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