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  1. #1
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    Default Damaged Stepper Controller?

    Hi,

    I recently completed (first stage) of the wiring of my CNC machine build, it has three Wantai DQ542MA drivers:

    Damaged Stepper Controller?-img_1058-jpg

    I'm having issues with the Z-axis driver, like I don't get any movement when under MACH3 control. Honestly forces me to admit I did have a fault in the wiring whereby the motor outputs were connected the wrong way (i.e the two pairs to each other rather than separate as they should be if that makes sense?) The outputs have never been shorted out however.

    Currently I'm getting a green LED on the driver (same as the others), also the enable/disable is working fine.

    So I had assumed I have killed it.

    HOWEVER.... when I connect simple pulse generator to the inputs, it springs into life! (I made a simple Arduino program to generate a pulsed output). Connecting 5v or 0v to the direction input also changes the motor rotation direction as expected.

    I have also swapped the connectors in my control box, plus the motor outputs, checked all the wiring and confirmed the issue is definitely with the driver itself.

    In summary, it seems 'half dead', i.e. works with an Arduino based pulsed input, but not with one of my existing Mach3 outputs, which is known to be working. The faulty axis is Z, if I swap all the plugs on the driver for the ones which are known to be working for the X and Y axes, I get nothing. It's almost like it no longer handles 'shorter' pulses from Mach3 vs the Arduino timing?

    Looking at the picture, it's the top driver is not working. If I pull the three connectors from the middle one (which is working fully) and move them to the top one, I get nothing. The three connectors are the MACH3 pulse/dir input, the MACH3 enable input, and the stepper output.

    Any thoughts?

    Thanks!

    Similar Threads:
    Last edited by Richster; 04-28-2019 at 07:42 AM.


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    Default Re: Damaged Stepper Controller?

    Try setting the pulse widths in Mach3 to 15.
    And measure the voltage at the drive on the DIR pin.

    Gerry

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    Default Re: Damaged Stepper Controller?

    1.87V - this is about the same voltage I see at the 'working' drive step and dir inputs. HIGH = about 1.87v. low = 0.3V. I have a simple GCODE program running that runs forward, then back on all axes.

    One thought I did have was whether it could have anything to do with there being two PSUs in the box (2 drives are off one, 1 plus all the elecronics off the other). However I think this is a non-issue since all the inputs are opto-isolated so in no way linked electrically to the 'drive' side of the stepper drivers.



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    Default Re: Damaged Stepper Controller?

    It's not going to work with 1.87V. Most drives need 5V signals.
    If you 're running from a parallel port, try getting a breakout board that brings the signals up to 5V.

    Gerry

    UCCNC 2017 Screenset
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    JointCAM - CNC Dovetails & Box Joints
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    Default Re: Damaged Stepper Controller?

    Thanks Gerry

    I do have a breakout board, it's the DB25-1205 made by Longs/Wantai. This is being supplied with 5VDC.

    The 1.87V I'm seeing at all three drives I assume to be an 'average' based on the pulsed signal. I don't have an oscilloscope so I can't confirm that. I did a check on my arduino circuit, the output measures 0.26V on that, again it's just an 'average' of what is ultimately a 5V square wave signal.

    What I'm not understanding is why two of the drives are working, and one isn't. They are all connected identically to the BOB.



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    Default Re: Damaged Stepper Controller?

    Measure the Direction signal, while jogging back and forth. Not the Step signal.

    Did you try setting the pulse width to 15 as I suggested?

    Gerry

    UCCNC 2017 Screenset
    [URL]http://www.thecncwoodworker.com/2017.html[/URL]

    Mach3 2010 Screenset
    [URL]http://www.thecncwoodworker.com/2010.html[/URL]

    JointCAM - CNC Dovetails & Box Joints
    [URL]http://www.g-forcecnc.com/jointcam.html[/URL]

    (Note: The opinions expressed in this post are my own and are not necessarily those of CNCzone and its management)


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    Default Re: Damaged Stepper Controller?

    Yes this is the DIR signal with the pulse width set to 15. I wouldn't expect to see 5V ever (on a simple digital multimeter) unless the input is at 100% duty cycle. My understanding is the DIR signal is also pulsed, so the only way of checking would be with a fancier voltmeter or a scope.

    Regardless, I'm seeing the same at the terminals of the two working drives and the one which is giving me problems i.e. about 1.9V one direction, 0.3v the other.

    If you'll forgive me, I'm not sure what we're testing for here?



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    Default Re: Damaged Stepper Controller?

    I have one of those boards and it took me a bit of time to make it work.The difference was that I chose to use LinuxCNC rather than Mach 3.It works and I have been using it today.The positive thing about the DB25-1205 is the use of opto-isolators,so it shouldn't come to much harmAt the left hand end of the BOB in the photograph I can see at least one connection which should be supplying 5V to the board-where are you getting the supply from?



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    Default Re: Damaged Stepper Controller?

    The direction pulse is On in one direction, Off in the other. So you should see 0V in one direction, and 5V in the other.

    If you're only providing 1.9V signals to your drives, they won't work reliably.

    Gerry

    UCCNC 2017 Screenset
    [URL]http://www.thecncwoodworker.com/2017.html[/URL]

    Mach3 2010 Screenset
    [URL]http://www.thecncwoodworker.com/2010.html[/URL]

    JointCAM - CNC Dovetails & Box Joints
    [URL]http://www.g-forcecnc.com/jointcam.html[/URL]

    (Note: The opinions expressed in this post are my own and are not necessarily those of CNCzone and its management)


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    Default Re: Damaged Stepper Controller?

    Thanks again Gerry.

    One thing did occur to me - on the drivers, I have the outputs from the BOB connected to the opto-couplers, which are in turn connected to 0v. So the BOB is sourcing the current. I had to set the the axes as 'active low' in MACH3 for them to work. The other thing I could try would be connecting 5V to the drive inputs, then sinking the 0v to the BOB. Perhaps I have things wired the wrong way around? Still doesn't explain why two work and one doesn't, but worth a try maybe?

    Thanks



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    Default Re: Damaged Stepper Controller?

    I fixed it - and thanks for your tips!

    A couple of findings....

    The buck converter was only giving 4.3V to the Breakout Board, not the full 5v. I adjusted it back up to 5V. This actually fixed the issue, the voltages I saw at the DIR pin were low = 0.3V (as before) the 'high' was now up to 2V which is enough to trigger the opto-coupler. I guess the 3rd driver has a slight difference in sensitivity on the coupler vs the other two, which is why I thought it was fried...

    Better... is what I figured in my previous post, i.e sink the current into the BOB. This gives me lows of 0v at the DIR pin, still only 3.75 on High state but this is obviously a better solution than my previous efforts.

    I apologise if I had misunderstood the 'correct' wiring of the BOB, but there were no instructions with it!

    Hope this helps someone else...

    Last edited by Richster; 05-01-2019 at 03:31 AM.


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    Default Re: Damaged Stepper Controller?

    Good work Richster and good advice Geryy.
    3.75v still seems low but at least it works now.
    I ,personally, would prefer a bit more head room than that. Maybe do some googling and see if it can be lifted some more.
    Is the BOB getting enough current? If not, that can cause output voltages to be low.
    Whats the max supply voltage of the BOB? If its not being powered by a USB port,you might be able to raise a little bit.....maybe 5.5V?
    Just thinking out loud....

    Steve



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    Default Re: Damaged Stepper Controller?

    Thanks Steve

    The buck converter supplying the 5V is rated at up to 4A, so there shouldn't be any issues there.

    I can't find any online examples showing it setup as I now have it i.e. connecting the drive to 5V then sinking the PUL and DIR into the BOB, but this setup works much more reliably for me. Most schematics look like this:
    https://www.robotics.org.za/57BYGH115-003
    or this
    https://www.steppermotorcanada.ca/db25-1205f.pdf

    I'd be cautious of raising the voltage since I have an additional 'logic board' I built, this has 5V ICs on it. It uses the same PSU.

    For what it's worth, I do have the PC-side electronics isolated using a DC-DC converter, so I'm using both sets of power inputs on this particular board. But, I tried also with the jumpers in place (running both 'sides' of the BOB from the same PSU), and it made no difference. The reason for isolating the PC ground is I have another (homemade) board which works with a MPG. Anyway, running the BOB on its own without any of my other electronics made no difference to the voltages I was seeing.



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    Default Re: Damaged Stepper Controller?

    Quote Originally Posted by routalot View Post
    I have one of those boards and it took me a bit of time to make it work.The difference was that I chose to use LinuxCNC rather than Mach 3.It works and I have been using it today.The positive thing about the DB25-1205 is the use of opto-isolators,so it shouldn't come to much harmAt the left hand end of the BOB in the photograph I can see at least one connection which should be supplying 5V to the board-where are you getting the supply from?
    The 5V to the board is from a buck converter board, fed from same PSU as the steppers (about 40V). That's the board with the red LED on it just under that main PSUs. I'm also supplying an 'isolated' 5V to the 2nd set of power connections on the board (the 'PC' side) which is sourced from a DC-DC converter.



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    Default Re: Damaged Stepper Controller?

    I found good advice on the breakout board similarly hard to come by-especially in English.I found youtube quite helpful and the diagram from Long's motor website finally made the difference.The key was a separate 5V power supply and a cheapy from ebay soon arrived.Then I had the challenge of making it work with LinuxCNC,for which advice was in short supply since it seems to have a much smaller user base than Mach.

    Attached Thumbnails Attached Thumbnails Damaged Stepper Controller?-longs-motor-website-jpg  


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    Default Re: Damaged Stepper Controller?

    Quote Originally Posted by routalot View Post
    Then I had the challenge of making it work with LinuxCNC,for which advice was in short supply since it seems to have a much smaller user base than Mach.
    I suspect you are not asking questions about linuxcnc via the right forum. Try here https://forum.linuxcnc.org/ Its a very active forum and people are only too willing to help. I did not see any of your questions there and I try to read every post.

    That break outboard is quite well known there. I have one myself but Its not in use. I did sit down and work out hoe it all worked and got it working. I don't remember having to add a 5 volt power supply but we started on a test bench before connecting it. It has been reported that the opto couplers are quite slow. Personally, I much prefer Mesa hardware and the ability to use 24 volt logic signals for inputs and outputs.

    Rod Webster
    www.vmn.com.au


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    Default Re: Damaged Stepper Controller?

    Quote Originally Posted by routalot View Post
    I found good advice on the breakout board similarly hard to come by-especially in English.I found youtube quite helpful and the diagram from Long's motor website finally made the difference.The key was a separate 5V power supply and a cheapy from ebay soon arrived.Then I had the challenge of making it work with LinuxCNC,for which advice was in short supply since it seems to have a much smaller user base than Mach.
    Interesting - that image shows the configuration I ended up using. So there's potentially a lot of mis-information about there on the Internet, since most schematics show the PUL and DIR inputs grounded and the 5V signal inputs connected to the BOB.



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    Default Re: Damaged Stepper Controller?

    Quote Originally Posted by Richster View Post
    Thanks Steve
    The buck converter supplying the 5V is rated at up to 4A, so there shouldn't be any issues there.
    Ok, can't imagine a BOB needing more than 4A.



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    Default Re: Damaged Stepper Controller?

    I need to rename my thread from 'Damaged Stepper Controller?', because I now know it isn't!



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