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IndustryArena Forum > CNC Electronics > Stepper Motors / Drives > need some assistnace with closed loop stepper set-up
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  1. #1
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    need some assistnace with closed loop stepper set-up

    so I've been running these closed loop steppers on my mill for a while (using the NEMA 34 version) and never had a problem. I've building a lathe right now, using the smaller nema 23 steppers as they are about perfect for the size lathe I have. So here's the issue. The steppers work perfect until I put load on them, and them I get a following error from the control. I wasn't given any software to chance the control settings, but i didn't have to for the ones on my mill either.

    So I guess my question to you guys who know more about steppers than I do, is there something I could have wired up incorrectly to get significantly lower toque from the motors? I power supply is giving the controls 48VDC, and is seems like they should be working.

    I suppose the other issue could be the feedback loop. if it's trying to hold to tight a error it would fault out any time it's moved....

  2. #2
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    Re: need some assistnace with closed loop stepper set-up

    How do you like the performance on the size 34, what speed can you get ?
    Manufacturer of CNC routers and Viper Servo Drives
    www.LarkenCNC.com and www.Viperservo.com

  3. #3
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    Re: need some assistnace with closed loop stepper set-up

    I like them. My only gripe is if for whatever reason you do get a following error, there is no way to reset them without turning them off, and back on. Which for me, means restarting my entire control enclosure.

    I've had my mill whipping around at 150IPM, and i'm pretty sure I could go faster if I tried. I also have they geared down 2:1.

  4. #4
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    Re: need some assistnace with closed loop stepper set-up

    Every motor has a following error, it just depends how much.

    Are you saying they Fault or trip when they have a following error ?
    Manufacturer of CNC routers and Viper Servo Drives
    www.LarkenCNC.com and www.Viperservo.com

  5. #5
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    Re: need some assistnace with closed loop stepper set-up

    the control faults, but only when there is load on the stepper. Free wheeling, they work perfectly.

    Yes, I agree everything has error, but maybe the control is set to too tight a tolerance. Only thing is I don't know how to check that, I didn't receive any software with the controls.

    From the manual:
    "RS232 Communication Port
    It is used to configure the peak current, microstep, active level, current loop parameters and antiresonance
    parameters. See EM driver’s software operational manual for more information."

    so apparently there is software somewhere, but I don't see it on the automation technologies website

  6. #6
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    Re: need some assistnace with closed loop stepper set-up

    Gerry

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    JointCAM - CNC Dovetails & Box Joints
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    (Note: The opinions expressed in this post are my own and are not necessarily those of CNCzone and its management)

  7. #7
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    Re: need some assistnace with closed loop stepper set-up

    that looks like the guy i need. thanks.

  8. #8
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    Re: need some assistnace with closed loop stepper set-up

    So played around with that software, and after downloading 4 different versions of it, I finally got one that would connect to the control box. Played around with the following error setting and it got a little better, but it still seems like the steppers just don't have any torque. The leadscrew it's connected to, I can easily spin with 2 fingers, so this stepper should have NO problem jogging it.

    So any other ideas? Maybe my power supply isn't outputting enough current? I'm a a loss for other ideas.

  9. #9
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    Re: need some assistnace with closed loop stepper set-up

    Does it do the same thing on the other axis too ?

    Is this a motor drive package you bought together, or are you using a size 23 motor with the bigger drive you talked about.
    (There is a leadshine forum here , but there seems to be no techsupport on it.)

    Have you talked to john at Keling about the problem ?
    Manufacturer of CNC routers and Viper Servo Drives
    www.LarkenCNC.com and www.Viperservo.com

  10. #10
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    Re: need some assistnace with closed loop stepper set-up

    yes, both axis. I bought them as a kit, including drive and stepper together. The only thing I purchased separately was the power supply, but it's the exact same part number used in the 3 axis kit that they offer.

    I have not as it's the weekend, but I'll be giving them a call tomorrow.

  11. #11
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    Re: need some assistnace with closed loop stepper set-up

    One more question, Is that a stepper motor or a brushless 3phase motor, because on kelings web page it says both ?

    With the motor disconnected, can you turn the motor easily and smoothly in your fingers, or do you feel the fine (and hard to turn) detent bumps of a stepper ?

    Can you post a picture of the drive and motor so we can see the writing on the labels , please

    Larry
    Manufacturer of CNC routers and Viper Servo Drives
    www.LarkenCNC.com and www.Viperservo.com

  12. #12
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    Re: need some assistnace with closed loop stepper set-up

    pretty sure they are true steppers. You can feel the steps as you rotate the stepper, but it's not hard to turn

    Attachment 255472

    Attachment 255474

  13. #13
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    Re: need some assistnace with closed loop stepper set-up

    Hmm,they have a single 3 phase winding, but no hall sensors.
    Can you count how many magnetic bumps per turn ? It says 1.2deg and oppose to 1.8 on a standard stepper. On a 1.8 deg stepper there are 50 bumps /turn.

    What you first turn them on, do they do a dance back and forth ?

    Definitely a weird motor not a stepper, but a hybrid of a stepper and brushless. The problem with a system like that is you prpbably won't be able to get replacement drive or motor separately in a year from now.


    I've started to make a closed loop stepper (Cobra-sv) that uses any standard stepper and any encoder 500line or 1000 line encoder. Its very new, and i still have some switching noise when the motor is stopped, so i need to make a 4 layer board, but they work good. I'm using the KL23H2100-35-4B motor from keling and a 500 line US digital encoder. It doesn't add more performance to the stepper system, but just reliability.

    Larry
    Manufacturer of CNC routers and Viper Servo Drives
    www.LarkenCNC.com and www.Viperservo.com

  14. #14
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    670

    Re: need some assistnace with closed loop stepper set-up

    I haven't counted the ticks/rev yet, but nothing I seem to do with the software seems to work. I tried increasing the stiffness, still faults. Tried increasing the current, still faults.

    I shot keling an email....crossing my fingers they can help me out. I'm stumped...

  15. #15
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    Re: need some assistnace with closed loop stepper set-up

    Whats your powersupply voltage ? Put a voltmeter on the PS and see if it drops down as you add load.
    Is it a linear or a switching supply ?
    Manufacturer of CNC routers and Viper Servo Drives
    www.LarkenCNC.com and www.Viperservo.com

  16. #16
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    Re: need some assistnace with closed loop stepper set-up

    Quote Originally Posted by Larken View Post
    Every motor has a following error, it just depends how much.

    Are you saying they Fault or trip when they have a following error ?
    There will be an error between the commanded movement and the actual movement due to inductance and other electrical phenomena. The encoder being on the shaft should have very little following errors though, unless there's a true stall or heavy load.

    Quote Originally Posted by Larken View Post
    Hmm,they have a single 3 phase winding, but no hall sensors.
    Can you count how many magnetic bumps per turn ? It says 1.2deg and oppose to 1.8 on a standard stepper. On a 1.8 deg stepper there are 50 bumps /turn.

    What you first turn them on, do they do a dance back and forth ?

    Definitely a weird motor not a stepper, but a hybrid of a stepper and brushless. The problem with a system like that is you prpbably won't be able to get replacement drive or motor separately in a year from now.


    I've started to make a closed loop stepper (Cobra-sv) that uses any standard stepper and any encoder 500line or 1000 line encoder. Its very new, and i still have some switching noise when the motor is stopped, so i need to make a 4 layer board, but they work good. I'm using the KL23H2100-35-4B motor from keling and a 500 line US digital encoder. It doesn't add more performance to the stepper system, but just reliability.

    Larry

    They appear to be true closed loop steppers, in the manual you can set microsteps ranging from 200-51,200 steps per revolution. They are clearly 1.8° stepper motors, that'd be the only way to get the price point on the physical stepper and controller. The controller uses the encoder as a commutator to close a position loop - in essence you are turning them into a servo, just one with discrete poles.

    If your encoders are single ended I strongly recommend going with an encoder with a reference signal - A, A-, B, B-, Z, Z-. The single ended encoders are very susceptible to noise. I know US Digital makes both, but if I had to make a recommendation... these here are a bargain and perform wonderfully:
    Omron E6B2 CWZ6C 1000p R abz Encoder Without Losing Pulse | eBay


    For the OP:

    I would download the protune software
    Leadshine Technology Co., Ltd.
    Download the manual for the motor - should say "software operational manual"
    Leadshine Technology Co., Ltd.

    Other closed loop stepper controllers I have seen allow for shaping of the current pulses to the stepper - allowing slight overshoots of the current for very brief periods of time (both are settable). You can essentially squeeze more performance out of a stepper than its rated performance.

    It's not clear to me if this closed loop stepper implementation can take advantage of the PPR of the quadrature wave - essentially turning your 1000 points per revolution into 4000 discrete points. It eludes to this, but doesn't say it explicitly.

    Things to consider:
    Are you wired up correctly?
    What kind of amperage is your power supply? It looks like these things can handle up to 6amps.
    Do you know your actual torque requirements for your system? A holding torque of 2 Nm (~282oz-in) really is about 70-80% of that in the very low RPM range, then will continue to decrease. Really you're probably at around 225-200oz-in torque in the 100RPM range.
    What RPM are you running your steppers at?
    Lin Engineering has a great tool in the designers corner that will give you torque curves for your stepper motors based off your power supply. If you're not providing 6amps, it'll give you a good idea of what you're getting (select a comparable nema23 motor to yours)

    I did notice in the manual that the position following error is set to 1000 pulses default. I would get the software, adjust this parameter to 4000 pulses.

  17. #17
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    Re: need some assistnace with closed loop stepper set-up

    UA_Iron,

    If you zoom in on the pictures in post #12 of this thread, you can see where it says 1.2 deg on the motor, then on the drive it has a 3wire U,V,W connection to the windings instead of a 4 wire phase A and phase B.

    I think this is the motor here
    Leadshine Technology Co., Ltd.
    because its 5.8 amp, like in the picture

    (I think its a special high pole count brushless 3phase motor. )

    Larry
    Manufacturer of CNC routers and Viper Servo Drives
    www.LarkenCNC.com and www.Viperservo.com

  18. #18
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    Re: need some assistnace with closed loop stepper set-up

    Quote Originally Posted by Larken View Post
    UA_Iron,

    If you zoom in on the pictures in post #12 of this thread, you can see where it says 1.2 deg on the motor, then on the drive it has a 3wire U,V,W connection to the windings instead of a 4 wire phase A and phase B.

    I think this is the motor here
    Leadshine Technology Co., Ltd.
    because its 5.8 amp, like in the picture

    (I think its a special high pole count brushless 3phase motor. )

    Larry
    You're right. Wow, usually costs of steppers with more than 2 phases starts to get high - including the controllers. I convinced myself that it couldn't be that cheap if it were 3 phases - hah.

    Thanks for informing me.

  19. #19
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    670

    Re: need some assistnace with closed loop stepper set-up

    Wow, lots of action in here. Thanks guys!

    Power supply is at 48VDC. I'll check tonight to see if voltage drops under load. It's a toroidal power supply (part number: KL-4820)

    It's not clear to me if this closed loop stepper implementation can take advantage of the PPR of the quadrature wave - essentially turning your 1000 points per revolution into 4000 discrete points. It eludes to this, but doesn't say it explicitly.
    Yes I believe it does. PPR is set to 4000 from the factory.

    Things to consider:
    Are you wired up correctly? I believe so, they work just peachy without any load, and they come prewired from the factory. All I did was extend the leads on them and add a connector to plug into my enclosure

    What kind of amperage is your power supply? It looks like these things can handle up to 6amps. 20A max could I be pushing too much current thru them? Hope I didn't burn anything out!

    Do you know your actual torque requirements for your system? A holding torque of 2 Nm (~282oz-in) really is about 70-80% of that in the very low RPM range, then will continue to decrease. Really you're probably at around 225-200oz-in torque in the 100RPM range. I did not, but I use smaller steppers on my other mini mill, and they have WAY more torque at 48V than these buggers do.

    What RPM are you running your steppers at? I've tried varying the RPM with no real difference. I've gone down to 10RPM up to around 200 RPM with no noticable difference

  20. #20
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    Re: need some assistnace with closed loop stepper set-up

    Quote Originally Posted by CS900 View Post
    Wow, lots of action in here. Thanks guys!

    Power supply is at 48VDC. I'll check tonight to see if voltage drops under load. It's a toroidal power supply (part number: KL-4820)

    Yes I believe it does. PPR is set to 4000 from the factory.
    It looks like your power supply is good - more than enough amperage. You're running in the right RPM range... I'm kind of at a loss.

    Might try swapping them out with your smaller ones and see how it runs.

    I'd contact the supplier for support in this case

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