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IndustryArena Forum > CNC Electronics > General CNC Machine Related Electronics > M16D: How to have ±10 V analog for servo velocity control?
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  1. #1
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    M16D: How to have ±10 V analog for servo velocity control?

    Hi,

    My servo drive (ABB Microflex e150) needs -10v/+10v analog signal for speed and direction control. The M16D board has 3 onboard relays:

    Relay 1: it gets triggered on PWM
    Relay 2: According to the manual it is bound to Pokeys pin #23
    Relay 3: it gets activated when when the board is enable. It is for SCHP I think. So I think can not use it for speed control.

    The board also have output for 0-10v

    Having these, how can I get the -10v/+10v for speed and direction?

    Heres the manual for the M16D board: https://www.cnc4pc.com/pub/media/pro...NUAL_V.3.6.pdf

    Thanks in advance,
    Suat

  2. #2
    Community Moderator Al_The_Man's Avatar
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    Re: M16D: How to have ±10 V analog for servo velocity control?

    That board does not appear to support ±10vdc servo input .
    In all the DIY projects I have designed or set up, they have all been analogue input using drives in the torque mode.
    To operate these drives there is Linux, Galil, Kanalog etc.
    CNC, Mechatronics Integration and Custom Machine Design

    “Logic will get you from A to B. Imagination will take you everywhere.”
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  3. #3
    Community Moderator Jim Dawson's Avatar
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    Re: M16D: How to have ±10 V analog for servo velocity control?

    What Al said ^^^^^^^^^
    Jim Dawson
    Sandy, Oregon, USA

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    Re: M16D: How to have ±10 V analog for servo velocity control?

    Hi,
    are you using the servo as a servo or a spindle motor?

    If you are using it as a spindle motor then do you really require reverse rotation?. If not then 0-10V analogue from your PWM output would be
    sufficient to control spindle speed in the forward direction. Your controller could enable/disable the spindle motor, or alternately you could
    use a comparator to drive relays...with or without some logic.

    If you want both directions then you need to make an amplifier that had positive and negative outputs, an opamp with +15V and -15V supplies.
    Eminently possible. I could help you with a circuit diagram should you want to do that.

    Craig

  5. #5
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    Re: M16D: How to have ±10 V analog for servo velocity control?

    Hi,

    Machine is a mill. I only need CCW for rigid tapping.

    I've been searching the web, can a dpdt relay be used for this?

    Sent from my MI 5s Plus using Tapatalk

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    Re: M16D: How to have ±10 V analog for servo velocity control?

    Hi,
    I would have thought that you need both directions for rigid tapping? One to wind the tap in and then the other direction to wind it out.

    I seldom do rigid tapping. I have an Allen Bradley servo as a spindle motor. Under normal milling circumstances I use it in analogue speed mode
    with a PWM voltage controlling the speed. On those few occasions when I want to rigid tap I use Step/Direction mode, and my spindle
    becomes a C axis which can be coordinated with the Z axis via Gcode. My knowledge of using a servo in speed mode and synching the Z axis to it
    is pretty thin and I would not comment on its feasibility.

    Craig

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    Re: M16D: How to have ±10 V analog for servo velocity control?

    So your servo works both on analog and step/dir?

    For step/dir my servo wants EtherCat connection. I couldn't manage it to work directly with step/dir signal so my only chance was to use it with analog control.

    I did connect the encoder to the M16D by splitting A,B and Z wires (common ground). Now I have encoder feedback on the controller side. Mach4 can display the true spindle RPM.

    Now I have analog control and encoder feedback. Can I do rigid tapping?

    By the way, I didn't try the servo in torque mode. Is it better than velocity for a milling machine? What do you think?

  8. #8
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    Re: M16D: How to have ±10 V analog for servo velocity control?

    Quote Originally Posted by Azalin View Post
    So your servo works both on analog and step/dir?
    Mine does too.
    (Lichuan A4).

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    Re: M16D: How to have ±10 V analog for servo velocity control?

    Ok I tried a dpdt relay I have in the shelf. When the coil is energized the output polarity is inversed. I will connect the 0-10v analog signal (from M16D) to the common terminals. Output will be -/+ dependant to the coil switch. Now I need one of the onboard (M16D) relays to trigger this relay when M4 command is given (i have no idea how to do this in mach4 tho)

    Does this sound good to you or am I still missing something?

    Sent from my MI 5s Plus using Tapatalk

  10. #10
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    Re: M16D: How to have ±10 V analog for servo velocity control?

    Quote Originally Posted by joeavaerage View Post
    Hi,
    are you using the servo as a servo or a spindle motor?

    If you are using it as a spindle motor then do you really require reverse rotation?. If not then 0-10V analogue from your PWM output would be
    sufficient to control spindle speed in the forward direction. Your controller could enable/disable the spindle motor, or alternately you could
    use a comparator to drive relays...with or without some logic.

    If you want both directions then you need to make an amplifier that had positive and negative outputs, an opamp with +15V and -15V supplies.
    Eminently possible. I could help you with a circuit diagram should you want to do that.

    Craig
    You only need to flip from + to - with a 10v Dc supply you don't need anything fancy to do this if this, if this is for a spindle, using PWM to analog you can also change direction
    Mactec54

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    Re: M16D: How to have ±10 V analog for servo velocity control?

    Quote Originally Posted by Azalin View Post
    Ok I tried a dpdt relay I have in the shelf. When the coil is energized the output polarity is inversed. I will connect the 0-10v analog signal (from M16D) to the common terminals. Output will be -/+ dependant to the coil switch. Now I need one of the onboard (M16D) relays to trigger this relay when M4 command is given (i have no idea how to do this in mach4 tho)

    Does this sound good to you or am I still missing something?

    Sent from my MI 5s Plus using Tapatalk
    Note that if you are using a DPDT relay to swap the breakout board analog output pins, you may have problems if the breakout analog output
    is not isolated (since you will be connecting the drives input common to the BOBs analog output and the BOBs common to the drives analog input)

  12. #12
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    Re: M16D: How to have ±10 V analog for servo velocity control?

    By common I meant the common terminal of the DPDT relay, not the drive or BOB.

    So far it goes promising. However I have a new problem. When I stop the spindle (M5) it does a hard stop. How bad is this for a mill spindle? Can I do something like a 200 ms to zero on M5 command?



  13. #13
    Community Moderator Al_The_Man's Avatar
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    Re: M16D: How to have ±10 V analog for servo velocity control?

    Quote Originally Posted by Azalin View Post
    However I have a new problem. When I stop the spindle (M5) it does a hard stop. How bad is this for a mill spindle? Can I do something like a 200 ms to zero on M5 command?
    That is to be expected if a servo drive, probably the answer is to make up a decay circuit for the ±10vdc signal.
    CNC, Mechatronics Integration and Custom Machine Design

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    Re: M16D: How to have ±10 V analog for servo velocity control?

    Hi,

    So your servo works both on analog and step/dir?
    Yes, most modern AC servos have multiple modes to choose from, Position mode with Step/Dir or CCW/CW or quadrature, analogue velocity
    or analog torque. Further most modern servos can be dual mode, as in my case its set up to be analogue velocity (99% of the time) or Step/Dir.
    You can change mode by asserting or de-asserting one digital input to the drive. Very convenient.

    For step/dir my servo wants EtherCat connection. I couldn't manage it to work directly with step/dir signal so my only chance was to use it with analog control.
    Depending on the manufacturer Ethercat servos may miss on some features. For example Delta Ethercat servos miss out on analogue inputs.

    By the way, I didn't try the servo in torque mode. Is it better than velocity for a milling machine? What do you think?
    There are two main application areas of torque mode servos. Firstly they are very useful in conveyor or printing applications as they maintain constant tension
    in the belt or paper. The other use is with a controller like Galill or Kanalog to do position control with the control loop closed by the controller.
    In the early days of servos they were ALL torque mode, with resolvers and/or tachogenerators. They still work and do a good job but are pretty old
    fashioned by todays standards. Today the servo drive closes the loop, and given that the drive is manufactured by the same company as the servo,
    employ some very sophisticated tuning aids, difficult if not impossible to replicate with older style PID capable controllers.

    Now I have analog control and encoder feedback. Can I do rigid tapping?
    Good question, I don't know. I understand you are using Mach4 as I do. I know there is provision for rigid tapping in Mach4 despite Mach4 not being a genuine feedback
    capable software solution like LinuxCNC. When I do rigid tapping I rely on coordination of the C axis (ie spindle) and the Z axis by Gcode, so I have not tried
    the Mach4 tapping feature.

    A DPDT relay would work but the caution by PCW_MESA is very important. If the 0V common of the servo is tied to the 0V common of your BoB then
    potentially a DPDT relay could short the servo-side 10V supply with damage to either the BoB or drive. I would investigate VERY carefully BEFORE I
    did that. My servos are about $500USD each, allowing for some shipping, and I do NOT want to blow the drives.

    Craig

  15. #15
    Community Moderator Al_The_Man's Avatar
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    Re: M16D: How to have ±10 V analog for servo velocity control?

    Quote Originally Posted by joeavaerage View Post
    Hi,

    The other use is with a controller like Galill or Kanalog to do position control with the control loop closed by the controller.
    In the early days of servos they were ALL torque mode, with resolvers and/or tachogenerators.

    Craig
    The early drives were velocity/ voltage feedback, used a comparitor input and required double tuning procedure, Inner loop, motor-tach-drive, and the outer loop encoder to controller.
    The later non-intelligent drives were simple transconductance (torque mode) amplifiers just closed closed loo[ from motor to controller.
    You can also run these drives in Voltage mode if needed. If and when you have the option, torque mode is preferred, IMO.
    CNC, Mechatronics Integration and Custom Machine Design

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    Re: M16D: How to have ±10 V analog for servo velocity control?

    Hi,

    The early drives were voltage feedback, used a comparitor input and required double tuning procedure, Inner loop, motor-tach-drive, and the outer loop encoder to controller.
    Significant and interesting detail.....but its still not applicable here. Without a PID capable controller like a Galill or maybe MESA/LinuxCNC then position mode control is out
    of the question be it torque mode or velocity mode.

    OP requires very good speed control, which presumably the servo and drive deliver, with encoder feedback so that the Z axis can be synched to the rotation of the spindle.
    Assuming Mach4 can do that, and I have no experience with that feature, then he does not require true position control.

    I was able to use the built in smarts of my Allen Bradley servo drive so I could have both a free-running analogue driven motor, and then at will, a genuine position controlled
    C axis for indexing and/or tapping. Best of both worlds! Got to love modern AC servos.

    Craig

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    Re: M16D: How to have ±10 V analog for servo velocity control?

    Quote Originally Posted by Azalin View Post
    By common I meant the common terminal of the DPDT relay, not the drive or BOB.

    So far it goes promising. However I have a new problem. When I stop the spindle (M5) it does a hard stop. How bad is this for a mill spindle? Can I do something like a 200 ms to zero on M5 command?


    Check the Drive Parameters you may have to much DC Braking applied you want little to no Dc braking for what you are doing you can also give it a longer ramp down time this can be all done in the servo drive as to how the motor will react

    Sounds like you have to much Gain on the servo as well it should not be making that noise, so you have work to do with your Drive setup

    If you can feed the encoder back to Mach4 then you will be able to do the rigid Tapping, so if your servo drive has an encoder output then that is what you would use
    Mactec54

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    Re: M16D: How to have ±10 V analog for servo velocity control?

    Quote Originally Posted by Azalin View Post
    Now I have analog control and encoder feedback. Can I do rigid tapping?
    You need to have a good long read of the manuals.
    My servo states:
    Analogue quantity signal - Input= 2 inputs (1 for speed mode / both for torque mode). Output= none.

    So looks to me like my 3 way pulse output (A,B,Z) for ffedback only works in position mode.
    However, the wiring diagrams show these wired in on both speed and torque as well.

    So I have a lot to learn about too as a relative noob to servo.

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    Re: M16D: How to have ±10 V analog for servo velocity control?

    Hi,
    Yes, I configured the ramp-up and ramp-down on the drive to 250ms. With this I am able to accelerate and decelerate soft. This works fine. But I wired the relay #1 on the M16D (which is triggered on PWM) to the drives drive enable input. So the drive enables itself when this relay is triggered. I think here comes the critical part: When M5 is commanded and relay #1 disengages, the drive also gets disabled. I think the drive electronically stops the motor before (or while) disable itself. When its disabled there is no holding torque though.

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    Re: M16D: How to have ±10 V analog for servo velocity control?

    Quote Originally Posted by dazp1976 View Post
    You need to have a good long read of the manuals.
    My servo states:
    Analogue quantity signal - Input= 2 inputs (1 for speed mode / both for torque mode). Output= none.

    So looks to me like my 3 way pulse output (A,B,Z) for ffedback only works in position mode.
    However, the wiring diagrams show these wired in on both speed and torque.

    So I have a lot to learn about too as a relative noob to servo.
    I have M16 (successor of M16D) board on my lathe. Spindle motor is an induction motor. I added an incremental encoder to the spindle. This way I can do threading. With the same logic I should be able to rigid tapping on the mill too. Because both machines use different motors but same analog control. Both have encoder feedback.

    I confess that I may be never do rigid tapping but since I'm in the middle of my scratch project my aim is the best I can have. You know, rigid tapping sounds cool : d

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