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IndustryArena Forum > CNC Electronics > Gecko Drives > Can you take step / direction from G540 to run old analog servo motor?
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  1. #1
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    Can you take step / direction from G540 to run old analog servo motor?

    I have a Gecko G540 setup running Linux cnc (with steppers on the x, y, z). I plan to add a 4th rotary axis but given the size of my gear, I'd like to use a larger motor than what could be run from a g540.

    I have some old 400 watt Yaskawa AC servo motors and drives that came with my linear actuators. They appear to take standard step / direction. Is it possible to take the step / direction signal from my G540 to run the AC servo (for just the 4th axis)? Obviously I would not take power through the g540 as the servo drive uses 240 ac. Essentially, I want to use the g540 as a breakout board for one axis.

    So... Does anyone know if this is possible and safe?

  2. #2
    Super Moderator Al_The_Man's Avatar
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    Re: Can you take step / direction from G540 to run old analog servo motor?

    If they take standard step direction there should be no problem but is there commutation and position feedback on the motor for the drive?
    How were they controlled previously?
    Al. .
    CNC, Mechatronics Integration and Custom Machine Design

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  3. #3
    Community Moderator ger21's Avatar
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    Re: Can you take step / direction from G540 to run old analog servo motor?

    You'd probably need to split the step/direction wires out before the parallel cable goes into the G540, because the G540 doesn't give you access to the step/dir wires.
    Gerry

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    Re: Can you take step / direction from G540 to run old analog servo motor?

    Quote Originally Posted by Al_The_Man View Post
    If they take standard step direction there should be no problem but is there commutation and position feedback on the motor for the drive?
    How were they controlled previously?
    Al. .
    I don't know. I never saw what the actuator was used for before I bought it. I just pulled the servos out and replaced them with steppers. I later bought a Yaskawa servo drive to match the servo motor model. Then they sat in my project box until now.

    My hope was that I could run power through the servo drive and run it with just step and direction without hooking up the feedback / closed loop cable. I.e. Run it like a more powerful stepper motor but I don't know if these servos will even run without a feedback loop.

    The older Yaskawa drives are a bit of a nightmare to figure out. Every connection uses a custom plug that I don't know the name of, the instructions are terrible (and very long). It's like "here's a copy of War and Peace, the answer is in there somewhere, good luck"... I can just about recognize the power input and output plus the step / direction in. Yaskawa's customer service is somewhere between terrible and non-existent for people like me...

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    Re: Can you take step / direction from G540 to run old analog servo motor?

    Quote Originally Posted by ger21 View Post
    You'd probably need to split the step/direction wires out before the parallel cable goes into the G540, because the G540 doesn't give you access to the step/dir wires.
    I thought that maybe I could have taken it from two of the pins on the 4th db9 output. I guess it is potentially simpler if I just buy a db25 breakout board and take before it goes through the G540.

    What about the feedback side? Do you happen to know if analog AC servos can be run without a closed loop? Having to buy any sort of Yaskawa encoder cable automatically make it now worth it financially....

  6. #6
    Community Moderator ger21's Avatar
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    Re: Can you take step / direction from G540 to run old analog servo motor?

    Afaik, no servos can be used without the encoder feedback. Without feedback, the motor would just run continuously. But without feedback, the drive won't even work, as it needs to know where the motor is.
    Servos don't move in steps like a stepper. They move until they reach their commanded position, determined by the encoder.
    Gerry

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  7. #7
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    Re: Can you take step / direction from G540 to run old analog servo motor?

    Quote Originally Posted by ger21 View Post
    Afaik, no servos can be used without the encoder feedback. Without feedback, the motor would just run continuously. But without feedback, the drive won't even work, as it needs to know where the motor is.
    Servos don't move in steps like a stepper. They move until they reach their commanded position, determined by the encoder.
    OK, so I would need to figure out how to connect the encoder cable. I feel a migraine coming on....

  8. #8
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    Re: Can you take step / direction from G540 to run old analog servo motor?

    Quote Originally Posted by Goemon View Post
    I thought that maybe I could have taken it from two of the pins on the 4th db9 output. I guess it is potentially simpler if I just buy a db25 breakout board and take before it goes through the G540.

    What about the feedback side? Do you happen to know if analog AC servos can be run without a closed loop? Having to buy any sort of Yaskawa encoder cable automatically make it now worth it financially....
    The DB9 is from the driver to the motor and will not have step and direction in those wires. It will have coil A and coil B wires for the stepper.

    The G540 consists of a mother board and 4 G250x stepper drivers. The G250x's mount to the mother board with pin headers. I would probably pull the driver for the 4th axis off of the mother board and connect to the step and direction at the pin header connection. You can find out which pins are correct by downloading the G250x manual from the geckodrive site. No to caveat, the motherboard has built in diagnostics, and I'm not sure if removing one of the G250x drivers will make the motherboard think there is a problem.

  9. #9

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    Re: Can you take step / direction from G540 to run old analog servo motor?

    Quote Originally Posted by Goemon View Post
    I don't know. I never saw what the actuator was used for before I bought it. I just pulled the servos out and replaced them with steppers. I later bought a Yaskawa servo drive to match the servo motor model. Then they sat in my project box until now.

    My hope was that I could run power through the servo drive and run it with just step and direction without hooking up the feedback / closed loop cable. I.e. Run it like a more powerful stepper motor but I don't know if these servos will even run without a feedback loop.

    The older Yaskawa drives are a bit of a nightmare to figure out. Every connection uses a custom plug that I don't know the name of, the instructions are terrible (and very long). It's like "here's a copy of War and Peace, the answer is in there somewhere, good luck"... I can just about recognize the power input and output plus the step / direction in. Yaskawa's customer service is somewhere between terrible and non-existent for people like me...
    They are not going to run without the encoder connection to the servo drive, you most likely need an 8 wire cable for the encoder cable try Ebay for cables you might get lucky and find one with the correct plug on for the drive end

    What is the model # of the Drive
    Mactec54

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