Parallel L298s for controlling 2 motors

Discussion in 'General Electronics Chat' started by matthew798, Aug 19, 2013.

  1. matthew798

    Thread Starter Member

    Jan 16, 2013

    I need to control 2 stepper motors so that they move EXACTLY in sync. They are on either side of a sheet of aluminum that will change height and must stay level. So I am wondering if it's possible to drive 2 L298s from one L297 chip. If so, how would I go about wiring up the chopper circuitry? Should I wire only one of the L298s sens to the 297 or both?

    I am NOT trying to pull more current for one motor, I know that question has been asked many times on the forum.

    Thanks in advance!
  2. BillB3857

    AAC Fanatic!

    Feb 28, 2009
    Unless you have a means of secondary feedback, or have the steppers so lightly loaded that they cannot miss movement on a step command, you will still have the chance of skew. On large machines, error detection is a requirement with split or slaved drives.
  3. matthew798

    Thread Starter Member

    Jan 16, 2013
    Thanks for the reply.

    Error detection is not an option for me. My budget won't allow it. So back to my original question, can I parallel 2 L298s or not?
  4. tubeguy

    Well-Known Member

    Nov 3, 2012
    If you want to make use of the current limiting feature, I believe you would need a separate L297/L298 pair for each motor.
    I agree with BillB3857. If they must be exactly synchronized, some type of error checking is needed. Optical encoders are available to match the step resolution of standard steppers.

    How are you controlling the position?

    To lift the ends of the sheet evenly, is it feasible to mechanically couple the two (lifting?) shafts?
  5. matthew798

    Thread Starter Member

    Jan 16, 2013
    Unfortunately, again for budgetary reasons, it would be impossible for me to purchase the necessary components to mechanically attach the z axis motors. I will look into optical encoders, though I have no notion of what they are.

    Why WOULD a motor miss a step if it is within it's load limits?

    Thanks for your help - i will keep the thread updated.
  6. shortbus

    AAC Fanatic!

    Sep 30, 2009
    All components are different, this includes stepper motors. Even two made on the same machine one after the other. This is why there needs to be a feedback.

    The L298 is an old and not so good chip, in its day it was the only thing available. There is a newer version that is better, it's the SN75441ONE

    And to answer your original question, yes more than one can be controlled by the L297, but that won't synchronize the motor movement. And you must follow the output limits for the L297.