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LS7366R encoder counter issues - Page 3 — Parallax Forums

LS7366R encoder counter issues

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Comments

  • MicksterMickster Posts: 2,693
    edited 2019-05-07 13:57
    Just curious, but does your design have a software or hardware limit switch for an e-stop function to avoid hitting an end stop? Guess virtual troubleshooting, kibitzing or whatever makes good mental excercise. Besides, it's the suburban substitute for the old sidewalk supervisors seen looking through cutouts in the fence around hi-rise projects.......

    Darned machine designers; I have 10m of linear range and then they give me 25mm before I hit a dead-stop. 500LBs hurtling along at 70m/min. Dynamic braking can stop the motor dead but I might snap the motor shaft or wreck the transmission... can't win :lol:
  • Mickster wrote: »
    Can't remember the last time I had an encoder failure so do we surmise that whatever was causing the LS7366 to fail has also damaged the encoder?

    However, that doesn't look like electronic damage, does it?
  • evanhevanh Posts: 15,915
    edited 2019-05-07 12:08
    Mickster wrote: »
    Is that a normal mark-space ratio, BTW?

    That's likely related to the mode of failure. Maybe the end-stop shock gave that encoder a whack somehow.

    T Chap,
    It might be best to use a non-shaft-mount encoder so that you can then have an inline mechanical coupler to provide some shock absorption against these accidents. I know this'll be a pain to do but it might be worth it for reliability.

  • T ChapT Chap Posts: 4,223
    edited 2019-05-07 12:27
    I am thinking this was a bad solder connection and vibration was affecting it. Apparently made during sleep deprivation! Barely in tact. I’ll re test the encoder next week. I’m just glad it wasn’t a repeat of the 7366 issue. Encoders never have problems on my systems so this was a fluke.
  • evanhevanh Posts: 15,915
    The mark-space should be close to 50:50. I would expect within 5%. 75:25 is pretty far off.
  • evanh wrote: »
    The mark-space should be close to 50:50. I would expect within 5%. 75:25 is pretty far off.

    +1
  • I vote mech shock, agree with the ratio being so far out. Maybe the sensors have shifted internally. Missing pulse makes me think fracture in the encoder disk, thin glass disks may not do so well with a sudden shock. Interesting to see back on the bench if the missing pulse is repeatable at the same shaft position. Oh, well, IO, IO, off to the salt mine I go......
  • Disc was fine. I missed the pulse overlap. But I noticed at the time the disc seemed a little lower in the slot that usually. The calibrate shim tool usually has the disc higher towards the top of the USDig E series. So it’s possible that sitting too low is affecting the overlap by some light angles etc. Not sure.
  • I looked at the site but it didn't mention what the disc was made of... metallic?
  • T ChapT Chap Posts: 4,223
    edited 2019-05-07 19:15
    Clear plastic. Flexible. Maybe poly carb not sure.
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