Andrew R

1734-VHSC24 Draw Wire Encoder rollover

2 posts in this topic

Hi all,

I am taking a Kubler draw wire encoder back to a 1734-VHSC24 and having a little bit of an issue with the rollover.  With the draw wire untouched the output value seems to be fluctuating over time and appears to be drifting backwards to the rollover value making our distance measurements completely useless.  Does anyone have any insight as to why that might be?

Share this post

Link to post
Share on other sites

I'm not familiar with that encoder but the high speed counter you're using is pretty reliable. You said, "with the draw wire untouched"; does that mean that your encoder data is drifting when the process is not running? If so, you've almost definitely got EMI somewhere in your control wiring, or there may be slight motion on the machine that you can't see, that's being detected. If you suspect EMI, check your grounds, shields, adjacent higher-power equipment, RF equipment (radios or wireless SCADA), etc. To eliminate (or identify) actual motion as the cause, look at the counter's tags in the controller and check the raw, unscaled data. The problem is that each of these two possible issues can mimic the other, so you may have to temporarily disable the encoder either physically or in code to isolate the problem.

That aside, I assume you've checked the usual suspects:

  • Wiring is good, including proper grounding, shielding, and verified no EMI.
  • Proper voltage / power is available to both devices.
  • Mounting and coupling on the encoder is good, and device driving the encoder is subject to excessive vibration. (No bad bearings anywhere).
  • The counter is set to encoder mode.
  • Configured resolution (and other parameters) in the card matches the name plate on the encoder.
  • The raw data being sent by the counter card to the controller is good, and the problem isn't somewhere in the controller's code. (Bad scaling / offsets are common).

Just in case you don't have it, here's a link to the counter card's user manual:


Hope this helps.



Share this post

Link to post
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now