Issue with correct trajectory reading using Labview and Compumotor

[Kirkwood]

Hi everyone,
I am having some issues with my compumotor/Labview communication and was wondering if anyone had any advice.
My setup is a National Instruments PCI-7432 control board linked to a
UMI-7762 Interface board then I have my driver and motor, the Compumotor
M83-135 R14, serial 18054. When I use the NI Measurement and Automation Explorer and tell it to go at a velocity, the velocity is no where near the commanded value.
It is not returning any errors either, I’ll tell it to do say 500 rpm’s and it will take ~2.5 seconds to make a complete revolution. I can get the motor to spin at a very fast rate so it is working, I just was wondering if there was something wrong that would cause it to deviate so far off the assigned velocity.
I didn't know if I accidentally changed a setting with labview that would cause it not to read the velocity correctly or something like that.


Thank You

Keith Kirkwood

[Allison_S]

Keith,

    It sounds like one possible issue is that your feedback is not correct.  In which case you'll want to check encoder feedback -- disable your motor in software but leave everything connected.  Then manually turn the motor and check if the 1-D Interactive section in MAX reports the correct steps per one revolution. If not, then check that the encoder setup section is correct, specifically the encoder counts per revolution.

    Also, your motor may need to be tuned, assuming that it hasn't already been tuned.  Is your motor a servo or stepper motor?  From what I could find online it looks like the M83-135 is probably a servo.  Here are a couple links to documents that will help you tune your motor, which often solves velocity issues:

Understanding Servo Tune

http://zone.ni.com/devzone/cda/tut/p/id/2923

And if that seems not to work,

Unable to Tune a Servo Motor

http://digital.ni.com/public.nsf/websearch/19668AB2D4997F3D86256E940082F1EF?OpenDocument

Let me know how it goes, or if you have more questions.  Thank you.

-Allison S.

Applications Engineering