I have an incremental rotary encoder that I can't determine its model number thus I can't get its data sheet, How can I measure its resolution manually?

  • \$\begingroup\$ Is it optical or mechanical? Can you post a picture? \$\endgroup\$
    – Mattman944
    Commented Apr 16, 2021 at 10:18
  • \$\begingroup\$ @Mattman944 it's an optical encoder \$\endgroup\$ Commented Apr 16, 2021 at 10:21
  • \$\begingroup\$ you can count the output pulses with a frequency counter or an oscilloscope and rotate it by hand one revolution. \$\endgroup\$
    – Luke Gary
    Commented Apr 16, 2021 at 18:32

1 Answer 1


For starters you might hook it up as you would any encoder, turn it 360 degrees and see how many counts you get.

  • \$\begingroup\$ I tried that but it's not precise, I know I will always get measuring error but the values I get vary a lot, between 2400 and 2700, Thank you for the suggestion anyway \$\endgroup\$ Commented Apr 16, 2021 at 10:25
  • \$\begingroup\$ That's probably because you're not being precise in your turning of the shaft. Rather than do it by hand, hook it up to a stepper motor and turn it EXACTLY 360 degrees. \$\endgroup\$
    – jwh20
    Commented Apr 16, 2021 at 10:27
  • \$\begingroup\$ I haven't thought of that, Thank you! \$\endgroup\$ Commented Apr 16, 2021 at 10:30
  • \$\begingroup\$ Even by hand you may be able to do better than that if you can fix a small arm to the shaft to point at a farther away point. I was thinking if you're uncertain of the sensing apparatus be sure not to exceed the maximum turn rate or your sample rate. \$\endgroup\$
    – K H
    Commented Apr 16, 2021 at 11:00
  • \$\begingroup\$ Average over multiple revolutions to get more precise. Turn N number of revolutions and then divide the total number of counts by N. \$\endgroup\$
    – kkrambo
    Commented Apr 16, 2021 at 16:04

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