EP4 frequency

[ryanm222]

Hi,
I am new to this site and new to encoders so bear with me. I am using the EP4-100-079-D-H-T-B single-ended encoder on a 200 RPM motor, and I am not getting the frequencies I expected. I hook one of the output channels to an oscilloscope and get a clear square wave except the frequency is about 1.5 kHz when I am running the motor at about 20 RPM when I excepted the frequency to be about 33 Hz. The encoder is hooked up to a 5V supply as specified. Am I getting the correct output or is something causing the frequency to be high? If that is the excepted frequency for 20 RPM, why is so much more than I excepted? Thank you for any help.

Ryan