Hello Bill Stonier,
Thank you for contacting National Instruments.
How are you reading your measurements? Are you using LabVIEW? If so, what version are you using?
You can measure rotational speed and direction in LabVIEW by using two different counters with different DAQmx tasks. In Measurement and Automation Explorer (MAX) set up one task/counter for edge counting (up and down) and the other task/counter for frequency measurement. You must have LabVIEW 7.0 to take advantage of DAQmx.
For edge counting (up and down) you must wire the A pulse output from your encoder to the source of your counter. B gets wired to the counter gate.
For frequency measurement, wire the A output to the gate of your second counter. The source will be internal
ly wired to a pulse train of a known frequency.
To determine direction of rotation, a case structure is used which outputs positive velocity for counter-clockwise rotation and negative velocity for clockwise rotation.
See the attached example VI.
I hope this helps.
Sean C.
Applications Engineer
National Instruments
