National Instruments Data Acquisition Device NI USB-621x - Manual (Page 9)

Contents
© National Instruments Corporation ix NI USB-621x User Manual
Semi-Period Measurement ..............................................................................8-8
Single Semi-Period Measurement.....................................................8-8
Buffered Semi-Period Measurement.................................................8-8
Frequency Measurement .................................................................................8-9
Choosing a Method for Measuring Frequency .................................8-13
Position Measurement .....................................................................................8-15
Measurements Using Quadrature Encoders ......................................8-15
Measurements Using Two Pulse Encoders .......................................8-17
Two-Signal Edge-Separation Measurement....................................................8-18
Single Two-Signal Edge-Separation Measurement ..........................8-18
Buffered Two-Signal Edge-Separation Measurement ......................8-19
Counter Output Applications .........................................................................................8-20
Simple Pulse Generation .................................................................................8-20
Single Pulse Generation ....................................................................8-20
Single Pulse Generation with Start Trigger ......................................8-20
Retriggerable Single Pulse Generation .............................................8-21
Pulse Train Generation ....................................................................................8-22
Continuous Pulse Train Generation ..................................................8-22
Frequency Generation .....................................................................................8-23
Using the Frequency Generator ........................................................8-23
Frequency Division .........................................................................................8-24
Pulse Generation for ETS................................................................................8-24
Counter Timing Signals .................................................................................................8-25
Counter n Source Signal..................................................................................8-26
Routing a Signal to Counter n Source...............................................8-26
Routing Counter n Source to an Output Terminal ............................8-26
Counter n Gate Signal .....................................................................................8-27
Routing a Signal to Counter n Gate ..................................................8-27
Routing Counter n Gate to an Output Terminal................................8-27
Counter n Aux Signal ......................................................................................8-27
Routing a Signal to Counter n Aux ...................................................8-27
Counter n A, Counter n B, and Counter n Z Signals .......................................8-28
Routing Signals to A, B, and Z Counter Inputs ................................8-28
Counter n Up_Down Signal ............................................................................8-28
Counter n HW Arm Signal ..............................................................................8-28
Routing Signals to Counter n HW Arm Input...................................8-29
Counter n Internal Output and Counter n TC Signals .....................................8-29
Routing Counter n Internal Output to an Output Terminal...............8-29
Frequency Output Signal.................................................................................8-29
Routing Frequency Output to a Terminal .........................................8-29
Default Counter/Timer Pinouts......................................................................................8-30
Counter Triggering ........................................................................................................8-31