National Instruments NI cDAQTM-9138, User Manual

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Contents
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Semi-Period Measurement........................................................................................5-8
Single Semi-Period Measurement ....................................................................5-9
Implicit Buffered Semi-Period Measurement...................................................5-9
Pulse versus Semi-Period Measurements .........................................................5-10
Frequency Measurement...........................................................................................5-10
Low Frequency with One Counter....................................................................5-11
High Frequency with Two Counters.................................................................5-12
Large Range of Frequencies with Two Counters .............................................5-13
Sample Clocked Buffered Frequency Measurement ........................................5-14
Choosing a Method for Measuring Frequency .................................................5-15
Which Method Is Best?.....................................................................................5-16
Period Measurement .................................................................................................5-18
Position Measurement...............................................................................................5-19
Measurements Using Quadrature Encoders......................................................5-19
Channel Z Behavior ..................................................................................................5-20
Measurements Using Two Pulse Encoders.......................................................5-21
Buffered (Sample Clock) Position Measurement .............................................5-21
Two-Signal Edge-Separation Measurement .............................................................5-22
Single Two-Signal Edge-Separation Measurement..........................................5-22
Implicit Buffered Two-Signal Edge-Separation Measurement ........................5-23
Sample Clocked Buffered Two-Signal Separation Measurement ....................5-23
Counter Output Applications ............................................................................................5-24
Simple Pulse Generation...........................................................................................5-24
Single Pulse Generation....................................................................................5-24
Single Pulse Generation with Start Trigger ......................................................5-25
Pulse Train Generation .............................................................................................5-25
Finite Pulse Train Generation ...........................................................................5-26
Retriggerable Pulse or Pulse Train Generation.................................................5-26
Continuous Pulse Train Generation..................................................................5-27
Buffered Pulse Train Generation ......................................................................5-28
Finite Implicit Buffered Pulse Train Generation ..............................................5-28
Continuous Buffered Implicit Pulse Train Generation .....................................5-29
Finite Buffered Sample Clocked Pulse Train Generation ................................5-29
Continuous Buffered Sample Clocked Pulse Train Generation .......................5-30
Frequency Generation...............................................................................................5-30
Using the Frequency Generator ........................................................................5-31
Frequency Division...................................................................................................5-32
Pulse Generation for ETS .........................................................................................5-32
Counter Timing Signals ....................................................................................................5-33
Counter n Source Signal ...........................................................................................5-33
Routing a Signal to Counter n Source ..............................................................5-34
Routing Counter n Source to an Output Terminal............................................5-34
Counter n Gate Signal...............................................................................................5-34
Routing a Signal to Counter n Gate ..................................................................5-34
Routing Counter n Gate to an Output Terminal ...............................................5-35