National Instruments X Series User Manual page 11

Contents
Chapter 7
Counters
Counter Timing Engine .................................................................................................... 7-2
Counter Input Applications............................................................................................... 7-3
Counting Edges......................................................................................................... 7-3
Single Point (On-Demand) Edge Counting ...................................................... 7-4
Buffered (Sample Clock) Edge Counting......................................................... 7-4
Controlling the Direction of Counting.............................................................. 7-5
Pulse-Width Measurement........................................................................................ 7-5
Single Pulse-Width Measurement .................................................................... 7-6
Implicit Buffered Pulse-Width Measurement...................................................7-6
Sample Clocked Buffered Pulse-Width Measurement ..................................... 7-7
Hardware-Timed Single Point Pulse-Width Measurement .............................. 7-7
Pulse Measurement ................................................................................................... 7-8
Single Pulse Measurement................................................................................ 7-8
Implicit Buffered Pulse Measurement .............................................................. 7-8
Sample Clocked Buffered Pulse Measurement ................................................ 7-9
Hardware-Timed Single Point Pulse Measurement.......................................... 7-9
Pulse versus Semi-Period Measurements ......................................................... 7-10
Semi-Period Measurement........................................................................................ 7-10
Single Semi-Period Measurement .................................................................... 7-11
Implicit Buffered Semi-Period Measurement...................................................7-11
Frequency Measurement...........................................................................................7-11
Low Frequency with One Counter.................................................................... 7-12
High Frequency with Two Counters................................................................. 7-12
Large Range of Frequencies with Two Counters ............................................. 7-13
Sample Clocked Buffered Frequency Measurement ........................................ 7-14
Hardware-Timed Single Point Frequency Measurement.................................. 7-16
Choosing a Method for Measuring Frequency ................................................. 7-16
Period Measurement ................................................................................................. 7-20
Position Measurement............................................................................................... 7-21
Measurements Using Quadrature Encoders...................................................... 7-21
Measurements Using Two Pulse Encoders....................................................... 7-23
Buffered (Sample Clock) Position Measurement ............................................. 7-23
Hardware-Timed Single Point Position Measurement ..................................... 7-24
Two-Signal Edge-Separation Measurement ............................................................. 7-24
Single Two-Signal Edge-Separation Measurement .......................................... 7-24
Implicit Buffered Two-Signal Edge-Separation Measurement ........................ 7-25
Sample Clocked Buffered Two-Signal Separation Measurement .................... 7-25
Hardware-Timed Single Point Two-Signal Separation Measurement ............. 7-26
Counter Output Applications ............................................................................................ 7-26
Simple Pulse Generation...........................................................................................7-27
Single Pulse Generation.................................................................................... 7-27
Single Pulse Generation with Start Trigger ...................................................... 7-27
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