National Instruments NI 6238 User Manual

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Contents

National Instruments NI 6238 User Manual Manual pdf 8 page image

ContentsNI 6238/6239 User Manual viii ni.comChapter 7CountersCounter Input Applications ........................................................................................... 7-3Counting Edges ............................................................................................... 7-3Single Point (On-Demand) Edge Counting ...................................... 7-3Buffered (Sample Clock) Edge Counting......................................... 7-4Non-Cumulative Buffered Edge Counting ....................................... 7-5Controlling the Direction of Counting.............................................. 7-5Pulse-Width Measurement .............................................................................. 7-6Single Pulse-Width Measurement .................................................... 7-6Buffered Pulse-Width Measurement ................................................ 7-6Period Measurement ....................................................................................... 7-7Single Period Measurement.............................................................. 7-8Buffered Period Measurement.......................................................... 7-8Semi-Period Measurement .............................................................................. 7-9Single Semi-Period Measurement .................................................... 7-9Buffered Semi-Period Measurement ................................................ 7-10Frequency Measurement ................................................................................. 7-10Method 1—Measure Low Frequency with One Counter ................. 7-10Method 1b—Measure Low Frequency with One Counter(Averaged) ..................................................................................... 7-11Method 2—Measure High Frequency with Two Counters .............. 7-12Method 3—Measure Large Range of Frequencies Using TwoCounters ......................................................................................... 7-13Choosing a Method for Measuring Frequency ................................. 7-14Position Measurement..................................................................................... 7-16Measurements Using Quadrature Encoders...................................... 7-16Measurements Using Two Pulse Encoders ...................................... 7-18Two-Signal Edge-Separation Measurement ................................................... 7-19Single Two-Signal Edge-Separation Measurement.......................... 7-19Buffered Two-Signal Edge-Separation Measurement...................... 7-20Counter Output Applications......................................................................................... 7-21Simple Pulse Generation................................................................................. 7-21Single Pulse Generation.................................................................... 7-21Single Pulse Generation with Start Trigger ...................................... 7-21Retriggerable Single Pulse Generation............................................. 7-22Pulse Train Generation.................................................................................... 7-23Continuous Pulse Train Generation.................................................. 7-23Frequency Generation ..................................................................................... 7-24Using the Frequency Generator ........................................................ 7-24Frequency Division ......................................................................................... 7-25Pulse Generation for ETS ............................................................................... 7-25