Instruction Manual

Contents
NI 6236 User Manual viii ni.com
Chapter 7
Counters
Counter Input Applications ........................................................................................... 7-2
Counting Edges ............................................................................................... 7-2
Single Point (On-Demand) Edge Counting ...................................... 7-2
Buffered (Sample Clock) Edge Counting......................................... 7-3
Non-Cumulative Buffered Edge Counting ....................................... 7-4
Controlling the Direction of Counting.............................................. 7-4
Pulse-Width Measurement.............................................................................. 7-5
Single Pulse-Width Measurement .................................................... 7-5
Buffered Pulse-Width Measurement ................................................ 7-5
Period Measurement ....................................................................................... 7-6
Single Period Measurement.............................................................. 7-7
Buffered Period Measurement.......................................................... 7-7
Semi-Period Measurement.............................................................................. 7-8
Single Semi-Period Measurement .................................................... 7-8
Buffered Semi-Period Measurement ................................................ 7-9
Frequency Measurement ................................................................................. 7-9
Method 1—Measure Low Frequency with One Counter ................. 7-9
Method 1b—Measure Low Frequency with One Counter
(Averaged) ..................................................................................... 7-10
Method 2—Measure High Frequency with Two Counters .............. 7-11
Method 3—Measure Large Range of Frequencies Using
Two Counters................................................................................. 7-12
Choosing a Method for Measuring Frequency ................................. 7-13
Position Measurement..................................................................................... 7-15
Measurements Using Quadrature Encoders...................................... 7-15
Measurements Using Two Pulse Encoders ...................................... 7-17
Two-Signal Edge-Separation Measurement ................................................... 7-18
Single Two-Signal Edge-Separation Measurement.......................... 7-18
Buffered Two-Signal Edge-Separation Measurement...................... 7-19
Counter Output Applications......................................................................................... 7-20
Simple Pulse Generation................................................................................. 7-20
Single Pulse Generation.................................................................... 7-20
Single Pulse Generation with Start Trigger...................................... 7-20
Retriggerable Single Pulse Generation............................................. 7-21
Pulse Train Generation.................................................................................... 7-22
Continuous Pulse Train Generation.................................................. 7-22
Frequency Generation ..................................................................................... 7-23
Using the Frequency Generator ........................................................ 7-23
Frequency Division ......................................................................................... 7-24
Pulse Generation for ETS ............................................................................... 7-24