NI CompactDAQ cDAQ-917 Series - Page 7

NI cDAQ-917x User Manual
© National Instruments | vii
Change Detection Event ........................................................................................... 4-7
Routing Change Detection Event to an Output Terminal................................. 4-7
Change Detection Acquisition.......................................................................... 4-7
Digital Output ........................................................................................................... 4-8
Digital Output Data Generation Methods......................................................... 4-8
Digital Output Triggering Signals .................................................................... 4-9
Digital Output Timing Signals ......................................................................... 4-10
Getting Started with DO Applications in Software .......................................... 4-13
Digital Input/Output Configuration for NI 9401 ...................................................... 4-13
PFI .................................................................................................................................... 4-13
PFI Filters ................................................................................................................. 4-13
Chapter 5
Counters
Counter Timing Engine .................................................................................................... 5-1
Counter Input Applications .............................................................................................. 5-3
Counting Edges......................................................................................................... 5-3
Single Point (On-Demand) Edge Counting ...................................................... 5-3
Buffered (Sample Clock) Edge Counting......................................................... 5-4
Controlling the Direction of Counting.............................................................. 5-4
Pulse-Width Measurement ....................................................................................... 5-5
Single Pulse-Width Measurement .................................................................... 5-5
Implicit Buffered Pulse-Width Measurement................................................... 5-5
Sample Clocked Buffered Pulse-Width Measurement ..................................... 5-6
Pulse Measurement................................................................................................... 5-7
Single Pulse Measurement................................................................................ 5-7
Implicit Buffered Pulse Measurement.............................................................. 5-7
Sample Clocked Buffered Pulse Measurement ................................................ 5-8
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 ................................................................... 5-10
High Frequency with Two Counters ................................................................ 5-11
Large Range of Frequencies with Two Counters ............................................. 5-12
Sample Clocked Buffered Frequency Measurement ........................................ 5-13
Choosing a Method for Measuring Frequency................................................. 5-14
Which Method Is Best? .................................................................................... 5-15
Period Measurement ................................................................................................. 5-17
Position Measurement .............................................................................................. 5-18
Measurements Using Quadrature Encoders ..................................................... 5-18
Channel Z Behavior.................................................................................................. 5-19
Measurements Using Two Pulse Encoders ...................................................... 5-20
Buffered (Sample Clock) Position Measurement............................................. 5-20