National Instruments PCI-6251 User Manual page 11

Contents
Counter Timing Signals .................................................................................................... 7-24
Counter n Source Signal ...........................................................................................7-24
Routing a Signal to Counter n Source .............................................................. 7-25
Routing Counter n Source to an Output Terminal ............................................ 7-25
Counter n Gate Signal............................................................................................... 7-25
Routing a Signal to Counter n Gate .................................................................. 7-26
Routing Counter n Gate to an Output Terminal ............................................... 7-26
Counter n Aux Signal ............................................................................................... 7-26
Routing a Signal to Counter n Aux................................................................... 7-26
Counter n A, Counter n B, and Counter n Z Signals ................................................ 7-27
Routing Signals to A, B, and Z Counter Inputs ................................................ 7-27
Routing Counter n Z Signal to an Output Terminal ......................................... 7-27
Counter n Up_Down Signal...................................................................................... 7-27
Counter n HW Arm Signal ....................................................................................... 7-27
Routing Signals to Counter n HW Arm Input .................................................. 7-27
Counter n Internal Output and Counter n TC Signals .............................................. 7-28
Routing Counter n Internal Output to an Output Terminal .............................. 7-28
Frequency Output Signal .......................................................................................... 7-28
Routing Frequency Output to a Terminal ......................................................... 7-28
Default Counter/Timer Pinouts......................................................................................... 7-28
Counter Triggering ........................................................................................................... 7-29
Other Counter Features ..................................................................................................... 7-30
Cascading Counters .................................................................................................. 7-30
Counter Filters .......................................................................................................... 7-30
Prescaling.................................................................................................................. 7-32
Duplicate Count Prevention...................................................................................... 7-32
Example Application That Works Correctly (No Duplicate Counting) ........... 7-33
Example Application That Works Incorrectly (Duplicate Counting)............... 7-33
Example Application That Prevents Duplicate Count ...................................... 7-34
When To Use Duplicate Count Prevention....................................................... 7-34
Enabling Duplicate Count Prevention in NI-DAQmx ...................................... 7-35
Synchronization Modes ............................................................................................ 7-35
80 MHz Source Mode....................................................................................... 7-36
Other Internal Source Mode ............................................................................. 7-36
External Source Mode ...................................................................................... 7-36
Chapter 8
PFI
Using PFI Terminals as Timing Input Signals.................................................................. 8-2
Exporting Timing Output Signals Using PFI Terminals .................................................. 8-2
Using PFI Terminals as Static Digital I/Os ...................................................................... 8-3
Connecting PFI Input Signals ...........................................................................................8-3
PFI Filters ......................................................................................................................... 8-4
I/O Protection.................................................................................................................... 8-5
Programmable Power-Up States ....................................................................................... 8-5
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