Device Overview; Digital I/O; Prescaling - National Instruments NI 6602 User Manual

Device Overview

Digital I/O

Prescaling

© National Instruments Corporation
This chapter provides information about NI 660x device functionality.
The NI 660x devices have a 32-bit DIO port on PFI <0..31>. Digital I/O
consists of asynchronous reads and writes to the digital port upon software
command. You can individually configure each line for digital input or
output. For output, you can individually configure PFI <8..31> for either
counter-associated output or digital output. You must specify whether you
are using the PFI line for counter I/O or digital I/O only if that line is being
used as an output. For input, both counter I/O and digital I/O can share the
lines on PFI <0..31>.
For more information about the signals that can be driven onto PFI lines,
refer to the I/O Connector Pinout
For information about how to implement specific digital I/O functions,
refer to the application software documentation.
Prescaling allows the counter to count a signal that is faster than the
maximum timebase of the counter. The counters on the NI 660x offer
8X and 2X prescaling on each counter (prescaling can be disabled).
Each prescaler consists of a small, simple counter that counts to eight
(or two) and rolls over. This counter is specifically designed for this
application and can count signals that are faster than the general purpose
counters. The CtrnSource signal on the general purpose counter will be the
divided signal from the simple counter.
section of this document.
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NI 660x User Manual