Are NI Digital IO Modules Simultaneously Sampled?

Updated Sep 20, 2024

Reported In

Hardware

  • Digital Module for VXI
  • PXI Digital I/O Module
  • Digital I/O Device

Issue Details

When looking through NI's Digital I/O offerings, I noticed that they either do not give a clock rate or give the clock rate in Hertz.  For the modules which give a clock rate, does this mean that all lines can be sampled at that rate at the same time (i.e. simultaneous sampling)?

Solution

Yes.  Because digital I/O modules do not use an ADC or DAC, National Instruments does not use multiplexers to MUX through the channels as they do for some Analog Input modules.  So when a digital modules specifies a rate, that means that all lines can be updated or acquired at that rate at the same time.

 

Additional Information

The digital modules which do not have a clock rate specified are static or unstrobed digital modules.  These modules must be software-timed and cannot use a clock, but they can still update/acquire from multiple lines at the same time.

Some digital modules with hardware timing have limitations. For more information see: Simultaneous Hardware-timed Input and Output in NI Digital I/O C Series and TestScale Devices

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