Ao Range; Minimizing Glitches On The Output Signal; Analog Output Data Generation Methods; Software-Timed Generations - National Instruments NI USB-621x User Manual

Chapter 7 Analog Output

AO Range

Minimizing Glitches on the Output Signal

Analog Output Data Generation Methods

Software-Timed Generations

Hardware-Timed Generations

NI USB-621x User Manual
DACs. It allows you to download the points of a waveform to your M Series
device without host computer interaction.
AO Sample Clock
The AO Sample Clock signal reads a sample from the DAC FIFO and
generates the AO voltage.
The AO Range is ±10 V for NI 621x devices.
When you use a DAC to generate a waveform, you may observe glitches on
the output signal. These glitches are normal; when a DAC switches from
one voltage to another, it produces glitches due to released charges. The
largest glitches occur when the most significant bit of the DAC code
changes. You can build a lowpass deglitching filter to remove some of these
glitches, depending on the frequency and nature of the output signal. Visit
for more information about minimizing glitches.
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When performing an analog output operation, you either can perform
software-timed or hardware-timed generations.
With a software-timed generation, software controls the rate at which data
is generated. Software sends a separate command to the hardware to initiate
each DAC conversion. In NI-DAQmx, software-timed generations are
referred to as on-demand timing. Software-timed generations are also
referred to as immediate or static operations. They are typically used for
writing a single value out, such as a constant DC voltage.
With a hardware-timed generation, a digital hardware signal controls the
rate of the generation. This signal can be generated internally on your
device or provided externally.
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