Minimizing Glitches On The Output Signal; Analog Output Data Generation Methods; Software-Timed Generations; Hardware-Timed Generations - National Instruments DAQ X Series User Manual

Minimizing Glitches on the Output Signal

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.
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Analog Output Data Generation Methods

When performing an analog output operation, you can perform
software-timed or hardware-timed generations.

Software-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.

Hardware-Timed Generations

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.
Hardware-timed generations have several advantages over software-timed
generations:
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Hardware-timed operations can be buffered or hardware-timed single point
(HWTSP). A buffer is a temporary storage in computer memory for
to-be-transferred samples.
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The time between samples can be much shorter.
The timing between samples can be deterministic.
Hardware-timed acquisitions can use hardware triggering.
Hardware-timed single point (HWTSP)—Typically, HWTSP
operations are used to write single samples at known time intervals.
While buffered operations are optimized for high throughput, HWTSP
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Chapter 5 Analog Output
X Series User Manual