Minimizing Glitches On The Output Signal; Analog Output Data Generation Methods; Software-Timed Generations; Hardware-Timed Generations - National Instruments NI 6221 User Manual

Chapter 5 Analog Output

Minimizing Glitches on the Output Signal

Analog Output Data Generation Methods

Software-Timed Generations

Hardware-Timed Generations

M Series User Manual
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.
ni.com/support
When performing an analog output operation, you either can perform
software-timed or hardware-timed generations. Hardware-timed
generations can be non-buffered or buffered.
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.
Hardware-timed generations have several advantages over software-timed
acquisitions:
• The time between samples can be much shorter.
• The timing between samples can be deterministic.
• Hardware-timed acquisitions can use hardware triggering.
Hardware-timed operations can be buffered or non-buffered. A buffer is a
temporary storage in computer memory for to-be-generated samples.
5-4 ni.com