National Instruments USB-621 Series, User Manual

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Glossary
© National Instruments Corporation G-13 NI USB-621x User Manual
S
s Seconds.
S Samples.
sample co u nter The clock that co u nts the o u tp u t of the channel clock, in other words, the
n u mber of samples taken. On devices with sim u ltaneo u s sampling, this
co u nter co u nts the o u tp u t of the scan clock and hence the n u mber of scans.
scan One or more analog or digital inp u t samples. Typically, the n u mber of inp u t
samples in a scan is eq u al to the n u mber of channels in the inp u t gro u p. For
example, one p u lse from the scan clock prod u ces one scan which acq u ires
one new sample from every analog inp u t channel in the gro u p.
scan interval Controls how often a scan is initialized; is reg u lated by the AI Sample
Clock signal.
scan rate Reciprocal of the scan interval.
sensor A device that responds to a physical stim u l u s (heat, light, so u nd, press u re,
motion, flow, and so on), and prod u ces a corresponding electrical signal.
Primary characteristics of sensors are sensitivity, freq u ency range, and
linearity.
signal conditioning 1. Electronic eq u ipment that makes transd u cer or other signals s u itable in
level and range to be transmitted over a distance, or to interface with
voltage inp
u t instr u ments.
2. The manip u lation of signals to prepare them for digitizing.
signal so u rce A generic term for any instr u ment in the family of signal generators.
signals Signals are waveforms containing information. Altho u gh physical signals
can be in the form of mechanical, electromagnetic, or other forms, they are
most often converted to electronic form for meas
u rement.
single trigger mode When the arbitrary waveform generator goes thro u gh the staging list only
once.
single-b u ffered Describes a device that acq u ires a specified n u mber of samples from one or
more channels and ret u rns the data when the acq u isition is complete.
single-ended inp u t A circ u it that responds to the voltage on one inp u t terminal and gro u nd.
See also differential inp u t .