Glossary
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National Instruments Corporation
G-13
RTSI bus
real-time system integration bus—the National Instruments timing bus that
connects DAQ devices directly, for precise synchronization of functions.
For PCI devices, the connection is made by means of connectors on top of
the device. For PXI devices, the connection is made across the PXI trigger
bus.
S
s
seconds
S
samples
S/H
sample-and-hold—a circuit that acquires and stores an analog voltage on a
capacitor for a short period of time
S/s
samples per second—used to express the rate at which a DAQ device
samples an analog signal
sample counter
the clock that counts the output of the channel clock, in other words, the
number of samples taken. On devices with simultaneous sampling, this
counter counts the output of the scan clock and hence the number of scans.
scan
one or more analog or digital input samples. Typically, the number of input
samples in a scan is equal to the number of channels in the input group. For
example, one pulse from the scan clock produces one scan which acquires
one new sample from every analog input channel in the group.
scan clock
the clock controlling the time interval between scans.
scan rate
the number of scans per second. For example, a scan rate of 10 Hz means
sampling each channel 10 times per second.
SCXI
Signal Conditioning eXtensions for Instrumentation—the National
Instruments product line for conditioning low-level signals within an
external chassis near sensors so only high-level signals are sent to DAQ
devices in the noisy PC environment
SE
single-ended—a term used to describe an analog input that is measured
with respect to a common ground
self-calibrating
a property of a DAQ device that has an extremely stable onboard reference
and calibrates its own A/D and D/A circuits without manual adjustments by
the user