National Instruments Data Acquisition Device NI USB-621x, User Manual

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Glossary
© National Instruments Corporation G-3 NI USB-621x User Manual
arm The process of getting an instr u ment ready to perform a f u nction. For
example, the trigger circ u itry of a digitizer is armed, meaning that it is
ready to start acq u iring data when an appropriate trigger condition is met.
ASIC Application-specific integrated circ u it—A proprietary semicond u ctor
component designed and man u fact u red to perform a set of specific
f u nctions for a specific c u stomer.
asynchrono u s 1. Hardware—A property of an event that occ u rs at an arbitrary time,
witho u t synchronization to a reference clock.
2. Software—A property of a f u nction that begins an operation and
ret u rns prior to the completion or termination of the operation.
B
b Bit—One binary digit, either 0 or 1.
B Byte—Eight related bits of data, an eight-bit binary n u mber. Also u sed to
denote the amo u nt of memory req u ired to store one byte of data.
block diagram A pictorial description or representation of a program or algorithm.
b u ffer 1. Temporary storage for acq u ired or generated data.
2. A memory device that stores intermediate data between two devices.
b u s, b u ses The gro u p of electrical cond u ctors that interconnect individ u al circ u itry in
a comp u ter. Typically, a b u s is the expansion vehicle to which I/O or other
devices are connected. Examples of PC b u ses are the PCI, AT (ISA), and
EISA b u s.
C
C Celsi u s.
calibration The process of determining the acc u racy of an instr u ment. In a formal
sense, calibration establishes the relationship of an instr u ment’s
meas u rement to the val u e provided by a standard. When that relationship is
known, the instr u ment may then be adj u sted (calibrated) for best acc u racy.
cascading Process of extending the co u nting range of a co u nter chip by connecting to
the next higher co u nter.