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Glossary
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National Instruments Corporation
G-3
device
a plug-in data acquisition board, card, or pad that can contain multiple
channels and conversion devices. Plug-in boards, PC cards, and devices
such as the DAQPad-1200, which connects to your computer parallel port,
are all examples of DAQ devices. SCXI modules are distinct from devices,
with the exception of the SCXI-1200, which is a hybrid.
DGND
digital ground signal
DIFF
differential configuration
differential input
an analog input consisting of two terminals, both of which are isolated from
computer ground, whose difference is measured
DIN
Deutsche Industrie Norme
DIO
digital input/output
DNL
differential nonlinearity—a measure in LSB of the worst-case deviation of
code widths from their ideal value of 1 LSB
drivers/driver software
software that controls a specific hardware device such as a DAQ device
F
F
farads
FIFO
first-in first-out memory buffer—the first data stored is the first data sent to
the acceptor. FIFOs are often used on DAQ devices to temporarily store
incoming or outgoing data until that data can be retrieved or output. For
example, an analog input FIFO stores the results of A/D conversions until
the data can be retrieved into system memory, a process that requires the
servicing of interrupts and often the programming of the DMA controller.
This process can take several milliseconds in some cases. During this time,
data accumulates in the FIFO for future retrieval. With a larger FIFO,
longer latencies can be tolerated. In the case of analog output, a FIFO
permits faster update rates, because the waveform data can be stored on the
FIFO ahead of time. This again reduces the effect of latencies associated
with getting the data from system memory to the DAQ device.
FSR
full-scale reading