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PCI-6023E/6024E/6025E User Manual G-6
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National Instruments Corporation
EXTSTROBE external strobe signal
F
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.
filtering a type of signal conditioning that allows you to filter unwanted signals from
the signal you are trying to measure
floating signal sources signal sources with voltage signals that are not connected to an absolute
reference or system ground. Also called nonreferenced signal sources.
Some common example of floating signal sources are batteries,
transformers, or thermocouples.
FREQ_OUT frequency output signal
ft feet
G
gain the factor by which a signal is amplified, sometimes expressed in decibels
gain accuracy a measure of deviation of the gain of an amplifier from the ideal gain
GATE gate signal
glitch an unwanted momentary deviation from a desired signal
GPCTR general purpose counter
GPCTR0_GATE general purpose counter 0 gate signal
PCI.book Page 6 Wednesday, September 16, 1998 9:09 AM