Glossary
G-6
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FIFO
first-in first-out memory buffer—FIFOs are often used on DAQ devices
to temporarily store incoming or outgoing data until that data can be
read or written. For example, an analog input FIFO stores the results of
A/D conversions until the data can be read into system memory.
Programming the DMA controller and servicing interrupts 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 in the FIFO ahead of
time. This again reduces the effect of latencies associated with getting
the data from system memory to the DAQ device.
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
GATE
gate signal
GPCTR
general-purpose counter signal
GPCTR0_GATE
general-purpose counter 0 gate signal
GPCTR0_OUT
general-purpose counter 0 output signal
GPCTR0_SOURCE
general-purpose counter 0 clock source signal
GPCTR0_UP_DOWN
general-purpose counter 0 up down signal
GPCTR1_GATE
general-purpose counter 1 gate signal
GPCTR1_OUT
general-purpose counter 1 output signal
GPCTR1_SOURCE
general-purpose counter 1 clock source signal
