National Instruments DAQPad-1200, User Manual

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Glossary
DAQCard-1200 User Manual G-4 ni.com
DO digital output
DOUT digital output signal
E
EEPROM electrically erasable programmable read-only memory — ROM that can be
erased with an electrical signal and reprogrammed
EISA Extended Industry Standard Architecture
ESP Engineering Software Package
EXTCONV external control signal to trigger A/D conversions
EXTINT external interrupt signal
EXTTRIG External Trigger — external control singal to trigger a DAQ operation
EXTUPDATE External Update — external control singal to update DAC outputs
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.