Glossary
NI6013/6014 User Man ual G-4 ni.com
dithering the addition of Gaussian noise to an AI signal
DMA directmemory access—a method by which data can be transferred to/from
computer memory from/to a deviceo r memory on the buswhile the
processor does something else. DMA is the fastest method of transferring
data to/from computer memory.
DNL differentialnonlinearity—a measure in least significant bit ofthe
worst-casedeviation of code widths fro m their ideal valueof 1 LSB
DO digital output
DoC Declaration of Conformity
DOC Department of Communicatio ns
driver softwarethat controls a specific hardware device such as a DAQdevice or
aG PIB interface board
E
EEPROM electricallyerasable programmable read-only memory—ROM that can be
erased with an electricalsignal and reprogrammed
EXTSTROBE externalstrobe signal
F
FCC Federal Communications Commission
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 retrievedo r output. For
example,an AI FIFO stores the results of A/D conversions until the data
canbe retrieved into system memory, a process that requires the servicing
ofi nterrupts and often the programming of the DMA controller.This
processcan take several milliseconds in some cases. During this time, data
accumulatesin th e FIFO for future retrieval.With a larger FIFO, longer
latencies can be tolerated. In the case of analog output, a FIFO permits
fasterupdate rates, because the waveform data can be stored on the FIFO
ahead oft ime. This again reduces the effectof latencies asso ciated with
getting the data from system memory to the DAQdevice.