National Instruments NI 781xR User Manual
Page 43
Glossary
G-2
© National Instruments Corporation
CMRR
Common-mode rejection ratio—A measure of an instrument’s ability to
reject interference from a common-mode signal, usually expressed in
decibels (dB).
common-mode
voltage
Any voltage present at the instrumentation amplifier inputs with respect to
amplifier ground.
CompactPCI
Refers to the core specification defined by the PCI Industrial Computer
Manufacturer’s Group (PICMG).
D
D/A
Digital-to-analog.
DAC
Digital-to-analog converter—An electronic device, often an integrated
circuit, that converts a digital number into a corresponding analog voltage
or current.
DAQ
Data acquisition—A system that uses the computer to collect, receive, and
generate electrical signals.
dB
Decibel—The unit for expressing a logarithmic measure of the ratio of
two signal levels: dB = 20log10 V1/V2, for signals in volts.
DC
Direct current.
DGND
Digital ground signal.
DIFF
Differential mode.
DIO
Digital input/output.
DIO<i>
Digital input/output channel signal.
DMA
Direct memory access—A method by which data can be transferred
to/from computer memory from/to a device or memory on the bus while the
processor does something else. DMA is the fastest method of transferring
data to/from computer memory.
DNL
Differential nonlinearity—A measure in LSB of the worst-case deviation of
code widths from their ideal value of 1 LSB.
DO
Digital output.