Glossary
© National Instruments Corporation
G-5
Getting Started with Your PCI/PXI-6810 SDA
current sinking
the ability of an instrument to dissipate current for analog or digital
output signals
current sourcing
the ability of an instrument to supply current for analog or digital output
signals
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—(1) collecting and measuring electrical signals from
sensors, transducers, and test probes or fixtures and inputting them to a
computer for processing; (2) collecting and measuring the same kinds
of electrical signals with A/D and/or DIO boards plugged into a
computer, and possibly generating control signals with D/A and/or DIO
boards in the same computer
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
DC coupled
allowing the transmission of both AC and DC signals
device
a plug-in instrument card or pad that can contain multiple channels and
conversion devices. Plug-in boards and PCMCIA cards, which connects
to your computer parallel port, are examples of devices.
digital trigger
a TTL level signal having two discrete levels—a high and a low level
DIN
Deutsche Industrie Norme
DIO
digital input/output
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.
down counter
performing frequency division on an internal signal
