National Instruments DAQ X Series User Manual page 271

D
DAC Digital-to-Analog Converter—An electronic device, often an integrated
circuit, that converts a digital number into a corresponding analog voltage
or current.
In the instrumentation world, DACs can be used to generate arbitrary
waveform shapes, defined by the software algorithm that computes the
digital data pattern, which is fed to the DAC.
DAQ 1. Data acquisition—The process of collecting and measuring electrical
2. Data acquisition—The process of collecting and measuring the same
DAQ device A device that acquires or generates data and can contain multiple channels
and conversion devices. DAQ devices include plug-in devices, PCMCIA
cards, and DAQPad devices, which connect to a computer USB port. SCXI
modules are considered DAQ devices.
DAQ-STC3 Third generation data acquisition system timing controller chip.
data acquisition The general concept of acquiring data, as in begin data acquisition or data
acquisition and control. See also DAQ.
data transfer A technique for moving digital data from one system to another.
Options for data transfer are DMA and programmed I/O. For programmed
I/O transfers, the CPU in the PC reads data from the DAQ device whenever
the CPU receives a software signal to acquire a single data point. DMA
transfers use a DMA controller, instead of the CPU, to move acquired data
from the device into computer memory. Even though high-speed data
transfers can occur with programmed I/O transfers, they require the use of
the CPU to transfer data. DMA transfers are able to acquire data at high
speeds and keep the CPU free for performing other tasks at the same time.
dB Decibel—The unit for expressing a logarithmic measure of the ratio of
two signal levels: dB = 20log10 V1/V2, for signals in volts.
© National Instruments
Artisan Technology Group - Quality Instrumentation ... Guaranteed | (888) 88-SOURCE | www.artisantg.com
signals from sensors, transducers, and test probes or fixtures and
inputting them to a computer for processing.
kinds of electrical signals with A/D and/or DIO devices plugged into a
computer, and possibly generating control signals with D/A and/or
DIO devices in the same computer.
G-5
Glossary
X Series User Manual