Glossary

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Glossary

Numbers and Symbols

-	negative of, or minus
<	less than
>	greater than
≤	less than or equal to
≥	greater than or equal to
/	per
%	percent
±	plus or minus

A
ADE	Application Development Environment
API	Application Programming Interface—a standardized set of subroutines or functions, along with the parameters that a program can call.
B
b	bits
B	bytes
buffer	Temporary storage for acquired or generated data (software). A collection of samples.
C
clock	Hardware component that controls timing for reading from or writing to channels. Periodic digital edges that can be used to measure time.
counter/timer	A circuit that counts external pulses or clock pulses (timing).
D
DAQ	Data Acquisition—Collecting and measuring electrical signals from sensors, transducers, and test probes or fixtures and inputting them to a computer for processing. Also refers to collecting and measuring the same kinds of electrical signals with analog-to-digital and/or digital devices plugged into a PC, and possibly generating control signals with digital-to-analog and/or digital devices in the same PC.
default setting	Default parameter value recorded in the driver. In many cases, the default input of a control is a certain value (often 0) that means use the current default setting.
device	Plug-in data acquisition board, card, or pad that can contain multiple channels and conversion devices. Plug-in boards, PCMCIA cards, and devices that connects to your computer parallel port, are all examples of DAQ devices.
digital trigger	Level signal having two discrete levels: a high and a low level. See trigger.
DIO	digital input/output
E
event	Events are emitted to signify a device state change, the arrival of a certain kind of sample, the production of a certain number of samples, or the passage of time.
F
function	Set of software instructions executed by a single line of code that can have input and/or output parameters and returns a value when executed.
H
high level	For generation, the high level is the voltage produced when a binary one is generated. For acquisition, the high level is the voltage threshold above which the input will be sampled as a binary one.
I
I/O	input/output—Transfer of data to/from a computer system involving communications channels, operator interface devices, and/or data acquisition and control interfaces.
idle state	Specifies the values of the channels when the generation operation is paused or has completed.
initial state	Specifies the values of the channels when the generation operation has not yet started.
instructions	Statements used to define a script.
L
latch
line	Represents the value of one bit of a sample over all samples. A line is independent of any hardware I/O connector.
low level	For generation, the low level is the voltage produced when a binary zero is generated. For acquisition, the low level is the voltage threshold below which the input will be sampled as a binary one.
LSB	least significant bit
M
Marker event	An event that the device generates in relation to a waveform that is generated. You can configure the position(s) at which Marker events are generated.
MB/s	Unit for data transfer that means one million or 2²⁰ bytes per second.
P
Pause trigger	Trigger used to indicate to the device that it should stop generating and/or acquiring. The device resumes when the pause trigger becomes inactive.
posttrigger	Acquiring data that occurs after a trigger.
pretrigger	Acquiring data that occurs before a trigger.
propagation delay	The amount of time required for a signal to pass through a circuit.
R
reference clock	Clock to which a device phase locks another, usually faster, clock. A common source for the reference clock is the 10 MHz oscillator present on the PXI backplane.
S
s	seconds
S	sample
sample	The value being generated/acquired on all channels during a single sample clock cycle.
Sample clock	Samples are generated or acquired based on Sample clock cycles.
script	Collection of instructions that describe the order and timing of one or more waveforms.
Script trigger	General-purpose trigger that has a role that is determined by the context of the script.
software trigger	Programmed event that triggers an operation such as data acquisition.
T
terminal	Named location where a signal is either produced (generated) or consumed (acquired).
transfer rate	Rate, measured in bytes/s or samples/s, at which data is moved from source to destination after software initialization and set up operations; the maximum rate at which the hardware can operate.
trigger	A signal sent to the device to control the device in some way. In the context of the NI digital waveform generator/analyzer, triggers are essentially the opposite of events.
V
VI	Virtual Instrument A combination of hardware and/or software elements, typically used with a PC, that has the functionality of a classic stand-alone instrument. A LabVIEW software module (VI), which consists of a front panel user interface and a block diagram program.
virtual channels	Channel names that can be defined outside the application and used without having to perform scaling operations.
W
waveform	A collection of samples generated or acquired on a channel.

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