A | Amperes. |
A/D | Analog-to-digital; analog/digital. |
absolute coordinates | Picture coordinates relative to the origin (0,0) of the picture indicator. |
absolute path | File or directory path that describes the location relative to the top level of the file system. |
AC | Alternating current. |
access level | Determines access privileges a user has for certain LabVIEW utilities. Access level values range from 0 to 255. |
active window | Window that is currently set to accept user input, usually the frontmost window. The titlebar of an active window is highlighted. Make a window active by clicking it or by selecting it from the Windows menu. |
AI | Analog input. |
Am9513-based devices | These MIO devices do not have an E- in their names. These devices include the NB-MIO-16, NB-MIO-16X, NB-TIO-10, and NB-DMA2800 on the Macintosh; and the AT-MIO-16, AT-MIO-16F-5, AT-MIO-16X, AT-MIO-16D, and AT-MIO-64F-5 in Windows. |
analog multiplexer | Devices that increase the number of measurement channels while still using a single instrumentation amplifier. Also called AMUX devices. |
analog trigger | Trigger that occurs at a user-selected level and slope on an incoming analog signal. You can set triggering to occur at a specified voltage on either an increasing or a decreasing signal (positive or negative slope). |
ANSI | American National Standards Institute. |
Application Programming Interface (API) | Programming interface for controlling some software packages, such as Microsoft Visual SourceSafe. |
application software | Application created using the LabVIEW Development System and executed in the LabVIEW Run-Time System environment. |
array | Ordered, indexed list of data elements of the same type. |
array shell | Front panel object that houses an array. An array shell consists of an index display, a data object window, and an optional label. It can accept various data types. |
artificial data dependency | Condition in a dataflow programming language in which the arrival of data, rather than its value, triggers execution of a node. |
ASCII | American Standard Code for Information Interchange. |
asynchronous execution | Mode in which multiple processes share processor time. For example, one process executes while others wait for interrupts during device I/O or while waiting for a clock tick. |
auto-indexing | Capability of loop structures to disassemble and assemble arrays at their borders. As an array enters a loop with auto-indexing enabled, the loop automatically disassembles it extracting scalars from ID arrays, ID arrays extracted from 2D arrays, and so on. Loops assemble data into arrays as data exit the loop in the reverse order. |
autoscaling | Ability of scales to adjust to the range of plotted values. On graph scales, autoscaling determines maximum and minimum scale values. |
autosizing | Automatic resizing of labels to accommodate text you enter. |
Bessel filters | These filters have a maximally flat response in both magnitude and phase. The phase response in the passband, which is usually the region of interest, is nearly linear. Use Bessel filters to reduce nonlinear phase distortion inherent in all IIR filters. |
Bessel function | The Bessel function of the first kind of order n is defined by

with n = 0, 1, ...
The Bessel function of the second kind of order n, is defined by

with n = 0, 1, ... |
Bessel polynomial | The Bessel polynomial of order n is defined by a recurrence relation

for n = 2, 3, ... where and  |
beta function | An integral defined by

or, in terms of the gamma function
 |
binomial coefficient | The binomial coefficient is given by
 |
bit array tag | Multibit value representation of a connection to a real-world I/O point or memory variable. In LabVIEW, this type of tag can be comprised of up to 32 discrete values. |
block diagram | Pictorial description or representation of a program or algorithm. The block diagram, consists of executable icons called nodes and wires that carry data between the nodes. The block diagram is the source code for the VI. The block diagram resides in the block diagram window of the VI. |
BNF | Backus-Naur Form. A common representation for language grammars in computer science. |
Boolean controls and indicators | Front panel objects to manipulate and display Boolean (TRUE or FALSE) data. |
bracketing interval | A bracketing triplet (a, b, c) of a continuous 1D function f is a combination of three points with f(a) > f(b) and f(c) > f(b). This guarantees the existence of a local minimum of f in the interval (a, c). |
bracketing of a minimum | A root of a continuous function is said to be bracketed by a pair of points, a < b, when f(a) and f(b) are of opposite signs. A minimum is bracketed when there are three points, a < b < c, with f(a) > f(b) and f(c) > f(b). |
breakpoint | Pause in execution used for debugging. |
Breakpoint tool | Tool to set a breakpoint on a VI, node, or wire. |
Brent Method | For solving nonlinear equations, methods that converge rapidly to the solution are unreliable because convergence may not occur unless started close enough to the actual solution. On the other hand, the more reliable methods are slower. The Brent method is a hybrid method that combines both the safety of the bisection method and the rapid convergence of inverse quadratic interpolation. |
broken Run button | Button that replaces the Run button when a VI cannot run because of errors. |
broken VI | VI that cannot or run because of errors; signified by a broken arrow in the broken Run button. |
buffer | Temporary storage for acquired or generated data. |
bundle node | Function that creates clusters from various types of elements. |
byte stream file | File that stores data as a sequence of ASCII characters or bytes. |
caption label | Label on a front panel object used to name the object in the user interface. You can translate this label to other languages without affecting the block diagram source code. See also Name Label. |
case | One subdiagram of a Case structure. |
Case structure | Conditional branching control structure, that executes one of its subdiagrams based on the input to the Case structure. It is the combination of the IF, THEN, ELSE, and CASE statements in control flow languages. |
Cash Karp method | Numerical method for solving ordinary differential equations with start conditions. The Cash Karp method is an embedded Runge Kutta formula and is based on a fifth order strategy with six steps. The Cash Karp method works with an adaptive step rate and is computationally more efficient than the Euler method or the Runge Kutta method. |
cast | To change the type descriptor of a data element without altering the memory image of the data. |
channel | Pin or wire lead to which you apply or from which you read the analog or digital signal. Analog signals can be single-ended or differential. For digital signals, you group channels to form ports. Ports usually consist of either four or eight digital channels. |
channel clock | Clock that controls the time interval between individual channel sampling within a scan. Products with simultaneous sampling do not have this clock. |
channel name | Unique name given to a channel configuration in the DAQ Channel Wizard. |
chart | 2D display of one or more plots in which the display retains previous data, up to a maximum that you define. The chart receives the data and updates the display point by point or array by array, retaining a certain number of past points in a buffer for display purposes. See also scope chart, strip chart, and sweep chart. |
Chebyshev polynomial | The Chebyshev polynomial, for real numbers x, is given by . This results in and so on. |
checkbox | Small square box in a dialog box you can select or clear. Checkboxes generally are associated with multiple options that you can set. You can select more than one checkbox. |
chi-squared | An error function given by

In this equation, are the input data points, and is the nonlinear function where are coefficients. If the measurement errors are independent and normally distributed with constant, standard deviation , this is also the least-square estimation. |
CIN | See Code Interface Node (CIN) |
clock | Hardware component that controls timing for reading from or writing to groups. |
cloning | To make a copy of a control or another object by clicking it while pressing the <Ctrl> key and dragging the copy to its new location.
Macintosh Press <Option>, Sun Press <Meta>, Linux Press <Alt>.
UNIX You also can clone an object by clicking the object with the middle mouse button and then dragging the copy to its new location. |
cluster | A set of ordered, unindexed data elements of any data type, including numeric, Boolean, string, array, or cluster. The elements must be all controls or all indicators. |
cluster shell | Front panel object that contains the elements of a cluster. |
Code Interface Node (CIN) | CIN. Special block diagram node through which you can link text-based code to a VI. |
coercion | Automatic conversion LabVIEW performs to change the numeric representation of a data element. |
coercion dot | Dot on a terminal that indicates that one of two terminals wired together LabVIEW has converted to match the data type of the other. |
Color Copy tool | Copies colors for pasting with the Coloring tool. |
Coloring tool | Tool to set foreground and background colors. |
compile | Process that converts high-level code to machine-executable code. LabVIEW compiles VIs automatically before they run for the first time after you create or edit alteration. |
conditional terminal | Terminal of a While Loop that contains a Boolean value that determines if the VI performs another iteration. |
configuration utility | Refers to Measurement & Automation Explorer on Windows and to the NI-DAQ Configuration Utility on Macintosh. |
conjugate gradient method | This method can be used for multidimensional unconstrained minimization. It determines the local minimum of a function of n independent variables. The direction of the gradient is modified at each iteration. This is done by forming a sequence of conjugate (the inner product being orthogonal) search directions and tends to avoid slow convergence, which may result by repeated searching in the same direction. To minimize the function f(x), given an initial guess first calculate . The rest of the algorithm consists of following a sequence of steps until convergence. One of these steps consists of solving for a quantity where
(Fletcher & Reeves) or
(Polak & Ribiere). |
connector | Part of the VI or function node that contains input and output terminals. Data pass to and from the node through a connector. |
connector pane | Region in the upper right corner of a front panel or block diagram window that displays the VI terminal pattern. It defines the inputs and outputs you can wire to a VI. |
constant | See universal constant and user-defined constant. |
Context Help window | Special window in LabVIEW that displays the names and locations of the terminals for a VI or function, the description of controls and indicators, the values of universal constants, and descriptions and data types of control attributes. |
continued fraction | The continued fraction of two sequences and is defined by the following term

Continued fractions are valuable tools for calculating special functions. |
continuous run | Execution mode in which a VI runs repeatedly until the operator stops it. Click the Continuous Run button to run a VI repeatedly. |
Continuous Run button | Icon that indicates a VI is set to execute repeatedly until the user stops it. |
contour plot | Plot where contour lines are used to connect points of equal value. |
control | Front panel object for entering data to a VI interactively or to a subVI programmatically, such as a knob, push button, or dial. |
control flow | Programming system in which the sequential order of instructions determines execution order. Most text-based programming languages are control flow languages. |
Controls palette | Palette that contains front panel controls, indicators, and decorative objects. |
conversion | Changing the type of a data element. |
cosine integral | The cosine integral is defined by

with the Euler constant and x as any real non-negative number. |
count terminal | Terminal of a For Loop whose value determines the number of times the For Loop executes its subdiagram. |
counter/timer group | Collection of counter/timer channels. Use this type of group for simultaneous operation of multiple counter/timers. |
coupling | Manner in which a signal connects from one location to another. |
current VI | VI whose front panel, block diagram, or Icon Editor is the active window. |
curve in 3D | Special parametric plot (x(t), y(t), z(t)), where the parameter t runs over a given interval. |
DAQ | See data acquisition. |
DAQ Channel Wizard | Utility that guides you through naming and configuring your DAQ analog and digital channels. Available in the Data Neighborhood of Measurement & Automation Explorer on Windows or DAQ Channel Wizard on Macintosh. |
DAQ Solution Wizard | Utility that guides you through specifying your DAQ application, and it provides a custom DAQ solution. |
DAQ-STC | Data Acquisition System Timing Controller. |
data acquisition | DAQ. Process of acquiring data, typically from A/D or digital input plug-in devices. |
data dependency | Condition in a dataflow programming language in which a node cannot execute until it receives data from another node. See also artificial data dependency. |
data flow | Programming system that consists of executable nodes that execute only when they receive all required input data and produce output automatically when they execute. LabVIEW is a dataflow system. |
datalogging | Generally, to acquire data and simultaneously store it in a disk file. LabVIEW file I/O VIs and functions can log data. |
data storage formats | Arrangement and representation of data stored in memory. |
data type | Format for information. In LabVIEW, acceptable data types for most VIs and functions are numeric, array, string, Boolean, path, refnum, enumeration, waveform, and cluster. |
data type descriptor | Code that identifies data types; used in data storage and representation. |
datalog file | File that stores data as a sequence of records of a single, arbitrary data type that you specify when you create the file. Although all the records in a datalog file must be a single type, that type can be complex. For instance, you can specify that each record is a cluster that contains a string, a number, and an array. |
Daubechies4 Function | Daubechies wavelet with 4 coefficients. |
DDE | See dynamic data exchange. |
deadband | In process instrumentation, the range through which an input signal can vary, upon reversal of direction, without initiating an observable change in output signal. Deadband is usually expressed in percent of range. |
default | Preset value. Many VI inputs use a default value if you do not specify a value. |
default input | Default value of a front panel control. |
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. For example, the default input for a parameter can be do not change current setting, and the default setting can be no AMUX-64T boards. If you change the value of such a parameter, the new value becomes the new setting. You can set default settings for some parameters in the configuration utility. |
dialog box | Window that appears when an application needs further information to carry out a command. |
digital trigger | TTL signal that you can use to start or stop a buffered data acquisition operation, such as buffered analog input or buffered analog output. |
dimension | Size and structure of an array. |
directory | Structure for organizing files into convenient groups. A directory is like an address that shows the location of files. A directory can contain files or subdirectories of files. |
discrete | Having discontinuous values of the independent variable, usually time. |
DLL | Dynamic Link Library. |
DMA | Direct Memory Access. A method by which you can transfer data to computer memory from a device or memory on the bus, (or from computer memory to a device), while the processor does something else. DMA is the fastest method of transferring data to or from computer memory. |
Downhill Simplex |
Method Determines a local minimum of a function of n independent variables. The Downhill Simplex algorithm, also called the Nelder and Mead method, works without partial derivatives. The algorithm consists of catching the minimum of the function, f(X), with the help of simple geometrical bodies, namely with a simplex. A simplex in 2D is a triangle, a simplex in 3D is a tetrahedron, and so on. You must have n + 1 starting points, each of dimension n, forming the initial simplex. The user must enter only one point of these (n+1). The (n+1) dimensional simplex is automatically constructed. The algorithm generates a new simplex by some elementary operations like reflections, expansions, and contractions. In the end, the minimum is concentrated in a very small simplex. |
drag | To use the cursor on the screen to select, move, copy, or delete objects. |
drive | Letter in the range az followed by a colon (:), to indicate a logical disk drive. |
driver | Software that controls a specific hardware device, such as a DAQ device. |
DSP | Digital Signal Processing. |
dynamic data exchange | DDE. Method to pass data between applications, without user involvement or monitoring. |
eigenvalues | Values of l for which the matrix equation Ax = lx has a nontrivial solution are known as eigenvalues or characteristic values. |
eigenvectors | Solutions of x for which the matrix equation Ax = lx has a nontrivial solution are known as eigenvectors or characteristic vectors. |
empty array | Array that has zero elements but has a defined data type. For example, an array that has a numeric control in its data display window but has no defined values for any element is an empty numeric array. |
end of file (EOF) | Character offset of the end of file relative to the beginning of the file. The EOF is the size of the file. |
Engineering Unit (EU) | Term of data measurement, as degrees Celsius, pounds, grams, and so on. |
error in | Error structure that enters a VI. |
error message | Indication of a software or hardware malfunction or of an unacceptable data entry attempt. |
error out | The error structure that leaves a VI. |
error structure | Consists of a Boolean status indicator, a numeric code indicator, and a string source indicator. |
Euler method | Numerical method for solving ordinary differential equations with start conditions. This is a single-step method because it depends on information at only one point in time to advance to the next point. |
event | Condition or state of an analog or digital signal. |
Event Data Node | Node attached to the left and right sides of an Event structure indicating the available data for the event you configured that case to handle. If you configure a single case to handle multiple events, only the data that is common to all handled event types is available. |
event driven |
programming Method of programming whereby the program waits on an event to occur before executing one or more functions. |
execution highlighting | Debugging technique that animates VI execution to illustrate the data flow in the VI. |
external trigger | Voltage pulse from an external source that triggers an event, such as A/D conversion. |
extrema | Maxima and minima. |
FFFT | Fractional Fast Fourier Transform. |
FFT | Fast Fourier transform. |
file refnum | See refnum. |
filtering | Type of signal conditioning that allows you to filter unwanted signals from the signal you are trying to measure. |
flattened data | Data of any type that has been converted to a string, usually for writing the data to a file. |
Fletcher & Reeves | See conjugate gradient method. |
For Loop | Iterative loop structure that executes its subdiagram a set number of times. Equivalent to text-based code: For i = 0 to n 1, do.... |
Formula Node | Node that executes equations you enter as text. Especially useful for lengthy equations too cumbersome to build in block diagram form. |
frame | Subdiagram of a Sequence structure. |
free label | Label on the front panel or block diagram that does not belong to any other object. |
front panel | Interactive user interface of a VI. Front panel appearance imitates physical instruments, such as oscilloscopes and multimeters. |
function | Built-in execution element, comparable to an operator, function, or statement in a text-based programming language. |
Functions palette | Palette that contains VIs, functions, block diagram structures, and constants. |
G | Graphical programming language LabVIEW uses. |
gain | Amplification or attenuation of a signal. |
gamma function | The gamma function of x is the generalization of the common factorial function n!. The relation between these two functions is for all natural numbers n. The gamma function is defined by

for real and complex x and has the property . |
GATE input pin | Counter input pin that controls when counting in your application occurs. |
General Purpose Interface Bus | GPIBsynonymous with HP-IB. The standard bus used for controlling electronic instruments with a computer. Also called IEEE 488 bus because it is defined by ANSI/IEEE Standards 488-1978, 488.1-1987, and 488.2-1992. |
global variable | Accesses and passes data among several VIs on a block diagram. |
glyph | Small picture or icon. |
graph | 2D display of one or more plots. A graph receives and plots data as a block. |
graph control | Front panel object that displays data in a Cartesian plane. |
group | Collection of input or output channels or ports that you define. Groups can contain analog input, analog output, digital input, digital output, or counter/timer channels. A group can contain only one type of channel. Use a task ID number to refer to a group after you create it. You can define up to 16 groups at one time.
To erase a group, pass an empty channel array and the group number to the group configuration VI. You do not need to erase a group to change its membership. If you reconfigure a group whose task is active, LabVIEW clears the task and returns a warning. LabVIEW does not restart the task after you reconfigure the group. |
I/O | Input/Output. The transfer of data to or from a computer system involving communications channels, operator input devices, and/or data acquisition and control interfaces. |
IAC | Interapplication communication. |
icon | Graphical representation of a node on a block diagram. |
Icon Editor | Interface similar to that of a graphics program for creating VI icons. |
icon pane | Region in the upper right corner of the front panel and block diagram windows that displays the VI icon. |
IEEE | Institute for Electrical and Electronic Engineers. |
immediate digital I/O | Type of digital acquisition/generation where LabVIEW updates the digital lines or port states immediately or returns the digital value of an input line. Also called nonlatched digital I/O. |
incomplete betafunction | The incomplete beta function is defined by

with a, b > 0 and where B(a, b) denotes the beta function of a and b |
incomplete gamma function | The incomplete gamma function is defined by

for a > 0 |
indicator | Front panel object that displays output, such as a graph or LED. |
Inf | Digital display value for a floating-point representation of infinity. |
instrument driver | VI that controls a programmable instrument. |
integer | Any of the natural numbers, their negatives, or zero. |
intensity map/plot | Method of displaying three dimensions of data on a 2D plot with the use of color. |
interrupt | Signal that indicates that the central processing unit should suspend its current task to service a designated activity. |
interval scanning | Scanning method where there is a longer interval between scans than there is between individual channels that comprises a scan. |
IP | Internet protocol. |
iteration terminal | Terminal of a For Loop or While Loop that contains the current number of completed iterations. |
Lab/1200 device | Devices, such as the Lab-PC-1200 and the DAQCard-1200, that use the 8253 type counter/timer chip. |
label | Text object used to name or describe objects or regions on the front panel or block diagram. |
Labeling tool | Tool to create labels and enter text into text windows. |
LabVIEW | Laboratory Virtual Instrument Engineering Workbench. LabVIEW is a graphical programming language that uses icons instead of lines of text to create programs. |
LED | Light-emitting diode. |
Legacy MIO device | Devices, such as the AT-MIO-16, that typically are configured with jumpers and switches and are not Plug and Play compatible. They also use the 9513 type counter/timer chip. |
legend | Object a chart or graph owns to displays the names and plot styles of plots on that chart or graph. |
Legendre elliptic integral | The Legendre Elliptic Integral of the 1st kind is defined by the following equation
|
library | See VI library. |
linear programming | Suppose that we are given f, a linear function of the variables x1, x2, x3,.....xn, and a set of constraints on these variables in terms of linear inequalities. Linear programming consists of methods for maximizing or minimizing f. Such problems usually are found in the areas of economics, distribution of goods, production, and approximation theory. |
linearization | Type of signal conditioning in which LabVIEW linearizes the voltage levels from transducers so the voltages can be scaled to measure physical phenomena. |
listbox | Box within a dialog box that lists all available choices for a command. For example, a list of filenames on a disk. |
LLB | VI Library. |
local variable | Variable that enables you to read or write to one of the controls or indicators on the front panel of a VI. |
LSB | Least Significant Bit. |
marquee | Moving, dashed border that surrounds selected objects. |
matrix | 2D array. |
maxima | Maximum value(s) of a function. |
MB | Megabytes of memory. 1 MB is equal to 1,024 KB. |
Measurement & Automation Explorer | The standard National Instruments hardware configuration and diagnostic environment for Windows. |
memory buffer | See buffer. |
menu bar | Horizontal bar that lists the names of the main menus of an application. The menu bar appears below the titlebar of a window. Each application has a menu bar that is distinct for that application, although some menus and commands are common to many applications. |
method | A procedure that is executed when an object receives a message. A method is always associated with a class. |
minima | Minimum value(s) of a function. |
MSB | Most Significant Bit. |
multiplexed mode | SCXI operating mode in which analog input channels are multiplexed into one module output so that your cabled DAQ device can access the module's multiplexed output and the outputs on all other multiplexed modules in the chassis through the SCXI bus. Also called serial mode. |
multiplexer | Set of semiconductor or electromechanical switches with a common output that can select one of a number of input signals and that you commonly use to increase the number of signals by one ADC measures. |
multithreaded application | Application that runs several different threads of execution independently. On a multiple processor computer, the different threads might be running on different processors simultaneously. |
Name Label | Label of a front panel object used to name the object and as distinguish it from other objects. The label also appears on the block diagram terminal, local variables, and property nodes that are part of the object. See also caption label. |
NaN | Digital display value for a floating-point representation of not a number. Typically the result of an undefined operation, such as log(1). |
Newton Raphson method | Determines a zero of a 1D function close to two points with the help of the derivative of this 1D function. The two values form a search limit for the unknown zero of the 1D function. The Newton Raphson method, or Newton method, is an iterative method for solving equations of the form f(x) = 0 where the derivative of f, f', is continuous. Given two values, x1 and x2, with f(x1)·f(x2) < 0, first use the midpoint method to calculate
(1)
Then use the Newton method to calculate
(2)
Replace x(n) by x(n+1) and repeat equation 2 until a certain termination condition is met. This termination condition could be either after a given number of repetitions or if . This is a fast and simple method. |
NI-DAQ | Comprehensive driver software included with all National Instruments DAQ hardware. |
node | Program execution element. Nodes are analogous to statements, operators, functions, and subroutines in text-based programming languages. On a block diagram, nodes include functions, structures, and subVIs. |
non-displayable characters | ASCII characters that cannot be displayed, such as null, backspace, tab, and so on. |
nonsingular matrix | Matrix in which no row or column is a linear combination of the other rows or columns, respectively. In other words, the rows or columns are linearly independent. This matrix has a unique inverse, and it has a nonzero determinant. |
not-a-refnum | Predefined value that indicates the refnum is invalid. |
numeric controls and indicators | Front panel objects to manipulate and display numeric data. |
object | Generic term for any item on the front panel or block diagram, including controls, indicators, nodes, wires, and imported pictures. |
Object Shortcut Menu tool | Tool to access a shortcut menu for an object. |
ODE | Ordinary Differential Equation. |
OLE | Object Linking and Embedding. |
one-dimensional | Having one dimension, as in the case of an array that has only one row of elements. |
Operating tool | Tool to enter data into controls operate them. |
operator | Person who initiates and monitors the operation of a process. |
optimal step | For a function that has many maxima, minima, or singularities, the standard method (using equidistant points) may yield incorrect results. In such cases, the optimal step method is better. This method starts off with taking equidistant points but also checks the steepness of the curve between these points. In very steep portions (determined by the value of epsilon on the front panel) of the graph, a new point is generated in between. As a rule, the smaller the value of epsilon, the more the points that are generated and the better the graph. |
Pade approximation | Determines the coefficients of a rational polynomial to best suit a given set of first derivatives. Let f be a given function with known values 
A unique rational polynomial exists

with 
The rational polynomial can be determined by solving a special linear equation. |
palette | Display of icons that represent possible options. |
panel window | VI window that contains the front panel, the toolbar, and the icon and connector panes. |
parametric plot | Plot of the variables (such as x and y) that are given in terms of another variable t (called a parameter), resulting in the parametric equations x = f(t) and y = g(t). Each value of t determines a point (x,y). As t is varied, the point (x,y) = (f(t), g(t)) varies and traces a curve, to plot. |
parser | VI that scans a string to determine the function of each of the elements in the string. |
partial derivative | Derivative taken with respect to one of two or more independent variables, with the others treated as constants. |
picture | Series of graphics instructions that a picture indicator uses to create a picture. |
picture indicator | General-purpose indicator for displaying pictures that can contain lines, circles, text, and other types of graphic shapes. |
PID | See Proportional Integral Derivative (PID). |
pixel | Smallest unit of a digitized picture. |
pixmap | Standard format for storing pictures in which a color value represents each pixel. A bitmap is a black and white version of a pixmap. |
PLC | See Proportional Integral Derivative (PID) Control. |
plot | Graphical representation of an array of data shown either on a graph or a chart. |
point | Cluster that contains two 16-bit integers that represent horizontal and vertical coordinates. |
Polak & Ribiere | See conjugate gradient method. |
polling | Method of sequentially observing each I/O point or user interface control to determine if it is ready to receive data or request computer action. |
Positioning tool | Tool to move and resize objects. |
power spectrum fractional FFT | Magnitude of the FFFT. |
PPC | Program-to-program communication. |
prime FFT | Special case of the FFT where the signal length is prime. The prime FFT VI is computationally more efficient than the classical FFT algorithms. |
probe | Debugging feature for checking intermediate values in a VI. |
Probe tool | Tool to create probes on wires. |
Programmable Logic Control (PLC) | Device with multiple inputs and outputs that contains a program you can alter. LabVIEW Device Servers establish communication with PLCs. |
programmatic printing | Automatic printing of a VI front panel after execution. |
Property Node | Sets or finds the properties of a VI or application. |
Proportional Integral Derivative (PID) | Control Combination of proportional, integral, and derivative control actions. Refers to a control method in which the controller output is proportional to the error, its time history, and the rate at which it is changing. The error is the difference between the observed and desired values of a variable that is under control action. |
prototype | Simple, quick implementation of a particular task to demonstrate that the design has the potential to work. The prototype usually has missing features and might have design flaws. In general, prototypes should be thrown away, and the feature should be reimplemented for the final version. |
pseudocode | Simplified language-independent representation of programming code. |
pull-down menus | Menus accessed from a menu bar. Pull-down menu options are usually general in nature. |
pulse trains | Multiple pulses. |
PXI | PCI eXtensions for Instrumentation. A modular, computer-based instrumentation platform. |
race condition | Occurs when two or more pieces of code that execute in parallel change the value of the same shared resource, typically a global or local variable. |
range | Region between the limits within which a quantity is measured, received, or transmitted. Expressed by stating the lower and upper range values. |
rational polynomial | Quotient of polynomials. The advantage they have over polynomials for approximating functions is that they can be used to model functions with poles. |
read mark | Points to the scan at which a read operation begins. Analogous to a file I/O pointer, the read mark moves every time you read data from an input buffer. After the read is finished, the read mark points to the next unread scan. Because multiple buffers are possible, you need both the buffer number and the scan number to express the position of the read mark. |
real Laplace transform | Laplace transform for real s. |
real-time | Pertaining to the performance of a computation during the actual time that the related physical process transpires so results of the computation can be used in guiding the physical process. |
rectangle | Cluster that contains four 16-bit integers. The first two values describe the vertical and horizontal coordinates of the top left corner. The last two values describe the vertical and horizontal coordinates of the bottom right corner. |
reentrant execution | Mode in which calls to multiple instances of a subVI can execute in parallel with distinct and separate data storage. |
refnum | Reference number. An Identifier that LabVIEW associates with a file you open. Use the refnum to indicate that you want a function or VI to perform an operation on the open file. |
relative coordinates | Picture coordinates relative to the current location of the pen. |
representation | Subtype of the numeric data type, of which there are signed and unsigned byte, word, and long integers, as well as single-, double-, and extended-precision floating-point numbers. |
resizing handles | Angled handles on the corner of objects that indicate resizing points. |
ring control | Special numeric control that associates 32-bit integers, starting at 0 and increasing sequentially, with a series of text labels or graphics. |
RMS | Root Mean Square. |
roots | Zeros of a function Values of the variable(s) for which the function is equal to zero. |
row-major order | Way to organize the data in a 2D array by rows. |
RTD | Resistance Temperature Detector. A temperature-sensing device whose resistance increases with increases in temperature. |
RTSI | Real-Time System Integration bus. The National Instruments timing bus that interconnects data acquisition devices directly by means of connectors on top of the devices for precise synchronization of functions. |
Runge Kutta method | Numerical method for solving ordinary differential equations with start conditions. The Runge Kutta method works with a fixed step rate but with a higher degree of accuracy than the common Euler method. |
S | Sample. |
sample | Single analog or digital input or output data point. |
sampling period | Time interval between observations in a periodic sampling control system. |
scalar | Number that a point on a scale can represent. A single value as opposed to an array. Scalar Booleans and clusters are explicitly singular instances of their respective data types. |
scale | Part of chart, graph, and some numeric controls and indicators that contains a series of marks or points at known intervals to denote units of measure. |
scan | One or more analog or digital input samples. Typically, the number of input samples in a scan equals the number of channels in the input group. For example, one pulse from the scan clock produces one scan that acquires one new sample from every analog input channel in the group. |
scan clock | Clock that controls the time interval between scans. On products with interval scanning support (for example, the AT-MIO-16F-5), this clock gates the channel clock on and off. On products with simultaneous sampling (for example, the EISA-A2000), this clock times the track-and-hold circuitry. |
scan rate | Number of times, (or scans), per second that LabVIEW acquires data from channels. For example, at a scan rate of 10Hz, LabVIEW samples each channel in a group 10 times per second. |
Scroll tool | Tool to move through windows. |
SCXI | Signal Conditioning eXtensions for Instrumentation. The National Instruments product line for conditional low-level signals within an external chassis near sensors, so only high-level signals in a noisy environment are sent to DAQ devices. |
sec | Seconds. |
sensor | Device that produces a voltage or current output representative of a physical property being measured, such as speed, temperature, or flow. |
sequence local | Terminal to pass data between the frames of a Sequence structure. |
Sequence structure | Program control structure that executes its subdiagrams in numeric order. Use this structure to force nodes that are not data dependent to execute in the order you want. |
shift register | Optional mechanism in loop structures to pass the value of a variable from one iteration of a loop to a subsequent iteration. |
shortcut menu | Menu accessed by right-clicking an object. Menu options pertain to that object specifically. |
simplex | Simple geometrical body. A simplex in 2D is a triangle, a simplex in 3D is a tetrahedron, and so on. Used in finding the minimum of a function. |
sine integral | The sine integral is defined by

si(x) = si(x) where x is any real number. |
singular matrix | Square matrix in which a row or column is a linear combination of the other rows or columns, respectively. The rows or columns are linearly dependent. This matrix does not have an inverse, and its determinant is equal to zero. |
slider | Moveable part of slide controls and indicators. |
software trigger | Programmed event that triggers an event, such as data acquisition. |
software triggering | Method of triggering in which you simulate an analog trigger using software. Also called conditional retrieval. |
SOURCE input pin | Counter input pin where the counter counts the signal transitions. |
sparse signals | Signals with a large number of zero values. |
spectrogram | Particular representation of a signal that describes the distribution of the energy of the time waveform in the joint time-frequency domain. |
spike function | The spike function is defined by
 |
square function | The square function is defined as

where x is any real number. |
STC | System Timing Controller. |
step function | The step function is defined by

where x is any real number. |
STFT | Short-Time Fourier Transform. |
strain gauge | Thin conductor, which is attached to a material, that detects stress or vibrations in that material. |
string | Representation of a value as text. |
string controls and indicators | Front panel objects to manipulate and display text. |
string tag | ASCII character representation of a connection to a real-world I/O point. |
strip chart | Numeric plotting indicator modeled after a paper strip chart recorder, which scrolls as it plots data. |
structure | Program control element, such as a Sequence structure, Case structure, For Loop, or While Loop. |
subdiagram | Block diagram within the border of a structure. |
substitution of variables | Method commonly used in calculus for finding solutions to equations, where a variable is substituted in terms of another variable to make the equation tractable or solvable. It is also a good method to simplify complex terms. |
subVI | VI used on the block diagram of another VI. Comparable to a subroutine. |
supervisory control | Control in which the control loops operate independently subject to intermittent corrective action. |
sweep chart | Numeric indicator modeled on the operation of an oscilloscope. It is similar to a scope chart, except that a line sweeps across the display to separate old data from new data. |
syntax | Set of rules to which statements must conform in a particular programming language. |
task | Timed I/O operation using a particular group. See ask ID. |
task ID | Number LabVIEW generates to identify the task at hand for the NI-DAQ drive. The following table gives the function code definitions.
Function Code |
I/O Operation |
1 |
analog input |
2 |
analog output |
3 |
digital port I/O |
4 |
digital group I/O |
5 |
counter/timer I/O |
|
TCP | Transmission Control Protocol. |
terminal | Object or region on a node through which data pass. |
ticks | Time in milliseconds required for the entire calculation. |
timed digital I/O | Type of digital acquisition/generation where LabVIEW updates the digital lines or port states at a fixed rate. The timing is controlled either by a clock or by detection of a change in the pattern. Timed digital I/O is either finite or continuous. Also called pattern generation or pattern digital I/O. |
tip strip | Small yellow text banners that identify the terminal name and make it easier to identify terminals for wiring. |
tool | Special cursor to perform specific operations. |
toolbar | Bar that contains command buttons to run and debug VIs. |
Tools palette | Palette that contains tools you can use to edit and debug front panel and block diagram objects. |
top-level VI | VI at the top of the VI hierarchy. This term distinguishes the VI from its subVIs. |
trigger | Any event that causes or starts some form of data capture. |
TTL | Transistor-Transistor Logic. |
tunnel | Data entry or exit terminal on a structure. |
two-dimensional | Having two dimensions, as in the case of an array that has several rows and columns. |
type definition | Master copy of a custom object that several VIs can use. |