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Block Diagram Objects: (a) VI, (b) Express VI, (c) Function

One can display subVIs or Express VIs as icons or expandable nodes. If a subVI is displayed as an expandable node, the background appears yellow. Icons can be used to save space in a block diagram and expandable nodes can be used to achieve easier wiring or better readability. One can resize expandable nodes to show their connection nodes more clearly. Three appearances of a VI/Express VI are shown in [link] .

Icon versus Expandable Node

Terminal icons

Front panel objects are displayed as terminal icons in a block diagram. A terminal icon exhibits an input or output as well as its data type. [link] shows two terminal icon examples consisting of a double precision numerical control and indicator. As shown in this figure, one can display terminal icons as data type terminal icons to conserve space in a block diagram.

Terminal Icon Examples Displayed in a Block Diagram


Wires transfer data from one node to another in a block diagram. Based on the data type of a data source, the color and thickness of its connecting wires change.

Wires for the basic data types used in LabVIEW are shown in [link] . In addition to the data types shown in this figure, there are some other specific data types. For example, the dynamic data type is always used for Express VIs, and the waveform data type, which corresponds to the output from a waveform generation VI, is a special cluster of waveform components incorporating trigger time, time interval and data value.

Basic Wire Types


A structure is represented by a graphical enclosure. The graphical code enclosed in the structure gets repeated or executed conditionally. A loop structure is equivalent to a for loop or a while loop statement in text-based programming languages, while a case structure is equivalent to an if-else statement.

For loop

A for loop structure is used to perform repetitions. As illustrated in [link] , the displayed border indicates a for loop structure, where the count terminal represents the number of times the loop is to be repeated. It is set by wiring a value from outside of the loop to it. The iteration terminal denotes the number of completed iterations, which always starts at zero.

For Loop

While loop

A while loop structure allows repetitions depending on a condition (see [link] ). The conditional terminal initiates a stop if the condition is true. Similar to a for loop , the iteration terminal provides the number of completed iterations, always starting at zero.

While Loop

Case structure

A case structure (see [link] ) allows the running of different sets of operations depending on the value it receives through its selector terminal, which is indicated by . In addition to Boolean type, the input to a selector terminal can be of integer, string, or enumerated type. This input determines which case to execute. The case selector shows the status being executed. Cases can be added or deleted as needed.

Case Structure

Grouping data: array and cluster

An array represents a group of elements having the same data type. An array consists of data elements having a dimension up to 2 31 1 size 12{2 rSup { size 8{"31"} } - 1} {} . For example, if a random number is generated in a loop, it is appropriate to build the output as an array because the length of the data element is fixed at 1 and the data type is not changed during iterations.

Similar to the structure data type in text-based programming languages, a cluster consists of a collection of different data type elements. With clusters, one can reduce the number of wires on a block diagram by bundling different data type elements together and passing them to only one terminal. One can add or extract an individual element to or from a cluster by using the cluster functions such as Bundle by Name and Unbundle by Name .

Debugging and profiling vis

Probe tool

VIs can be debugged as they run by checking values on wires with the Probe tool. Note that the Probe tool can be accessed only in a block diagram window.

With the Probe tool, breakpoints and execution highlighting, one can identify the source of an incorrect or an unexpected outcome. To visualize the flow of data during program execution, a breakpoint can be used to pause the execution of a VI at a specific location.

Profile tool

Timing and memory usage information – in other words, how long a VI takes to run and how much memory it consumes – can be gathered with the Profile tool. It is required to make sure that a VI is stopped before setting up a Profile window.

An effective way to become familiar with LabVIEW programming is to review examples. In the lab that follows, we explore most of the key LabVIEW programming features by building simple VIs.

Containers and decoration tools

Containers and Decoration tools can be used to organize front panel controls and indicators. Container tools are grouped in the Containers pallete (Controls Modern Containers Classic Classic Containers) and Decoration tools are grouped in the Decorations pallete (Controls Modern Decorations) .

One can use Tab Control (Controls Modern Containers Tab Control Classic Classic Containers Tab Control) to display various controls and indicators within a limited screen area. This feature helps one to organize controls and indicators under different tabs as illustrated in [link] . To add more tabs or delete tabs, right-click the border area and choose one of the following options: Add Page After , Add Page Before , Duplicate Page or Remove Page .

Tab Control

Questions & Answers

where we get a research paper on Nano chemistry....?
Maira Reply
what are the products of Nano chemistry?
Maira Reply
There are lots of products of nano chemistry... Like nano coatings.....carbon fiber.. And lots of others..
Even nanotechnology is pretty much all about chemistry... Its the chemistry on quantum or atomic level
no nanotechnology is also a part of physics and maths it requires angle formulas and some pressure regarding concepts
Preparation and Applications of Nanomaterial for Drug Delivery
Hafiz Reply
Application of nanotechnology in medicine
what is variations in raman spectra for nanomaterials
Jyoti Reply
I only see partial conversation and what's the question here!
Crow Reply
what about nanotechnology for water purification
RAW Reply
please someone correct me if I'm wrong but I think one can use nanoparticles, specially silver nanoparticles for water treatment.
yes that's correct
I think
Nasa has use it in the 60's, copper as water purification in the moon travel.
nanocopper obvius
what is the stm
Brian Reply
is there industrial application of fullrenes. What is the method to prepare fullrene on large scale.?
industrial application...? mmm I think on the medical side as drug carrier, but you should go deeper on your research, I may be wrong
How we are making nano material?
what is a peer
What is meant by 'nano scale'?
What is STMs full form?
scanning tunneling microscope
how nano science is used for hydrophobicity
Do u think that Graphene and Fullrene fiber can be used to make Air Plane body structure the lightest and strongest. Rafiq
what is differents between GO and RGO?
what is simplest way to understand the applications of nano robots used to detect the cancer affected cell of human body.? How this robot is carried to required site of body cell.? what will be the carrier material and how can be detected that correct delivery of drug is done Rafiq
analytical skills graphene is prepared to kill any type viruses .
Any one who tell me about Preparation and application of Nanomaterial for drug Delivery
what is Nano technology ?
Bob Reply
write examples of Nano molecule?
The nanotechnology is as new science, to scale nanometric
nanotechnology is the study, desing, synthesis, manipulation and application of materials and functional systems through control of matter at nanoscale
Is there any normative that regulates the use of silver nanoparticles?
Damian Reply
what king of growth are you checking .?
What fields keep nano created devices from performing or assimulating ? Magnetic fields ? Are do they assimilate ?
Stoney Reply
why we need to study biomolecules, molecular biology in nanotechnology?
Adin Reply
yes I'm doing my masters in nanotechnology, we are being studying all these domains as well..
what school?
biomolecules are e building blocks of every organics and inorganic materials.
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Source:  OpenStax, An interactive approach to signals and systems laboratory. OpenStax CNX. Sep 06, 2012 Download for free at http://cnx.org/content/col10667/1.14
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