LabVIEW Interview Questions and Answers

Laboratory Virtual Instrument Engineering Workbench (LabVIEW) is a system-design platform and development environment for a visual programming language from National Instruments.The graphical language is named “G”; not to be confused with G-code. Originally released for the Apple Macintosh in 1986, LabVIEW is commonly used for data acquisition, instrument control, and industrial automation on a variety of operating systems (OSs), including Microsoft Windows, various versions of Unix, Linux, and macOS.

1.What Is Labview?

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Labview is a graphical programming language designed and developed by National Instruments. It uses icons inplace of text. This language labview is mostly used for test automation and different control applications. It become more popular among industry due to simple and efficient architecture along with its interface to use C language in the backend. (labview interview questions)

2.How Do I Validate a Labview Application?

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To verify and for cetifying a LabVIEW application, you need to demonstrate similar development practices like with any of the programming languages. By this, you can make sure that any kind of risk associated with the application has been adequately mitigated.

3.What Are The Advantages Of Labview?

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 Labview comes with a lot of advantages associated with it, that can simply be seen in the following points mentioned below:

• Graphical User Interface (UI).
• Hierarchical design and modular design.
• Drag-and-drop functionalities.
• Professional development tools.
• Multiple high-level development tools.
• Preserves investment and reduces cost.
• Multi-platforms
  Instrument and connectivity control.
• Scalability and flexibility.
• Visualization capabilities.
• Distributed development.
• Compiled languages for fast execution.
• Rapid development with express technology.

4.What Is the full form  Of Labview?

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Laboratory Virtual Instrument Engineering Workbench.

5.How we can normalize the EMG signals with respect to mean by using LabView?

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After collecting all the data in CSV files, you will need to follow the steps given below to normalize an EMG signal with respect to mean:

Read the data in terms of an array. Check out how to do it via the company’s official page. (Online training Institute)

Get the array’s size. Check out how to do it via the company’s official webpage. 

Sum all of the array’s elements. Check out how to do it via the company’s official webpage.

Dividing one by another will get you the mean of the desired signal. Now, simply subtract the mean value from all the elements of the array and you will get the normalized signal.

6.Can I Merge Labview Vis?

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Yes. LabVIEW 8.5 introduce the graphical merge, which automates the process of combining changes made to separate VIs. You can show this operation from within LabVIEW, or you can setup source code control applications to automatically run this routine when conflicting changes require merging.

7.Is LabView can recommended platform for a live streaming system?

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LabView is a great platform, if we talk about a live streaming system, it is not the best in market solution. You will not get convinient results if you use LabView for many live streaming systems like infrared eye-tracking systems etc.

8.In What Way I Perform Static Code Analysis on Lab-view Vis?

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To show Static Code Analysis on Lab-View, one can simply take the help of the NI Style Guide. Apart from this, Lab-View offered its VI (Virtual Instruments) Analyser. the Toolkit which can be used to automate the entire process. By using the Analyser Toolkit, you 

will easily detect all the improper coding techniques by used during the operation that can detract from an application’s maintainability and performance.

9.Is Lab-view a compiled programming language?

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Yes. Lab-view has a sophisticated compiler Which is always running as you develop your application. When the compiler finds a syntactical mistake the run arrow is broken to show that the application cannot run. the Continuous investment in the Lab-view compiler enabled optimised application performance and, among other things, determine to take full advantage of different-core technologies.

10.What assurance do I have to LabVIEW is a high-quality software product?

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LabView is a software built by the National Instruments, that is operating under ISO standards since 1995. Moreover, in 2005, Lloyd’s Register Quality Assurance Inc. approved the National Instruments as an ISO 9001:2000 i.e. latest standard for effective quality management practices.

11.How Do I Make benfit Of External Libraries In Labview?

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LabVIEW can communicate with any application or development environment which provides standard interfaces. in the same way LabVIEW applications provide standard interfaces for re-using VIs in another development environments.

12.How can I able to what modifications were made to a VI?

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LabVIEW enables developers to show side-by-side comparisons of code in order to compare modifications with other VIs. LabVIEW can also shows side-by-side comparisons with older versions stored in source code control.

13.Name the two panels used in lab-view programming?

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There are two types of panels.one is front panel and oter is the block diagram. Block diagram acts the panel where all the programming is carried out. Front panel acts the one visible as user programmable interface i.e. GUI interface.

14.Is there any simple code in LabView to reset all parameters at a default value for each time of execution while using Matlab scripts?

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This type of problem happens sometimes when your program is working fine with every single run but faces some assignment and resizing problems after changing the condition. To resolve it, you can simply put another Matlab script code at the end of the program gets sequence and set all the variables at zero. Apart from this, you can also try right-clicking on the variable, select the ‘Data Operations’ option, and then select ‘Make current value default’. This can make your program run without causing any issue.

15.Can Labview Be Integrated Into insert Software Engineering Practices?

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Yes. An increasing number of large, mission-critical LabVIEW applications have been increased in LabVIEW. with software increment standards set by regulatory agencies such as the DOD and FDA. The same practices which are applied to text based increment can be applied to graphical code with the proper understanding of tools and practices.

16.What is the figure as shown below?

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There will be different choices such as Paint Window, Icon Editor in Lab view, Property Window etc

17.What type of files can we use apart from .txt as input in LabView?

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You can use a lot of file types from ASCII files to binary files. You just want to make a proper reader or use the appropriate VI for this. Moreover, you can also use the XML files as the software also comes with an XML parser for it. Apart from this, you can easily check out the LabView online help document to get all of your answers.

18.How do I document graphical code in LabView?

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Code descriptions and comments can easily be attained along with the print out of codes by using the ‘VI Documentation’ option available in the LabView print menu. Apart from this, you can easily use the NI Requirements Gateway for more sophisticated documentation. This will provide trackable links to the specification documentation.

19.In What way Do I Track The History Of Revisions To My Labview Application??

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Integration with source code control gives automatic tracking of iterative development for LabVIEW VIs. Use the built-in VI History window to synchronized any version it will stored in source code control and view comments entered by a user at the time it was edited. You can also use the built-in comparison tool to see a side-by-side view of VIs in order to able to what changes have been made between versions.

20.What is LabView SignalExpress?

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LabView SignalExpress is usually the newest member of the National Instruments LabView family. It simply extends the acquisition, analysis, and presentation capabilities of LabView to the applications that does not require programming.

21.How to generate the two channels of digital output from one PWM signal in LabView, one for the heater and other for the cooler?

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You can simply use the relay’s NO & NC contacts for cooler and heater. However, there can be a case when one wants to be neither warming nor cooling, in such case, you will have to ready a code for it.

22.What is a State Machine in LabView?

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A state machine having the fundamental parts or architectures it frequently used by the LabView developers to build applications.

23.Is LabView read excel data continuously from Etap Software?

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You need to check out whether Etap is offering API for that particular role . If there is no such type of API, you can simply let the Etap dump data to any file. After that, easily make a code in LabView to read data from that specific file.

24.How can we make cyclic programs in LabView?

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To have a Cyclic program, you will need to use the For-Loop function. You can understand the working of For-Loop via to the official webpage of the company.

25.Can LabView bebenfit for program a PLC?

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No, you can’t be able to program a PLC by using LabView. However, you can read and write to your PLC code by helping a LabView application. Hence, a LabView application can be used to write a control loop setpoint to a PLC, and read back the system to response.

26.How to develop the N-Dimensional nested loop in LabView?

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You can easily develop the N-dimensional nested loop in LabVIEW with the help of a recursive vi. It simply pulls out the 0 indexes of array and loops over the min/max/delta of element 0.

27.How can we modulate (AM) to any sound or voice files on LabView?

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LabView is self-determination to reading asound files directly from your sound card to your computer as well as opening an audio file. Moreover, you can also try implementing an AM modulator by using single mathematical operations. For example, you can use the following equation for low pass signals:

XAM(t) = A(1+mx(t))Cos wct . where m is the modulation index, who have the carrier frequency, x(t) is the message and A is the carrier amplitude.

28.How will the mixed data types are combined and passed from one file or place to the other file in LabVIEW?

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 Mixed data kinds can be combined and passed from one place or file to another in LabView by creating a cluster of choice. Clusters usually group the data elements of mixed types, like a bundle of wires in a telephone cable. Each wire in the cable shows a specific element of a cluster.

29.What Is The variation Between Local Variable And Global Variable In Labview?

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Local Variables: Local variables can be seen in the structures palette of the Block Diagram (BD) and are used to make a connection with any control or indicator. If you place a local variable in a block diagram panel, you can see a question mark symbol at the top end of it. Now, you can simply connect it with any indicator/control by just right-clicking on it and choosing ‘Select Item’. from this, you can also create a local variable by right-clicking on the indicator either in BD or in Front Panel and selecting ‘Create Local Variable’.

Global Variable: Global variables can be used to pass and having data among several Virtual Instruments (VIs). The global variable apppears for seeing a question mark with a globe symbol after placing it on the Block Diagram. If you can shows a global variable in any of the LabVIEW Virtual Instruments, the LabVIEW engine will create ‘global variable vi’ at the same time in the following directory automatically. Moreover, you have to keep in mind that only the front panel exists of the global variable.

30.How will we make a waveform chart in LabView?

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To ready a waveform chart in LabView, you have to include both the arrays in a cluster and then simply use an XY Graph. Moreover, you can also choose to take a look at the 

official NI documentation which is related to the XY Graphs. if one of the axis is timestamps, you can take t=0, so you can save memory if you are using alarge amount of data. You need to check out the official documentation made by the National Instruments.

31.In What Way we add channel names to an LVM file?

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For add a channel name, you can easily use the ‘Set Dynamic Data Attributes’ Virtual Instrument.

32.In What Way We resolve file space issues in CDAQ Controller with LabView Test System?

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If the in-built storage of your system is completely filled up, there are commonly three ways to you can save your test data:

• Save to a USB flash drive
• Save to a network share
• Save to an SD card

33.How we programmatically build and deploy any web service?

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You can simply build and deploy web services either by using the project tree or by using a VI offered by LabView. LabView offers G APIs (Google APIs), that can be used to open a project and every member defined within the project. You are also have to open a project programmatically by using the invoke node. Moreover, you can also have the targets defined in a project using the property node.

34.In What way to get a column selected by default for a multi column list box in a LabView VI?

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You can easily wire a numeric constant to the multicolumn Listbox. Moreover, we recommend you to make sure that you are performing this task where you already know that it will be executed as soon as the VI is called.

35.Is this possible to interface Labview with JAVA GUI?

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Yes, you can interface Labview with JAVA GUI, you will have to follow the given steps to make it done. initially use TCP/IP to communicate between Java and Labview.

Then easily build DLL from your Labview code and call it using JNI.

After that, develop the web service using the LabVIEW and call it using Java.

36.What is a Formula Node in LabView?

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The node expressed as where you are allowed to write mathematical expressions and formulas just like C coding.

37.In biosignal applications (EMG), can it be good to use ‘Average Rectification Value (ARV)’ or ‘ABS’-function for full rectification by using LabView?

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It completely depends on what you desire to do with your rectified signal. The ABS function will only changes all of your negative values into positive. Whereas, the ARV will also add another treatment as taking the mean over a time window in order to 

smoothen your rectified signal. Generally, we need to do a bit of smoothening after the rectification of EMG. Hence, ARV can prove to be a good option in this case by choosing the right time window. you choose the EMG or ARV, and must always remember to eliminate the DC offset from your EMG by subtracting the mean of your raw signal.

38.In what way you deal with very low excitation current for Silicon diode while using LabView?

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For this, youhave to build a constant microampere current source yourself and then use the LabView devices to sense the voltage drop

39.Which kind of Virtual Instruments in LabView does not have a block diagram?

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There are commonly two types of Virtual Instruments available in the LabView that do not have a block diagram. They are:

• Global Variable VI
• Polymorphic VI

40.What is the “Code Width” of an input signal and how do calculate it in LabView?

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The device range and resolution of a measurement device shows the smallest detectable change, which can also be termed as the code width of the input signal. Smaller code width will result in precise measurements. You can simply measure the code width by using the below-given formula.

41.How will u get all of the windows services in LabView?

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You can get all the windows services in LabView by using the given code string into the System Exec.vi:

The string must be used without quotes. by this will get you all the windows services in your LabView.

42.Is create PWM signals in LabView for controlling the speed of an Induction Motor?

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Yes, you can use create and use DAQmx to program to a PWM signal if you are using a product from the RIO or DAQ platform (i.e. cRIO, cDAQ, myRIO, roboRIO).

43.How will remotely invoke a web service from G-based applications?

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You can simply invoke web services in LabView 2010 by using the LabView HTTP Client API. You cannot get this API compatible with LabView 8.6 and 2009. To access this particular API, you can easily select Functions Palette > Data Communication > Protocols > HTTP Client. Moreover, the SSL support (HTTPS) for an HTTP client wants the LabView Internet Toolkit 2010.

44.Can I form a 32-bit version executable from the LabView 64-bit application builder?

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No, currently there is no facility available to create a 32-bit version of an executable by using the LabView 64-bit application builder.

45.How can we convert a default recording device using LabView?

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To convert a default recording device using LabView, you can simply follow the below-given instructions:

• Tap on setting
• Select my device
• Choose difficult device
• Select and activate
• from this you can also select to visit Control Panel > Device Activity > Difficult Setting.

46.Does Labview Vis Work With Source Code Control Providers?

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yes, LabVIEW connect to source code control providers within the developing environment, and there was enabling developers to communicate with generic source code control functionality without leaving LabVIEW.

47.How can we change data from Python to LabView?

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You can use the Command Line Interface to send the desired data from an existing Python script into LabView code. LabView can be used to execute a python script via command line and receive feedback from that command-line interface.

48.What LabView platforms/versions support web services?

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The National Instruments introduced for web services in its Labview Real-Time Targets and LabView 8.6 for Windows platforms. The web services runtime engine in 2009 and 8.6 is loaded and run with the help of LabView form in web server. Moreover, the 

webserver is also available to used on Linux and Macintosh versions of the LabView, but without any availability of web support. Notably, web services increment requires a windows version of LabView 8.6, 2009, or 2010 coupled with a student, full, or professional edition license.

49.How can we add MySQL functionality in LabView?

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we can simply use the Database Connectivity Toolkit to add the MySQL functionality in LabView. while you are using the LabView 2017, then you must take a look at the LabSQL. It is a tool which allows the connection of a MySQL database without the NI’s LabView Database Connectivity Toolkit.

50.What are the features of Labview?

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LabView consists a lot of fascinating features that can make your developing experience even more enjoyable. Some of its fentastic features can be seen in the below-given points:

• It comes with support for RS485, RS232, GPIB, VXI, PXI, and plug-in DAQ devices.
• It gives easy interfacing with RF and additional hardware by using different drivers offered by NI.
• It is blessed with TCP/IP networking and ActiveX bull, which means you can simply create executable applications and shared libraries.
• Interfacing with C and .net programming languages

51.Does LabView decrease the speed of the microcontroller?

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Yes, your microcontroller will work a bit slowly if you are using the LabView platform in your system.

52.What Are The Building Blocks Of Labview Language?

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some of the building blocks of labview language :

Front Panel : The Front Panel allows you to interact with your LabVIEW VI.

Block Diagram : The Block Diagram is where you will develop the code of your program. In this way the User Interface (Front Panel) is separated from the source code (Block Diagram).

53.While Loops?

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Loops allow you to repeatedly execute a specific portion of code. The different Loops and Structures available are located in the Structures sub palette in the Functions palette on the Block Diagram. The most important loops are For Loops and While Loop.

54.Plotting?

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LabVIEW has powerful features for plotting your data. You can graphically visualize data in LabVIEW using two basic methods: a waveform chart and waveform graph. This module introduces a waveform graph and a waveform chart and explains when you should use them.

55.SubVIs?

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SubVIs are VIs within your VI. They increase readability and reusability. SubVIs are like functions or methods used in other programming languages.

56.Case Structures?

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Case structures are some of the features you probably use most in LabVIEW. It is similar to using “If .. Else ..” in text based programming languages. In LabVIEW we dont have If.. Else, so we need to use the Case Structure.

57.Arrays

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Typically, when dealing with data logging, etc, you need to deal with arrays. LabVIEW has lots of built in functions for manipulating data within arrays.

58.Clusters

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Clusters grouped data elements of mixed types, and handy to use when you want to structure your data into a manageable package. It’s similar to struct or record (or a “miniature” class) used in other programming languages.

59.Property Nodes

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Property Nodes, Invoke Nodes and References are powerful features in LabVIEW. Lets start with Property Nodes.

60.Project Explorer

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The Project Explorer lets you structure all your files that your LabVIEW Application consists of, similar to, e.g., Solution Explorer in Visual Studio. You also need to use the project Explorer if you need to create executable files, or create more advanced applications like Real-Time Applications, etc.

61.Debugging in LabVIEW

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Debugging is the process of locating and fixing or bugs (errors) in your computer program code, in this case your LabVIEW program. LabVIEW has powerful features for Debugging your Code, such as: Broken Run Arrow, Highlight Execution, Probes and Breakpoints.

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62.LabVIEW Programming

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Now you have learned the basics regarding LabVIEW Programming, such as Front Panels, Block Diagrams, While Loops, Plotting, SubVIS, etc. The video below summarize all these things.

63.LabVIEW Programming using State Machine

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Typically engineers often create simple LabVIEW VIs that eventually grow out of control, because they don’t have the proper structure and best practices. The solution to this problem is organizing your code and data in a way that enables modularity, readability, and reuse. Using a state machine approach is a good way to make it right from the early beginning.

The state machine is one of the fundamental architectures LabVIEW developers frequently use to build applications.

In LabVIEW software, you can create a basic state machine with a While loop, a Shift Register, a Case Structure, and some form of case selector.

64.LabVIEW Programming Guidelines

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Typically engineers often create simple LabVIEW VIs that eventually grow out of control, because they don’t have the proper structure and best practices. The solution to this problem is organizing your code and data in a way that enables modularity, readability, and reuse.

Some examples are:

• Intuitive GUI (Front Panels): Add Units, Use Controls and Indicators from the same Palette, Resizing the Window size, Don’t use “strong” Colors, etc.
• Structured Code (Block Diagram): Make and use SubVIs, Avoid Spaghetti Code, Resizing the Window size, Use Labels, Always use Project Explorer, use State Machine, etc.

65.Why do we need LabVIEW?

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The following factors will explain why we need LabVIEW,

1) Acquiring, saving and loading data

2) To find and use math and complex analysis functions

3) To work with data types like arrays and clusters

4) Easy to display and print the results

5) Instead of text, we can use icons to represent the programming applications.

6) User can easily work on LabVIEW architecture environment and data flow execution

7) Many complex graphical interface related problems can be solved easily.

66.What is the block diagram panel?

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Block diagram is a graphical code, in this data travel on wires from controls to function through indicators. This executes the code in the form of a flow diagram.

67.What is the Front Panel?

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The front panel is a user interface tool that consists of controls as Inputs and indicators as output.

68.Which company is the vendor of LabVIEW software?

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The mother company of LabVIEW software is National Instruments Inc.

69.How do I vs Time and Q vs Time works?

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 I vs Time: This is mainly used to configure the time delays in VI expressed in the form of seconds this happens once the iteration of the loop is done.

Q vs Time:

Configured special timed while loop for the desired date.