Top 35+ LabVIEW Interview Questions [ ANSWERED ]

Last updated on 04th Jul 2020, Blog, Interview Questions

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) Is Labview A Compiled Programming Language?

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Yes.  LabVIEW has a sophisticated compiler that is always running as you develop your application.  When the compiler finds a syntactical error the run arrow is broken to indicate that the application cannot run.  Continuous investment in the LabVIEW compiler has enabled optimized application performance and, amongst other things, the ability to take full advantage of multicore technologies.

2) How Do I Make Use Of External Libraries In Labview?

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LabVIEW can communicate with any application or development environment that provides standard interfaces. Similarly, LabVIEW applications provide standard interfaces for re-using VIs in other development environments.

3) Can Labview Be Integrated Into Existing Software Engineering Practices?

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

4) Do Labview Vis Work With Source Code Control Providers?

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Yes.  LabVIEW allows you to connect to source code control providers from within the development environment, thereby enabling developers to communicate with generic source code control functionality without leaving LabVIEW.

5) How Do I Track The History Of Revisions To My Labview Application?

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Integration with source code control provides automatic tracking of iterative development for LabVIEW VIs. Use the built-in VI History window to synchronize to any version 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 determine what changes have been made between versions.

6) Can I Merge Labview Vis?

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

7) How Can I Determine What Modifications Were Made To A Vi?

Ans:

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

8) How Do I Validate A Labview Application?

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Certification of a LabVIEW application requires demonstration of the same development practices as with any programming language in order to ensure that any risk associated with the application has been adequately mitigated.

9) What Assurance Do I Have That Lab-view Is A High-quality Software Product?

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National Instruments has operated under ISO standards since 1995.  In 2004, Lloyd’s Register Quality Assurance, Inc. approved National Instruments for certification to ISO 9001:2000, the latest standard for effective quality management practices.

10) How Do I Perform Static Code Analysis On Lab-view Vis?

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Static code analysis can be performed in Lab-VIEW in accordance with the NI Style Guide. The Lab-VIEW VI Analyser Toolkit is also available to automate the process in order to detect improper coding techniques that may detract from an application’s performance and maintainability.

11) How Do I Document Graphical Code?

Ans:

Code comments and descriptions can be provided with print-outs of code by selecting the ‘VI Documentation’ option in the Lab-view print menu.  For more sophisticated documentation, use NI Requirements Gateway to provide traceable links to specification documentation.

12) How Do I Validate A Lab-view Application?

Ans:

Certification of a Lab-view application requires demonstration of the same development practices as with any programming language in order to ensure that any risk associated with the application has been adequately mitigated.

13) What Are Two Panels Used In Labview Programming?

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

14) What Is The Difference Between Local Variable And Global Variable In Labview?

Ans:

Local Variables: The Local Variable item is located on the Structures palette on the Block Diagram(BD).
When you place a Local variable in BD panel, it will look like a question mark symbol. After this just right click on the local variable & choose ‘Select Item’ & select which Indicator/Control you would like to connect it to. The other way to create the local variable is to right-click on a Indicator/Control either in Front Panel or in BD and select ‘Create  Local Variable’.
Global Variables: Use global variables to access and pass data among several VIs. When you place a global variable on the Block Diagram, it looks like a question mark with globe symbol.
Once you create global variable in any labview VI, labview engine automatically creates ‘global variable vi’ in the following directory. Pls. note that only front panel of the global variable exists.

15) What Is Labview?

Ans:

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

16) Can Lab-view Be Integrated Into Existing Software Engineering Practices?

Ans:

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

17) How Do I Track The History Of Revisions To My Lab-view Application?

Ans:

Integration with source code control provides automatic tracking of iterative development for Lab-VIEW VIs. Use the built-in VI History window to synchronise to any version 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 determine what changes have been made between versions.

18) How I Vs Time, Q Vs Time, Transmit Power And Power Spectrum Is Plotted Using Lab-view.

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IQ data file with two columns have been provided as input data file.

19) What Is Abbreviation Of Labview?

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Laboratory Virtual Instrument Engineering Workbench.

20) What Are The Features Of Labview?

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• Support for RS232,RS485,GPIB,VXI,PXI,plug in DAQ devices.
• TCP/IP networking ,ActiveX bull;  One can create executable application,shared libraries for example DLLs .
• Easily interface with RF and other hardware using drivers provided by NI.
• Interfacing with .net and C languages.
• Easy to use GUI based drag and drop programming.

21) 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).

22) What Are The Advantages Of Labview?

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The following are the advantages of LabVIEW:

• Graphical user interface.
• Drag-and-drop built-in functions.
• Modular design and hierarchical design.
• Multiple high level development tools.
• Professional Development Tools.
• Multi platforms.
• Reduces cost and preserves investment.
• Flexibility and scalability.
• Connectivity and instrument control.
• Distributed development.
• Visualization capabilities.
• Rapid development with express technology.
• Compiled language for fast execution.

23) 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.

24) 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.

25) 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.

26) 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.

27) 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.

28) 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.

29) Property Nodes

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

30) 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.

31) 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.

32) 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.

33) 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.

34) 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.