LabVIEW Interview Questions and Answers

This document presents a set of LabVIEW interview questions and answers, designed to help candidates prepare for LabVIEW programmer job interviews. These questions are also suitable for college viva examinations. Expect objective tests with multiple-choice questions in most interviews.

Question 1: What are the two panels used in LabVIEW programming?

Answer: There are two primary panels: the front panel and the block diagram.

• Block diagram: This is the panel where all the programming logic is implemented.
• Front panel: This panel serves as the user programmable interface, essentially the GUI.

Question 2: What is a shift register? How is it implemented in LabVIEW?

Answer: A shift register is a mechanism to pass data from one iteration of a loop to the next. It “shifts” the data. In LabVIEW, it is implemented by right-clicking on a ‘For Loop’ or ‘While Loop’ structure in the block diagram panel.

Question 3: What is the difference between a local variable and a global variable in LabVIEW?

Answer:

• Local Variable: Exists only within the VI (Virtual Instrument) where it is defined. Changes to a local variable only affect that specific VI.

• Global Variable: Can be accessed and modified from any VI. Changes to a global variable are reflected everywhere it’s used. Global variables can make debugging more complex and should be used with caution.

Question 4: How are mixed data types combined and passed from one file or place to another in LabVIEW?

Answer: This is achieved by creating a cluster. A cluster is essentially a grouping of different data types into a single data structure. This allows you to treat multiple related data points as a single unit.

Question 5: What is the figure as shown below?

Answer: The figure depicts the Icon Editor in LabVIEW.

Question 6: How are I vs time, Q vs time, transmit power, and power spectrum plotted using LabVIEW, given an IQ data file with two columns as input?

Answer: Check Source-code section or else search in the box to find URL.

(Note: Without specifics, a general answer would involve reading the data file, separating the I and Q components, calculating transmit power (e.g., $P = I^2 + Q^2$), performing an FFT to obtain the power spectrum, and then using LabVIEW’s built-in plotting functions to display the results.)

Question 7: Write a simple LabVIEW program for a binary number generator.

Answer: Check Source-code section or else search in the box to find URL.

(Note: A simple program would likely involve using a random number generator (0 or 1) within a loop, converting these numbers to strings, and concatenating them to form a binary number string.)

Question 8: Write a simple LabVIEW program for a 2-to-4 decoder.

Answer: Check Source-code section or else search in the box to find URL.

(Note: This would likely involve using a Case Structure with two input terminals (representing the 2 input bits). Each case (00, 01, 10, 11) would activate a corresponding output.)

Question 9: Write LabVIEW programs for different types of flip-flops such as SR, JK, T, and D flip-flops.

Answer: Check Source-code section or else search in the box to find URL.

(Note: Each flip-flop could be implemented using a combination of logic gates (AND, OR, NOT, NAND, NOR, XOR) built within LabVIEW. Shift registers could also be used to maintain state.)

Question 10: Write a simple LabVIEW code for a decimal-to-binary converter.

Answer: Check Source-code section or else search in the box to find URL.

(Note: LabVIEW likely has built-in functions for this. If not, you could use a loop with repeated division by 2, storing the remainders (0 or 1) as the binary digits.)

This set of LabVIEW interview questions and answers is useful for both freshers and experienced job seekers. Remember to tailor your answers to your own experience and the specific requirements of the job. Good luck!