LabVIEW Questions and Answers for Viva

Answer-1: LabVIEW (Laboratory Virtual Instrument Engineering Workbench) is a graphical programming environment used for data acquisition, instrument control, and automation.

Answer-2: A VI is a LabVIEW program consisting of a front panel (user interface) and a block diagram (code logic).

Answer-3: A VI has a Front Panel, Block Diagram, and Connector Pane.

Answer-4: Open LabVIEW, click on "New VI," and start designing the Front Panel and Block Diagram.

Answer-5: The Front Panel acts as the user interface where controls (inputs) and indicators (outputs) are placed.

Answer-6: The Block Diagram contains the graphical code that determines the VI's functionality.

Answer-7: Controls are user inputs like numeric controls, sliders, and buttons.

Answer-8: Indicators are outputs like graphs, LEDs, and numeric displays.

Answer-9: A While Loop repeatedly executes code until a stop condition is met.

Answer-10: A For Loop executes code a specified number of times.

Answer-11: Drag a While Loop or For Loop structure from the Functions Palette to the Block Diagram.

Answer-12: A Shift Register retains values between loop iterations and passes them to the next iteration.

Answer-13: A Case Structure executes different code depending on the value of a selector input.

Answer-14: A While Loop runs until a condition is met; a For Loop runs for a fixed number of iterations.

Answer-15: Common data types include Numeric, Boolean, String, Array, and Cluster.

Answer-16: Place an Array container from the Controls Palette and insert a data type like Numeric.

Answer-17: A Cluster groups different data types into a single container, similar to a record or struct in other languages.

Answer-18: Use NI-DAQmx, VISA, or instrument drivers to interface with hardware.

Answer-19: A SubVI is a reusable VI that can be used as a function in other VIs.

Answer-20: Select code on the Block Diagram, right-click, and choose "Create SubVI."

Answer-21: The Connector Pane defines the input and output terminals for a VI when used as a SubVI.

Answer-22: A Property Node allows you to programmatically control or read properties of Front Panel objects.

Answer-23: A Local Variable allows you to read or write data to Front Panel controls or indicators.

Answer-24: A Global Variable is used to share data between multiple VIs.

Answer-25: Use DAQmx VIs to interface with National Instruments hardware or other acquisition tools.

Answer-26: Use File I/O functions like "Write to Spreadsheet File.vi" or "Write to Text File.vi".

Answer-27: Use File I/O functions like "Read from Spreadsheet File.vi" or "Read from Text File.vi".

Answer-28: An Event Structure handles user interface events, like button presses or value changes.

Answer-29: Use tools like Breakpoints, Probes, Highlight Execution, and the Error List.

Answer-30: Build Array creates arrays dynamically; Initialize Array creates arrays of fixed size with default values.

Answer-31: Data Flow programming executes code based on the availability of data at inputs rather than sequential order.

Answer-32: Use the Error Cluster and error-handling functions like "Simple Error Handler.vi."

Answer-33: Use graph indicators like Waveform Graph or XY Graph on the Front Panel.

Answer-34: A Formula Node allows you to write mathematical expressions using text-based syntax.

Answer-35: A Feedback Node retains the value of a signal from one iteration of a loop to the next.

Answer-36: Use TCP/IP, UDP, ActiveX, or shared variables for inter-application communication.

Answer-37: A Timed Loop allows you to execute code at precise time intervals, often used in real-time systems.

Answer-38: VI Server is an API that allows programmatic control of LabVIEW VIs and applications.

Answer-39: It ensures sequential execution of code, one frame at a time.

Answer-40: A Chart shows data in real-time with history, while a Graph plots all data at once.

Answer-41: Use a Boolean control connected to the loop?s stop terminal.

Answer-42: LabVIEW Real-Time is used for developing deterministic, time-critical applications on RT targets.

Answer-43: Use the Project Explorer to deploy VIs to targets like NI cRIO, PXI, or RT systems.

Answer-44: LabVIEW FPGA allows graphical programming of FPGA hardware for high-speed, deterministic applications.

Answer-45: A State Machine is a design pattern that transitions between states based on inputs or conditions.

Answer-46: Use a While Loop with a Case Structure, controlled by a shift register or enumerated type.

Answer-47: Shared Variables allow data sharing between VIs or across a network.

Answer-48: A Queue is a FIFO data structure used for inter-thread communication.

Answer-49: A Notifier is used for one-to-many communication, where a single message is broadcast to multiple listeners.

Answer-50: Use the "New Project" option in LabVIEW to create and organize VIs, libraries, and hardware targets.