CLAD Software Development Best Practices 2 — Questions and Answers
Question 1: In LabVIEW, which practice best supports code reusability across multiple projects?
- Copying VIs directly into each project folder
- Building subVIs with well-defined connectors and saving them to a shared library (Correct answer)
- Using global variables to share data between projects
- Hard-coding all parameters inside each VI
Correct answer: Building subVIs with well-defined connectors and saving them to a shared library
Creating subVIs with clearly defined connectors and storing them in a shared library allows multiple projects to reuse the same tested code.
Question 2: What is the recommended LabVIEW practice when a subVI needs to report errors to its caller?
- Display a dialog box inside the subVI
- Use a local variable to store the error code
- Wire error cluster outputs back to the calling VI (Correct answer)
- Ignore errors and log them to a file internally
Correct answer: Wire error cluster outputs back to the calling VI
Wiring error clusters from subVI outputs to the calling VI propagates errors correctly through the hierarchy.
Question 3: Which LabVIEW feature helps enforce consistent coding standards across a team?
- VI Analyzer Toolkit (Correct answer)
- NI-DAQmx
- Measurement & Automation Explorer
- LabVIEW Real-Time Module
Correct answer: VI Analyzer Toolkit
The VI Analyzer Toolkit automatically checks VIs against configurable coding standards and best practices.
Question 4: When designing a state machine in LabVIEW, where should the state transition logic primarily reside?
- Inside a flat sequence structure
- In a dedicated case structure that maps current state to next state (Correct answer)
- In global variables updated by each case
- In a separate loop running in parallel
Correct answer: In a dedicated case structure that maps current state to next state
A case structure that determines the next state based on current state and inputs keeps transition logic centralized and readable.
Question 5: What is a key benefit of using LabVIEW's built-in error handling rather than custom error dialogs inside subVIs?
- It prevents the program from compiling with errors
- It allows the calling VI to decide how to handle the error (Correct answer)
- It automatically fixes the error condition
- It eliminates the need for error clusters entirely
Correct answer: It allows the calling VI to decide how to handle the error
Passing errors up via clusters lets the highest-level VI or the user decide the appropriate response rather than forcing a fixed reaction inside a subVI.
Question 6: In LabVIEW, what does 'defensive programming' typically involve?
- Writing code that only runs in debug mode
- Adding checks for unexpected input values and handling edge cases gracefully (Correct answer)
- Using password-protected VIs to prevent editing
- Avoiding the use of subVIs to reduce complexity
Correct answer: Adding checks for unexpected input values and handling edge cases gracefully
Defensive programming means anticipating invalid inputs and boundary conditions and handling them without crashing.
Question 7: Which strategy improves LabVIEW application maintainability when updating hardware interfaces?
- Embed all hardware calls directly in the main VI
- Abstract hardware access into dedicated driver subVIs (Correct answer)
- Use global variables to store hardware references
- Avoid using instrument drivers and communicate via raw VISA
Correct answer: Abstract hardware access into dedicated driver subVIs
Isolating hardware calls in driver subVIs means only those VIs need updating when hardware changes, leaving the rest of the application untouched.
CLAD Software Development Best Practices 2
In LabVIEW, which practice best supports code reusability across multiple projects?