CLAD Debugging & Troubleshooting Techniques 5

Question 1

What does the 'Clean Up Diagram' feature in LabVIEW do, and why should it be used cautiously during debugging?

Accepted Answer

It auto-reroutes wires and repositions nodes, which can obscure the original logical layout you were tracing

Answer

Clean Up Diagram rearranges nodes and wires algorithmically, which can destroy a carefully arranged layout that was helping you trace data flow during debugging.

Question 2

In LabVIEW, which VI property can you check to determine if a subVI is currently loaded in memory and could be causing stale data issues?

Accepted Answer

VI Properties > General > In Memory

Answer

The 'In Memory' status in VI Properties > General shows whether a VI is currently loaded, which helps identify if an old compiled version is cached and causing unexpected behavior.

Question 3

You notice a LabVIEW timing loop drifts over time. Which debugging tool would best reveal if the loop body is taking longer than the intended period?

Accepted Answer

Profile Performance and Memory tool

Answer

The Profile Performance and Memory tool measures actual execution time per node and loop iteration, directly showing if the loop body exceeds its timing budget.

Question 4

What is a 'stale subVI' problem in LabVIEW, and what is the correct fix?

Accepted Answer

A subVI on disk that has been edited but whose calling VIs are still using the old compiled image; fix by saving all and reloading

Answer

A stale subVI occurs when the source VI file is modified on disk but callers still have the old compiled version loaded; saving all VIs and doing a Mass Compile resolves this.

Question 5

Which LabVIEW error code range typically indicates hardware or driver-level errors such as DAQmx communication failures?

Accepted Answer

Error codes -200000 to -299999

Answer

DAQmx and NI hardware driver errors typically fall in the -200000 to -299999 range, which you can look up in NI's error code database or the Explain Error dialog.

CLAD Practice Test

CLAD Practice Test

CLAD Debugging & Troubleshooting Techniques 5