CTA Sequence Development & Customization 3 — Questions and Answers
Question 1: A CTA is designing a sequence that must support both interactive operator runs and automated batch runs. Which TestStand mechanism best handles UI-dependent steps conditionally?
- Use separate sequence files for each mode
- Use the Execution.Interactive property to conditionally show UI prompts (Correct answer)
- Disable all UI steps in the batch profile
- Use a station callback to swap process models
Correct answer: Use the Execution.Interactive property to conditionally show UI prompts
Checking RunState.Execution.Interactive at runtime allows sequences to conditionally display UI elements only during interactive runs.
Question 2: When should a TestStand developer use the 'Goto' step instead of a loop construct?
- When looping over an array of test parameters
- When implementing a state machine with non-linear flow (Correct answer)
- When executing a subsequence multiple times
- When retrying a failed step a fixed number of times
Correct answer: When implementing a state machine with non-linear flow
Goto steps are appropriate for implementing state machines or exceptional flow transfers that loop constructs cannot elegantly express.
Question 3: What is the effect of enabling 'Ignore Run-time Errors' on a TestStand step?
- The step's result is always set to Passed
- Errors from the code module do not propagate and the sequence continues (Correct answer)
- The step retries automatically on error
- Error details are hidden from the test report
Correct answer: Errors from the code module do not propagate and the sequence continues
With 'Ignore Run-time Errors' enabled, the step catches any error thrown by its code module and continues sequence execution without propagating the error.
Question 4: In TestStand sequence development, what is a 'Callback' step type primarily used for?
- Invoking an external DLL function asynchronously
- Calling a user-defined sequence that overrides default process model behavior (Correct answer)
- Registering an event listener for hardware triggers
- Scheduling a step to run at a specific time
Correct answer: Calling a user-defined sequence that overrides default process model behavior
Callback steps invoke named sequences that override specific process model hooks, allowing site or project-level customization of standard behavior.
Question 5: Which TestStand data type should be used when a sequence needs to store a collection of UUT serial numbers of unknown size at design time?
- String array with a fixed size of 1000
- Container with named string fields
- Array of String with dynamic resizing (Correct answer)
- A LabVIEW cluster reference
Correct answer: Array of String with dynamic resizing
TestStand arrays support dynamic resizing at runtime using the Resize Array expression, making them ideal for collections of unknown size.
Question 6: A sequence uses a 'For Loop' step to iterate 100 times, but a mid-loop condition requires an early exit. Which step type achieves this cleanly?
- Goto step jumping past the loop's End step
- Break step inside the loop body (Correct answer)
- Setting the loop counter to 100 manually
- Using an IIF expression on the loop step
Correct answer: Break step inside the loop body
The Break step exits the innermost active loop immediately, providing a clean structured early-exit mechanism.
Question 7: What is the recommended way to share configuration data (such as hardware addresses) across multiple sequence files in the same test system?
- Hardcode values in each sequence file
- Store them in StationGlobals and load at system startup (Correct answer)
- Pass them as parameters on every subsequence call
- Write them to a text file and read per sequence
Correct answer: Store them in StationGlobals and load at system startup
StationGlobals persist for the entire station session and are the standard location for system-wide configuration data accessible by all sequences.
CTA Sequence Development & Customization 3
A CTA is designing a sequence that must support both interactive operator runs and automated batch runs.
Which TestStand mechanism best handles UI-dependent steps conditionally?