CTA Deployment & Troubleshooting 3 — Questions and Answers
Question 1: After deploying an updated sequence file to a production test station, technicians report that the new limits are not being applied. The old sequence appears to still be running. What is the most likely cause?
- The station cache has the old sequence locked in memory and the process must be restarted
- The sequence file was deployed to the wrong directory and the station is loading from a cached path (Correct answer)
- The TestStand Runtime License does not support sequence updates
- The operator interface does not support hot-swapping sequence files
Correct answer: The sequence file was deployed to the wrong directory and the station is loading from a cached path
If the deployed file lands in a different directory than the one configured in the station's search path, the station continues loading the old version from its original location.
Question 2: A TestStand sequence uses a LabVIEW code module. On the deployment target, the code module runs but produces incorrect results. The same module works correctly on the development machine. What should you suspect first?
- The LabVIEW Run-Time Engine version on the target does not match the version used to build the code module (Correct answer)
- The TestStand sequence has a variable type mismatch
- The deployment package excluded the LabVIEW source VI
- The LabVIEW module is not digitally signed
Correct answer: The LabVIEW Run-Time Engine version on the target does not match the version used to build the code module
A mismatch between the LabVIEW RTE version on the target and the version used to build the .llb or .exe can cause incorrect behavior due to API or behavior differences.
Question 3: Which TestStand tool is used to analyze and compare two sequence files to identify differences between a deployed version and an updated version?
- Sequence Analyzer
- TestStand Diff & Merge Tool (Correct answer)
- Deployment Utility Comparison Mode
- Version Control Integration Plug-in
Correct answer: TestStand Diff & Merge Tool
The TestStand Diff & Merge Tool allows developers to visually compare two sequence files and identify structural and parameter differences.
Question 4: A test station running a deployed TestStand application periodically hangs during sequence execution with no error message. CPU usage is near 0%. What is the most likely root cause?
- A deadlock caused by two threads waiting on each other's locked resources (Correct answer)
- Excessive logging filling the disk
- A missing code module causing silent retry loops
- High network latency causing step timeouts
Correct answer: A deadlock caused by two threads waiting on each other's locked resources
A CPU-near-zero hang in a multi-threaded TestStand execution is a classic symptom of a deadlock, where two execution threads are each waiting for resources held by the other.
Question 5: When deploying a TestStand system that uses custom user interfaces built with LabVIEW, which additional component must be included in the installer?
- LabVIEW Development System
- LabVIEW Run-Time Engine matching the LabVIEW build version (Correct answer)
- NI-VISA Runtime
- TestStand Development License
Correct answer: LabVIEW Run-Time Engine matching the LabVIEW build version
LabVIEW-based user interfaces require the LabVIEW Run-Time Engine (matching the build version) to execute on machines without LabVIEW installed.
Question 6: A sequence step using an ActiveX/COM code module fails on the deployed station with 'Class not registered'. What corrective action is required?
- Recompile the sequence file on the target machine
- Register the COM/ActiveX server on the target machine using regsvr32 or include it in the installer with registration (Correct answer)
- Copy the DLL to the System32 folder manually
- Add the DLL path to the Windows PATH environment variable
Correct answer: Register the COM/ActiveX server on the target machine using regsvr32 or include it in the installer with registration
COM/ActiveX components must be registered in the Windows Registry on each target machine, either manually with regsvr32 or automatically through an installer that handles registration.
Question 7: Which TestStand Station Options setting directly affects how errors propagate when a step fails in a called subsequence?
- Error Handling > On Subsequence Error
- Execution > Propagate Errors from Subsequences (Correct answer)
- Debugging > Break on First Error
- Logging > Log Subsequence Errors
Correct answer: Execution > Propagate Errors from Subsequences
The 'Propagate Errors from Subsequences' setting determines whether an error in a called subsequence automatically causes the calling sequence to also enter an error state.
CTA Deployment & Troubleshooting 3
After deploying an updated sequence file to a production test station, technicians report that the new limits are not being applied.
The old sequence appears to still be running.
What is the most likely cause?