How to conditionally run cleanup steps

[hotovecj]

We need to run some cleanup steps only on test UUT end. We do not want these steps to be re-run on every test-uut loop. Therefore:
How is the test UUT state detected? or is it possible to detect this state versus the single pass execution?

[Shannon R]

Hotovecj,

The Process Model is the component of TestStand which handles the execution mode. The Process Model is the controlling sequence in your execution. It controls how your client sequence is executed, including what steps are executed before, after, and during your client sequence execution. One of the aspects of the process model are the different Execution Entry Points. Test UUTs and Single Pass are two examples of Execution Entry Points. These are sequences which are executed that have a certain set of steps that affect how the client sequence file is executed. For example, in the Test UUTs execution entry point, there are steps to show the dialog that prompts you for the serial number. In the Single Pass execution entry point, there is no need for this step since we will only be testing one unit, so this step doesn't exist in the single pass execution point.

If you look within any of the default Process Models, these 2 Execution Entry Points will appear in the sequence file. While the process models are controlling sequences, they are still regular TestStand sequence files, so you can open them and add steps and delete steps just as you would edit a client sequence file. So, to answer your question, if you wanted to run some cleanup steps after all the units have been tested, you could edit the Test UUTs execution entry point to have these additional steps execute. Depending on what process model you are using, the exact location where you would add your steps would be different. An high-level overview of the steps within the sequential process model is below:

1. Pre UUT Loop - Steps that need to execute before any unit begins testing.
2. Pre UUT - Steps that execute before every unit
3. MainSequence - Execute the client sequence
4. Post UUT - Steps that execute after every unit
5. TestReport - Generate report for that unit
6. Post UUT Loop - Perform any steps after all the units have been tested.

As you can probably guess, you would modify the PostUUT Loop if you wanted steps to execute only on Test UUT end.

Please be aware that any edits you make to the process model will affect all client sequences that use that particular process model. If you do not want your changes to affect every client sequence file, consider using another feature called callbacks. Callbacks allow you to define a set behavior within your process model and override callback sequences within your client sequence file. This allows you to use the same process model for client sequence files that have different requirements for execution flow. In fact, the Post UUT Loop sequence that executes in the process model is a callback, so if you'd like you could override that callback in your client sequence. Then add those cleanup steps to the callback in your client sequence. This would ensure that other sequences that use the same process model wouldn't also perform those cleanup steps, but the steps would not be executed until the process model reached that point in its execution.

There is a brief FAQ that addresses the process model and callbacks that might be of help to you. TestStand FAQ There is also a document that briefly describes callbacks: What is a Callback?

I'd also recommend taking a look at the TestStand User Manual because it describes all of these components. Another great resource would be the TestStand Course. You can find more information about our courses online at www.ni.com/training

Hope that helps. If you have any questions, just let us know.

Regards,
Shannon R
Applications Engineer
National Instruments