Which part of the process model to avoid when changed

[InspectorGadget123123]

At our factory I need to change the process model, eg. how to extract the part number.

When I change the process model, must I avoid changing the call backs(eg. preUUTloop) in the process model or is it recommended to put the change in the call back?

[MBengths]

Hi,

There are two options, and what suits you best depends on the nature of your application.

Scenario 1:

If you plan to or are developing multiple different test sequences that will all share this common functionality. It is preferred to modify the process model itself.

See Modifying Process Model Sequence Files

Scenario 2:

If you plan to add this functionality only to a small subset of test sequences. You can override process model callbacks using model callbacks  

Using Callbacks in NI TestStand

I hope this answered your question.

Cheers!

//Marcus Bengths

[InspectorGadget123123]

The situation is like this:

All of our test at the factory will use the same proces model(seq,batch,par.).

At the start of a test, we override the callback 'PreUUTloop' to initialize the HAL measure instruments.

The problem now is that you cannot add or remove parameters in de 'PreUUTLoop' of the process model because it will not be compatible with the tests, which are previous made, which override the callback 'PreUUTLoop'. 

[MBengths · Accepted solution]

Hi again,

I think I understand your situation.

It is true what you say, that overriding a callback from the process model affects all test sequences using that said process model. Therefore, if you were to edit a callback from the process model you must also edit the corresponding model callbacks in all the test sequences already existing.

In your situation you can either edit the callback in the process model, which inevitably requires you to correct the corresponding model callbacks in your affected test sequences; or you can edit the model callbacks in your test sequences directly. The work load is similar. However, the best option depends whether or not this new feature of the callback will be the new default. If you plan to have this as a new default behavior for future test sequences, you should make the edit in the process model. But if this behavior is test sequence specific I suggest you edit the model callbacks for the relevant test sequences only.

Generally, if one would like to edit/customize the process model itself, this is best done before one even starts developing any test sequences. Otherwise one could eventually end up in a situation similar to yours, where if one decides to change the process model in the middle of the development process, all the existing test sequences have to be edited manually.

Note, if you ever plan to make a custom process model, add and work with a copy of the pre-existing ones (sequential, batch, parallel) instead of overwriting them. This is to avoid the risk of needing to reinstall TestStand in case something goes wrong.

Best regards,

// Marcus Bengths

[InspectorGadget123123]

Hi,

That's what I was concerned about, thank you for your time.

Bart