Updated the TestStand sequence of NI DCPower measurement to make it simpler

[Tharun-Sundar]

• This contribution adheres to CONTRIBUTING.md.

What does this Pull Request accomplish?

• Updates the TestStand sequence in the DC-Power example measurement to make it simpler by moving the process setup and process cleanup steps to the main sequence.
• Combines the logic for registering pin map into a single step in the Setup section. Previously this was handled in three steps.

Why should this Pull Request be merged?

Based on the feedback discussed in this Teams post, moving the process setup and process cleanup steps to the main sequence will simplify the example sequence as the user will only need to run the main sequence to get the expected result. Though this sequence is not efficient for multi-site use case, this change is encouraged as the example sequence is expected to be tailored to users who are beginners in TestStand.

What testing has been done?

Manually executed the TestStand example sequence with a simulated DC-Power instrument and verified the result.

[Tharun-Sundar]

@bkeryan When executing the TestStand sequence, the pin map file is not found even if it is available in the sequence directory. I updated the code as shown below to make sure that the logic is similar to the LabVIEW example sequence.

sequence_file = self._sequence_context.SequenceFile
(_, file_path, _, _, _) = self._sequence_context.Engine.FindFileEx(file_name, searchContext=sequence_file)
return file_path

But it is not having any impact in the search. Please share your thoughts on this.

[bkeryan]

@bkeryan When executing the TestStand sequence, the pin map file is not found even if it is available in the sequence directory. I updated the code as shown below to make sure that the logic is similar to the LabVIEW example sequence.

sequence_file = self._sequence_context.SequenceFile
(_, file_path, _, _, _) = self._sequence_context.Engine.FindFileEx(file_name, searchContext=sequence_file)
return file_path

But it is not having any impact in the search. Please share your thoughts on this.

@Tharun-Sundar @vigkre

The first time you call FindFileEx, the win32com module dynamically generates this code:

"def FindFileEx(self, fileToFind=pythoncom.Missing, absolutePath=pythoncom.Missing, srchDirType=pythoncom.Missing, searchDirectoryIndex=pythoncom.Missing\n\t\t\t, userCancelled=pythoncom.Missing, promptOption=1, srchListOption=1, isCommand=False, searchContext=pythoncom.Missing\n\t\t\t, reserved=pythoncom.Missing):\n\treturn self._ApplyTypes_(1050, 1, (11, 0), ((8, 1), (16392, 2), (16387, 2), (16387, 2), (16395, 2), (3, 49), (3, 49), (11, 49), (12, 17), (12, 17)), 'FindFileEx', None,fileToFind\n\t\t\t, absolutePath, srchDirType, searchDirectoryIndex, userCancelled, promptOption\n\t\t\t, srchListOption, isCommand, searchContext, reserved)\n"

When you call FindFileEx(file_name, searchContext=sequence_file), this leaves absolutePath, srchDirType, etc. unspecified, so they default to pythoncom.Missing.

The problem is that PyIDispatch stops passing parameters when it encounters pythoncom.Missing: https://github.com/mhammond/pywin32/blob/main/com/win32com/src/PyIDispatch.cpp#L369

Passing None for the output parameters seems to work. I initially tried it with positional arguments:

        (_, file_path, _, _, _) = self._sequence_context.Engine.FindFileEx(
            file_name, # fileToFind
            None, # absolutePath
            None, # srchDirType
            None, # searchDirectoryIndex
            None, # userCancelled
            1, # promptOption=FindFile_PromptHonorUserPreference
            1, # srchListOption=FindFile_SrchAskUser
            False, # isCommand
            self._sequence_context.SequenceFile, # searchContext
        )
        return file_path

Using keyword arguments allows us to leave promptOption, srchListOption, and isCommand unspecified. Their default values are defined in TestStand's IDL, so leaving them unspecified does the right thing.

Let's do this:

        (_, file_path, _, _, _) = self._sequence_context.Engine.FindFileEx(
            fileToFind=file_name,
            absolutePath=None,
            srchDirType=None,
            searchDirectoryIndex=None,
            userCancelled=None,
            searchContext=self._sequence_context.SequenceFile,
        )
        return file_path