tTestData and tTestError are currently for use with the CVI adapter only. The function you call must adhere to the standard CVI test prototype. The CVI adapter does support calling DLLs.
You can't add parameters to the CVI standard prototype. Either pass all of your parameters using the flexible dll adapter, or use the CVI adapter with the standard prototype and access the extra data you need via the TestStand API.
The flexible DLL adapter does not currently support tTestData and tTestError because the defined function of these structures requires additional processing beyond just passing the data to and from the function. A future version of TestStand might support the additional processing for these types in the flexible dll adapter.
