Hello Assumptha,
It sounds like you are trying to pass strings from a dll to TestStand. With any dll, you do not want to pass out a reference to memory created inside the dll, which is what your dll would mostly do (I am assuming the VI you attached would be complied into a dll). Also, you might want to consider calling the VI directly from TestStand instead of compiling the LabVIEW code into a dll?
Also, if you want to pass strings to TestStand from LabVIEW, I would recommend using the TestStand API, namely
SetValString, to set TestStand's memory directly from your VI (or dll). I hope this helps!
Best Regards,
Software Engineer
Jett R