I am still not sure what you want to kno, I am sure you are clear, but I am inexperienced. But following could be an answer to your question.
Yes, the dll was provided by Vernier Hardware and they have a detailed documentation of each function in the dll.
Like I mentioned in my very first post. I first used 'extern "C" __declspec(dllimport)' to get the functions. Then I used them in my program normally. But that was without including the header files.
The header already had declarations of the functions. So, after using the headers if i used dllimport, then it gave some error of re-declaration/ function overloading. So I removed the dllimport. I just used the functions normally. like function(arg1,arg2);
I hope this answers your question.