Why can't I open certain .dll files?

Question

On an old computer i Have a file called atmcd32d.dll that says type labview vi library. When I open it it shows me a library of vi functions that I need to run an instrument. I've downloaded updated drivers from the instrument website and the new file is still atmcd32d.dll but the type now says DLL File and doesn't open. WHen I double click nothing happens. when I transfer the old file from the old computer to the new one it opens just the same. 
Do I have to extract .dll files or what?
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Answer 1

TSCline -
dll's are dynamically linked libraries.  They are a binary format that can be executed only on Window's based machines (i.e. not on Macs).  It should not be possible to open a dll (if you opened it in notepad you should only see nonsense).  In order to use dll's, they first have to be compiled and linked for your OS.  Then, you have to know the hooks to get into the dll.  In Labview, you interact with dll's via the Call Library Function node and you have to know how the function is called that you can properly specify the input and output parameters (a header file will tell you what functions are available in the dll and how to interact with them).  I think you can find more about ATMCD32D.H here.
Hope this helps.  Cheers, Matt
Matt Richardson
Certified LabVIEW Developer
MSR Consulting, LLC