Thank you so much for the detailed explanation of my errors!. Changing the "F" to "D" for the float64 parameter eliminated the crash.

The clarifications provided by you and Tye on passing the NULL pointer was also very helpful. For some reason the function kept returning "Reserved Parameter must be NULL." until I re-installed Win32::API on my development machine.

I think I have the code working properly and I'm now packaging it for deployment to my test hardware! Thanks again perlmonks!