Hi,
I can think of a few reasons this error might appear:
-Perhaps the binary FF file is corrupted or is not really a binary file.
-Perhaps the binary file was generated on a Unix system and you are using it on a PC (or vice versa).
-Perhaps the FAST executable was compiled with different compilation flags than we use.
-Perhaps the FAST executable was compiled with the wrong Sys*.f90 file from the NWTC Subroutine Library, or your compiler needs a different Sys*.f90 file than is included in the NWTC Subroutine Library archive.
If you were able to open the wind file with a version of FAST you didn’t compile, that eliminates the first 2 options. The issue then comes down to how you compiled your code. Something is likely causing the binary file to be opened incorrectly so the code does not read the first number from the file correctly. A similar problem is discussed here: FAST compiled with G95- reading full-field wind (where the OPEN command in OpenBinInpFile() had to be changed for the GNU compiler).
If you get the error when you compile with SysIVF.f90 (and use the compile options in the FAST documentation), you may have to modify subroutine OpenBinInpFile(). I have not compiled with IVF 9.1, so I’m not sure what issues it may have.