Issues ROSCO libdiscon.dll for 64-bit Windows

[adenijio-byte]

Hello everyone,

I am new to OpenFAST, TurbSim etc. I will be using the softwares to estimate AEP production from wind turbines for my thesis. Currently, I'm having a lot of trouble and dificulty to run OpenFAST with ServoDyn file and pitch control mode on number 5 which needs the DLL file. I am using Openfast Version 4.1.2 and I downloaded my .dll file from the latest release here: https://github.com/NREL/ROSCO/releases I am encountering this issue regarding the .dll file not being compatible for 64-bit Windows, where can I find this file or am I to change something else:

OpenFAST-v4.1.2
Compile Info:

• Compiler: Intel(R) Fortran Compiler 2021
• Architecture: 64 bit
• Precision: single
• OpenMP: No
• Date: Aug 06 2025
• Time: 19:22:48
  Execution Info:
• Date: 12/03/2025
• Time: 14:04:30-0000

OpenFAST input file heading:
IEA 15 MW offshore reference model monopile configuration

Running ElastoDyn.
Running InflowWind.

Reading a 31x31 grid (285 m wide, 7.5 m to 292.5 m above ground) with a characteristic wind
speed of 8.7012 m/s. This full-field file was generated by TurbSim (from OpenFAST-v4.1.2) on
03-Dec-2025 at 12:49:17.

Processed 19656 time steps of 20-Hz grid-field data (982.75 seconds).
Running SeaState.
Generating incident wave kinematics and current time history.
Running AeroDyn.
AeroDyn: projMod: 1
Projection: legacy (NoSweepPitchTwist), BEM: legacy (2D)
Running HydroDyn.
Running SubDyn.
Fixed bottom case detected
Guyan extra moment will be included in loads (fixed-bottom case detected)
Performing Craig-Bampton reduction 114 DOFs -> 0 modes + 6 DOFs
Using static improvement method for gravity and ext. loads
Calculating Full System Modes for output files
Exporting Summary file
Running ServoDyn.
Running ServoDyn Interface for Bladed Controllers (using Intel Visual Fortran for Windows).

FAST_InitializeAll:ED_Init:ED_ReadInput:ReadBladeInputs:ReadBladeFile:The ElastoDyn Blade file,
C:\aep_thesis\thesis_openfast\IEA-15-240-RWT-master\openfast_v4_1_2_latest\IEA-15-240-RWT-Monopile
_naomi../IEA-15-240-RWT/IEA-15-240-RWT_ElastoDyn_blade.dat, DISTRIBUTED BLADE PROPERTIES table
contains the PitchAxis column. This column is unused and will be removed in future releases
FAST_InitializeAll:SrvD_Init:BladedInterface_Init:The dynamic library
C:\aep_thesis\thesis_openfast\IEA-15-240-RWT-master\openfast_v4_1_2_latest\IEA-15-240-RWT_naomi\Se
rvoData\libdiscon_v210.3_32.dll could not be loaded. Check that the file exists in the specified
location and that it is compiled for 64-bit applications.

� OpenFAST encountered an error during module initialization.
Simulation error level: FATAL ERROR

Aborting OpenFAST.

I appreciate any guidance given, thank you!

[andrew-platt]

Dear @adenijio-byte,

I suspect you will need to recompile the ROSCO controller in 64 bit to use it.

Regards,

[dzalkind]

The pre-compiled binaries can also be downloaded here: https://anaconda.org/channels/conda-forge/packages/rosco/files