Dear Dana,
The input parameters in the ServoDyn input file relating to the optimal mode and the turque-speed look-up table are inputs that mimic equivalent inputs in GH Bladed, so that FAST can be set up to mimic corresponding GH Bladed simulations. These inputs are not used by FAST, but are simply passed to the GH Bladed-style DLL for use by the DLL. However, you must be using a DLL that makes use of these inputs if you want to use them. I’m not sure what controller you are using, but the baseline controller for the NREL 5-MW turbine that NREL has provided does not make use of these inputs.
The GH Bladed User’s Manual is your best source for documentation of the interface requirements for GH Bladed DLL controllers.
Best regards,