Bladed DLL, Variables


I have not found in the documentation the list of records used in communication between FAST and the DLL. I assume the records not listed on the Table 4 of FAST User’s Guide (Differences Between FAST’s and Bladed’s Interface to Master Controller DLLs) are identical to Bladed. But I’m receiving some records as cero. For example, I’m unable to read a correct value on records 14 and 15, which are mechanical and electrical power on the shaft.


I have found that it is necessary to enable the outputs in ServoDyn file, but I don’t know exactly which records are each variable. Is it possible to enable more?

BlPitchC1: Blade 1 pitch angle command. Positive towards feather about the minus zc1- and minus zb1-axes. (Record 04)
BlPitchC2: Blade 2 pitch angle command. Positive towards feather about the minus zc2- and minus zb2-axes. (Record 33)
BlPitchC3: Blade 3 pitch angle command. Positive towards feather about the minus zc3- and minus zb3-axes. (Record 34)

GenTq: Electrical generator torque. Positive reflects power extracted and negative represents a motoring-up situation (power input)
GenPwr: Electrical generator power. Same sign as GenTq. (Record 14?)

HSSBrTq: High-speed shaft brake torque (i.e., the moment applied to the high-speed shaft by the brake). Always positive (indicating dissipation of power)

YawMomCom: YawMom. Nacelle yaw moment command About the zn- and zp-axes

We have not documented everything that gets passed between FAST/ServoDyn and the BladedDLL, but you can see which records are used by looking at the source code in routine Fill_avrSWAP() in BladedInterface.f90 of FAST v8. We do set values of records 14 and 15, so if they are not what you expect, there may be an issue with your FAST model instead.

Enabling outputs in ServoDyn has no effect on the coupling of modules–the outputs are calculated regardless of whether they are listed in the output file. It should have absolutely no effect on the values sent to the DLL.

Thank you very much, Bonnie. That was really helpful, I’ll keep working.