What is the Fanatec SDK or what can you do with it?

The fanatec SDK is a package (VS based library) which lets programmers and developers use the extended features of our Fanatec Wheel and Pedal products. With use of the SDK code your game/software can

...make use of the additional wheel vibration/rumble motors (not the FFB motors)
...make use of the tuning display (for gear display, speeder, ...)
...make use of the vibration motors on ClubSport Pedals
...make use of the rev leds on ClubSport Wheel rims
...detect different Fanatec products if they have the same USB product ID (CSR or CSR Elite, etc.)
...detect the rim type connected to the ClubSport Wheel Base
...etc.

Is the Fanatec SDK available for anybody?

No, not in general. If you want to use the Fanatec SDK please contact our support team and mention what your plans are to use the SDK. After reviewing those plans you might receive a NDA which has to be signed before the SDK would be sent to you.

What is not a function of the Fanatec SDK?

The SDK is not necessary to get any output (pedal axis, steering wheel axis/rotation, button inputs) from our hardware. This is controlled by DirectInput only as our devices are HID standard devices.
The SDK is not necessary to send force feedback effects to the wheel. For that you will only need to install the driver and to send standard direct input commands for FFB.

So in gerneral all input/output and FFB features of our products do not need the SDK. It is only need for special Fanatec functions as mentioned on top of this article.

In general we are not able to provide developer support how to read and control force feedback devices (which works 100% the same way for Fanatec hardware as for Logitech, Thrustmaster etc.). Please use Microsofts documentation. Here are some useful links to get you into the topic:
DirectInput - Enumerating devices - https://msdn.microsoft.com/en-us/library/windows/desktop/bb153253(v=vs.85).aspx
DirectInput - Capturing from Devices - https://msdn.microsoft.com/en-us/library/windows/desktop/bb153252(v=vs.85).aspx
DirectInput - Using Force Feedback - https://msdn.microsoft.com/en-us/library/windows/desktop/bb153254(v=vs.85).aspx