Here is a video showing an earlier application that I had made called, "Attitude Inidcator", with the UDP code added to it. In this video, I have an Arduino that is reading sensor data from a Razor 6DOF board (3-axis accelerometer & 3-axis gyro). The Arduino has code to "fuse" this data into 3 angles: pitch, roll and yaw. Those three angles are sent through the serial port to the C# program. This data is then sent to X-Plane.
At the beginning of the video, you can see the control surfaces on the aircraft move relative to my movements. Works perfectly!