Hello.
These pictures are from schematics and build instructions. Black wire is ground, green is pin 2 and red pin 1. Hope this helps to figure out from where to read data. You might be able to figure data formatting from source code. I have no skill to do it right away but might figure it out eventually when staring at the code long enough. Hehehe.
See serial.c and cougar.c at
Index of /firmware/cougar-v1.11b
Main loop has something serial output related. At the end of the file cougar.c it is.