mechanism of SYS port on gladiator series (for making DIY devices)

[tallplay7777]

is there any info about how the SYS port work?
such as ,the function of each pin ,and the diagram of sending certain signal (axis and buttons).

would like to make some DIY devices such as custom made throttle.
would be great if i don`t have to mod the mainboard by just using SYS port.