LXNav S80 Vario Digital Input Wiring Question

I would like to wire the sensor switches that I already have in place for my landing gear and spoilers to my LXNav S80 vario. The S80 user's manual offers little information on how to accomplish this. Hopefully, others before me have got this working, and can offer some advice.

I understand that the IN0 and IN1 pins of the D15 connector are to be used. Are these pins TTL-level digital inputs with internal pull-up resistors, such that they should either be left open (i.e., floating) or grounded, depending upon the position of the sensor switch?

Or, are there no internal pull-up resistors, such that I am required to supply a positive DC voltage or ground, depending upon the position of the sensor switches? If so, what voltage is expected?

Also, are these digital inputs isolated in any way (i.e., optically-isolated), or do I need to use shielded cabling to avoid injecting noise into my radio?

Thanks in advance,

Jordan