Like many people here, I wanted to make an arduino physical display then quickly realized unity does not have the required serial IO name space. So the solution is to borrow someone else's code (http://sourceforge.net/projects/serialportnet/), which turns out is kind of incomplete but works. This plugin sends/receives data packets over the serial port, which should make it much easier for people wanting to build hardware for KSP but can't be bothered with making plugins as well.
Note: curre
@zitronen
Did some testing on windows 10 because I was bored.
I purchased two Unos that use the WCH340 chip, they both work perfectly. Reading over the entire thread I saw a mention of using a proxy app to receive UDP from KSP and relay that out the serial port using System.IO.Ports. I gave that a shot, but again it fails with the Uno using the Atmel 8u2, but works great with the WCH340 chips.
The WCH340 chips keep on working as long as I keep the UDP listening, but the ATmel chip