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