Looking for details on OSC over USB

Question

I'm starting to play with OSC over a USB port, and I have a couple of questions. 
 I have the lighthack USB test program working on Arduino, and the EOS software sees it fine. 
 As far as the PC is concerned, the Arduino is just another COM port. I didn't configure anything in EOS to tell it which port to use. How does it know what port to use? Does it try to open all COM ports? Does it look for a USB connected COM port? Does the communication have to use SLIP? What are the baud rate limitations? 
 If someone can point me to documentation that would be great.

Richard · Accepted Answer

The lighthack documentation is on the lighthack github: https://github.com/ETCLabs/lighthack 
 In short, Eos, Cobalt and ColorSource attempts to send the string "ETCOSC?" to each detected USB Serial adapter, and uses the first one that replies "OK". It is assumed that anything else will either ignore this as garbage data or will already be exclusively controlled by some other application. 
 OSC is message-based, while serial is a stream so SLIP required to unambiguously package the OSC messages into the serial stream. 
 Baud rate limitations (if any) are entirely down to which Arduino (or similar) you're using, you'll need to check the documentation of your specific device.