My Problem is to find the USB port name in android, in PC you can see the name of the USB port (COM5 for example) but in Android i don’t know how i can see these.
When I call these:
SerialPort serial = new SerialPort(“COM5”,9600);
the game works on PC but not in android because I dont know what is the name port.
I try everything
COM0, COM1, COM2
tty/USB
“/dev/bus/usb/001/005”
I need to find this. 
Has anyone a solution for this problem? Got exactly the same. With a Serial Monitor App, i can communicate with the serial device but not within unity…
I need to solve this same problem! Anyone?
I have the same problem… I made the game in Unity and I want to connect an Android Device with Arduino to play the game via USB connection!!!
Download a terminal app from Google Play then type the following command into it:
ls /dev
Repeat with the device plugged in, and look for a file that appears in your ‘/dev’ folder when you connect the device. That’s your device name: ‘/dev/’
BTW, There may be a problem with unity in this respect, as the dll’s necessary for SerialPort don’t get loaded with the android version for some reason. Trying to figure this out.