/dev/cuaU?
ucom4
Usb tty support
Usage
device ucom
Overview
The ucom driver attaches to USB modems, serial ports, and other devices that need to look like a tty. The ucom driver shows a behavior like a tty(4). This means that normal programs such as tip(1) or pppd(8) can be used to access the device.
The portno locater can be used to decide which port to use for devices that have multiple external ports.