CDC protocol over USB 2.0

[Geoffrey]

I wish to upload and download BASIC programs between Ubuntu's Terminal
and another device over a USB serial interface. I'm advised that there
is native support for the CDC(Communications Device Class) protocol
implementation required, which, for Linux, is called the 'cdc-acm
driver'. 
Could someone tell me where to find this driver, how to install and how
the Terminal may be used to exchange program information.
Note; I have yet to connect the device (it's still being constructed)
and so I have not tried a hardware driver search.
Geoffrey