USB0 built-in module is available only for product versions from 12.00.xx5 and from 13.00.xx6.
The USB0 built-in module is an interface between the Python core and the device first mini USB port USB0. You need to use the USB0 built-in module if you want to send data from the Python script to the first mini USB port USB0 and to receive data from the first mini USB port USB0 to the Python script. This USB port handling module can be used, for example, to interface the module with an external device and read/send its data.
If you want to use USB0 built-in module you need to import it:
import USB0
then you can use its methods, like in the following example:
b = USB0.send('test')
c = USB0.sendbyte(0x0d)
d = USB0.read()
which sends 'test' followed by <CR> and receives data.
More details about USB0 built-in module methods can be found in the following paragraphs.