SER2 built-in module is available only for product versions from 12.00.xx4, from 13.00.xx5 and from 18.11.004.
The SER2 built-in module is an interface between the Python core and the device trace serial port over the RX_AUX/TX_AUX pins direct handling. You need to use the SER2 built-in module if you want to send data from the Python script to the serial port USIF1 and to receive data from the serial port USIF1 to the Python script. This serial port has not the flow control physical lines.
This module is available for all products.
It is Python script developer responsibility to use it properly.
In fact serial port USIF1 is usually dedicated to trace and debug purposes and importing this module will make trace and debug unavailable. Moreover importing this module might interfere with device serial port configuration (see HE910 UE910 Family Ports Arrangements User Guide from version 12.xx.xx4, GE910 Family Ports Arrangements User Guide from version 13.xx.xx5 or CE Family Ports Arrangements User Guide for version 18.11.004).
If you want to use SER2 built-in module you need to import it:
import SER2
then you can use its methods, like in the following example:
a = SER2.set_speed('9600')
b = SER2.send('test')
c = SER2.sendbyte(0x0d)
d = SER2.read()
which sends 'test' followed by <CR> and receives data.
More details about SER2 built-in module methods can be found in the following paragraphs.