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For make a the Serial COM sw I suggest: pySerial
http://pyserial.sourceforge.net/index.html
Now see also (starting with V3.0):
moved to github: https://github.com/pyserial/pyserial
docs: https://pyserial.readthedocs.org/en/latest/
See also:
http://pypi.python.org/pypi/pyserial
Old pages (up to V2.7):
http://sourceforge.net/projects/pyserial/
For test your Serial COM under Linux I suggest to use MINICOM.
For install MINICOM on LUBUNTU use this command:
sudo apt install minicom
For run MINICOM use this command:
minicom -s
Next enter in: Serial Port SetUp
and configure the parameters of your Serial Port.
If you use a USB to SERIAL converter, normally the port is: /dev/ttyUSB0