pyserial-asyncio 
Async I/O extension package for the Python Serial Port Extension for OSX, Linux, BSD
It depends on pySerial and is compatible with Python 3.4 and later.
Documentation
Stable:
- Documentation: http://pythonhosted.org/pyserial-asyncio/
- Download Page: https://pypi.python.org/pypi/pyserial-asyncio
Latest:
- Documentation: http://pyserial-asyncio.readthedocs.io/en/latest/
- Project Homepage: https://github.com/pyserial/pyserial-asyncio