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====================
Short introduction
====================
Opening serial ports
====================
Open port at "9600,8,N,1", no timeout::
>>> import serial
>>> ser = serial.Serial('/dev/ttyUSB0') # open serial port
>>> print(ser.name) # check which port was really used
>>> ser.write(b'hello') # write a string
>>> ser.close() # close port
Open named port at "19200,8,N,1", 1s timeout::
>>> with serial.Serial('/dev/ttyS1', 19200, timeout=1) as ser:
... x = ser.read() # read one byte
... s = ser.read(10) # read up to ten bytes (timeout)
... line = ser.readline() # read a '\n' terminated line
Open port at "38400,8,E,1", non blocking HW handshaking::
>>> ser = serial.Serial('COM3', 38400, timeout=0,
... parity=serial.PARITY_EVEN, rtscts=1)
>>> s = ser.read(100) # read up to one hundred bytes
... # or as much is in the buffer
Configuring ports later
=======================
Get a Serial instance and configure/open it later::
>>> ser = serial.Serial()
>>> ser.baudrate = 19200
>>> ser.port = 'COM1'
>>> ser
Serial<id=0xa81c10, open=False>(port='COM1', baudrate=19200, bytesize=8, parity='N', stopbits=1, timeout=None, xonxoff=0, rtscts=0)
>>> ser.open()
>>> ser.is_open
True
>>> ser.close()
>>> ser.is_open
False
Also supported with :ref:`context manager <context-manager>`::
with serial.Serial() as ser:
ser.baudrate = 19200
ser.port = 'COM1'
ser.open()
ser.write(b'hello')
Readline
========
Be careful when using :meth:`readline`. Do specify a timeout when opening the
serial port otherwise it could block forever if no newline character is
received. Also note that :meth:`readlines` only works with a timeout.
:meth:`readlines` depends on having a timeout and interprets that as EOF (end
of file). It raises an exception if the port is not opened correctly.
Do also have a look at the example files in the examples directory in the
source distribution or online.
.. note::
The ``eol`` parameter for :meth:`readline` is no longer supported when
pySerial is run with newer Python versions (V2.6+) where the module
:mod:`io` is available.
EOL
---
To specify the EOL character for :meth:`readline` or to use universal newline
mode, it is advised to use io.TextIOWrapper_::
import serial
import io
ser = serial.serial_for_url('loop://', timeout=1)
sio = io.TextIOWrapper(io.BufferedRWPair(ser, ser))
sio.write(unicode("hello\n"))
sio.flush() # it is buffering. required to get the data out *now*
hello = sio.readline()
print(hello == unicode("hello\n"))
.. _io.TextIOWrapper: http://docs.python.org/library/io.html#io.TextIOWrapper
Testing ports
=============
Listing ports
-------------
``python -m serial.tools.list_ports`` will print a list of available ports. It
is also possible to add a regexp as first argument and the list will only
include entries that matched.
.. note::
The enumeration may not work on all operating systems. It may be
incomplete, list unavailable ports or may lack detailed descriptions of the
ports.
.. versionadded: 2.6
Accessing ports
---------------
pySerial includes a small console based terminal program called
:ref:`miniterm`. It can be started with ``python -m serial.tools.miniterm <port_name>``
(use option ``-h`` to get a listing of all options).
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