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')
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.
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"))
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.
The enumeration may not work on all operating systems. It may be incomplete, list unavailable ports or may lack detailed descriptions of the ports.
pySerial includes a small console based terminal program called
:ref:`miniterm`. It can be started with
python -m serial.tools.miniterm <port_name>
-h to get a listing of all options).