Open port 0 at “9600,8,N,1”, no timeout:
>>> import serial >>> ser = serial.Serial(0) # open first serial port >>> print ser.portstr # check which port was really used >>> ser.write("hello") # write a string >>> ser.close() # close port
Open named port at “19200,8,N,1”, 1s timeout:
>>> ser = serial.Serial('/dev/ttyS1', 19200, timeout=1) >>> x = ser.read() # read one byte >>> s = ser.read(10) # read up to ten bytes (timeout) >>> line = ser.readline() # read a '\n' terminated line >>> ser.close()
Open second port at “38400,8,E,1”, non blocking HW handshaking:
>>> ser = serial.Serial(1, 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
Get a Serial instance and configure/open it later:
>>> ser = serial.Serial() >>> ser.baudrate = 19200 >>> ser.port = 0 >>> 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.isOpen() True >>> ser.close() >>> ser.isOpen() False
Be carefully when using readline(). Do specify a timeout when opening the serial port otherwise it could block forever if no newline character is received. Also note that readlines() only works with a timeout. 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.
The eol parameter for readline() is no longer supported when pySerial is run with newer Python versions (V2.6+) where the module io is available.
To specify the EOL character for 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")
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.