API Reference

serial.Serial(
    port=None,
    baudrate=9600,
    bytesize=EIGHTBITS,
    parity=PARITY_NONE,
    stopbits=STOPBITS_ONE,
    timeout=None,
    xonxoff=False,
    rtscts=False,
    write_timeout=None,
    dsrdtr=False,
    inter_byte_timeout=None,
    exclusive=None,
)

import serial

# Minimal
ser = serial.Serial('/dev/ttyUSB0', 9600)

# Full configuration
ser = serial.Serial('/dev/ttyUSB0', 115200,
    bytesize=8, parity='N', stopbits=1,
    timeout=1, write_timeout=1, rtscts=True)

# Create without opening
ser = serial.Serial()
ser.port = '/dev/ttyUSB0'
ser.baudrate = 9600
ser.open()

import serial

ser = serial.Serial('/dev/ttyUSB0', 9600, timeout=1)

print(f"Port: {ser.port}")
print(f"Open: {ser.is_open}")
print(f"Baud: {ser.baudrate}")
print(f"Input buffer: {ser.in_waiting} bytes")
print(f"CTS: {ser.cts}, DSR: {ser.dsr}")

# Change settings on the fly
ser.baudrate = 115200
ser.timeout = 2.0

ser.close()

import serial

ser = serial.Serial('/dev/ttyUSB0', 9600, timeout=2)

# Read exactly 1 byte
byte = ser.read()

# Read up to 10 bytes
data = ser.read(10)
if len(data) < 10:
    print(f"Timeout: got {len(data)} of 10 bytes")

ser.close()

import serial

ser = serial.Serial('/dev/ttyUSB0', 9600, timeout=1)

line = ser.readline()
text = line.decode('utf-8').strip()
print(text)

# With size limit
line = ser.readline(100)

ser.close()

import serial

ser = serial.Serial('/dev/ttyUSB0', 9600, timeout=2)

# Read until "OK" response
response = ser.read_until(b'OK')

# Read until custom packet delimiter
packet = ser.read_until(b'</packet>')

# With size limit
data = ser.read_until(b'END', size=1000)

ser.close()

import serial
import time

ser = serial.Serial('/dev/ttyUSB0', 9600, timeout=1)

time.sleep(0.5)  # let data accumulate
if ser.in_waiting:
    data = ser.read_all()
    print(f"Got {len(data)} bytes")

ser.close()

import serial
import struct

ser = serial.Serial('/dev/ttyUSB0', 9600, timeout=1)

# Write raw bytes
ser.write(b'Hello\n')

# Write encoded string
ser.write("AT+GMR\r\n".encode('utf-8'))

# Write binary struct
data = struct.pack('>HHf', 1234, 5678, 25.6)
ser.write(data)

ser.close()

import serial

ser = serial.Serial('/dev/ttyUSB0', 9600, timeout=1)

commands = [b'AT\r\n', b'ATE0\r\n', b'AT+GMR\r\n']
ser.writelines(commands)

ser.close()

import serial

ser = serial.Serial('/dev/ttyUSB0', 9600, timeout=1)

ser.write(b'COMMAND\r\n')
ser.flush()  # wait until bytes are on the wire
response = ser.readline()

ser.close()

import serial

ser = serial.Serial()
ser.port = '/dev/ttyUSB0'
ser.baudrate = 9600

ser.open()
print(f"Opened: {ser.is_open}")
ser.close()

import serial

ser = serial.Serial('/dev/ttyUSB0', 9600)
# ... do work ...
ser.close()

import serial

ser = serial.Serial('/dev/ttyUSB0', 9600, timeout=1)

# Discard stale data before sending a command
ser.reset_input_buffer()
ser.write(b'AT\r\n')
response = ser.readline()

ser.close()

import serial

ser = serial.Serial('/dev/ttyUSB0', 9600)
ser.send_break(0.5)
ser.close()

import serial.tools.list_ports

for port in serial.tools.list_ports.comports():
    print(f"{port.device}: {port.description}")
    if port.vid:
        print(f"  USB VID:PID = {port.vid:04X}:{port.pid:04X}")

import serial

# Loopback for testing (no hardware needed)
ser = serial.Serial('loop://', timeout=1)
ser.write(b'test')
print(ser.read(4))  # b'test'
ser.close()

# TCP socket to a serial-over-IP device
ser = serial.Serial('socket://192.168.1.100:7777', timeout=1)

# Find FTDI device by USB IDs
ser = serial.Serial('hwgrep://0403:6001')

import serial

try:
    ser = serial.Serial('/dev/ttyUSB0', 9600, timeout=1)
    ser.write(b'test')
    data = ser.read(10)
except serial.SerialTimeoutException:
    print("Operation timed out")
except serial.SerialException as e:
    print(f"Serial error: {e}")
except PermissionError:
    print("Permission denied")
except FileNotFoundError:
    print("Port not found")
finally:
    if 'ser' in locals() and ser.is_open:
        ser.close()

import serial

with serial.Serial('/dev/ttyUSB0', 9600, timeout=1) as ser:
    ser.write(b'data\n')
    response = ser.read(100)
# port is closed automatically

import serial

print(serial.__version__)  # e.g., '3.5'