How to read and write from a COM Port using PySerial?

This could be what you want. I'll have a look at the docs on writing. In windows use COM1 and COM2 etc without /dev/tty/ as that is for unix based systems. To read just use s.read() which waits for data, to write use s.write().

import serial

s = serial.Serial('COM7')
res = s.read()
print(res)

you may need to decode in to get integer values if thats whats being sent.

On Windows, you need to install pyserial by running

pip install pyserial

then your code would be

import serial
import time

serialPort = serial.Serial(
    port="COM4", baudrate=9600, bytesize=8, timeout=2, stopbits=serial.STOPBITS_ONE
)
serialString = ""  # Used to hold data coming over UART
while 1:
    # Wait until there is data waiting in the serial buffer
    if serialPort.in_waiting > 0:

        # Read data out of the buffer until a carraige return / new line is found
        serialString = serialPort.readline()

        # Print the contents of the serial data
        try:
            print(serialString.decode("Ascii"))
        except:
            pass

to write data to the port use the following method

serialPort.write(b"Hi How are you \r\n")

note:b"" indicate that you are sending bytes