conexion a puerto com

import serial
import time
import csv
comandos =[]
comandos2 =[]
with open("hosts.txt",newline="") as f:
    reader = csv.reader(f,delimiter=",")
    for listado in reader:
        psw = listado[2]

with open("comandos.txt",newline="") as c:
    reader2 = csv.reader(c,delimiter=",")
    for z in reader2:
        comandos.append(z)
for y in comandos:
    comandos2.append(y[0])


with serial.Serial(port="com4",baudrate = 9600) as ser:
    if ser.isOpen():
        print("si")
        ser.write(b"\r\n")
        time.sleep(2)
        ser.write(b"\r\n")
        time.sleep(2)
        by = ser.inWaiting()
        output = ser.read(by)
        if "assword" in output.decode("UTF-8"):
            ser.write(psw.encode("ascii")+b"\n")
            time.sleep(2)
        ser.write(b"enable\n")
        time.sleep(2)
        ser.write(psw.encode("ascii")+b"\n")
        time.sleep(2)
        ser.write(b"enable\n")
        time.sleep(2)
        ser.write(b"config t\n")
        time.sleep(2)
        for x in comandos2:
            ser.write(x.encode("ascii")+b"\n")
            time.sleep(2)
        ser.write(b"end\n")
        time.sleep(2)


        ser.close()