Read / Write some serial data

RFID-readSerial.py

import serial
import json
import sys

ser = serial.Serial(
    port='/dev/ttyUSB0',\
    baudrate=9600,\
    parity=serial.PARITY_NONE,\
    stopbits=serial.STOPBITS_ONE,\
    bytesize=serial.EIGHTBITS,\
        timeout=0)

print("connected to: " + ser.portstr)

option = input("Type 0: ")
while option != '-1':
    #this will store the line
    line = ""
    data = {}

    ser.write(option.encode())
    while True:
        try:
            c = ser.read().decode()
            if c:
                line += c
                if c == '\n':
                    line = line[:-1].strip()
                    if line == "M01":
                        print("Place the card!")
                    elif line == "M02":
                        # ser.close()
                        print(data)
                        print('Remove the card!')
                        # sys.exit()
                        # exit()
                        break
                    else:
                        try:
                            data = json.loads(line)
                        except Exception:
                            pass
                    line = ""
        except KeyboardInterrupt:
            try:
                ser.close()
            except Exception:
                pass
                
    option = input("Type 0: ")
ser.close()