Arduino restarting when starting python code execution

Question

I am new in the development part and mainly in using the Arduino. I am developing a python web application with some functions, one of them is to turn a light bulb on and off (my problem). I developed the code, used some ready-made web (for testing) and the big question is, when running python code, Arduino simply restarts and does not run the connection between the code and Arduin. I noticed that when starting the connection (connection = serial.Serial('COM3', 9600), the problem occurs. I tested with this piece of code inside Try and the problem persists. Does anyone know what might be going on and any idea how to fix it? ps: I am using Pyserial.

Python code:

import serial
import time
from time import sleep

conexao = serial.Serial('COM3', 9600) 
def escrever_porta():

   try: 
       valor = (raw_input("Digite o valor a ser enviado: "))
       conexao.write(valor)
       conexao.close()

   except serial.SerialException:
       print"ERRO: Verifique se ha algum dispositivo conectado na porta!"

   return valor

Arduino code (I’ve tried several):

#include "EmonLib.h"
#include <SPI.h>

int pin = 7;
char dados = 0;

void setup() {
  pinMode(pin, OUTPUT);
  Serial.begin(9600);
  while (!Serial) {
    ;
  }
}

void loop() {
  if (Serial.available()) {
    while (Serial) {
      if (Serial.available()) {
        dados =(char)Serial.read();

        if (dados == "0") {
          delay(1);
          Serial.end();
          if (dados == "1") {
            digitalWrite(pin, HIGH);
          } else {
            if (dados == "2") {
              digitalWrite(pin, LOW);
            }
          }
          dados = "" ;
        }
      }
    }
  }
}

Answer 1

Make sure the door is right, it is quite common for Sos to play Andy to another port, you are not actually using a virtual serial port (FTDI)?

Answer 2

The python code is in Python2, would there be a chance that your python would be 3? If it is, the code should have some changes:

raw_input now is input and print will have parentheses ( counteúdo )

import serial
import time
from time import sleep

conexao = serial.Serial('COM3', 9600) 
def escrever_porta():

   try: 
       valor = (input("Digite o valor a ser enviado: ")) 
      #Esses parenteses antes do input é realmente necessário?
      #valor = input("Digite o valor a ser enviado: ")

       conexao.write(valor)
       conexao.close()

   except serial.SerialException:
   #tente também apenas "except:"
       print("ERRO: Verifique se ha algum dispositivo conectado na porta!")

   return valor

I hope I helped... If python really is 2.x, then the problem is just the valor