Arduino serial communication

arduino_code.ino

#include <LiquidCrystal.h>

LiquidCrystal lcd(12,11,5,4,3,2);
const int sensorPin = A0;
const int messageBufferSize = 17;
char messageBuffer[17];

void read_serial()
{
  char inputChar = -1;
  int index = 0;

  //clear the buffer ready for a new message
  memset(&messageBuffer[0], 0, sizeof(messageBuffer));

  //first check we have data available
  while(Serial.available()> 0)
  {
    //check that we don't overflow the buffer
    if (index < messageBufferSize-1)
    {
      inputChar = Serial.read();
      messageBuffer[index] = inputChar;
      ++index;
      messageBuffer[index] = '\0';
    }
  }
}

void setup()
{
  Serial.begin(9600);
  lcd.begin(16,2);
}

void loop()
{
  int sensorValue = analogRead(sensorPin);
  float voltage = (sensorValue/1024.0) * 5.0;
  float temperature = (voltage - 0.5) * 100;

  //write temperature to serial
  Serial.println(temperature);
  //read response from serial
  read_serial();
  
  lcd.clear();
  lcd.setCursor(0,0);
  lcd.print(messageBuffer);
  
  delay(1000);
}

listen.py

import serial
ser = serial.Serial('/dev/tty.usbmodem1411', 9600)
while True:
	print ser.readline()
	ser.write("hello");