barcode scanner python gui

main.py

from tkinter import *
import requests
import json
import serial
import pymodbus

from pymodbus.client.sync import ModbusSerialClient

barcode = ""
toggle = True

def callapi(barcode):
  myapp.lstatus["text"] = "Loading..."
  mywin.update()

  url = 'https://api.upcdatabase.org/product/' + barcode + '/097093029E4C133C95259D03085DC466'
  headers = { "Accept": "application/json" }
  response = requests.get(url, headers = headers)
  print ("Api status: ",  response.status_code)
  print ("Api return: ",  response.text)
  jsondata = json.loads(response.text)

  global myapp
  myapp.lstatus["text"] = jsondata.get("title", 'Not Found')
  if jsondata.get("title", False):
    client.write_coil(16, True, unit=1)
  else:
    client.write_coil(16, False, unit=1)

class MyAppClass(Frame):
  def __init__(self, master=None):
    Frame.__init__(self, master)
    self.grid()
    self.create_label()
    self.create_button()
    
  def create_label(self):
    self.lattrs = Label(self)
    self.lattrs["text"] = "Scan Barcode"
    self.lattrs.grid()
    self.lstatus = Label(self)
    self.lstatus["text"] = "..."
    self.lstatus.grid()
    
  def create_button(self):
    self.battrs = Button(self)
    self.battrs["text"] = "Click Me"
    self.battrs["command"] = self.my_event
    self.battrs.grid()

  def my_event(self):
    global toggle
    toggle = not toggle
    client.write_coil(17, toggle, unit=1)
    
  def up(self,e):
    global barcode
    if e.keysym == 'Return':
      self.lattrs["text"] = barcode
      print (barcode)
      callapi(barcode)
      barcode = ""
    else:
      barcode = barcode + e.char

mywin = Tk()
mywin.title("Rasp PI GUI")
myapp = MyAppClass(mywin)
#mywin.bind('<KeyPress>', myapp.down)
mywin.bind('<KeyRelease>', myapp.up)

client = ModbusSerialClient(method='rtu', port='/dev/ttyUSB0', timeout=1, baudrate=9600, parity='N', bytesize=8)
if client.connect():
  myapp.lstatus["text"] = "Modsbus connection success"
else:
  myapp.lstatus["text"] = "Modsbus connection failed"

mywin.mainloop()