I am new to python and multiprocessing (Electronics background). I am writing an GUI application to communicate with micro controller over serial port. The interaction with user is through some buttons on the GUI, which sends some command on serial port to the MCU and displays data received from MCU in the same GUI(there can be data from MCU without any command being sent). I am using PyQt5 module and QT designer to design the UI. I converted the UI to py code using uic.compileUi. I am then calling this python file in my main code.
After reading through several documents and stack overflow posts I decided to use to QThreads for the application.
I am however facing issue with serial communication when being used inside thread (It works fine if used in a single main loop without threads).
My code is:
from PyQt5 import uic
from PyQt5.QtWidgets import QApplication,QWidget,QMainWindow #
from PyQt5.QtCore import QCoreApplication, QObject, pyqtSignal, pyqtSlot, QThread
import serial
from GUI import Ui_MainGUIWindow
import sys
serialString = ""
def ClosePort():
serialPort.close()
# print("port closed")
def OpenPort():
serialPort.open()
#print("port open")
def sendFV():
serialPort.write('fv\r'.encode())
def configSerial(port,baudRate):
global serialPort
serialPort=serial.Serial(port = port, baudrate=baudRate, bytesize=8, timeout=None, stopbits=serial.STOPBITS_ONE)
if not serialPort.isOpen():
serialPort.open()
class Worker(QObject):
finished = pyqtSignal()
dataReady = pyqtSignal(['QString'])#[int], ['Qstring']
print("workerinit")
def run(self):
print ("worker run")
while(1):
if(serialPort.in_waiting > 0):
serialString = serialPort.read()
self.dataReady.emit(str(serialString))
self.finished.emit()
class GUI(QWidget):
def __init__(self):
self.obj = Worker()
self.thread = QThread()
self.obj.dataReady.connect(self.onDataReady)
self.obj.moveToThread(self.thread)
self.obj.finished.connect(self.thread.quit)
self.thread.started.connect(self.obj.run)
self.thread.finished.connect(app.exit)
self.thread.start()
self.initUI()
def initUI(self):
#Form, Window = uic.loadUiType("TestGUI.ui")
#print(Form,Window)
#self.window = Window()
#self.form=Form()
self.window = QMainWindow()
self.form = Ui_MainGUIWindow()
self.form.setupUi(self.window)
self.form.FVButton.clicked.connect(sendFV)
print("guiinit")
self.window.show()
def onDataReady(self, serialString):
print("here")
print(serialString.decode('Ascii'))
self.form.plainTextOutput.insertPlainText((serialString.decode('Ascii')))
self.form.plainTextOutput.ensureCursorVisible()
if __name__ == '__main__':
configSerial("COM20",9600)
"""
app = QCoreApplication.instance()
if app is None:
app = QCoreApplication(sys.argv)
"""
app = QApplication(sys.argv)
form=GUI()
app.exec_()
sys.exit(ClosePort())
I get following error on line if(serialPort.in_waiting > 0):
File "C:\Users\...\Anaconda3\lib\site-packages\serial\serialwin32.py", line 259, in in_waiting
raise SerialException("ClearCommError failed ({!r})".format(ctypes.WinError()))
SerialException: ClearCommError failed (OSError(9, 'The handle is invalid.', None, 6))
I found this post talking about similar issue, but do know how exactly to implement the suggested solution in my code.
Also I get "kernel died" error multiple times when I run the code on spyder IDE. I added a check if I am creating multiple instances of QT application but that did not help.Running the code from anaconda command prompt works fine.
This question already has answers here:
What is unittest in selenium Python?
(2 answers)
Closed 2 years ago.
This test case checks the error that can occur during login functionality
from selenium import webdriver
import unittest
class LoginCheck(unittest.TestCase):
def setUp(self):
self.driver = webdriver.Chrome()
def login_error_check(self):
browser = self.driver
browser.get('https://www.saucedemo.com/')
browser.maximize_window()
usr = browser.find_element_by_id('user-name')
password = browser.find_element_by_id('password')
button = browser.find_element_by_xpath('//input[#value="LOGIN"]')
print('Hello')
usr.send_keys('standard_user')
password.send_keys('password')
button.click()
def tearDown(self):
self.driver.quit()
if __name__ == '__main__':
unittest.main()
I am getting below message
Ran 0 tests in 0.000s
OK
repl process died unexpectedly
was expecting that it will be success but couldn't see anything. I'm learning selenium.
test ran by prefixing the 'test' to the method
from selenium import webdriver
import unittest
class LoginCheck(unittest.TestCase):
def setUp(self):
self.driver = webdriver.Chrome()
def test_login_error_check(self):
browser = self.driver
browser.get('https://www.saucedemo.com/')
browser.maximize_window()
usr = browser.find_element_by_id('user-name')
password = browser.find_element_by_id('password')
button = browser.find_element_by_xpath('//input[#value="LOGIN"]')
print('Hello')
usr.send_keys('standard_user')
password.send_keys('password')
button.click()
def tearDown(self):
self.driver.quit()
if __name__ == '__main__':
unittest.main()
This will work.
Flask appears to prevent PyQt5 UI from updating.
The respective code works properly for either PyQt5 or Flask - but not together. I understand that it may need to do with the way threading is set up.
Any assistance would be greatly appreciated. TIA.
`
import sys
import serial
import threading
from PyQt5.QtWidgets import QWidget, QLabel, QApplication
from flask import Flask, render_template, request, redirect, url_for
app1 = Flask(__name__)
ser = serial.Serial ("/dev/ttyS0", 57600,timeout=3) #Open port with baud rate
count=0
temp = []
class Example(QWidget):
def __init__(self):
super().__init__()
self.initUI()
def initUI(self):
global count
count = 1
self.setGeometry(300, 300, 250, 150)
self.setWindowTitle('PyQt5 vs Flask')
self.lbl1 = QLabel('Count '+str(count), self)
self.lbl1.move(100, 50)
self.show()
threading.Timer(5,self.refresh).start()
def refresh(self):
global count
count +=1
print("UI ",count)
self.lbl1.setText('Count'+str(count))
threading.Timer(5,self.refresh).start()
def get_uart():
global temp
if ser.inWaiting()>0:
temp =[str(float(x.decode('utf-8'))) for x in ser.read_until().split(b',')]
print(temp)
threading.Timer(1,get_uart).start()
#app1.route("/")
def index():
global temp
templateData = {'temp1' : temp[1] ,'temp2' : temp[2]}
return render_template('index.html',**templateData)
if __name__ == "__main__":
app = QApplication(sys.argv)
pyqt5 = Example()
threading.Timer(1,get_uart).start()
ser.flushInput()
#app1.run(host='0.0.0.0',threaded=True, port=5000) # ,debug=True)
sys.exit(app.exec_())
`
Need to have a UI to control the data analysis to be displayed on Website.
[SOLVED]
All Flask parameters can be defined as:
port = int(os.environ.get('PORT', local_port))
kwargs = {'host': '127.0.0.1', 'port': port , 'threaded' : True, 'use_reloader': False, 'debug':False}
threading.Thread(target=app.run, daemon = True, kwargs=kwargs).start()
and Flask will NOT Block and run with the parameters defined in kwargs.
The better way deal with (possibly waiting) processes, is to use Qt's own threads.
In this example I've created a QObject subclass that does all processing and eventually sends a signal whenever the condition is valid. I can't install flask right now, so I've not tested the whole code, but you'll get the idea.
The trick is to use a "worker" QObject that does the processing. Once the object is created is moved to a new QThread, where it does all its processing without blocking the event loop (thus, the GUI).
You can also create other signals for that object and connect to your slots (which might also be standard python functions/methods outside the QtApplication) which will be called whenever necessary.
class Counter(QtCore.QObject):
changed = QtCore.pyqtSignal(str)
def __init__(self):
super().__init__()
self.count = 0
def run(self):
while True:
self.thread().sleep(1)
if ser.inWaiting() > 0:
self.changed.emit('{}: {}'.format(self.count, [str(float(x.decode('utf-8'))) for x in ser.read_until().split(b',')]))
self.count += 1
class Example(QtWidgets.QWidget):
def __init__(self):
super().__init__()
self.counter = Counter()
self.counterThread = QtCore.QThread()
self.counter.moveToThread(self.counterThread)
self.counterThread.started.connect(self.counter.run)
self.initUI()
def initUI(self):
self.setGeometry(300, 300, 250, 150)
self.setWindowTitle('PyQt5 vs Flask')
self.lbl1 = QtWidgets.QLabel('Count {}'.format(self.counter.count), self)
self.lbl1.move(100, 50)
self.counter.changed.connect(self.lbl1.setText)
self.counterThread.start()
if __name__ == "__main__":
app = QtWidgets.QApplication(sys.argv)
pyqt5 = Example()
pyqt5.show()
I think the problem stems from how Flask is activated. If the app.run command is given any parameters (even if in a Thread), then it blocks other commands.
The only way I was able to make Flask and PyQt5 work at the same time, was to activate Flask in a dedicated Thread WITHOUT any parameters - SEE BELOW for the various combinations.
Question: Is this a Flask/Python Bug or Feature or some other explanation related to Development vs Production deployment??
In any case, I would like any help with finding a way to deploy flask in a Port other than 5000 - WITHOUT Flask Blocking other code.
import sys
import serial
import threading
import atexit
from PyQt5.QtWidgets import QWidget, QLabel, QApplication
from flask import Flask, render_template, request, redirect, url_for
ser = serial.Serial ("/dev/ttyS0", 57600,timeout=3) #Open port with baud rate
app = Flask(__name__)
count=0
temp = []
class Example(QWidget):
def __init__(self):
super().__init__()
self.initUI()
def initUI(self):
global count
count = 1
self.setGeometry(300, 300, 250, 150)
self.setWindowTitle('PyQt5 vs Flask')
self.lbl1 = QLabel("Count "+str(count)+" ", self)
self.lbl1.move(100, 50)
self.show()
threading.Timer(5,self.refresh).start()
def refresh(self):
global count
global str_data
count +=1
self.lbl1.setText("Count "+str(count)+" ")
threading.Timer(0.5,self.refresh).start()
def get_uart():
global temp
if ser.inWaiting()>0:
temp =[str(float(x.decode('utf-8'))) for x in ser.read_until().split(b',')]
print(temp)
threading.Timer(1,get_uart).start()
#app.route("/")
def blank():
global count
data="Count "+str(count)
return data
if __name__ == "__main__":
threading.Timer(5,get_uart).start()
#app.run ## Does not block further execution. Website IS NOT available
#app.run() ## Blocks further execution. Website available at port 5000 without Refresh value
#app.run(port=5123) ## Blocks further execution. Website available at port 5123 without Refresh value
#app.run(threaded=True) ## Blocks further execution. Website available at port 5000 without Refresh value
#threading.Thread(target=app.run()).start() ## Blocks further execution. Website available at port 5000 without Refresh value
#threading.Thread(target=app.run(port=5123)).start() ## Blocks further execution. Website available at port 5123 without Refresh value
#threading.Thread(target=app.run(threaded=True)).start() ## Blocks further execution. Website available at port 5000 without Refresh value
threading.Thread(target=app.run).start() ## Flask DOES NOT block. Website is available at port 5000 with Refresh value
print("Flask does not block")
app1 = QApplication(sys.argv)
pyqt5 = Example()
sys.exit(app1.exec_())
Hi I am try to create an Python GUI using tkinter package. Everything working perfectly but I want to insert or print some text while code is running. My code is little length process, I did not include all the code, to execute i need some update information on the Text area, so that user know coding is running and getting some information from internet.
Could you please kindly check this code. In this code number will insert in the Tkinter GUI and will be increase continuously. But i want to inset text form the given list. How can I insert text form the list. Please kindly help.
from tkinter import *
import threading
import queue
from time import sleep
import random
import tkinter as tk
list1 = ['Text 1', 'Text 2','Text 3','Text 4','Text 5','Text 6','Text 7',
'Text 8','Text 9','Text 10','Text 11']
class Thread_0(threading.Thread):
def __init__(self):
threading.Thread.__init__(self)
def run(self):
count = 0
while True:
count+=1
hmi.thread_0_update(count)
sleep(random.random()/100)
class HMI:
def __init__(self):
self.master= tk.Tk()
self.master.geometry('200x200+1+1')
f=tk.Frame(self.master)
f.pack()
self.l0=tk.Label(f)
self.l0.pack()
self.q0=queue.Queue()
self.master.bind("<<Thread_0_Label_Update>>",self.thread_0_update_e)
def start(self):
self.master.mainloop()
self.master.destroy()
def thread_0_update(self,val):
self.q0.put(val)
self.master.event_generate('<<Thread_0_Label_Update>>',when='tail')
def thread_0_update_e(self,e):
while self.q0.qsize():
try:
val=self.q0.get()
self.l0.config(text=str(val))
# self.l0.config(text=val)
except queue.Empty:
pass
##########################
if __name__=='__main__':
hmi=HMI()
t0=Thread_0()
t0.start()
hmi.start()
When i run python-pyside2 project server first, then it works well.
And the site also work well, but if i press F5 btn to refresh in browser.
Site shows error page Runtime at/
import sys
from urllib.request import urlopen
from bs4 import BeautifulSoup
from PySide2.QtGui import *
from PySide2.QtCore import *
from PySide2.QtWebKitWidgets import *
from PySide2.QtWidgets import QApplication
class dynamic_render(QWebPage):
def __init__(self, url):
self.frame = None
self.app = QApplication(sys.argv)
QWebPage.__init__(self)
self.loadFinished.connect(self._loadFinished)
self.mainFrame().load(QUrl(url))
QTimer.singleShot(0, self.sendKbdEvent)
QTimer.singleShot(100, app.quit)
self.app.exec_()
def _loadFinished(self, result):
self.frame = self.mainFrame()
self.app.quit()
self.app = None
Below, scaping code using pyside2:
I don't know how can i fix it?
Best regards.
Thanks.
Check if already an instance of QApplication is present or not as the error occurs when an instance is already running and you are trying to create a new one.
Write this in your main function:
if not QtWidgets.QApplication.instance():
app = QtWidgets.QApplication(sys.argv)
else:
app = QtWidgets.QApplication.instance()
For my pyside2 unit test the following worked fairly well
import PySide2
import unittest
class Test_qapplication(unittest.TestCase):
def setUp(self):
super(Test_qapplication, self).setUp()
if isinstance(PySide2.QtGui.qApp, type(None)):
self.app = PySide2.QtWidgets.QApplication([])
else:
self.app = PySide2.QtGui.qApp
def tearDown(self):
del self.app
return super(Test_qapplication, self).tearDown()
it was loosely based on stack overflow : unit-and-functional-testing-a-pyside-based-application