CODEWITHSUNDEEP
pythonmultithreadingqmlpyqt5
Jarrett Dunn
Jarrett Dunn

Reputation: 31

Signals not passing from thread to GUI

This telemetry program that reads data in from a serial string coming in on a USB port. The GUI is defined in a QML file and reading the serial port is taken care of by a string. The GUI loads and works correctly. The button on the GUI send has an event handler that that causes a signal to be sent back to the GUI. That works perfectly. The serial read thread starts and runs correctly. It reads and parses the data and prints it to the screen. However the signals are not making it back to the GUI.

This is driving me crazy, thanks for the help.

main.py

import sys
import serial
from io import StringIO
import csv
from openpyxl import Workbook
import datetime
from PyQt5.QtGui import QGuiApplication
from PyQt5.QtQml import QQmlApplicationEngine
from PyQt5.QtCore import QObject, pyqtSignal, pyqtSlot, QThread

global ser
#define and open the serial port
ser=serial.Serial('COM6')

class Dash(QObject):
    def __init__(self):
        QObject.__init__(self)

    ampHourvalue = pyqtSignal(int, arguments=['amphour'])


    @pyqtSlot(int)
    def reset(self, value):

        value=100  #put amp hour capacity here
        self.ampHourvalue.emit(value)

class ThreadClass(QThread):
    # Create the signal
    auxVoltage = pyqtSignal(str, arguments=['auxvolt'])
    mainVoltage = pyqtSignal(int, arguments=['mainvolt'])
    arrayCurrent = pyqtSignal(int, arguments=['arraycurrent'])
    motorCurrent = pyqtSignal(int, arguments=['motorcurrent'])


    def __init__(self, parent=None):
        super(ThreadClass, self).__init__(parent)

    def run(self):
        try:
            wb=load_workbook("History.xls") #attemps to open the history excel file
        except:
            wb=Workbook() #creates and empty excel workbook if histortory is not found

        WorkSheetName=datetime.date.today() #get todays date
        ws = wb.create_sheet("%s" %WorkSheetName) #create worksheet with the date as tittle

        while True:
            data=ser.readline(120) #read the stream
            print(data)
            data=data.decode() #convert stream from bytes to characters
            data=StringIO(data)#convert a stream of characters into string
            dataset=csv.reader(data, delimiter= ',') #read the CSV string into individual array
            dataset=list(dataset) #convert the array to list

            ws.append(dataset[0])
            wb.save("History.xls")

            #extract individual data points
            aux=dataset[0][1]
            print("Aux ", aux)
            mainvolt=dataset[0][2]
            print("Main ", mainvolt)
            arraycurrent=dataset[0][3]
            motorcurrent=dataset[0][4]

            # Emit the signals
            self.auxVoltage.emit(aux)
            self.mainVoltage.emit(mainvolt)
            self.arrayCurrent.emit(arraycurrent) 
            self.motorCurrent.emit(motorcurrent) 

            pass       


def main():
    import sys
    # Create an instance of the application
    app = QGuiApplication(sys.argv)

    #start the thread
    threadclass=ThreadClass()
    threadclass.start()


    # Create QML engine
    engine = QQmlApplicationEngine()
    # Create a Dash object
    dashboard = Dash()
    # And register it in the context of QML
    engine.rootContext().setContextProperty("dashboard", dashboard)
    # Load the qml file into the engine
    engine.load("take2.qml")

    engine.quit.connect(app.quit)
    sys.exit(app.exec_())


if __name__ == "__main__":
    main()

take2.qml

import QtQuick 2.5
import QtQuick.Controls 1.4
import QtQuick.Layouts 1.2
import QtQuick.Extras 1.4


ApplicationWindow {
id: applicationWindow
visible: true
width: 1000
height: 500
color: "black"
title: "I like Telemetry"

Text {
    id: text1
    x: 300
    y: 6
    width: 353
    height: 34
    text: qsTr("Solar Car Telemetry System")
    anchors.horizontalCenter: parent.horizontalCenter
    horizontalAlignment: Text.AlignHCenter
    font.family: "Times New Roman"
    font.pixelSize: 30
    color: "grey"
}


CircularGauge {
    id: circularGauge
    x: 55
    y: 111
    width: 308
    height: 279
    anchors.verticalCenter: rowLayout.verticalCenter

    Text {
        id: text2
        x: 143
        y: 226
        text: qsTr("Speed")
        anchors.horizontalCenter: parent.horizontalCenter
        horizontalAlignment: Text.AlignHCenter
        font.pixelSize: 12
        color: "grey"
    }
}

CircularGauge {
    id: auxvoltgauge
    x: 381
    y: 92
    width: 151
    height: 141
    stepSize: .5
    maximumValue: 15
    value:1


Text {
    id: text3
    x: 445
    width: 69
    text: qsTr("Aux Battery")
    anchors.top: parent.top
    anchors.topMargin: -17
    horizontalAlignment: Text.AlignHCenter
    anchors.horizontalCenter: parent.horizontalCenter
    font.pixelSize: 12
    color: "grey"
}

Text {
    id: text5
    x: 64
    y: 106
    text: qsTr("Volts")
    anchors.bottom: parent.bottom
    anchors.bottomMargin: 10
    font.pixelSize: 12
    color: "grey"
}
}

CircularGauge {
    id: circularGauge2
    x: 381
    y: 288
    width: 151
    height: 141
    visible: true


Text {
    id: text4
    x: 445
    y: 259
    text: qsTr("Main Battery")
    anchors.top: parent.top
    anchors.topMargin: -17
    fontSizeMode: Text.FixedSize
    horizontalAlignment: Text.AlignHCenter
    anchors.horizontalCenter: parent.horizontalCenter
    font.pixelSize: 12
    color: "grey"
}
Text {
    id: text6
    x: 64
    y: 106
    text: qsTr("Volts")
    anchors.bottom: parent.bottom
    anchors.bottomMargin: 10
    font.pixelSize: 12
    color: "grey"
}
}

Gauge {
    id: amphourgauge
    x: 803
    y: 103
    width: 114
    height: 294
    anchors.verticalCenterOffset: 0
    anchors.verticalCenter: parent.verticalCenter
    value: 50

    Text {
        id: text7
        x: 30
        y: 260
        text: qsTr("AMP HOURS")
        anchors.bottom: parent.bottom
        anchors.bottomMargin: -25
        anchors.horizontalCenter: parent.horizontalCenter
        font.pixelSize: 18
        color: "grey"
    }

}



Button {
    id: amphourreset
    objectName: amphourreset
    x: 795
    y: 434
    text: qsTr("Reset")

    onClicked: dashboard.reset(amphourgauge.value)
}



Gauge {
    id: arraycurrent
    x: 621
    y: 160

    Text {
        id: text10
        text: qsTr("Array Current")
        font.pixelSize: 12
        color: "grey"
        anchors.top: parent.top
        anchors.topMargin: -17
        fontSizeMode: Text.FixedSize
        horizontalAlignment: Text.AlignHCenter
        anchors.horizontalCenter: parent.horizontalCenter
    }
}

Gauge {
    id: motorcurrent
    x: 710
    y: 160

    Text {
        id: text9
        text: qsTr("Motor Current")
        font.pixelSize: 12
        color: "grey"
        anchors.top: parent.top
        anchors.topMargin: -17
        fontSizeMode: Text.FixedSize
        horizontalAlignment: Text.AlignHCenter
        anchors.horizontalCenter: parent.horizontalCenter
    }
}

Connections {
    target: dashboard

    onAmpHourvalue: {
    // sub was set through arguments=['amphour']
        amphourgauge.value = amphour
        }

    onAuxVoltage: {
    // sub was set through arguments=['auxvolt']
        auxvoltgauge.value = auxvolt
        }
}

}

Upvotes: 1

Views: 160

Answers (1)

Jarrett Dunn
Jarrett Dunn

Reputation: 31

@daegontaven was correct. The problem was the thread was not connected to the thread containing the GUI. Connecting the two threads solve the issue. I to reorder some of the code. 

class ThreadClass(QThread):
    # Create the signal
    ampHourvalue = pyqtSignal(float, arguments=['amphour'])
    auxVoltage = pyqtSignal(float, arguments=['auxvolt'])
    mainVoltage = pyqtSignal(float, arguments=['mainvolt'])
    arrayCurrent = pyqtSignal(float, arguments=['arraycurrent'])
    motorCurrent = pyqtSignal(float, arguments=['motorcur'])


    def __init__(self, parent=None):
        super(ThreadClass, self).__init__(parent)
        #connects  the signals from the thread to the signals in the thread that is running the GUI

        self.auxVoltage.connect(dashboard.auxVoltage)
        self.mainVoltage.connect(dashboard.mainVoltage)
        self.motorCurrent.connect(dashboard.motorCurrent)
        self.arrayCurrent.connect(dashboard.arrayCurrent)
        self.ampHourvalue.connect(dashboard.ampHourvalue)

Upvotes: 1

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