import sys
from PyQt5 import QtCore, QtWidgets
from PyQt5.QtWidgets import QMainWindow, QLabel, QGridLayout, QWidget
from PyQt5.QtWidgets import QPushButton
from PyQt5.QtCore import QSize

import serial

#ser = serial.Serial('\\\\.\\COM7/dev/ttyUSB0') //This is my serial port address (Windows only need the COM declared, so I left only it)
#print(ser.name)
#ser.write(b'1')
#ser.close()


class Interface(QWidget):

    def __init__(self):
        super().__init__()

        self.initUI()


    def initUI(self):
        pybutton = QPushButton('OK', self)           //My button will contain the "OK" written
        pybutton.clicked.connect(self.clickMethod)	 //The "OK" button can be clicked
        pybutton.resize(100,32)
        pybutton.move(100, 100)						//Numbers referred to the position the widget has on the screen
        self.setMinimumSize(QSize(300, 200))

        self.setWindowTitle('MY WIDGET')			//Title I want to see on my window's interface
        self.show()

    def clickMethod(self):
        print('Clicked button.')
        ser = serial.Serial('COM7')
        print(ser.name)
        ser.write(b'1')
        ser.close()


if __name__ == "__main__":
    app = QtWidgets.QApplication(sys.argv)
    mainWin = Interface()
    mainWin.show()
    sys.exit( app.exec_() )