pyqt5用exec（）弹出Dialog无法传递Dialog的信号

问题遇到的现象和发生背景

pyqt5用exec（）弹出Dialog无法传递Dialog的信号

问题相关代码，请勿粘贴截图

Dialog

# -*- coding: utf-8 -*-

# Form implementation generated from reading ui file 'Dialog.ui'
#
# Created by: PyQt5 UI code generator 5.15.4
#
# WARNING: Any manual changes made to this file will be lost when pyuic5 is
# run again.  Do not edit this file unless you know what you are doing.


from PyQt5 import QtCore, QtGui, QtWidgets
from PyQt5.QtWidgets import *
from PyQt5.QtCore import *


class Ui_Dialog(object):
    def setupUi(self, Dialog):
        Dialog.setObjectName("Dialog")
        Dialog.resize(400, 300)
        self.buttonBox = QtWidgets.QDialogButtonBox(Dialog)
        self.buttonBox.setGeometry(QtCore.QRect(90, 210, 201, 32))
        self.buttonBox.setOrientation(QtCore.Qt.Horizontal)
        self.buttonBox.setStandardButtons(QtWidgets.QDialogButtonBox.Cancel|QtWidgets.QDialogButtonBox.Ok)
        self.buttonBox.setObjectName("buttonBox")

        self.retranslateUi(Dialog)
        self.buttonBox.accepted.connect(Dialog.accept)
        self.buttonBox.rejected.connect(Dialog.reject)
        QtCore.QMetaObject.connectSlotsByName(Dialog)

    def retranslateUi(self, Dialog):
        _translate = QtCore.QCoreApplication.translate
        Dialog.setWindowTitle(_translate("Dialog", "Dialog"))


class fun_dialog(Ui_Dialog, QDialog):
    Signal_1 = pyqtSignal(str)

    def __init__(self):
        super(fun_dialog, self).__init__()
        self.setWindowModality(Qt.ApplicationModal)  # 该模式下，只有该dialog关闭，才可以关闭父界面
        self.setupUi(self)

    def accept(self) -> None:
        signal='1'
        self.Signal_1.emit(signal)

MainWindow

# -*- coding: utf-8 -*-

# Form implementation generated from reading ui file 'Main.ui'
#
# Created by: PyQt5 UI code generator 5.15.4
#
# WARNING: Any manual changes made to this file will be lost when pyuic5 is
# run again.  Do not edit this file unless you know what you are doing.


from PyQt5 import QtCore, QtGui, QtWidgets
from Dialog import fun_dialog

class Ui_MainWindow(object):
    def setupUi(self, MainWindow):
        MainWindow.setObjectName("MainWindow")
        MainWindow.resize(800, 600)
        self.centralwidget = QtWidgets.QWidget(MainWindow)
        self.centralwidget.setObjectName("centralwidget")
        self.pushButton = QtWidgets.QPushButton(self.centralwidget)
        self.pushButton.setGeometry(QtCore.QRect(340, 250, 93, 28))
        self.pushButton.setObjectName("pushButton")
        MainWindow.setCentralWidget(self.centralwidget)
        self.menubar = QtWidgets.QMenuBar(MainWindow)
        self.menubar.setGeometry(QtCore.QRect(0, 0, 800, 26))
        self.menubar.setObjectName("menubar")
        MainWindow.setMenuBar(self.menubar)
        self.statusbar = QtWidgets.QStatusBar(MainWindow)
        self.statusbar.setObjectName("statusbar")
        MainWindow.setStatusBar(self.statusbar)

        self.pushButton.clicked.connect(self.out_dialog)

        self.retranslateUi(MainWindow)
        QtCore.QMetaObject.connectSlotsByName(MainWindow)

    def retranslateUi(self, MainWindow):
        _translate = QtCore.QCoreApplication.translate
        MainWindow.setWindowTitle(_translate("MainWindow", "MainWindow"))
        self.pushButton.setText(_translate("MainWindow", "PushButton"))

    def out_dialog(self):
        self.dialog=fun_dialog()
        self.dialog.exec_()
        self.dialog.Signal_1.connect(self.get_signal)
    def get_signal(self,data):
        self.S=data
        print(self.S)

if __name__ == "__main__":
    import sys
    app = QtWidgets.QApplication(sys.argv)
    MainWindow = QtWidgets.QMainWindow()
    ui = Ui_MainWindow()
    ui.setupUi(MainWindow)
    MainWindow.show()
    sys.exit(app.exec_())

运行结果及报错内容

如果用show（）弹出Dialog可以打印self.S==>‘1’，exec_（）则不能。

我想要达到的结果

我目的是在弹出Dialog时，能阻塞主进程，同时能发出并接收Dialog的信号。

设置父窗口试试