读取串口数据实时显示到textbrower,但会线程阻塞，求大神指教

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

# Form implementation generated from reading ui file '22.ui'

#

# Created by: PyQt5 UI code generator 5.10.1

#

# WARNING! All changes made in this file will be lost!

import sys, serial, pexpect, time

from PyQt5 import QtCore, QtGui, QtWidgets

from PyQt5.QtCore import *

from PyQt5.QtGui import *

from PyQt5.QtWidgets import *

class BackendThread(QThread):

sec_changed_signal = pyqtSignal(int)

def __init__(self, sec=1000, parent=None):

super().__init__(parent)

self.sec = sec # 默认1000ms

def run(self):

for i in range(self.sec):

self.sec_changed_signal.emit(i)

time.sleep(0.001)

class Ui_MainWindow:

def setupUi(self, MainWindow):

self.window = MainWindow

MainWindow.setObjectName("MainWindow")

MainWindow.resize(970, 575)

self.centralwidget = QtWidgets.QWidget(MainWindow)

self.centralwidget.setObjectName("centralwidget")

self.textBrowser = QtWidgets.QTextBrowser(self.centralwidget)

self.textBrowser.setGeometry(QtCore.QRect(300, 10, 641, 521))

self.textBrowser.setMouseTracking(False)

self.textBrowser.setObjectName("textBrowser")

self.textBrowser.setVerticalScrollBarPolicy(QtCore.Qt.ScrollBarAlwaysOn)

self.textBrowser.setHorizontalScrollBarPolicy(QtCore.Qt.ScrollBarAlwaysOn)

self.widget = QtWidgets.QWidget(self.centralwidget)

self.widget.setGeometry(QtCore.QRect(10, 40, 281, 29))

self.widget.setObjectName("widget")

self.horizontalLayout = QtWidgets.QHBoxLayout(self.widget)

self.horizontalLayout.setContentsMargins(0, 0, 0, 0)

self.horizontalLayout.setObjectName("horizontalLayout")

# start com

self.lineEdit = QtWidgets.QLineEdit(self.widget)

self.lineEdit.setObjectName("lineEdit")

self.horizontalLayout.addWidget(self.lineEdit)

self.pushButton = QtWidgets.QPushButton(self.widget)

self.pushButton.setObjectName("pushButton")

self.horizontalLayout.addWidget(self.pushButton)

self.widget1 = QtWidgets.QWidget(self.centralwidget)

self.widget1.setGeometry(QtCore.QRect(40, 440, 221, 51))

self.widget1.setObjectName("widget1")

self.horizontalLayout_3 = QtWidgets.QHBoxLayout(self.widget1)

self.horizontalLayout_3.setContentsMargins(0, 0, 0, 20)

self.horizontalLayout_3.setObjectName("horizontalLayout_3")

self.pushButton_5 = QtWidgets.QPushButton(self.widget1)

self.pushButton_5.setFlat(False)

self.pushButton_5.setObjectName("pushButton_5")

self.horizontalLayout_3.addWidget(self.pushButton_5)

self.pushButton_4 = QtWidgets.QPushButton(self.widget1)

self.pushButton_4.setObjectName("pushButton_4")

self.horizontalLayout_3.addWidget(self.pushButton_4)

self.widget2 = QtWidgets.QWidget(self.centralwidget)

self.widget2.setGeometry(QtCore.QRect(1, 123, 301, 271))

self.widget2.setObjectName("widget2")

self.verticalLayout = QtWidgets.QVBoxLayout(self.widget2)

self.verticalLayout.setContentsMargins(0, 0, 0, 0)

self.verticalLayout.setObjectName("verticalLayout")

self.label = QtWidgets.QLabel(self.widget2)

self.label.setObjectName("label")

self.verticalLayout.addWidget(self.label)

self.checkBox_6 = QtWidgets.QCheckBox(self.widget2)

self.checkBox_6.setEnabled(True)

font = QtGui.QFont()

font.setBold(True)

font.setWeight(75)

self.checkBox_6.setFont(font)

self.checkBox_6.setAutoFillBackground(False)

self.checkBox_6.setChecked(True)

self.checkBox_6.setTristate(False)

self.checkBox_6.setObjectName("checkBox_6")

self.verticalLayout.addWidget(self.checkBox_6)

self.checkBox_2 = QtWidgets.QCheckBox(self.widget2)

self.checkBox_2.setObjectName("checkBox_2")

self.verticalLayout.addWidget(self.checkBox_2)

self.checkBox_5 = QtWidgets.QCheckBox(self.widget2)

self.checkBox_5.setObjectName("checkBox_5")

self.verticalLayout.addWidget(self.checkBox_5)

self.checkBox_4 = QtWidgets.QCheckBox(self.widget2)

self.checkBox_4.setObjectName("checkBox_4")

self.verticalLayout.addWidget(self.checkBox_4)

self.checkBox_3 = QtWidgets.QCheckBox(self.widget2)

self.checkBox_3.setObjectName("checkBox_3")

self.verticalLayout.addWidget(self.checkBox_3)

self.checkBox = QtWidgets.QCheckBox(self.widget2)

self.checkBox.setObjectName("checkBox")

self.verticalLayout.addWidget(self.checkBox)

MainWindow.setCentralWidget(self.centralwidget)

self.menubar = QtWidgets.QMenuBar(MainWindow)

self.menubar.setGeometry(QtCore.QRect(0, 0, 970, 25))

self.menubar.setObjectName("menubar")

MainWindow.setMenuBar(self.menubar)

self.statusbar = QtWidgets.QStatusBar(MainWindow)

self.statusbar.setObjectName("statusbar")

MainWindow.setStatusBar(self.statusbar)

self.retranslateUi(MainWindow)

QtCore.QMetaObject.connectSlotsByName(MainWindow)

def retranslateUi(self, MainWindow):

_translate = QtCore.QCoreApplication.translate

MainWindow.setWindowTitle(_translate("MainWindow", "MainWindow"))

self.lineEdit.setText(_translate("MainWindow", "请输入当前系统密码"))

self.pushButton.setText(_translate("MainWindow", "PushButton"))

self.lineEdit.selectAll()

self.lineEdit.setFocus()

self.pushButton.setText(_translate("MainWindow", "启动串口"))

self.pushButton.clicked.connect(self.startCom)

# 读取按钮和取消按钮功能连接

# 启动线程

thread = BackendThread()

thread.sec_changed_signal.connect(self.update)

self.pushButton_5.setText(_translate("MainWindow", "开始读取"))

self.pushButton_5.clicked.connect(lambda: thread.start())

self.pushButton_4.setText(_translate("MainWindow", "停止读取"))

self.pushButton_4.clicked.connect(lambda : thread.terminate())

self.label.setText(_translate("MainWindow", "选择串口位置："))

self.checkBox_6.setText(_translate("MainWindow", "All"))

self.checkBox_2.setText(_translate("MainWindow", "Head"))

self.checkBox_5.setText(_translate("MainWindow", "Wheel"))

self.checkBox_4.setText(_translate("MainWindow", "Arm"))

self.checkBox_3.setText(_translate("MainWindow", "Wheel"))

self.checkBox.setText(_translate("MainWindow", "Query"))

def startCom(self):

pass_word = self.lineEdit.text()

shell_cmd = 'cd /dev && sudo chmod 777 ttyUSB*'

child = pexpect.spawn('/bin/bash', ['-c', shell_cmd]).sendline(pass_word)

@staticmethod

def readData():

pos = True

with serial.Serial('/dev/ttyUSB0', '256000') as ser:

with open("shoulder.txt", 'a') as f:

while True:

s = ser.read()

h = hex(ord(s))

if h == '0xff' and pos:

f.write('\n')

f.write(time.strftime("%m-%d %H:%M:%S: ", time.localtime()))

f.write(h + " ")

pos = False

else:

f.write(

h + " "

)

pos = True

def update(self, sec):

self.readData()

text_edit = QPlainTextEdit()

text = open('shoulder.txt').read()

self.textBrowser.setPlainText(text)

if __name__ == "__main__":

app = QtWidgets.QApplication(sys.argv)

ex = Ui_MainWindow()

w = QtWidgets.QMainWindow()

ex.setupUi(w)

w.show()

sys.exit(app.exec_())

因为我要实时读取串口的数据存到一个文件，但将数据显示到textbrower时就会在readData()阻塞，不知道怎么办？