pyqt5 - PYTHON: Serial read freeze the GUI -

i'm implementing gui pyqt5 , pycharm ide 1 of systems communicates through serial interface. when send appropriate command, system starts data stream packets defined following:

| 0x01 | 0x00 | 0x00 | 0x02 | [...32 bytes...] | 0x03 |

the first, fourth, , last byte markers, second , third control bytes, , remaining 32 bytes information.

when start stream, system receives command gui freezes. started debug watching variable store incoming values.

the simplified code is

def main(): app = qtgui.qapplication(sys.argv)  main = mainwindow() main.show() # app.connect(notifier, signal('activated(int)'), update)  timer = qtcore.qtimer() timer.timeout.connect(main.update) timer.start(2)  app.exec_()  def update(self):     if self.read == true:         self.datain = self.serport.take()         # if self.datain == none:         #     pass         # else:         self.datalist = list(self.datain)         self.disp_chan_1.settext('%f' % (self.datalist[0] * 0.000535434481))         self.disp_chan_2.settext('%f' % (self.datalist[1] * 0.000535694653))         self.disp_chan_3.settext('%f' % (self.datalist[2] * 0.000537407175))         self.disp_chan_4.settext('%f' % (self.datalist[3] * 0.000534853598))         self.disp_chan_5.settext('%f' % (self.datalist[4] * 0.000536425262))         self.disp_chan_6.settext('%f' % (self.datalist[5] * 0.000536408834))         self.disp_chan_7.settext('%f' % (self.datalist[6] * 0.000536337893))         self.disp_chan_8.settext('%f' % (self.datalist[7] * 0.000536237792))     else:         pass  def take(self):     rxtemp1 = self.ser.read(4)     rxdata = self.ser.read(32)     rxtemp2 = self.ser.read(1)     value = struct.unpack('f'*4, rxdata)     return value 

and output of debugger these variables is

rxdata = {bytes}b'\xf2\xa4\xe7=\xc0y\xc4=\xdc\x15\xdc=\xae\xf2\xed=\x9ai;>\xff\xc3\xfe=\xab\x0e\x13>\xebd:a' rxtemp1 = {bytes}b'\x01\x00\x00\x02' rxtemp2 = {bytes}b'\x03' 

it shows rxtemp1 , rxtemp2 variables correct (they collect markers , control bytes) , rxdata variable collects information seems correct.

but gui freezes , have kill process.

what causing error?

i found solution. application freeze because line

value = struct.unpack('f'*4, rxdata) 

in rxdata there 32 bytes unpack command above wants 4 group of 4 bytes, 16 in all. correct command is

value = struct.unpack('f'*8, rxdata) 

i haven't see the output message error because pycharm set wrong.