为什么以下鼠标单击代码会导致Windows错误997？

Question

I am doing a mini project where a switch press results in a mouse click or in other words the switch acts as an alternative to my left mouse button.

My code is

import pyautogui , time , serial

port = serial.Serial('COM3',9600)
flag=0

while 1:
    reading=port.read()
    x=ord(reading)
    if x==1 and flag==0:
        flag=1
        pyautogui.mouseDown()
    elif x==2:
        flag=0
        pyautogui.mouseUp()

The serial transmission is such that it receives a

0 - Switch not pressed
1 - Switch pressed
2 - switch just left

A 2 is always transmitted in between a 1 and a 0.

My problem is that when I run this code the following error occurs after one mouse click.

Traceback (most recent call last):

File "C:\\Python27\\LeftClick.py", line 12, in pyautogui.mouseUp()

File "C:\\Python27\\lib\\site-packages\\pyautogui__init__.py", line 234, in mouseUp

platformModule._mouseUp(x, y, 'left')

File "C:\\Python27\\lib\\site-packages\\pyautogui_pyautogui_win.py", line 415, in _mouseUp

_sendMouseEvent(MOUSEEVENTF_LEFTUP, x, y)

File "C:\\Python27\\lib\\site-packages\\pyautogui_pyautogui_win.py", line 480, in _sendMouseEvent raise ctypes.WinError()

WindowsError: [Error 997] Overlapped I/O operation is in progress.

Answer 1

In the comments above, you say that if you take serial out, the program works as expected, if I read it correctly. You also say that mouse movement works OK on COM3, but if removing the serial comms fixes the issue, then I'd say that's a fairly strong indication that COM3 may be the culprit, it should certainly be investigated.

My suggestion: Use a different COM port for your serial device. You can change the number used by going into:

Device Manager > Ports (COM & LPT) > Right Click your device > Properties > Port Settings > Advanced > COM Port Number