Python: pyserial 超时似乎不适用于连接

Question

如果未连接 COM 端口，我试图让 python 失败：

import serial

ser = serial

print("ermrmrmrr")
try:
    ser = serial.Serial(
        port        = 'COM6',
        baudrate    = 115200,
        parity      = serial.PARITY_NONE,
        stopbits    = serial.STOPBITS_ONE,
        bytesize    = serial.EIGHTBITS,
        timeout     = 1,
        )
except:
    print("what what in the butt")
    ser.close()
    sys.exit(0)

print("grrrrr")

输出是：

ermrmrmrr
what what in the butt
Traceback (most recent call last):
  File "C:\Projects\Personal\Alex_Quadcopter\mine\scripts\lib\GetData.py", line 21, in <module>
    write_timeout = 1,
  File "C:\Users\dingleberry\AppData\Local\Programs\Python\Python36-32\lib\site-packages\serial\serialwin32.py", line 31, in __init__
    super(Serial, self).__init__(*args, **kwargs)
  File "C:\Users\dingleberry\AppData\Local\Programs\Python\Python36-32\lib\site-packages\serial\serialutil.py", line 240, in __init__
    self.open()
  File "C:\Users\dingleberry\AppData\Local\Programs\Python\Python36-32\lib\site-packages\serial\serialwin32.py", line 78, in open
    self._reconfigure_port()
  File "C:\Users\dingleberry\AppData\Local\Programs\Python\Python36-32\lib\site-packages\serial\serialwin32.py", line 222, in _reconfigure_port
    'Original message: {!r}'.format(ctypes.WinError()))
serial.serialutil.SerialException: Cannot configure port, something went wrong. Original message: OSError(22, 'The semaphore timeout period has expired.', None, 121)

During handling of the above exception, another exception occurred:

Traceback (most recent call last):
  File ".\PrincipalAxes.py", line 11, in <module>
    from lib import GetData as gd
  File "C:\Projects\Personal\Alex_Quadcopter\mine\scripts\lib\GetData.py", line 25, in <module>
    print("what what in the butt")

这个输出有点正常，除了它超时 30 秒 - 尝试连接后 1 分钟，而不是超时 1 秒后。

似乎 "The semaphore timeout period has expired." 超时，而不是实际的连接尝试。

Answer 1

问题是您无法关闭 ser，因为发生了致命的事情。

你应该将你的捕获分解为单独的异常，而不是捕获所有异常。例如：

except serial.SerialException as e:
    #There is no new data from serial port
    print str(e)
    sys.exit(1)
except TypeError as e:
    print str(e)
    ser.port.close()
    sys.exit(1)

另请注意，通常将 0 传递给 sys.exit 表示成功。您应该传递 1 或其他一些非零数字来表示失败。

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