在断开连接期间处理pyserial中的异常

Question

我有从串行端口读取数据的代码。

try: 
  dataIn = self.port.read(100) 
except serial.SerialException: 
  #do some work
  return None

若我断开设备的连接，我会发现无法处理的异常。

Traceback (most recent call last):
  File "/usr/local/lib/python3.4/dist-packages/serial/serialposix.py", line 475, in read
    raise SerialException('device reports readiness to read but returned no data (device disconnected or multiple access on port?)')
serial.serialutil.SerialException: device reports readiness to read but returned no data (device disconnected or multiple access on port?)
During handling of the above exception, another exception occurred:
Traceback (most recent call last):
  File "/home/katkov/work/obd2rds/obd2rds/testing/python/main.py", line 48, in <module>
    main()
  File "/home/katkov/work/obd2rds/obd2rds/testing/python/main.py", line 41, in main
    dataIn = serPort.read()
  File "/home/katkov/work/obd2rds/obd2rds/testing/python/uart.py", line 55, in read
    dataIn = self.port.read(100)
  File "/usr/local/lib/python3.4/dist-packages/serial/serialposix.py", line 480, in read
    if e[0] != errno.EAGAIN:
TypeError: 'SerialException' object does not support indexing

我如何才能捕捉到处理得当的异常。谢谢

Answer 1

感谢Jonathan Eunice！你的建议解决了我的问题。

现在我使用以下代码：

try:
    dataIn = self.port.read()
except serial.SerialException as e:
    #There is no new data from serial port
    return None
except TypeError as e:
    #Disconnect of USB->UART occured
    self.port.close()
    return None
else:
    #Some data was received
    return dataIn

Answer 2

您没有共享完整的代码，但如果您试图索引出错误号，那么AFAIK是不起作用的。尝试：

try: 
  dataIn = self.port.read(100) 
except serial.SerialException as e:
  # ...
  if e.errno != errno.EAGAIN:
  # ...

此外，如果您正在异常处理程序内部进行可能导致进一步异常的工作，则嵌套处理程序。例如：

try: 
  dataIn = self.port.read(100) 
except serial.SerialException as e:
  try:
    # more dangerous stuff
  except serial.SerialException as e2:
    # handle nested expression