Python串口模块配置端口失败
Python serial module failing to configure port
我正在使用 Python3.5.1 serial module。当我打开一个端口时，它失败并显示 OS 错误 22（Windows 错误 87），它表示 failure to configure port, one of the arguments in OPEN system call were incorrect, or malformed.
我的代码使用串行设置循环 - 向设备发送错误的数据包，直到设备以（可读的）错误消息响应（因此我知道我的串行端口配置正确）。是的，我应该只知道设备的设置，但这不是一个完美的世界。
import serial
import time
baud_rate = [50,75,110,134,150,200,300600,1200,1800,2400,4800,9600,19200,38400,57600,115200]
parity = [serial.PARITY_ODD,serial.PARITY_EVEN,serial.PARITY_NONE]
stop_bits = [serial.STOPBITS_TWO, serial.STOPBITS_ONE]
bytesize = [serial.SEVENBITS,serial.EIGHTBITS]
timeout = 5000
for b in baud_rate:
for p in parity:
for s in stop_bits:
for bs in bytesize:
ser = serial.Serial(port='COM3',baudrate=b,parity=p,stopbits=s,bytesize=bs)
try:
if ser.isOpen():
ser.write(b'TEST')
ser.reset_output_buffer()
time.sleep(1)
out = ser.read(3)
if out[0] == 64 and out[1] == 67 and out[2] == 32:
print("dumping settings")
print(ser.get_settings())
else:
ser.close()
except SerialException:
print("Serial Exception occured.")
pass
问题发生在windows 7 x64 service pack 1下。python版本是3.5。 cmd.exe 实例是 运行 作为管理员。
当我 运行 脚本
时，我非常确定 COM3 存在
import serial.tools.list_ports
ports = list(serial.tools.list_ports.comports())
for p in ports:
print(p)
我收到输出：
>python list_serial.py
COM3 - Prolific USB-to-Serial Comm Port (COM3)
所以我相信端口 URL/URI (idfk) 是正确的。
完整错误文本：
Traceback (most recent call last):
File "serial_reader.py", line 13, in <module>
ser = serial.Serial(port='COM3',baudrate=b,parity=p,stopbits=s,bytesize=bs)
File "C:\Users\FA1\AppData\Local\Programs\Python\Python35-32\lib\site-packages\serial\serialwin32.py", line 31, in __init__
SerialBase.__init__(self, *args, **kwargs)
File "C:\Users\FA1\AppData\Local\Programs\Python\Python35-32\lib\site-packages\serial\serialutil.py", line 180, in __init__
self.open()
File "C:\Users\FA1\AppData\Local\Programs\Python\Python35-32\lib\site-packages\serial\serialwin32.py", line 78, in open
self._reconfigure_port()
File "C:\Users\FA1\AppData\Local\Programs\Python\Python35-32\lib\site-packages\serial\serialwin32.py", line 220, in _reconfigure_port
raise SerialException("Cannot configure port, something went wrong. Original message: %r" % ctypes.WinError())
serial.serialutil.SerialException: Cannot configure port, something went wrong. Original message: OSError(22, 'The parameter is incorrect.', None, 87)
我已确保驱动程序已正确安装，但我在使用 2 个不同的串行转换器时收到此错误。所以我认为问题与硬件或驱动程序无关。
波特率 <100 在 Windows 7 中被视为配置错误。因此，以 50,75 波特开始循环都会产生错误。 110 波特不会 return 错误。
你说你"should just know the device's settings but this isn't a prefect world"。但是Windows does allow querying communication device properties via GetCommProperties. pySerial 似乎不支持这个，但是你可以使用ctypes直接调用这个函数。
下面定义了一个get_comm_properties函数来查询comm口的可设置属性。它接受现有的设备句柄（例如 pySerial 端口的 _handle 属性）或 DOS 设备名称（例如 COM1）或 WinAPI 设备名称（例如 \.\COM1）。
import collections
import ctypes
from ctypes import wintypes
kernel32 = ctypes.WinDLL('kernel32', use_last_error=True)
GENERIC_READ = 0x80000000
GENERIC_WRITE = 0x40000000
OPEN_EXISTING = 3
INVALID_HANDLE_VALUE = wintypes.HANDLE(-1).value
ERROR_FILE_NOT_FOUND = 0x0002
class COMMPROP(ctypes.Structure):
_fields_= (('wPacketLength', wintypes.WORD),
('wPacketVersion', wintypes.WORD),
('dwServiceMask', wintypes.DWORD),
('dwReserved1', wintypes.DWORD),
('dwMaxTxQueue', wintypes.DWORD),
('dwMaxRxQueue', wintypes.DWORD),
('dwMaxBaud', wintypes.DWORD),
('dwProvSubType', wintypes.DWORD),
('dwProvCapabilities', wintypes.DWORD),
('dwSettableParams', wintypes.DWORD),
('dwSettableBaud', wintypes.DWORD),
('wSettableData', wintypes.WORD),
('wSettableStopParity', wintypes.WORD),
('dwCurrentTxQueue', wintypes.DWORD),
('dwCurrentRxQueue', wintypes.DWORD),
('dwProvSpec1', wintypes.DWORD),
('dwProvSpec2', wintypes.DWORD),
('wcProvChar', wintypes.WCHAR * 1))
class _CONST:
COMMPROP_INITIALIZED = 0xE73CF52E
SP_SERIALCOMM = 0x00000001
BAUD_USER = 0x10000000 # programmable baud rate
DATABITS_16X = 0x0020 # hardware wide data path
PROV_SUBTYPE = collections.OrderedDict([
('UNSPECIFIED', 0x00000000),
('RS232', 0x00000001),
('PARALLELPORT', 0x00000002),
('RS422', 0x00000003),
('RS423', 0x00000004),
('RS449', 0x00000005),
('MODEM', 0x00000006),
('FAX', 0x00000021),
('SCANNER', 0x00000022),
('NETWORK_BRIDGE', 0x00000100),
('LAT', 0x00000101),
('TCPIP_TELNET', 0x00000102),
('X25', 0x00000103),
])
PROV_CAPABILITIES = collections.OrderedDict([
('DTRDSR', 0x0001), # data-terminal-ready / data-set-ready
('RTSCTS', 0x0002), # request-to-send / clear-to-send
('RLSD', 0x0004), # receive-line-signal-detect
('PARITY_CHECK', 0x0008),
('XONXOFF', 0x0010), # XON/XOFF flow control
('SETXCHAR', 0x0020), # settable XON/XOFF
('TOTALTIMEOUTS', 0x0040), # total (elapsed) time-outs
('INTTIMEOUTS', 0x0080), # interval time-outs
('SPECIALCHARS', 0x0100),
('16BITMODE', 0x0200),
])
SETTABLE_PARAMS = collections.OrderedDict([
('PARITY', 0x0001),
('BAUD', 0x0002),
('DATABITS', 0x0004),
('STOPBITS', 0x0008),
('HANDSHAKING', 0x0010), # flow control
('PARITY_CHECK', 0x0020),
('RLSD', 0x0040), # receive-line-signal-detect
])
SETTABLE_BAUD = collections.OrderedDict([
(75, 0x00000001),
(110, 0x00000002),
(134.5, 0x00000004),
(150, 0x00000008),
(300, 0x00000010),
(600, 0x00000020),
(1200, 0x00000040),
(1800, 0x00000080),
(2400, 0x00000100),
(4800, 0x00000200),
(7200, 0x00000400),
(9600, 0x00000800),
(14400, 0x00001000),
(19200, 0x00002000),
(38400, 0x00004000),
(56000, 0x00008000),
(57600, 0x00040000),
(115200, 0x00020000),
(128000, 0x00010000),
])
SETTABLE_DATA = collections.OrderedDict([
(5, 0x0001), # 5 data bits
(6, 0x0002), # 6 data bits
(7, 0x0004), # 7 data bits
(8, 0x0008), # 8 data bits
(16, 0x0010), # 16 data bits
])
SETTABLE_STOP = collections.OrderedDict([
(1, 0x0001), # 1 stop bit
(1.5, 0x0002), # 1.5 stop bits
(2, 0x0004), # 2 stop bits
])
SETTABLE_PARITY = collections.OrderedDict([
('NONE', 0x0100), # no parity
('ODD', 0x0200), # odd parity
('EVEN', 0x0400), # even parity
('MARK', 0x0800), # mark parity
('SPACE', 0x1000), # space parity
])
@property
def max_baud(self):
s = self.dwMaxBaud
m = self._CONST.SETTABLE_BAUD
if s == self._CONST.BAUD_USER:
return 0
else:
return m[s]
@property
def prov_subtype(self):
s = self.dwProvSubType
m = self._CONST.PROV_SUBTYPE
return [x for x, c in m.items() if c & s]
@property
def prov_capabilities(self):
s = self.dwProvCapabilities
m = self._CONST.PROV_CAPABILITIES
return [x for x, c in m.items() if c & s]
@property
def settable_params(self):
s = self.dwSettableParams
m = self._CONST.SETTABLE_PARAMS
return [x for x, c in m.items() if c & s]
@property
def settable_baud(self):
s = self.dwSettableBaud
m = self._CONST.SETTABLE_BAUD
return [x for x, c in m.items() if c & s]
@property
def user_settable_baud(self):
return bool(self.dwSettableBaud & self._CONST.BAUD_USER)
@property
def settable_data(self):
s = self.wSettableData
m = self._CONST.SETTABLE_DATA
return [x for x, c in m.items() if c & s]
@property
def wide_settable_data(self):
return bool(self.wSettableData & self._CONST.DATABITS_16X)
@property
def settable_stop(self):
s = self.wSettableStopParity
m = self._CONST.SETTABLE_STOP
return [x for x, c in m.items() if c & s]
@property
def settable_parity(self):
s = self.wSettableStopParity
m = self._CONST.SETTABLE_PARITY
return [x for x, c in m.items() if c & s]
LPCOMMPROP = ctypes.POINTER(COMMPROP)
class SECURITY_ATTRIBUTES(ctypes.Structure):
_fields_ = (('nLength', wintypes.DWORD),
('lpSecurityDescriptor', wintypes.LPVOID),
('bInheritHandle', wintypes.BOOL))
LPSECURITY_ATTRIBUTES = ctypes.POINTER(SECURITY_ATTRIBUTES)
kernel32.CreateFileW.restype = wintypes.HANDLE
kernel32.CreateFileW.argtypes = (
wintypes.LPCWSTR, # _In_ lpFileName
wintypes.DWORD, # _In_ dwDesiredAccess
wintypes.DWORD, # _In_ dwShareMode
LPSECURITY_ATTRIBUTES, # _In_opt_ lpSecurityAttributes
wintypes.DWORD, # _In_ dwCreationDisposition
wintypes.DWORD, # _In_ dwFlagsAndAttributes
wintypes.HANDLE) # _In_opt_ hTemplateFile
kernel32.CloseHandle.argtypes = (wintypes.HANDLE,)
kernel32.GetCommProperties.argtypes = (
wintypes.HANDLE, # _In_ hFile
LPCOMMPROP) # _Out_ lpCommProp
def get_comm_properties(handle_or_port):
if isinstance(handle_or_port, str):
handle = kernel32.CreateFileW(
handle_or_port,
GENERIC_READ | GENERIC_WRITE,
0, # exclusive access
None, # default security
OPEN_EXISTING,
0,
None)
if handle == INVALID_HANDLE_VALUE:
raise ctypes.WinError(ctypes.get_last_error())
close_handle = True
else:
handle = handle_or_port
close_handle = False
try:
prop = COMMPROP()
if not kernel32.GetCommProperties(handle, ctypes.byref(prop)):
raise ctypes.WinError(ctypes.get_last_error())
finally:
if close_handle:
kernel32.CloseHandle(handle)
return prop
示例：
if __name__ == '__main__':
for i in range(1, 10):
port = r'\.\COM%d' % i
try:
prop = get_comm_properties(port)
except WindowsError as e:
if e.winerror == ERROR_FILE_NOT_FOUND:
continue
print('%s properties' % port)
x = prop.dwMaxTxQueue if prop.dwMaxTxQueue else 'no limit'
print('\tMax output buffer size: %s' % x)
x = prop.dwMaxRxQueue if prop.dwMaxRxQueue else 'no limit'
print('\tMax input buffer size: %s' % x)
x = prop.dwCurrentTxQueue if prop.dwCurrentTxQueue else 'unavailable'
print('\tCurrent output buffer size: %s' % x)
x = prop.dwCurrentRxQueue if prop.dwCurrentRxQueue else 'unavailable'
print('\tCurrent input buffer size: %s' % x)
x = prop.max_baud if prop.max_baud else 'user programmable'
print('\tMax baud rate: %s' % x)
print('\tProvider subtypes:\n\t\t%s' %
'\n\t\t'.join(prop.prov_subtype))
print('\tProvider capabilities:\n\t\t%s' %
'\n\t\t'.join(prop.prov_capabilities))
print('\tSettable parameters:\n\t\t%s' %
'\n\t\t'.join(prop.settable_params))
print('\tSettable baud rates:\n\t\t%s' %
'\n\t\t'.join([str(x) for x in prop.settable_baud]))
print('\tSettable user baud rates: %s' %
prop.user_settable_baud)
print('\tSettable data bits:\n\t\t%s' %
'\n\t\t'.join([str(x) for x in prop.settable_data]))
print('\tSettable wide data bits: %s' %
prop.wide_settable_data)
print('\tSettable stop bits:\n\t\t%s' %
'\n\t\t'.join([str(x) for x in prop.settable_stop]))
print('\tSettable parity:\n\t\t%s' %
'\n\t\t'.join(prop.settable_parity))
输出：
\.\COM1 properties
Max output buffer size: no limit
Max input buffer size: no limit
Current output buffer size: unavailable
Current input buffer size: 4096
Max baud rate: user programmable
Provider subtypes:
RS232
RS422
RS449
FAX
LAT
X25
Provider capabilities:
DTRDSR
RTSCTS
RLSD
PARITY_CHECK
XONXOFF
SETXCHAR
TOTALTIMEOUTS
INTTIMEOUTS
Settable parameters:
PARITY
BAUD
DATABITS
STOPBITS
HANDSHAKING
PARITY_CHECK
RLSD
Settable baud rates:
75
110
134.5
150
300
600
1200
1800
2400
4800
7200
9600
14400
19200
38400
56000
57600
115200
Settable user baud rates: True
Settable data bits:
5
6
7
8
Settable wide data bits: False
Settable stop bits:
1
1.5
2
Settable parity:
NONE
ODD
EVEN
MARK
SPACE
我正在使用 Python3.5.1 serial module。当我打开一个端口时，它失败并显示 OS 错误 22（Windows 错误 87），它表示 failure to configure port, one of the arguments in OPEN system call were incorrect, or malformed.
我的代码使用串行设置循环 - 向设备发送错误的数据包，直到设备以（可读的）错误消息响应（因此我知道我的串行端口配置正确）。是的，我应该只知道设备的设置，但这不是一个完美的世界。
import serial
import time
baud_rate = [50,75,110,134,150,200,300600,1200,1800,2400,4800,9600,19200,38400,57600,115200]
parity = [serial.PARITY_ODD,serial.PARITY_EVEN,serial.PARITY_NONE]
stop_bits = [serial.STOPBITS_TWO, serial.STOPBITS_ONE]
bytesize = [serial.SEVENBITS,serial.EIGHTBITS]
timeout = 5000
for b in baud_rate:
for p in parity:
for s in stop_bits:
for bs in bytesize:
ser = serial.Serial(port='COM3',baudrate=b,parity=p,stopbits=s,bytesize=bs)
try:
if ser.isOpen():
ser.write(b'TEST')
ser.reset_output_buffer()
time.sleep(1)
out = ser.read(3)
if out[0] == 64 and out[1] == 67 and out[2] == 32:
print("dumping settings")
print(ser.get_settings())
else:
ser.close()
except SerialException:
print("Serial Exception occured.")
pass
问题发生在windows 7 x64 service pack 1下。python版本是3.5。 cmd.exe 实例是 运行 作为管理员。
当我 运行 脚本
时，我非常确定 COM3 存在 import serial.tools.list_ports
ports = list(serial.tools.list_ports.comports())
for p in ports:
print(p)
我收到输出：
>python list_serial.py
COM3 - Prolific USB-to-Serial Comm Port (COM3)
所以我相信端口 URL/URI (idfk) 是正确的。
完整错误文本：
Traceback (most recent call last):
File "serial_reader.py", line 13, in <module>
ser = serial.Serial(port='COM3',baudrate=b,parity=p,stopbits=s,bytesize=bs)
File "C:\Users\FA1\AppData\Local\Programs\Python\Python35-32\lib\site-packages\serial\serialwin32.py", line 31, in __init__
SerialBase.__init__(self, *args, **kwargs)
File "C:\Users\FA1\AppData\Local\Programs\Python\Python35-32\lib\site-packages\serial\serialutil.py", line 180, in __init__
self.open()
File "C:\Users\FA1\AppData\Local\Programs\Python\Python35-32\lib\site-packages\serial\serialwin32.py", line 78, in open
self._reconfigure_port()
File "C:\Users\FA1\AppData\Local\Programs\Python\Python35-32\lib\site-packages\serial\serialwin32.py", line 220, in _reconfigure_port
raise SerialException("Cannot configure port, something went wrong. Original message: %r" % ctypes.WinError())
serial.serialutil.SerialException: Cannot configure port, something went wrong. Original message: OSError(22, 'The parameter is incorrect.', None, 87)
我已确保驱动程序已正确安装，但我在使用 2 个不同的串行转换器时收到此错误。所以我认为问题与硬件或驱动程序无关。
波特率 <100 在 Windows 7 中被视为配置错误。因此，以 50,75 波特开始循环都会产生错误。 110 波特不会 return 错误。
你说你"should just know the device's settings but this isn't a prefect world"。但是Windows does allow querying communication device properties via GetCommProperties. pySerial 似乎不支持这个，但是你可以使用ctypes直接调用这个函数。
下面定义了一个get_comm_properties函数来查询comm口的可设置属性。它接受现有的设备句柄（例如 pySerial 端口的 _handle 属性）或 DOS 设备名称（例如 COM1）或 WinAPI 设备名称（例如 \.\COM1）。
import collections
import ctypes
from ctypes import wintypes
kernel32 = ctypes.WinDLL('kernel32', use_last_error=True)
GENERIC_READ = 0x80000000
GENERIC_WRITE = 0x40000000
OPEN_EXISTING = 3
INVALID_HANDLE_VALUE = wintypes.HANDLE(-1).value
ERROR_FILE_NOT_FOUND = 0x0002
class COMMPROP(ctypes.Structure):
_fields_= (('wPacketLength', wintypes.WORD),
('wPacketVersion', wintypes.WORD),
('dwServiceMask', wintypes.DWORD),
('dwReserved1', wintypes.DWORD),
('dwMaxTxQueue', wintypes.DWORD),
('dwMaxRxQueue', wintypes.DWORD),
('dwMaxBaud', wintypes.DWORD),
('dwProvSubType', wintypes.DWORD),
('dwProvCapabilities', wintypes.DWORD),
('dwSettableParams', wintypes.DWORD),
('dwSettableBaud', wintypes.DWORD),
('wSettableData', wintypes.WORD),
('wSettableStopParity', wintypes.WORD),
('dwCurrentTxQueue', wintypes.DWORD),
('dwCurrentRxQueue', wintypes.DWORD),
('dwProvSpec1', wintypes.DWORD),
('dwProvSpec2', wintypes.DWORD),
('wcProvChar', wintypes.WCHAR * 1))
class _CONST:
COMMPROP_INITIALIZED = 0xE73CF52E
SP_SERIALCOMM = 0x00000001
BAUD_USER = 0x10000000 # programmable baud rate
DATABITS_16X = 0x0020 # hardware wide data path
PROV_SUBTYPE = collections.OrderedDict([
('UNSPECIFIED', 0x00000000),
('RS232', 0x00000001),
('PARALLELPORT', 0x00000002),
('RS422', 0x00000003),
('RS423', 0x00000004),
('RS449', 0x00000005),
('MODEM', 0x00000006),
('FAX', 0x00000021),
('SCANNER', 0x00000022),
('NETWORK_BRIDGE', 0x00000100),
('LAT', 0x00000101),
('TCPIP_TELNET', 0x00000102),
('X25', 0x00000103),
])
PROV_CAPABILITIES = collections.OrderedDict([
('DTRDSR', 0x0001), # data-terminal-ready / data-set-ready
('RTSCTS', 0x0002), # request-to-send / clear-to-send
('RLSD', 0x0004), # receive-line-signal-detect
('PARITY_CHECK', 0x0008),
('XONXOFF', 0x0010), # XON/XOFF flow control
('SETXCHAR', 0x0020), # settable XON/XOFF
('TOTALTIMEOUTS', 0x0040), # total (elapsed) time-outs
('INTTIMEOUTS', 0x0080), # interval time-outs
('SPECIALCHARS', 0x0100),
('16BITMODE', 0x0200),
])
SETTABLE_PARAMS = collections.OrderedDict([
('PARITY', 0x0001),
('BAUD', 0x0002),
('DATABITS', 0x0004),
('STOPBITS', 0x0008),
('HANDSHAKING', 0x0010), # flow control
('PARITY_CHECK', 0x0020),
('RLSD', 0x0040), # receive-line-signal-detect
])
SETTABLE_BAUD = collections.OrderedDict([
(75, 0x00000001),
(110, 0x00000002),
(134.5, 0x00000004),
(150, 0x00000008),
(300, 0x00000010),
(600, 0x00000020),
(1200, 0x00000040),
(1800, 0x00000080),
(2400, 0x00000100),
(4800, 0x00000200),
(7200, 0x00000400),
(9600, 0x00000800),
(14400, 0x00001000),
(19200, 0x00002000),
(38400, 0x00004000),
(56000, 0x00008000),
(57600, 0x00040000),
(115200, 0x00020000),
(128000, 0x00010000),
])
SETTABLE_DATA = collections.OrderedDict([
(5, 0x0001), # 5 data bits
(6, 0x0002), # 6 data bits
(7, 0x0004), # 7 data bits
(8, 0x0008), # 8 data bits
(16, 0x0010), # 16 data bits
])
SETTABLE_STOP = collections.OrderedDict([
(1, 0x0001), # 1 stop bit
(1.5, 0x0002), # 1.5 stop bits
(2, 0x0004), # 2 stop bits
])
SETTABLE_PARITY = collections.OrderedDict([
('NONE', 0x0100), # no parity
('ODD', 0x0200), # odd parity
('EVEN', 0x0400), # even parity
('MARK', 0x0800), # mark parity
('SPACE', 0x1000), # space parity
])
@property
def max_baud(self):
s = self.dwMaxBaud
m = self._CONST.SETTABLE_BAUD
if s == self._CONST.BAUD_USER:
return 0
else:
return m[s]
@property
def prov_subtype(self):
s = self.dwProvSubType
m = self._CONST.PROV_SUBTYPE
return [x for x, c in m.items() if c & s]
@property
def prov_capabilities(self):
s = self.dwProvCapabilities
m = self._CONST.PROV_CAPABILITIES
return [x for x, c in m.items() if c & s]
@property
def settable_params(self):
s = self.dwSettableParams
m = self._CONST.SETTABLE_PARAMS
return [x for x, c in m.items() if c & s]
@property
def settable_baud(self):
s = self.dwSettableBaud
m = self._CONST.SETTABLE_BAUD
return [x for x, c in m.items() if c & s]
@property
def user_settable_baud(self):
return bool(self.dwSettableBaud & self._CONST.BAUD_USER)
@property
def settable_data(self):
s = self.wSettableData
m = self._CONST.SETTABLE_DATA
return [x for x, c in m.items() if c & s]
@property
def wide_settable_data(self):
return bool(self.wSettableData & self._CONST.DATABITS_16X)
@property
def settable_stop(self):
s = self.wSettableStopParity
m = self._CONST.SETTABLE_STOP
return [x for x, c in m.items() if c & s]
@property
def settable_parity(self):
s = self.wSettableStopParity
m = self._CONST.SETTABLE_PARITY
return [x for x, c in m.items() if c & s]
LPCOMMPROP = ctypes.POINTER(COMMPROP)
class SECURITY_ATTRIBUTES(ctypes.Structure):
_fields_ = (('nLength', wintypes.DWORD),
('lpSecurityDescriptor', wintypes.LPVOID),
('bInheritHandle', wintypes.BOOL))
LPSECURITY_ATTRIBUTES = ctypes.POINTER(SECURITY_ATTRIBUTES)
kernel32.CreateFileW.restype = wintypes.HANDLE
kernel32.CreateFileW.argtypes = (
wintypes.LPCWSTR, # _In_ lpFileName
wintypes.DWORD, # _In_ dwDesiredAccess
wintypes.DWORD, # _In_ dwShareMode
LPSECURITY_ATTRIBUTES, # _In_opt_ lpSecurityAttributes
wintypes.DWORD, # _In_ dwCreationDisposition
wintypes.DWORD, # _In_ dwFlagsAndAttributes
wintypes.HANDLE) # _In_opt_ hTemplateFile
kernel32.CloseHandle.argtypes = (wintypes.HANDLE,)
kernel32.GetCommProperties.argtypes = (
wintypes.HANDLE, # _In_ hFile
LPCOMMPROP) # _Out_ lpCommProp
def get_comm_properties(handle_or_port):
if isinstance(handle_or_port, str):
handle = kernel32.CreateFileW(
handle_or_port,
GENERIC_READ | GENERIC_WRITE,
0, # exclusive access
None, # default security
OPEN_EXISTING,
0,
None)
if handle == INVALID_HANDLE_VALUE:
raise ctypes.WinError(ctypes.get_last_error())
close_handle = True
else:
handle = handle_or_port
close_handle = False
try:
prop = COMMPROP()
if not kernel32.GetCommProperties(handle, ctypes.byref(prop)):
raise ctypes.WinError(ctypes.get_last_error())
finally:
if close_handle:
kernel32.CloseHandle(handle)
return prop
示例：
if __name__ == '__main__':
for i in range(1, 10):
port = r'\.\COM%d' % i
try:
prop = get_comm_properties(port)
except WindowsError as e:
if e.winerror == ERROR_FILE_NOT_FOUND:
continue
print('%s properties' % port)
x = prop.dwMaxTxQueue if prop.dwMaxTxQueue else 'no limit'
print('\tMax output buffer size: %s' % x)
x = prop.dwMaxRxQueue if prop.dwMaxRxQueue else 'no limit'
print('\tMax input buffer size: %s' % x)
x = prop.dwCurrentTxQueue if prop.dwCurrentTxQueue else 'unavailable'
print('\tCurrent output buffer size: %s' % x)
x = prop.dwCurrentRxQueue if prop.dwCurrentRxQueue else 'unavailable'
print('\tCurrent input buffer size: %s' % x)
x = prop.max_baud if prop.max_baud else 'user programmable'
print('\tMax baud rate: %s' % x)
print('\tProvider subtypes:\n\t\t%s' %
'\n\t\t'.join(prop.prov_subtype))
print('\tProvider capabilities:\n\t\t%s' %
'\n\t\t'.join(prop.prov_capabilities))
print('\tSettable parameters:\n\t\t%s' %
'\n\t\t'.join(prop.settable_params))
print('\tSettable baud rates:\n\t\t%s' %
'\n\t\t'.join([str(x) for x in prop.settable_baud]))
print('\tSettable user baud rates: %s' %
prop.user_settable_baud)
print('\tSettable data bits:\n\t\t%s' %
'\n\t\t'.join([str(x) for x in prop.settable_data]))
print('\tSettable wide data bits: %s' %
prop.wide_settable_data)
print('\tSettable stop bits:\n\t\t%s' %
'\n\t\t'.join([str(x) for x in prop.settable_stop]))
print('\tSettable parity:\n\t\t%s' %
'\n\t\t'.join(prop.settable_parity))
输出：
\.\COM1 properties
Max output buffer size: no limit
Max input buffer size: no limit
Current output buffer size: unavailable
Current input buffer size: 4096
Max baud rate: user programmable
Provider subtypes:
RS232
RS422
RS449
FAX
LAT
X25
Provider capabilities:
DTRDSR
RTSCTS
RLSD
PARITY_CHECK
XONXOFF
SETXCHAR
TOTALTIMEOUTS
INTTIMEOUTS
Settable parameters:
PARITY
BAUD
DATABITS
STOPBITS
HANDSHAKING
PARITY_CHECK
RLSD
Settable baud rates:
75
110
134.5
150
300
600
1200
1800
2400
4800
7200
9600
14400
19200
38400
56000
57600
115200
Settable user baud rates: True
Settable data bits:
5
6
7
8
Settable wide data bits: False
Settable stop bits:
1
1.5
2
Settable parity:
NONE
ODD
EVEN
MARK
SPACE