documentation/url_handlers.rst - platform/external/python/pyserial - Git at Google

 .. _URLs:

 ==============
  URL Handlers
 ==============

 .. module:: serial

 Overview
 ========
 The function :func:`serial_for_url` accepts the following types of URLs:

 - ``rfc2217://<host>:<port>[?<option>[&<option>...]]``
 - ``socket://<host>:<port>[?logging={debug|info|warning|error}]``
 - ``loop://[?logging={debug|info|warning|error}]``
 - ``hwgrep://<regexp>[&skip_busy][&n=N]``
 - ``spy://port[?option[=value][&option[=value]]]``
 - ``alt://port?class=<classname>``
 - ``cp2110://<bus>:<dev>:<if>``

 .. versionchanged:: 3.0 Options are specified with ``?`` and ``&`` instead of ``/``

 Device names are also supported, e.g.:

 - ``/dev/ttyUSB0`` (Linux)
 - ``COM3`` (Windows)

 Future releases of pySerial might add more types. Since pySerial 2.6 it is also
 possible for the user to add protocol handlers using
 :attr:`protocol_handler_packages`.


 ``rfc2217://``
 ==============
 Used to connect to :rfc:`2217` compatible servers. All serial port
 functions are supported. Implemented by :class:`rfc2217.Serial`.

 Supported options in the URL are:

 - ``ign_set_control`` does not wait for acknowledges to SET_CONTROL. This
   option can be used for non compliant servers (i.e. when getting an
   ``remote rejected value for option 'control'`` error when connecting).

 - ``poll_modem``: The client issues NOTIFY_MODEMSTATE requests when status
   lines are read (CTS/DTR/RI/CD). Without this option it relies on the server
   sending the notifications automatically (that's what the RFC suggests and
   most servers do). Enable this option when :attr:`cts` does not work as
   expected, i.e. for servers that do not send notifications.

 - ``timeout=<value>``: Change network timeout (default 3 seconds). This is
   useful when the server takes a little more time to send its answers. The
   timeout applies to the initial Telnet / :rfc:`2217` negotiation as well
   as changing port settings or control line change commands.

 - ``logging={debug|info|warning|error}``: Prints diagnostic messages (not
   useful for end users). It uses the logging module and a logger called
   ``pySerial.rfc2217`` so that the application can setup up logging
   handlers etc. It will call :meth:`logging.basicConfig` which initializes
   for output on ``sys.stderr`` (if no logging was set up already).

 .. warning:: The connection is not encrypted and no authentication is
              supported! Only use it in trusted environments.


 ``socket://``
 =============
 The purpose of this connection type is that applications using pySerial can
 connect to TCP/IP to serial port converters that do not support :rfc:`2217`.

 Uses a TCP/IP socket. All serial port settings, control and status lines
 are ignored. Only data is transmitted and received.

 Supported options in the URL are:

 - ``logging={debug|info|warning|error}``: Prints diagnostic messages (not
   useful for end users). It uses the logging module and a logger called
   ``pySerial.socket`` so that the application can setup up logging handlers
   etc. It will call :meth:`logging.basicConfig` which initializes for
   output on ``sys.stderr`` (if no logging was set up already).

 .. warning:: The connection is not encrypted and no authentication is
              supported! Only use it in trusted environments.


 ``loop://``
 ===========
 The least useful type. It simulates a loop back connection
 (``RX<->TX``  ``RTS<->CTS``  ``DTR<->DSR``). It could be used to test
 applications or run the unit tests.

 Supported options in the URL are:

 - ``logging={debug|info|warning|error}``: Prints diagnostic messages (not
   useful for end users). It uses the logging module and a logger called
   ``pySerial.loop`` so that the application can setup up logging handlers
   etc. It will call :meth:`logging.basicConfig` which initializes for
   output on ``sys.stderr`` (if no logging was set up already).


 ``hwgrep://``
 =============
 This type uses :mod:`serial.tools.list_ports` to obtain a list of ports and
 searches the list for matches by a regexp that follows the slashes (see Pythons
 :py:mod:`re` module for detailed syntax information).

 Note that options are separated using the character ``&``, this also applies to
 the first, where URLs usually use ``?``. This exception is made as the question
 mark is used in regexp itself.

 Depending on the capabilities of the ``list_ports`` module on the system, it is
 possible to search for the description or hardware ID of a device, e.g. USB
 VID:PID or texts.

 Unfortunately, on some systems ``list_ports`` only lists a subset of the port
 names with no additional information. Currently, on Windows and Linux and
 OSX it should find additional information.

 Supported options in the URL are:

 - ``n=N``: pick the N'th entry instead of the first
 - ``skip_busy``: skip ports that can not be opened, e.g. because they are
   already in use. This may not work as expected on platforms where the file is
   not locked automatically (e.g. Posix).


 .. _spy:

 ``spy://``
 ==========
 Wrapping the native serial port, this protocol makes it possible to
 intercept the data received and transmitted as well as the access to the
 control lines, break and flush commands. It is mainly used to debug
 applications.

 Supported options in the URL are:

 - ``file=FILENAME`` output to given file or device instead of stderr
 - ``color`` enable ANSI escape sequences to colorize output
 - ``raw`` output the read and written data directly (default is to create a
   hex dump). In this mode, no control line and other commands are logged.
 - ``all`` also show ``in_waiting`` and empty ``read()`` calls (hidden by
   default because of high traffic).
 - ``log`` or ``log=LOGGERNAME`` output to stdlib ``logging`` module. Default
   channel name is ``serial``. This variant outputs hex dump.
 - ``rawlog`` or ``rawlog=LOGGERNAME`` output to stdlib ``logging`` module. Default
   channel name is ``serial``. This variant outputs text (``repr``).

 The ``log`` and ``rawlog`` options require that the logging is set up, in order
 to see the log output.

 Example::

     import serial

     with serial.serial_for_url('spy:///dev/ttyUSB0?file=test.txt', timeout=1) as s:
         s.dtr = False
         s.write('hello world')
         s.read(20)
         s.dtr = True
         s.write(serial.to_bytes(range(256)))
         s.read(400)
         s.send_break()

     with open('test.txt') as f:
         print(f.read())

 Outputs::

     000000.002 Q-RX reset_input_buffer
     000000.002 DTR  inactive
     000000.002 TX   0000  68 65 6C 6C 6F 20 77 6F  72 6C 64                 hello world
     000001.015 RX   0000  68 65 6C 6C 6F 20 77 6F  72 6C 64                 hello world
     000001.015 DTR  active
     000001.015 TX   0000  00 01 02 03 04 05 06 07  08 09 0A 0B 0C 0D 0E 0F  ................
     000001.015 TX   0010  10 11 12 13 14 15 16 17  18 19 1A 1B 1C 1D 1E 1F  ................
     000001.015 TX   0020  20 21 22 23 24 25 26 27  28 29 2A 2B 2C 2D 2E 2F   !"#$%&'()*+,-./
     000001.015 TX   0030  30 31 32 33 34 35 36 37  38 39 3A 3B 3C 3D 3E 3F  0123456789:;<=>?
     000001.015 TX   0040  40 41 42 43 44 45 46 47  48 49 4A 4B 4C 4D 4E 4F  @ABCDEFGHIJKLMNO
     000001.016 TX   0050  50 51 52 53 54 55 56 57  58 59 5A 5B 5C 5D 5E 5F  PQRSTUVWXYZ[\]^_
     000001.016 TX   0060  60 61 62 63 64 65 66 67  68 69 6A 6B 6C 6D 6E 6F  `abcdefghijklmno
     000001.016 TX   0070  70 71 72 73 74 75 76 77  78 79 7A 7B 7C 7D 7E 7F  pqrstuvwxyz{|}~.
     000001.016 TX   0080  80 81 82 83 84 85 86 87  88 89 8A 8B 8C 8D 8E 8F  ................
     000001.016 TX   0090  90 91 92 93 94 95 96 97  98 99 9A 9B 9C 9D 9E 9F  ................
     000001.016 TX   00A0  A0 A1 A2 A3 A4 A5 A6 A7  A8 A9 AA AB AC AD AE AF  ................
     000001.016 TX   00B0  B0 B1 B2 B3 B4 B5 B6 B7  B8 B9 BA BB BC BD BE BF  ................
     000001.016 TX   00C0  C0 C1 C2 C3 C4 C5 C6 C7  C8 C9 CA CB CC CD CE CF  ................
     000001.016 TX   00D0  D0 D1 D2 D3 D4 D5 D6 D7  D8 D9 DA DB DC DD DE DF  ................
     000001.016 TX   00E0  E0 E1 E2 E3 E4 E5 E6 E7  E8 E9 EA EB EC ED EE EF  ................
     000001.016 TX   00F0  F0 F1 F2 F3 F4 F5 F6 F7  F8 F9 FA FB FC FD FE FF  ................
     000002.284 RX   0000  00 01 02 03 04 05 06 07  08 09 0A 0B 0C 0D 0E 0F  ................
     000002.284 RX   0010  10 11 12 13 14 15 16 17  18 19 1A 1B 1C 1D 1E 1F  ................
     000002.284 RX   0020  20 21 22 23 24 25 26 27  28 29 2A 2B 2C 2D 2E 2F   !"#$%&'()*+,-./
     000002.284 RX   0030  30 31 32 33 34 35 36 37  38 39 3A 3B 3C 3D 3E 3F  0123456789:;<=>?
     000002.284 RX   0040  40 41 42 43 44 45 46 47  48 49 4A 4B 4C 4D 4E 4F  @ABCDEFGHIJKLMNO
     000002.284 RX   0050  50 51 52 53 54 55 56 57  58 59 5A 5B 5C 5D 5E 5F  PQRSTUVWXYZ[\]^_
     000002.284 RX   0060  60 61 62 63 64 65 66 67  68 69 6A 6B 6C 6D 6E 6F  `abcdefghijklmno
     000002.284 RX   0070  70 71 72 73 74 75 76 77  78 79 7A 7B 7C 7D 7E 7F  pqrstuvwxyz{|}~.
     000002.284 RX   0080  80 81 82 83 84 85 86 87  88 89 8A 8B 8C 8D 8E 8F  ................
     000002.284 RX   0090  90 91 92 93 94 95 96 97  98 99 9A 9B 9C 9D 9E 9F  ................
     000002.284 RX   00A0  A0 A1 A2 A3 A4 A5 A6 A7  A8 A9 AA AB AC AD AE AF  ................
     000002.284 RX   00B0  B0 B1 B2 B3 B4 B5 B6 B7  B8 B9 BA BB BC BD BE BF  ................
     000002.284 RX   00C0  C0 C1 C2 C3 C4 C5 C6 C7  C8 C9 CA CB CC CD CE CF  ................
     000002.284 RX   00D0  D0 D1 D2 D3 D4 D5 D6 D7  D8 D9 DA DB DC DD DE DF  ................
     000002.284 RX   00E0  E0 E1 E2 E3 E4 E5 E6 E7  E8 E9 EA EB EC ED EE EF  ................
     000002.284 RX   00F0  F0 F1 F2 F3 F4 F5 F6 F7  F8 F9 FA FB FC FD FE FF  ................
     000002.284 BRK  send_break 0.25

 Another example, on POSIX, open a second terminal window and find out it's
 device (e.g. with the ``ps`` command in the TTY column), assumed to be
 ``/dev/pts/2`` here, double quotes are used so that the ampersand in the URL is
 not interpreted by the shell::

     python -m serial.tools.miniterm "spy:///dev/ttyUSB0?file=/dev/pts/2&color" 115200

 The spy output will be live in the second terminal window.

 .. versionadded:: 3.0
 .. versionchanged:: 3.6 Added ``log`` and ``rawlog`` options


 ``alt://``
 ==========
 This handler allows to select alternate implementations of the native serial
 port.

 Currently only the POSIX platform provides alternative implementations.

 ``PosixPollSerial``
     Poll based read implementation. Not all systems support poll properly.
     However this one has better handling of errors, such as a device
     disconnecting while it's in use (e.g. USB-serial unplugged).

 ``VTIMESerial``
     Implement timeout using ``VTIME``/``VMIN`` of TTY device instead of using
     ``select``. This means that inter character timeout and overall timeout
     can not be used at the same time. Overall timeout is disabled when
     inter-character timeout is used. The error handling is degraded.


 Examples::

     alt:///dev/ttyUSB0?class=PosixPollSerial
     alt:///dev/ttyUSB0?class=VTIMESerial

 .. versionadded:: 3.0


 ``cp2110://``
 =============
 This backend implements support for HID-to-UART devices manufactured by Silicon
 Labs and marketed as CP2110 and CP2114. The implementation is (mostly)
 OS-independent and in userland. It relies on `cython-hidapi`_.

 .. _cython-hidapi: https://github.com/trezor/cython-hidapi

 Examples::

     cp2110://0001:004a:00
     cp2110://0002:0077:00

 .. versionadded:: 3.5

 Examples
 ========

 - ``rfc2217://localhost:7000``
 - ``rfc2217://localhost:7000?poll_modem``
 - ``rfc2217://localhost:7000?ign_set_control&timeout=5.5``
 - ``socket://localhost:7777``
 - ``loop://?logging=debug``
 - ``hwgrep://0451:f432`` (USB VID:PID)
 - ``spy://COM54?file=log.txt``
 - ``alt:///dev/ttyUSB0?class=PosixPollSerial``
 - ``cp2110://0001:004a:00``
	.. _URLs:

	==============
	URL Handlers
	==============

	.. module:: serial

	Overview
	========
	The function :func:`serial_for_url` accepts the following types of URLs:

	- ``rfc2217://<host>:<port>[?<option>[&<option>...]]``
	- ``socket://<host>:<port>[?logging={debug\|info\|warning\|error}]``
	- ``loop://[?logging={debug\|info\|warning\|error}]``
	- ``hwgrep://<regexp>[&skip_busy][&n=N]``
	- ``spy://port[?option[=value][&option[=value]]]``
	- ``alt://port?class=<classname>``
	- ``cp2110://<bus>:<dev>:<if>``

	.. versionchanged:: 3.0 Options are specified with ``?`` and ``&`` instead of ``/``

	Device names are also supported, e.g.:

	- ``/dev/ttyUSB0`` (Linux)
	- ``COM3`` (Windows)

	Future releases of pySerial might add more types. Since pySerial 2.6 it is also
	possible for the user to add protocol handlers using
	:attr:`protocol_handler_packages`.


	``rfc2217://``
	==============
	Used to connect to :rfc:`2217` compatible servers. All serial port
	functions are supported. Implemented by :class:`rfc2217.Serial`.

	Supported options in the URL are:

	- ``ign_set_control`` does not wait for acknowledges to SET_CONTROL. This
	option can be used for non compliant servers (i.e. when getting an
	``remote rejected value for option 'control'`` error when connecting).

	- ``poll_modem``: The client issues NOTIFY_MODEMSTATE requests when status
	lines are read (CTS/DTR/RI/CD). Without this option it relies on the server
	sending the notifications automatically (that's what the RFC suggests and
	most servers do). Enable this option when :attr:`cts` does not work as
	expected, i.e. for servers that do not send notifications.

	- ``timeout=<value>``: Change network timeout (default 3 seconds). This is
	useful when the server takes a little more time to send its answers. The
	timeout applies to the initial Telnet / :rfc:`2217` negotiation as well
	as changing port settings or control line change commands.

	- ``logging={debug\|info\|warning\|error}``: Prints diagnostic messages (not
	useful for end users). It uses the logging module and a logger called
	``pySerial.rfc2217`` so that the application can setup up logging
	handlers etc. It will call :meth:`logging.basicConfig` which initializes
	for output on ``sys.stderr`` (if no logging was set up already).

	.. warning:: The connection is not encrypted and no authentication is
	supported! Only use it in trusted environments.


	``socket://``
	=============
	The purpose of this connection type is that applications using pySerial can
	connect to TCP/IP to serial port converters that do not support :rfc:`2217`.

	Uses a TCP/IP socket. All serial port settings, control and status lines
	are ignored. Only data is transmitted and received.

	Supported options in the URL are:

	- ``logging={debug\|info\|warning\|error}``: Prints diagnostic messages (not
	useful for end users). It uses the logging module and a logger called
	``pySerial.socket`` so that the application can setup up logging handlers
	etc. It will call :meth:`logging.basicConfig` which initializes for
	output on ``sys.stderr`` (if no logging was set up already).

	.. warning:: The connection is not encrypted and no authentication is
	supported! Only use it in trusted environments.


	``loop://``
	===========
	The least useful type. It simulates a loop back connection
	(``RX<->TX`` ``RTS<->CTS`` ``DTR<->DSR``). It could be used to test
	applications or run the unit tests.

	Supported options in the URL are:

	- ``logging={debug\|info\|warning\|error}``: Prints diagnostic messages (not
	useful for end users). It uses the logging module and a logger called
	``pySerial.loop`` so that the application can setup up logging handlers
	etc. It will call :meth:`logging.basicConfig` which initializes for
	output on ``sys.stderr`` (if no logging was set up already).


	``hwgrep://``
	=============
	This type uses :mod:`serial.tools.list_ports` to obtain a list of ports and
	searches the list for matches by a regexp that follows the slashes (see Pythons
	:py:mod:`re` module for detailed syntax information).

	Note that options are separated using the character ``&``, this also applies to
	the first, where URLs usually use ``?``. This exception is made as the question
	mark is used in regexp itself.

	Depending on the capabilities of the ``list_ports`` module on the system, it is
	possible to search for the description or hardware ID of a device, e.g. USB
	VID:PID or texts.

	Unfortunately, on some systems ``list_ports`` only lists a subset of the port
	names with no additional information. Currently, on Windows and Linux and
	OSX it should find additional information.

	Supported options in the URL are:

	- ``n=N``: pick the N'th entry instead of the first
	- ``skip_busy``: skip ports that can not be opened, e.g. because they are
	already in use. This may not work as expected on platforms where the file is
	not locked automatically (e.g. Posix).


	.. _spy:

	``spy://``
	==========
	Wrapping the native serial port, this protocol makes it possible to
	intercept the data received and transmitted as well as the access to the
	control lines, break and flush commands. It is mainly used to debug
	applications.

	Supported options in the URL are:

	- ``file=FILENAME`` output to given file or device instead of stderr
	- ``color`` enable ANSI escape sequences to colorize output
	- ``raw`` output the read and written data directly (default is to create a
	hex dump). In this mode, no control line and other commands are logged.
	- ``all`` also show ``in_waiting`` and empty ``read()`` calls (hidden by
	default because of high traffic).
	- ``log`` or ``log=LOGGERNAME`` output to stdlib ``logging`` module. Default
	channel name is ``serial``. This variant outputs hex dump.
	- ``rawlog`` or ``rawlog=LOGGERNAME`` output to stdlib ``logging`` module. Default
	channel name is ``serial``. This variant outputs text (``repr``).

	The ``log`` and ``rawlog`` options require that the logging is set up, in order
	to see the log output.

	Example::

	import serial

	with serial.serial_for_url('spy:///dev/ttyUSB0?file=test.txt', timeout=1) as s:
	s.dtr = False
	s.write('hello world')
	s.read(20)
	s.dtr = True
	s.write(serial.to_bytes(range(256)))
	s.read(400)
	s.send_break()

	with open('test.txt') as f:
	print(f.read())

	Outputs::

	000000.002 Q-RX reset_input_buffer
	000000.002 DTR inactive
	000000.002 TX 0000 68 65 6C 6C 6F 20 77 6F 72 6C 64 hello world
	000001.015 RX 0000 68 65 6C 6C 6F 20 77 6F 72 6C 64 hello world
	000001.015 DTR active
	000001.015 TX 0000 00 01 02 03 04 05 06 07 08 09 0A 0B 0C 0D 0E 0F ................
	000001.015 TX 0010 10 11 12 13 14 15 16 17 18 19 1A 1B 1C 1D 1E 1F ................
	000001.015 TX 0020 20 21 22 23 24 25 26 27 28 29 2A 2B 2C 2D 2E 2F !"#$%&'()*+,-./
	000001.015 TX 0030 30 31 32 33 34 35 36 37 38 39 3A 3B 3C 3D 3E 3F 0123456789:;<=>?
	000001.015 TX 0040 40 41 42 43 44 45 46 47 48 49 4A 4B 4C 4D 4E 4F @ABCDEFGHIJKLMNO
	000001.016 TX 0050 50 51 52 53 54 55 56 57 58 59 5A 5B 5C 5D 5E 5F PQRSTUVWXYZ[\]^_
	000001.016 TX 0060 60 61 62 63 64 65 66 67 68 69 6A 6B 6C 6D 6E 6F `abcdefghijklmno
	000001.016 TX 0070 70 71 72 73 74 75 76 77 78 79 7A 7B 7C 7D 7E 7F pqrstuvwxyz{\|}~.
	000001.016 TX 0080 80 81 82 83 84 85 86 87 88 89 8A 8B 8C 8D 8E 8F ................
	000001.016 TX 0090 90 91 92 93 94 95 96 97 98 99 9A 9B 9C 9D 9E 9F ................
	000001.016 TX 00A0 A0 A1 A2 A3 A4 A5 A6 A7 A8 A9 AA AB AC AD AE AF ................
	000001.016 TX 00B0 B0 B1 B2 B3 B4 B5 B6 B7 B8 B9 BA BB BC BD BE BF ................
	000001.016 TX 00C0 C0 C1 C2 C3 C4 C5 C6 C7 C8 C9 CA CB CC CD CE CF ................
	000001.016 TX 00D0 D0 D1 D2 D3 D4 D5 D6 D7 D8 D9 DA DB DC DD DE DF ................
	000001.016 TX 00E0 E0 E1 E2 E3 E4 E5 E6 E7 E8 E9 EA EB EC ED EE EF ................
	000001.016 TX 00F0 F0 F1 F2 F3 F4 F5 F6 F7 F8 F9 FA FB FC FD FE FF ................
	000002.284 RX 0000 00 01 02 03 04 05 06 07 08 09 0A 0B 0C 0D 0E 0F ................
	000002.284 RX 0010 10 11 12 13 14 15 16 17 18 19 1A 1B 1C 1D 1E 1F ................
	000002.284 RX 0020 20 21 22 23 24 25 26 27 28 29 2A 2B 2C 2D 2E 2F !"#$%&'()*+,-./
	000002.284 RX 0030 30 31 32 33 34 35 36 37 38 39 3A 3B 3C 3D 3E 3F 0123456789:;<=>?
	000002.284 RX 0040 40 41 42 43 44 45 46 47 48 49 4A 4B 4C 4D 4E 4F @ABCDEFGHIJKLMNO
	000002.284 RX 0050 50 51 52 53 54 55 56 57 58 59 5A 5B 5C 5D 5E 5F PQRSTUVWXYZ[\]^_
	000002.284 RX 0060 60 61 62 63 64 65 66 67 68 69 6A 6B 6C 6D 6E 6F `abcdefghijklmno
	000002.284 RX 0070 70 71 72 73 74 75 76 77 78 79 7A 7B 7C 7D 7E 7F pqrstuvwxyz{\|}~.
	000002.284 RX 0080 80 81 82 83 84 85 86 87 88 89 8A 8B 8C 8D 8E 8F ................
	000002.284 RX 0090 90 91 92 93 94 95 96 97 98 99 9A 9B 9C 9D 9E 9F ................
	000002.284 RX 00A0 A0 A1 A2 A3 A4 A5 A6 A7 A8 A9 AA AB AC AD AE AF ................
	000002.284 RX 00B0 B0 B1 B2 B3 B4 B5 B6 B7 B8 B9 BA BB BC BD BE BF ................
	000002.284 RX 00C0 C0 C1 C2 C3 C4 C5 C6 C7 C8 C9 CA CB CC CD CE CF ................
	000002.284 RX 00D0 D0 D1 D2 D3 D4 D5 D6 D7 D8 D9 DA DB DC DD DE DF ................
	000002.284 RX 00E0 E0 E1 E2 E3 E4 E5 E6 E7 E8 E9 EA EB EC ED EE EF ................
	000002.284 RX 00F0 F0 F1 F2 F3 F4 F5 F6 F7 F8 F9 FA FB FC FD FE FF ................
	000002.284 BRK send_break 0.25

	Another example, on POSIX, open a second terminal window and find out it's
	device (e.g. with the ``ps`` command in the TTY column), assumed to be
	``/dev/pts/2`` here, double quotes are used so that the ampersand in the URL is
	not interpreted by the shell::

	python -m serial.tools.miniterm "spy:///dev/ttyUSB0?file=/dev/pts/2&color" 115200

	The spy output will be live in the second terminal window.

	.. versionadded:: 3.0
	.. versionchanged:: 3.6 Added ``log`` and ``rawlog`` options


	``alt://``
	==========
	This handler allows to select alternate implementations of the native serial
	port.

	Currently only the POSIX platform provides alternative implementations.

	``PosixPollSerial``
	Poll based read implementation. Not all systems support poll properly.
	However this one has better handling of errors, such as a device
	disconnecting while it's in use (e.g. USB-serial unplugged).

	``VTIMESerial``
	Implement timeout using ``VTIME``/``VMIN`` of TTY device instead of using
	``select``. This means that inter character timeout and overall timeout
	can not be used at the same time. Overall timeout is disabled when
	inter-character timeout is used. The error handling is degraded.


	Examples::

	alt:///dev/ttyUSB0?class=PosixPollSerial
	alt:///dev/ttyUSB0?class=VTIMESerial

	.. versionadded:: 3.0


	``cp2110://``
	=============
	This backend implements support for HID-to-UART devices manufactured by Silicon
	Labs and marketed as CP2110 and CP2114. The implementation is (mostly)
	OS-independent and in userland. It relies on `cython-hidapi`_.

	.. _cython-hidapi: https://github.com/trezor/cython-hidapi

	Examples::

	cp2110://0001:004a:00
	cp2110://0002:0077:00

	.. versionadded:: 3.5

	Examples
	========

	- ``rfc2217://localhost:7000``
	- ``rfc2217://localhost:7000?poll_modem``
	- ``rfc2217://localhost:7000?ign_set_control&timeout=5.5``
	- ``socket://localhost:7777``
	- ``loop://?logging=debug``
	- ``hwgrep://0451:f432`` (USB VID:PID)
	- ``spy://COM54?file=log.txt``
	- ``alt:///dev/ttyUSB0?class=PosixPollSerial``
	- ``cp2110://0001:004a:00``