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#! python
#
# This module implements a simple socket based client.
# It does not support changing any port parameters and will silently ignore any
# requests to do so.
#
# The purpose of this module is that applications using pySerial can connect to
# TCP/IP to serial port converters that do not support RFC 2217.
#
# This file is part of pySerial. https://github.com/pyserial/pyserial
# (C) 2001-2015 Chris Liechti <cliechti@gmx.net>
#
# SPDX-License-Identifier: BSD-3-Clause
#
# URL format: socket://<host>:<port>[/option[/option...]]
# options:
# - "debug" print diagnostic messages
import logging
import select
import socket
import time
try:
import urlparse
except ImportError:
import urllib.parse as urlparse
from serial.serialutil import SerialBase, SerialException, portNotOpenError, to_bytes
# map log level names to constants. used in from_url()
LOGGER_LEVELS = {
'debug': logging.DEBUG,
'info': logging.INFO,
'warning': logging.WARNING,
'error': logging.ERROR,
}
POLL_TIMEOUT = 2
class Serial(SerialBase):
"""Serial port implementation for plain sockets."""
BAUDRATES = (50, 75, 110, 134, 150, 200, 300, 600, 1200, 1800, 2400, 4800,
9600, 19200, 38400, 57600, 115200)
def open(self):
"""\
Open port with current settings. This may throw a SerialException
if the port cannot be opened.
"""
self.logger = None
if self._port is None:
raise SerialException("Port must be configured before it can be used.")
if self.is_open:
raise SerialException("Port is already open.")
try:
self._socket = socket.create_connection(self.from_url(self.portstr))
except Exception as msg:
self._socket = None
raise SerialException("Could not open port %s: %s" % (self.portstr, msg))
self._socket.settimeout(POLL_TIMEOUT) # used for write timeout support :/
# not that there anything to configure...
self._reconfigure_port()
# all things set up get, now a clean start
self.is_open = True
if not self._dsrdtr:
self._update_dtr_state()
if not self._rtscts:
self._update_rts_state()
self.reset_input_buffer()
self.reset_output_buffer()
def _reconfigure_port(self):
"""\
Set communication parameters on opened port. For the socket://
protocol all settings are ignored!
"""
if self._socket is None:
raise SerialException("Can only operate on open ports")
if self.logger:
self.logger.info('ignored port configuration change')
def close(self):
"""Close port"""
if self.is_open:
if self._socket:
try:
self._socket.shutdown(socket.SHUT_RDWR)
self._socket.close()
except:
# ignore errors.
pass
self._socket = None
self.is_open = False
# in case of quick reconnects, give the server some time
time.sleep(0.3)
def from_url(self, url):
"""extract host and port from an URL string"""
parts = urlparse.urlsplit(url)
if parts.scheme != "socket":
raise SerialException('expected a string in the form "socket://<host>:<port>[?logging={debug|info|warning|error}]": not starting with socket:// (%r)' % (parts.scheme,))
try:
# process options now, directly altering self
for option, values in urlparse.parse_qs(parts.query, True).items():
if option == 'logging':
logging.basicConfig() # XXX is that good to call it here?
self.logger = logging.getLogger('pySerial.socket')
self.logger.setLevel(LOGGER_LEVELS[values[0]])
self.logger.debug('enabled logging')
else:
raise ValueError('unknown option: %r' % (option,))
# get host and port
host, port = parts.hostname, parts.port
if not 0 <= port < 65536:
raise ValueError("port not in range 0...65535")
except ValueError as e:
raise SerialException('expected a string in the form "socket://<host>:<port>[?logging={debug|info|warning|error}]": %s' % e)
return (host, port)
# - - - - - - - - - - - - - - - - - - - - - - - -
@property
def in_waiting(self):
"""Return the number of bytes currently in the input buffer."""
if not self.is_open:
raise portNotOpenError
# Poll the socket to see if it is ready for reading.
# If ready, at least one byte will be to read.
lr, lw, lx = select.select([self._socket], [], [], 0)
return len(lr)
def read(self, size=1):
"""\
Read size bytes from the serial port. If a timeout is set it may
return less characters as requested. With no timeout it will block
until the requested number of bytes is read.
"""
if not self.is_open:
raise portNotOpenError
data = bytearray()
if self._timeout is not None:
timeout = time.time() + self._timeout
else:
timeout = None
while len(data) < size:
try:
# an implementation with internal buffer would be better
# performing...
block = self._socket.recv(size - len(data))
if block:
data.extend(block)
else:
# no data -> EOF (connection probably closed)
break
except socket.timeout:
# just need to get out of recv from time to time to check if
# still alive and timeout did not expire
pass
except socket.error as e:
# connection fails -> terminate loop
raise SerialException('connection failed (%s)' % e)
if timeout is not None and time.time() > timeout:
break
return bytes(data)
def write(self, data):
"""\
Output the given byte string over the serial port. Can block if the
connection is blocked. May raise SerialException if the connection is
closed.
"""
if not self.is_open:
raise portNotOpenError
try:
self._socket.sendall(to_bytes(data))
except socket.error as e:
# XXX what exception if socket connection fails
raise SerialException("socket connection failed: %s" % e)
return len(data)
def reset_input_buffer(self):
"""Clear input buffer, discarding all that is in the buffer."""
if not self.is_open:
raise portNotOpenError
if self.logger:
self.logger.info('ignored reset_input_buffer')
def reset_output_buffer(self):
"""\
Clear output buffer, aborting the current output and
discarding all that is in the buffer.
"""
if not self.is_open:
raise portNotOpenError
if self.logger:
self.logger.info('ignored reset_output_buffer')
def send_break(self, duration=0.25):
"""\
Send break condition. Timed, returns to idle state after given
duration.
"""
if not self.is_open:
raise portNotOpenError
if self.logger:
self.logger.info('ignored send_break(%r)' % (duration,))
def _update_break_state(self):
"""Set break: Controls TXD. When active, to transmitting is
possible."""
if self.logger:
self.logger.info('ignored _update_break_state(%r)' % (self._break_state,))
def _update_rts_state(self):
"""Set terminal status line: Request To Send"""
if self.logger:
self.logger.info('ignored _update_rts_state(%r)' % (self._rts_state,))
def _update_dtr_state(self):
"""Set terminal status line: Data Terminal Ready"""
if self.logger:
self.logger.info('ignored _update_dtr_state(%r)' % (self._dtr_state,))
@property
def cts(self):
"""Read terminal status line: Clear To Send"""
if not self.is_open:
raise portNotOpenError
if self.logger:
self.logger.info('returning dummy for cts')
return True
@property
def dsr(self):
"""Read terminal status line: Data Set Ready"""
if not self.is_open:
raise portNotOpenError
if self.logger:
self.logger.info('returning dummy for dsr')
return True
@property
def ri(self):
"""Read terminal status line: Ring Indicator"""
if not self.is_open:
raise portNotOpenError
if self.logger:
self.logger.info('returning dummy for ri')
return False
@property
def cd(self):
"""Read terminal status line: Carrier Detect"""
if not self.is_open:
raise portNotOpenError
if self.logger:
self.logger.info('returning dummy for cd)')
return True
# - - - platform specific - - -
# works on Linux and probably all the other POSIX systems
def fileno(self):
"""Get the file handle of the underlying socket for use with select"""
return self._socket.fileno()
#
# simple client test
if __name__ == '__main__':
import sys
s = Serial('socket://localhost:7000')
sys.stdout.write('%s\n' % s)
sys.stdout.write("write...\n")
s.write(b"hello\n")
s.flush()
sys.stdout.write("read: %s\n" % s.read(5))
s.close()
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