serial_server.py

# Copyright (C) 2007  Markus Ansmann
#
# This program is free software: you can redistribute it and/or modify
# it under the terms of the GNU General Public License as published by
# the Free Software Foundation, either version 2 of the License, or
# (at your option) any later version.
#
# This program is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
# GNU General Public License for more details.
#
# You should have received a copy of the GNU General Public License
# along with this program.  If not, see <http://www.gnu.org/licenses/>.
#
# Requires: pyserial >= 2.6:

"""
### BEGIN NODE INFO
[info]
name = Serial Server
version = 1.2
description =
instancename = %LABRADNODE% Serial Server

[startup]
cmdline = %PYTHON% %FILE%
timeout = 20

[shutdown]
message = 987654321
timeout = 20
### END NODE INFO
"""

import collections
import os
import os.path
import sys
import time
from time import sleep

from labrad import types as T
from labrad.errors import Error
from labrad.server import LabradServer, setting
from twisted.internet import reactor, threads
from twisted.internet.defer import inlineCallbacks, returnValue
from twisted.internet.task import deferLater
from serial import Serial
from serial.serialutil import SerialException
import serial.tools.list_ports


class NoPortSelectedError(Error):
    """Please open a port first."""
    code = 1


class NoPortsAvailableError(Error):
    """No serial ports are available."""
    code = 3


SerialDevice = collections.namedtuple('SerialDevice', ['name', 'devicepath'])


class SerialServer(LabradServer):
    """Provides access to a computer's serial (COM) ports."""
    name = '%LABRADNODE% Serial Server'

    def initServer(self):
        if sys.platform.startswith('win32'):
            self.enumerate_serial_windows()
        else:
            self.enumerate_serial_pyserial()

    def enumerate_serial_windows(self):
        """Manually Enumerate the first 20 COM ports.

        pyserial includes a function to enumerate device names, but it
        possibly doesn't work right on windows for COM ports above 4.
        http://stackoverflow.com/questions/12090503/listing-available-com-ports-with-python
        """
        self.SerialPorts = []
        print 'Searching for COM ports:'
        for a in range(1, 20):
            COMexists = True
            dev_name = 'COM{}'.format(a)
            dev_path = r'\\.\{}'.format(dev_name)
            try:
                ser = Serial(dev_name)
                ser.close()
            except SerialException as e:
                if e.message.find('cannot find') >= 0:
                    COMexists = False
            if COMexists:
                self.SerialPorts.append(SerialDevice(dev_name, dev_path))
                print "  ", dev_name
        if not len(self.SerialPorts):
            print '  none'

    def enumerate_serial_pyserial(self):
        """This uses the pyserial built-in device enumeration.

        We ignore the pyserial "human readable" device name
        because that appears to make no sense.  For instance, a
        particular FTDI USB-Serial adapter shows up as 'Microsoft
        Corp. Optical Mouse 200'.

        Following the example from the above windows version, we try to open
        each port and ignore it if we can't.
        """
        dev_list = serial.tools.list_ports.comports()
        self.SerialPorts = []
        for d in dev_list:
            dev_path = d[0]
            try:
                ser = Serial(dev_path)
                ser.close()
            except SerialException as e:
                pass
            else:
                _, _, dev_name = dev_path.rpartition(os.sep)
                self.SerialPorts.append(SerialDevice(dev_name, dev_path))

    def expireContext(self, c):
        if 'PortObject' in c:
            c['PortObject'].close()

    def getPort(self, c):
        try:
            return c['PortObject']
        except:
            raise NoPortSelectedError()

    @setting(1, 'List Serial Ports',
             returns=['*s: List of serial ports'])
    def list_serial_ports(self, c):
        """Retrieves a list of all serial ports.

        NOTES:
        This list contains all ports installed on the computer,
        including ones that are already in use by other programs."""
        print self.SerialPorts
        port_list = [x.name for x in self.SerialPorts]

        return port_list

    @setting(10, 'Open',
             port=[': Open the first available port',
                   's: Port to open, e.g. COM4'],
             returns=['s: Opened port'])
    def open(self, c, port=''):
        """Opens a serial port in the current context.

        args:
        port   device name as returned by list_serial_ports.

        On windows, the device name will generally be of the form
        COM1 or COM42 (i.e., without the device prefix \\\\.\\).  On
        linux, it will be the device node name (ttyUSB0) without the
        /dev/ prefix.  This is case insensitive on windows, case sensitive
        on Linux.  For compatibility, always use the same case.
        """
        c['Timeout'] = 0
        if 'PortObject' in c:
            c['PortObject'].close()
            del c['PortObject']
        if not port:
            for i in range(len(self.SerialPorts)):
                try:
                    c['PortObject'] = Serial(self.SerialPorts[i].devicepath,
                                             timeout=0)
                    break
                except SerialException:
                    pass
            if 'PortObject' not in c:
                raise NoPortsAvailableError()
        else:
            for x in self.SerialPorts:
                if os.path.normcase(x.name) == os.path.normcase(port):
                    try:
                        c['PortObject'] = Serial(x.devicepath, timeout=0)
                        return x.name
                    except SerialException, e:
                        if e.message.find('cannot find') >= 0:
                            raise Error(code=1, msg=e.message)
                        else:
                            raise Error(code=2, msg=e.message)
        raise Error(code=1, msg='Unknown port %s' % (port,))

    @setting(11, 'Close', returns=[''])
    def close(self, c):
        """Closes the current serial port."""
        if 'PortObject' in c:
            c['PortObject'].close()
            del c['PortObject']

    @setting(20, 'Baudrate',
             data=[': List baudrates',
                   'w: Set baudrate (0: query current)'],
             returns=['w: Selected baudrate', '*w: Available baudrates'])
    def baudrate(self, c, data=None):
        """Sets the baudrate."""
        ser = self.getPort(c)
        baudrates = ser.BAUDRATES
        if data is None:
            return baudrates
        else:
            if data in baudrates:
                ser.baudrate = data
            return long(ser.baudrate)

    @setting(21, 'Bytesize',
             data=[': List bytesizes',
                   'w: Set bytesize (0: query current)'],
             returns=['*w: Available bytesizes',
                      'w: Selected bytesize'])
    def bytesize(self, c, data=None):
        """Sets the bytesize."""
        ser = self.getPort(c)
        bytesizes = ser.BYTESIZES
        if data is None:
            return bytesizes
        else:
            if data in bytesizes:
                ser.bytesize = data
            return long(ser.bytesize)

    @setting(22, 'Parity',
             data=[': List parities',
                   's: Set parity (empty: query current)'],
             returns=['*s: Available parities',
                      's: Selected parity'])
    def parity(self, c, data=None):
        """Sets the parity."""
        ser = self.getPort(c)
        parities = ser.PARITIES
        if data is None:
            return parities
        else:
            data = data.upper()
            if data in parities:
                ser.parity = data
            return ser.parity

    @setting(23, 'Stopbits',
             data=[': List stopbits',
                   'w: Set stopbits (0: query current)'],
             returns=['*w: Available stopbits',
                      'w: Selected stopbits'])
    def stopbits(self, c, data=None):
        """Sets the number of stop bits."""
        ser = self.getPort(c)
        stopbits = ser.STOPBITS
        if data is None:
            return stopbits
        else:
            if data in stopbits:
                ser.stopbits = data
            return long(ser.stopbits)

    @setting(25, 'Timeout',
             data=[': Return immediately',
                   'v[s]: Timeout to use (max: 5min)'],
             returns=['v[s]: Timeout being used (0 for immediate return)'])
    def timeout(self, c, data=T.Value(0, 's')):
        """Sets a timeout for read operations."""
        c['Timeout'] = min(data['s'], 300)
        return T.Value(c['Timeout'], 's')

    @setting(30, 'RTS', data=['b'], returns=['b'])
    def RTS(self, c, data):
        """Sets the state of the RTS line."""
        ser = self.getPort(c)
        ser.rts = int(data)
        return data

    @setting(31, 'DTR', data=['b'], returns=['b'])
    def DTR(self, c, data):
        """Sets the state of the DTR line."""
        ser = self.getPort(c)
        ser.dtr = int(data)
        return data

    @setting(40, 'Write',
             data=['s: Data to send',
                   '*w: Byte-data to send'],
             returns=['w: Bytes sent'])
    def write(self, c, data):
        """Sends data over the port."""
        ser = self.getPort(c)
        if not isinstance(data, str):
            data = ''.join(chr(x & 255) for x in data)
        ser.write(data)
        return long(len(data))

    @setting(41, 'Write Line', data=['s: Data to send'],
             returns=['w: Bytes sent'])
    def write_line(self, c, data):
        """Sends data over the port appending CR LF."""
        ser = self.getPort(c)
        ser.write(data + '\r\n')
        return long(len(data) + 2)

    @setting(42, 'Pause', duration='v[s]: Time to pause', returns=[])
    def pause(self, c, duration):
        _ = yield deferLater(reactor, duration['s'], lambda: None)
        return

    @inlineCallbacks
    def _deferredRead(self, ser, timeout, count=1):
        stop_time = time.time() + timeout

        def doRead(count):
            while True:
                d = ser.read(count)
                if d:
                    return d
                sleep(0.01)
                if time.time() > stop_time:
                    return ''

        data = yield threads.deferToThread(doRead, count)
        returnValue(data)

    @inlineCallbacks
    def deferredRead(self, ser, timeout, count=1):
        killit = False

        def doRead(count):
            d = ''
            while not killit:
                d = ser.read(count)
                if d:
                    break
                sleep(0.010)
            return d

        data = threads.deferToThread(doRead, count)
        timeout_object = []
        start_time = time.time()
        r = yield util.maybeTimeout(data, min(timeout, 300), timeout_object)
        killit = True

        if r == timeout_object:
            elapsed = time.time() - start_time
            print "deferredRead timed out after {} seconds".format(elapsed)
            r = ''
        if r == '':
            r = ser.read(count)

        returnValue(r)

    @inlineCallbacks
    def readSome(self, c, count=0):
        ser = self.getPort(c)

        if count == 0:
            returnValue(ser.read(10000))

        timeout = c['Timeout']
        if timeout == 0:
            returnValue(ser.read(count))

        recd = ''
        while len(recd) < count:
            r = ser.read(count - len(recd))
            if r == '':
                r = yield self.deferredRead(ser, timeout, count - len(recd))
                if r == '':
                    ser.close()
                    ser.open()
                    break
            recd += r
        returnValue(recd)

    @setting(50, 'Read', count=[': Read all bytes in buffer',
                                'w: Read this many bytes'],
             returns=['s: Received data'])
    def read(self, c, count=0):
        """Read data from the port.

        Args:
            count:   bytes to read.

        If count=0, reads the contents of the buffer (non-blocking).  Otherwise
        reads for up to <count> characters or the timeout, whichever is first
        """
        return self.readSome(c, count)

    @setting(51, 'Read as Words',
             data=[': Read all bytes in buffer',
                   'w: Read this many bytes'],
             returns=['*w: Received data'])
    def read_as_words(self, c, data=0):
        """Read data from the port."""
        ans = yield self.readSome(c, data)
        returnValue([long(ord(x)) for x in ans])

    @setting(52, 'Read Line',
             data=[': Read until LF, ignoring CRs',
                   's: Other delimiter to use'],
             returns=['s: Received data'])
    def read_line(self, c, data=''):
        """Read data from the port, up to but not including the specified
        delimiter."""
        ser = self.getPort(c)
        timeout = c['Timeout']

        if data:
            delim, skip = data, ''
        else:
            delim, skip = '\n', '\r'

        recd = ''
        while True:
            r = ser.read(1)
            if r == '' and timeout > 0:
                # only try a deferred read if there is a timeout
                r = yield self.deferredRead(ser, timeout)
            if r in ('', delim):
                break
            if r != skip:
                recd += r
        returnValue(recd)

__server__ = SerialServer()

if __name__ == '__main__':
    from labrad import util
    util.runServer(__server__)