RS232 Reader / XML to CSV Converter

'''
    Read data from a Licor 820 and/or 840

    Written by Laurent Fournier, October 2016
    Thanks to David H. Hagan's work, May 2016

    To-do :
    - Devices switch
    - For 820: celltemp, cellpres, co2
    - For 840: celltemp, cellpres, co2, h2o, h2odewpoint
'''

import os, sys, subprocess
import time, datetime
import serial
import string

from bs4 import BeautifulSoup as bs

#-------------------------------------------------------------
#------------------ Open configurations ----------------------
#-------------------------------------------------------------

  ############
  # Settings #
  ############

DEBUG     = True
LOG       = True
FREQ      = 1
PORT      = '/dev/ttyUSB0'
BAUD      = 9600
PARITY    = 'N'
STOPBIT   = 1
BYTE_SZ   = 8
TIMEOUT   = 5.0
LOG_DIR   = 'logs/'

isLooping = 20                                                                          # Nr of data extractions
isStarted = False

device_nr = [820, 840]                                                                  # List of devices's models


#-------------------------------------------------------------
#----- Better know what you are doing from this point --------
#-------------------------------------------------------------

  ##################
  # Initialisation #
  ##################

class Licor:
    def __init__(self, **kwargs):
        self.port       = kwargs.pop('port',    '/dev/ttyUSB0')
        self.baud       = kwargs.pop('baud',    BAUD)
        self.timeout    = kwargs.pop('timeout', TIMEOUT)
        self.debug      = kwargs.pop('debug',   DEBUG)

        self._header    = [ 'timestamp',
                            'cell_temp',
                            'cell_pressure',
                            'co2',
                            'co2_abs',
                            'ivolt',
                            'raw']

    def connect(self):
        try:
            self.con = serial.Serial(self.port, self.baud, timeout=self.timeout)        # Connect to serial device

        except Exception as e:
            self.con = None
            return e

        return True

    def read(self):
        raw = bs(self.con.readline(), 'lxml')                                           # Read a complete row from IO stream

        raw = raw.li820.data                                                            # Define data structure
        res = [ datetime.datetime.now().isoformat(' '),
                raw.celltemp.string,
                raw.cellpres.string,
                raw.co2.string,
                raw.co2abs.string,
                raw.ivolt.string,
                raw.raw.string, ]

        if self.debug:
            print ("\nNew Data Point")
            for each in zip(self._header, res):
                print (each[0], each[1])

        return res

    def __repr__(self):
        return "Licor Model Li-820/840"


  ################
  # Main program #
  ################

filename = 'licor{}-data-{}.csv'.format(device_nr[0], datetime.datetime.now())

if LOG_DIR:                                                                             # If LOG_DIR is set, add it to filename
    filename = os.path.join(LOG_DIR, filename)

try:                                                                                    # Connect to device
    licor = Licor(port = PORT, baud = BAUD, timeout = TIMEOUT, debug = DEBUG)
    licor.connect()

except Exception as e:
    if DEBUG:
        print ("ERROR: {}".format(e))

    sys.exit("Could not connect to the device")

if LOG:                                                                                 # If logging enabled
    with open(filename, 'w') as fp:
        fp.write(';'.join(licor._header))                                               # Write headers
        fp.write('\n')

        while True:
            try:
                data = licor.read()                                                     # Read from device

                fp.write(';'.join(data))                                                # Write data
                fp.write('\n')

            except Exception as e:
                if DEBUG:
                    print ("ERROR: {}".format(e))

            time.sleep(FREQ)                                                            # Sleep for FREQ seconds
        fp.close()

else:                                                                                   # If logging Disabled
    while True:
        data = licor.read()
        time.sleep(FREQ)