Logging solar system performance from a Renogy Wanderer_

#!/usr/bin/env python3
''' solarmonitor.py (c) 2022 Matthew J. Ernisse <matt@going-flying.com>
All Rights Reserved.

Redistribution and use in source and binary forms,
with or without modification, are permitted provided
that the following conditions are met:

    * Redistributions of source code must retain the
      above copyright notice, this list of conditions
      and the following disclaimer.
    * Redistributions in binary form must reproduce
     the above copyright notice, this list of conditions
      and the following disclaimer in the documentation
      and/or other materials provided with the distribution.

THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
"AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS
OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR
TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE
USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
'''
import datetime
import minimalmodbus
import optparse
import time
import struct
import sys

from requests.exceptions import ConnectionError
from influxdb import InfluxDBClient
from influxdb.exceptions import InfluxDBServerError


class ModbusClient(object):
    def __init__(self, system_name, port):
        self.client = None
        self.port = port
        self.systemName = system_name

    @staticmethod
    def initalizeMeasurement(system_name):
        return {
            'measurement': 'solar_power_system',
            'tags': { 'name': system_name },
            'time': datetime.datetime.utcnow().isoformat() + 'Z',
            'fields': {}
        }

    def addPoint(self, p_name, val):
        self.points['fields'].update({p_name: val})

    def open(self):
        self.client = minimalmodbus.Instrument(self.port, 1)
        self.client.serial.baudrate = 9600
        self.client.serial.timeout = 5

    def sample(self):
        self.open()

        self.points = self.initalizeMeasurement(self.systemName)

        register = self.client.read_register(0x103)
        register = (register >> 8).to_bytes(1, 'big')

        # 'b' = signed char
        self.addPoint('sccTemp', struct.unpack('b', register)[0])

        register = self.client.read_register(0x106)
        self.addPoint('loadWatts', register)

        register = self.client.read_register(0x107)
        self.addPoint('pvVolts', float(register/10))

        register = self.client.read_register(0x108)
        self.addPoint('pvAmps', float(register/100))

        register = self.client.read_register(0x109)
        self.addPoint('pvWatts', register)

        register = self.client.read_register(0x101)
        self.addPoint('batVolts', float(register/10))
        self.stop()

    def stop(self):
        self.client.serial.close()
        self.client = None
        self.shouldStop = True


if __name__ == '__main__':
    parser = optparse.OptionParser()
    solar_group = optparse.OptionGroup(
        parser,
        'Solar System Options',
        'The MODBUS connection to a solar charge controller'
        ' needs a port and a name.'
    )
    solar_group.add_option(
        '-p',
        '--port',
        help='Serial port name to connect to.'
    )
    solar_group.add_option(
        '-n',
        '--name',
        help='Name of the system attached to the port.'
    )
    parser.add_option_group(solar_group)

    influxdb_group = optparse.OptionGroup(
        parser,
        'InfluxDB Options',
        'Configure the global connection to InfluxDB'
    )
    influxdb_group.add_option(
        '-H',
        '--hostname',
        help='Hostname of the InfluxDB server'
    )
    influxdb_group.add_option(
        '-P',
        '--dbport',
        default=8086,
        help='Port to connect to InfluxDB on',
        type='int'
    )
    influxdb_group.add_option(
        '-d',
        '--dbname',
        help='InfluxDB database name to query.'
    )
    influxdb_group.add_option(
        '-w',
        '--password',
        help='InfluxDB password.'
    )
    influxdb_group.add_option(
        '-u',
        '--username',
        help='InfluxDB username.'
    )
    parser.add_option_group(influxdb_group)

    options, _ = parser.parse_args()

    if not options.port or \
        not options.name or \
        not options.hostname or \
        not options.dbname:
        parser.error('Insufficient arguments.')


    client = ModbusClient(options.name, options.port)
    db = InfluxDBClient(
        options.hostname,
        options.dbport,
        options.username,
        options.password,
        options.dbname
    )

    while True:
        # modbus errors are fatal, InfluxDB errors are ignored.
        try:
            client.sample()

        except Exception as e:
            print(f'MODBUS ERROR: {e!s}')
            sys.exit(1)

        try:
            db.write_points([client.points])
        except (ConnectionError, InfluxDBServerError) as e:
            print(f'InfluxDB ERROR: {e!s}')
            pass

        time.sleep(60)