Read values from Landis & Gyr T230/330 / Qundis Qheat 5.5 heat meters

wmz.py

#!/usr/bin/python3

"""
Script to read values from Qundis Qheat 5.5 (which seems to be "identical" to Landis&Gyr T230/T330)
It's necessary to send 210 leading zeros before the actual request
Check https://www.sipatec.rs/files/uploads/T230.pdf for further protcol details (and subsequent messages)
Uses https://github.com/ganehag/pyMeterBus to decode M-BUS datagrams
"""

import binascii
import datetime
import json
import logging
import sys
from os import getenv
from time import sleep

import serial

sys.path.append('/home/pi/pyMeterBus')
import meterbus
from influxdb import InfluxDBClient

error_sleep_interval = 10

loglevel = getenv('LOGLEVEL', 'INFO').upper()

# InfluxDB
send_influx = bool(getenv('SEND_INFLUX', True))
dbclient = InfluxDBClient(getenv('INFLUX_HOST'),
                          getenv('INFLUX_PORT', 8086),
                          getenv('INFLUX_USER', ''),
                          getenv('INFLUX_PASS', ''),
                          getenv('INFLUX_DB', 'wmz'))
json_body = []
receiveTime = datetime.datetime.utcnow()
lookup_map = { 2: 'VIFUnit.ENERGY_WH',
               3: 'VIFUnit.VOLUME'}

# Serial
serial_port = getenv('SERIAL_PORT', '/dev/ttyUSB0')
ser = serial.Serial(serial_port, baudrate=2400, bytesize=8, parity="E", stopbits=1, timeout=2, xonxoff=0, rtscts=0)

def write_zeros():
    i = 210
    while i:
        ser.write(b'\x00')
        i = i - 1

def send_status_request():
    write_zeros()
    ser.write(b'\x68\05\x05\x68\x53\xFE\x51\x0F\x0F\xC0\x16')
    # see link from above to understand the actual values
    try:
        frame = meterbus.load(meterbus.recv_frame(ser))
        logging.debug(json.dumps(json.loads(frame.body.to_JSON()), indent=4, sort_keys=True))  # there might be an easier way
        return True
    except Exception as e:
        logging.error(f'Unable to decode datagram, please retry: {e}')
        return False

def get_data():
    write_zeros()
    ser.write(b'\x10\x7b\xFE\x79\x16')
    try:
        frame = meterbus.load(meterbus.recv_frame(ser))
        json_response = json.loads(frame.body.to_JSON())  # there might be an easier way
        return json_response
    except Exception as e:
        logging.error(f'Unable to parse data from WMZ: {e}')
        return False

def main():
    retries = getenv('RETRIES', 5)
    while retries:
        success = send_status_request()
        if not success:
            logging.error('WMZ did not correctly respond to status request. Retrying.')
            sleep(error_sleep_interval)
            retries -= 1
            continue
        wmz_data = get_data()
        if wmz_data:
            logging.debug(wmz_data)
            # correct datagram should show this as its first entry (Qheat 5.5)
            if wmz_data['records'][0]['type'] != 'VIFUnit.ACTUALITY_DURATION':
                logging.error('Incorrect datagram, retrying.')
                sleep(error_sleep_interval)
                continue
            else:
                for key in lookup_map.keys():
                    influx_entry =  { "measurement": "", "time": receiveTime, "fields": { "value": "" }}
                    try:
                        influx_entry['measurement'] = lookup_map[key].strip()
                        influx_entry['fields']['value'] = wmz_data['records'][key]['value']/1000
                        json_body.append(influx_entry)
                    except Exception as e:
                        logging.error(f'Unable to assign values from WMZ data to InfluxDB request data: {e}')
                        sleep(error_sleep_interval)
                        continue
            if send_influx:
                dbclient.write_points(json_body)
                logging.debug(json_body)
            print('Done.')
            return
        else:
            retries -= 1
            sleep(error_sleep_interval)
            continue
    logging.error(f'Did not get a meaningful response within {retries} retries. Please re-run later.')

if __name__ == "__main__":
    main()