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()

Hi,
thanks for the quick response. The referenced document helped a lot to understand what I'm doing, but it doesn't look like I'm doing anything wrong. Unfortunately I can't test your script directly, because I only have that ESP32 reader (can't run python), so I tried to rebuild it in Tasmota. I'll get another (USB) reader end of the week, then I can try with a raspberry pi/python. My meter is a T330, but I understand it is similar to the T230.
For now, I think I didn't even manage to wake up the meter... I'll try with different numbers of zeroes now. Let's see if that helps (otherwise I'll verify that your script works, once the reader arrives)
Thanks,
Oli