Meter data from the M-Center in Grafana

Step 1: Telegraf reads via Modbus TCP

Telegraf has a Modbus input plugin. For each meter you create a block with its device address. The example reads import and export of an electricity meter with device address 9:

[[inputs.modbus]]
  name = "m_center"
  controller = "tcp://192.168.1.50:502"
  slave_id = 9
  timeout = "5s"
  interval = "15m"
  holding_registers = [
    { name = "import_total",     byte_order = "ABCD", data_type = "FLOAT32-IEEE", scale = 1.0, address = [999, 1000] },
    { name = "export_total", byte_order = "ABCD", data_type = "FLOAT32-IEEE", scale = 1.0, address = [1149, 1150] },
  ]
  [inputs.modbus.tags]
    meter = "apartment_1"

Telegraf counts addresses from 0, the manual from 1: register 1000 becomes 999. Byte order ABCD corresponds to big endian with the high word first, as delivered by the M-Center. The notation of the options changes between Telegraf versions; the plugin documentation of your version applies.

Alternative: Telegraf reads via MQTT

With the MQTT licence, Telegraf subscribes to the M-Center’s topics with the plugin inputs.mqtt_consumer:

<prefix>/emu/mcenter/<MAC>/meterreading/+/byobis/#

How Telegraf evaluates the messages is set with data_format. So look at the content of the messages with an MQTT client first.

Step 2: InfluxDB and Grafana

1. In Telegraf, set the output to InfluxDB (outputs.influxdb_v2 with URL, token, organisation and bucket).
2. In Grafana, add InfluxDB as a data source.
3. Create a panel and query the reading. For consumption per day or month, take the difference of the meter reading over the time window.

Meter readings only rise. A bar chart with consumption per day is therefore usually more meaningful than the curve of the meter reading.