HOW-TO: Smart-MAIC D105 with Open Energy monitor sensor and Home Assistant

Hello,

did lot of searching in Internet, but didn't find any guides how to set up Smart-MAIC D105 pulse counter with Home Assistant and Open Energy Monitor sensor. Open energy monitor is sensor that counts pulses from utility company kWh-meter and as such, it can be [legally] installed without being electrician and removing panels from electric cabinet (which I still did, as I needed to wire Cat5 for sensor neatly). It also shows exactly same consumption utility compay is charging, since it's read from "official" energy meter. Also, you may avoid need to re-seal electric cabinet, since installing measurement coils may require opening sealed cabinet parts.

My config in Home Assistant sensor.yaml is following:

- platform: mqtt
  name: "kWh-mittari"
  unique_id: 'smartmaic_myunitnumber'
  state_topic: "myunitnumber/JSON"
  unit_of_measurement : "kWh"
  device_class: energy
  state_class: total_increasing
  value_template: '{{ value_json.TCh1 | float * 0.001 }}'

My energy meter sends 1000 pulses for every consumed 1kWh, therefore, value template uses float * 0.001. Some meters use other values, like 800 pulses / 1 kWh, then this value template probably would be float * 0.0125. For this config to work, you need to:

1. configure MQTT server in your Home Assistant (I'm using Mosquitto)

2. configure MQTT in Smart-MAIC D105 (there's page for it)

With this config you can see hourly, daily, weekly, monthly etc consumption in your Home Assistant energy page. Add your electric price, it will count costs. When you adjust price, old values will be retained and only new consumption values get new price (likely higher...)

There's in no need to change default Smart-MAIC D105 pulse counter settings! Just make sure Mode of operation-setting is Pulse counter.

Open Energy Monitor-sensor is to be connected to digital input lines, with three wire:

- OpenEnergy Monitor red, VCC - Smart-MAIC contact 5

- OpenEnergy Monitor blue, TTL Data - Smart-MAIC contact 2

- OpenEnergy Monitor black, GND - Smart-MAIC contact 1

(This config is called NPN-counter in Smart-MAIC documentation)
There is no need to additional electronic components (resistors etc.). I'm using unshielded Cat5e as signal cable, sensor is about 15m from counter and works well with Cat5e.