MQTT Signal Reference¶

Complete reference of the 88 signals exposed by vito2mqtt over MQTT. These exposed signals are organized into 7 domain groups, each published as a JSON object to its own MQTT topic. An additional internal command (system_time) exists in the registry but is not exposed via these topics.

Topic Layout¶

Topics follow the domain-grouped layout:

vito2mqtt/{device_id}/{group}/state    # Telemetry (read-only, JSON)
vito2mqtt/{device_id}/{group}/set      # Commands (writable, JSON)

With the default device_id of vitodens200w, example topics:

vito2mqtt/vitodens200w/outdoor/state
vito2mqtt/vitodens200w/hot_water/state
vito2mqtt/vitodens200w/hot_water/set
vito2mqtt/vitodens200w/burner/state
vito2mqtt/vitodens200w/heating_radiator/state
vito2mqtt/vitodens200w/heating_radiator/set
vito2mqtt/vitodens200w/heating_floor/state
vito2mqtt/vitodens200w/heating_floor/set
vito2mqtt/vitodens200w/system/state
vito2mqtt/vitodens200w/system/set
vito2mqtt/vitodens200w/diagnosis/state

Framework Topics¶

Alongside the device topics above, cosalette itself publishes two framework-owned topics under the vito2mqtt/ app prefix (not the device_id segment). Both are always on — no setting disables them — retained, QoS 1, and republished byte-identically on every broker connect.

Registry (vito2mqtt/_meta/registry)¶

The canonical AsyncAPI document describing every channel vito2mqtt publishes and subscribes to. Inbound command channels are stripped from the published copy so the command surface is not exposed to anyone who can subscribe on a shared broker.

State Model Drift (vito2mqtt/_meta/state_model_drift)¶

A machine-readable snapshot of state_model declaration drift (ADR-069): a handler whose state_model= argument disagrees with its return type annotation. The topic is published even when there is no drift — a clean app publishes drift_count: 0 rather than omitting the topic, so "no drift" is distinguishable from "never ran a version that publishes this topic".

{
  "schema_version": 1,
  "drift_count": 0,
  "entries": []
}

mosquitto_sub -t '+/_meta/state_model_drift'

ACL guidance¶

Both topics disclose handler names, channel addresses, and payload schemas. If you run a production broker ACL file, protect _meta/# the same way you protect _meta/registry. The mosquitto.conf shipped with vito2mqtt is dev-only (allow_anonymous true, no ACL file), so there is nothing to change in-repo — this note only applies if you deploy your own broker ACLs.

Signal Groups¶

Outdoor (3 telemetry signals)¶

Topic: vito2mqtt/{device_id}/outdoor/state

Hot Water (2 telemetry + 9 command signals)¶

Telemetry topic: vito2mqtt/{device_id}/hot_water/state

Command topic: vito2mqtt/{device_id}/hot_water/set

Burner (8 telemetry signals)¶

Topic: vito2mqtt/{device_id}/burner/state

Heating Radiator / M1 (7 telemetry + 13 command signals)¶

The M1 heating circuit controls traditional radiators.

Telemetry topic: vito2mqtt/{device_id}/heating_radiator/state

Command topic: vito2mqtt/{device_id}/heating_radiator/set

Heating Floor / M2 (8 telemetry + 13 command signals)¶

The M2 heating circuit controls underfloor heating.

Telemetry topic: vito2mqtt/{device_id}/heating_floor/state

Command topic: vito2mqtt/{device_id}/heating_floor/set

System (7 telemetry + 7 command signals)¶

Telemetry topic: vito2mqtt/{device_id}/system/state

Command topic: vito2mqtt/{device_id}/system/set

Diagnosis (11 telemetry signals)¶

Topic: vito2mqtt/{device_id}/diagnosis/state

Signal Totals Summary¶

Type Code Reference¶

Command Payloads¶

Writing values¶

To write values, publish a JSON object to the group's /set topic:

# Set hot water target temperature to 55°C
mosquitto_pub -h localhost \
  -t 'vito2mqtt/vitodens200w/hot_water/set' \
  -m '{"hot_water_setpoint": 55}'

Multiple signals can be set in a single message:

# Set both room setpoint and economy setpoint for the radiator circuit
mosquitto_pub -h localhost \
  -t 'vito2mqtt/vitodens200w/heating_radiator/set' \
  -m '{"room_temperature_setpoint_m1": 21, "room_temperature_setpoint_economy_m1": 18}'

Read-before-write optimization¶

For READ_WRITE signals, vito2mqtt reads the current value from the boiler before writing. If the desired value matches the current value, the write is skipped. This reduces serial bus traffic and avoids unnecessary EEPROM wear on the boiler controller.

The __force meta-key¶

To bypass the read-before-write comparison and write unconditionally, include the __force key set to true:

{
  "hot_water_setpoint": 55,
  "__force": true
}

Timer schedule format (CT type)¶

Timer schedules use the CycleTime format with 4 on/off slot pairs per day:

{
  "timer_hw_monday": [
    ["06:00", "08:00"],
    ["17:00", "22:00"],
    ["00:00", "00:00"],
    ["00:00", "00:00"]
  ]
}

Each slot is a [start, end] pair in "HH:MM" format. Unused slots should be set to ["00:00", "00:00"].