Need to connect M-Bus and MQTT? The Weble WBox routes M-Bus MQTT natively: one gateway speaks both protocols and maps data points in real time — no PC, no middleware, no cloud dependency.

M-Bus to MQTT gateway

The protocols

M-Bus

M-Bus reads heat, water, gas and electricity meters over a dedicated 2-wire bus.

M-Bus driver →

MQTT

MQTT is the lightweight publish/subscribe protocol used by IoT devices and cloud brokers.

MQTT driver →

Further reading: Wired vs wireless M-Bus: what is the difference? →

Typical use case

For cloud or IoT metering, the WBox reads wired or wireless M-Bus meters across a building and publishes their readings to an MQTT broker. Each meter becomes a tidy set of topics a metering platform, smart-me account or cloud dashboard can ingest for billing, sub-metering, benchmarking or alerts. No proprietary concentrator and no on-site PC: the gateway handles the readout and the gateway handles the upload.

In the field

Weble customers run this routing in production:

Customer story Sunflower Grid Continuous M-Bus meter reading (heat, water, electricity) with MQTT publishing to its collective self-consumption (RCP) platform. Read the case → Customer story Groupe E Collects building M-Bus meters and uplinks them to the Gestinergie 4.0 cloud (Azure IoT, MQTT). Read the case →

How the WBox bridges M-Bus and MQTT

Activate the M-Bus and MQTT drivers. The WBox polls each meter on a schedule, reads the records you select (energy, volume, power, error flags) and publishes them per meter as JSON on MQTT topics, with the last value retained for new subscribers. A Blockly or JavaScript step applies unit conversion (e.g. Wh to kWh), adds a timestamp or meter ID, or pushes the same values to a service such as smart-me in parallel.

Step by step

  1. Wire the field side — connect the meters through an M-Bus level converter.
  2. Enable the M-Bus and MQTT drivers on the WBox — licence-activated, no extra hardware.
  3. Map each point to a topic: a M-Bus value becomes site/area/point (publish), with QoS and the retained flag set per signal.
  4. Point the broker — host, port 8883, TLS and credentials — at your on-prem or cloud broker (AWS IoT, Azure, ThingsBoard, any MQTT 3.1.1/5).
  5. M-Bus is read-only, so the flow is publish-only — confirm every meter reading live in the WBox point monitor.

Example mapping

M-Bus meters are read-only, published as retained topics:

  • M-Bus meter #7 record 0 active energy (kWh) → MQTT topic meters/heat/7/energy_kwh
  • M-Bus meter #7 record 3 volume flow (m³/h) → MQTT topic meters/heat/7/flow
  • M-Bus meter #7 record 5 power (kW) → MQTT topic meters/heat/7/power

Capacity & limits

  • M-Bus — M-Bus drives up to 190 metering slaves through a Weble level converter (250 per the standard).
  • MQTT — MQTT imposes no point limit — topics scale with your broker and network.

On the WBox, a driver licence enables the whole protocol — there is no artificial per-point tier to unlock. Capacity scales with the gateway model, from the compact S103 to the E413: you are bounded by the field bus, not by your licence.

Frequently asked questions

How do I do M-Bus meter reading over MQTT?

The WBox reads the M-Bus meters (wired or wireless) and publishes the readings over MQTT to your metering platform.

How do I find all the M-Bus meters?

The gateway can scan secondary and primary meter addresses directly from the web interface.

Do I need an M-Bus converter?

For wired M-Bus, yes: an RS485toMBus or EthernettoMBus converter. For Wireless M-Bus, a radio stick is enough.

Where is the data sent?

To any MQTT broker or metering platform; topics and payloads are configurable.

What you need

One WBox gateway with these two driver licences:

M-Bus M-Bus Driver licence 100.00 CHF MQTT MQTT Driver licence 100.00 CHF

Route M-Bus MQTT on your project

Find the right WBox gateway for your installation, or get in touch to validate your case.

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