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wM-Bus Sensors

Here is list of tested sensors by HARDWARIO with basic configuration to use:

Name of sensorType of sensor
BMeters IWM-TX3Watermeter
BMeters IWM-TX5Watermeter

Wireless M-Bus (wM-Bus) Communication Overview

wM-Bus Architecture

Figure: Example architecture using Wireless M-Bus devices communicating with a gateway.

What is Wireless M-Bus?​

Wireless M-Bus (wM-Bus) is an extension of the wired M-Bus protocol defined by the EN 13757 standard. It enables wireless communication between utility meters and data collectors. It is primarily used in applications requiring remote meter reading over longer distances without physical cabling.

wM-Bus is optimized for low-power, low-bandwidth communication, making it ideal for battery-powered metering devices in residential, commercial, and industrial environments.

Wireless Modes and Frequencies​

wM-Bus supports several modes depending on the use case:

  • S-Mode: Stationary, one-way communication (e.g., daily metering)
  • T-Mode: Frequent transmissions with support for two-way communication
  • C-Mode: Continuous communication with acknowledgment (bidirectional)
  • R-Mode: Repeater mode for extending range

Frequency Bands​

  • 868 MHz (Europe)
  • 433 MHz (some regions)
  • Data rate typically ranges from 2.4 kbps to 100 kbps, depending on mode

Hardware Requirements​

Components​

  • wM-Bus Meters: Battery-powered smart meters (gas, water, heat, electricity)
  • wM-Bus Receiver or Gateway: Device with a radio module capable of demodulating and decoding wM-Bus frames
  • Antenna: Proper RF antenna required for 868 MHz operation

Power Consumption​

  • Designed for ultra-low power: meters may operate for >10 years on a single battery

Data Format​

wM-Bus shares its application layer with wired M-Bus (EN 13757-3):

  • Uses the same telegram structure with encrypted or plaintext payloads
  • Data is structured in DIF/VIF format
  • Support for AES-128 encryption (optional, standard in many implementations)

Message Structure​

  • Preamble
  • Synchronization
  • Header (CI field, Access number, status)
  • Payload (Application Data)
  • CRC checksum

Example Output (Parsed JSON)​

{
  "device_id": "WMBS-98765432",
  "timestamp": "2025-04-29T08:15:00Z",
  "water_m3": 35.42,
  "battery_voltage_v": 3.01,
  "rssi_dbm": -80
}

Applications​

  • Automated meter reading (AMR)
  • Smart city infrastructure
  • Remote monitoring in buildings and utilities
  • Energy efficiency audits

Advantages of wM-Bus​

  • No physical wiring required
  • Long battery life (5–15 years typical)
  • Reliable and standardized communication
  • Well-supported in European utility infrastructure
  • Support for encryption and secure authentication

Limitations​

  • Limited bandwidth (not suitable for large or frequent data uploads)
  • Susceptible to RF interference
  • Regional regulatory constraints on ISM bands