Terminology » Other Wireless » Wireless M-Bus (wM-Bus) Basics Explained

Wireless M-Bus (wM-Bus) Basics Explained

wireless mbus m-bus metering protocol wireless communication

This article explains what Wireless M-Bus is and covers the basics of Wireless Meter Bus.

wM-Bus stands for Wireless Metering Bus. It’s defined by the EN13757-4 standard, which specifies communication between meters and other system components, such as read-out devices and data collectors. These devices can be either stationary or mobile.

Wireless M Bus System

Figure: Wireless M-Bus communication system block diagram

The communication between the meter and other system components can be one-way or two-way.

wM-Bus PHY Modes

There are several physical layer (PHY) modes defined for wM-Bus. These modes are listed in the table below:

WM-Bus PHY ModeDescription
S-Mode (Stationary Mode)
S1-Mode (One way)
S1m-Mode (One way)
S2-Mode (two way)
T-Mode (Frequent Transmit Mode)
T1-Mode (one way)
T2-Mode (two way)
R-Mode (Frequent Receive Mode)
R2-Mode (two way)
N-Mode (Stationary Mode)
N1 Mode (one way)
N2 Mode (two way)
N2g-Mode (two way)
C-Mode (Frequent Transmit Mode)
C1 Mode (one way)
C2 Mode (two way)
F-Mode (Frequent Transmit Mode)
F1 Mode (one way)
F2 Mode (two way)

wM-Bus Frequency Bands

The following table outlines the wM-Bus modes and their corresponding SRD (Short Range Device) frequency bands:

wM Bus ModeSRD Frequency Band
S1-Mode, S2-Mode868 MHz
T1-Mode, T2-Mode868 MHz
C1-Mode, C2-Mode868 MHz
R2-Mode868 MHz
N1-Mode, N2-Mode169 MHz
F1-Mode, F2-Mode433 MHz

Wireless M-Bus (wM-Bus) Kits

Several companies offer wM-Bus kits, including both hardware and software components:

  • TEXAS INSTRUMENTS: Their CC112x and CC120x series support Wireless M-Bus Transceiver functionalities and operate in the 868, 433, and 169MHz frequency bands. They are compliant with ETSI 300-220 V2.3.1.

  • RENESAS: They provide a wireless M-Bus protocol stack and a Wireless M-Bus interface board with the following features:

    • Supports T1, S1, T2, S1-m, C1, S2, C2, N1, F2, and N2 modes as per EN 13757-4.
    • Operates in the 169 and 868 MHz frequency bands.
    • Offers protocol stack source code, data-link layer, and application layer software libraries.

Wireless M-Bus network

Figure: Wireless M-Bus network