RFWireless M-Bus (wM-Bus) Basics Explained
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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.
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 Mode | Description |
|---|---|
| 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 Mode | SRD Frequency Band |
|---|---|
| S1-Mode, S2-Mode | 868 MHz |
| T1-Mode, T2-Mode | 868 MHz |
| C1-Mode, C2-Mode | 868 MHz |
| R2-Mode | 868 MHz |
| N1-Mode, N2-Mode | 169 MHz |
| F1-Mode, F2-Mode | 433 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.
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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.
Figure: Wireless M-Bus network
