Wireless RF Modules and dongles for IoT | Coral RF

Wireless M-Bus (wM-Bus) is the only European standard for wireless meter reading. Widely adopted by major metering companies across the continent, if there is a wireless meter or heat cost allocator currently installed in Europe, chances are it is using this standard. wM-Bus is based on European standard (EN) 13757-4, covering the specification of communication between meters and data collectors, also known as gateways.

wM-Bus is a low-cost, low-power star network running on license-free industrial -scientific-medical bands. Because it is based on Sub-1 GHz, wM-Bus networks it can penetrate concrete walls and long distances, with networks of as many as 1,000 nodes per collector. There are modes for the 868MHz, 433MHz and 169MHz bands, enabling coverage over several kilometres.

The wireless M-Bus standard (EN13757-4:2005 and 2012) is used to define the radio frequency communication link between water meter, gas meter, heat meter, electricity meter and data collection device. At present, this standard is widely accepted by the European market and used for intelligent metering or advanced meter reading infrastructure (AMI) applications. Wireless M-Bus was originally defined for the 868MHz operating band, which can achieve a good balance between RF range and antenna size. Later, the wM Bus specification was extended to two other new bands (169MHz and 433MHz). These two narrowband solutions have higher link budgets, which can provide a solution with a longer distance than 868MHz.

Various modes

To help determine which frequency to choose for your meter, let’s start with the wM-Bus modes.

There are eight modes covering the three frequency bands mentioned here; however, only four modes have been widely adopted. Modes define how the meter operates. Stationary (S) mode is appropriate for meters that only need to only send data a few times a day. Frequent transmit (T) mode is applicable when sending greater amounts of data per day. Compact (C) mode can handle even higher data rates. These three modes operate on 868MHz.

If you don’t need a high data rate, but your network is spread over a wide area, then the solution is a narrowband network on 169MHz. Narrowband (N) mode is known for long range, tripling the areas covered by S, T and C modes. The other four modes – R, F, P and Q – are less common.

Characteristic

Unidirectional S1, T1, and C1 mode instrument configurations at 868MHz

Two way S2, T2 and C2 mode instrument configuration at 868MHz

Two way S2, T2 and C2 mode data collector configuration at 868MHz

115.2kbps UART interface with serial command interpreter (connected to external host MCU)

API interface for integrating wM Bus stack into its own application

OMSv3.0.1 Compatibility

Ultra low power consumption in sleep state (UART interface is inactive)

Binary Meter images for TI wM-Bus stack for S1, S2 or T1_C1 and T2_C2 combined wM-Bus modes for OMSv4.1.2 for a Meter device
Binary Meter images for TI wM-Bus stack for S2 or T2 and C2 (C2_T2 combined) wM-Bus modes for OMSv4.1.2 for a Data Collector
CCS project configurations for “Serial” or Network processor function for each mode and either Meter or Data Collector
CCS project configurations for “Embedded” or “API” function for each S-, T and C-mode and either Meter or Data Collector
Extensive documentation of both Serial and API interfaces in HTML format