Wireless M-Bus protocol is designed as a robust, power-saving, long-range wireless communications solution that runs on unlicensed ISM bands. This protocol is widely used in the energy industry for data transmission from machine to machine (M2M).
Wireless M-Bus was first released in 2003. Since then, the foundation has been developed with feedback from thousands of field installations in very demanding environments.
The wireless M-bus protocol is especially known for the quality of radio coverage, the easy relationship between other technologies, the simplicity of the deployment and installation of the equipment. Secure and encrypted Wireless M-Bus data, as well as providing reliable billing data to the utility, can show the user real-time consumption values if needed.
It is very useful for battery powered devices as the power consumption of the wireless M-bus protocol is very low.
The operating frequency band of the Wireless M-Bus protocol is between 169 MHz and 915 MHz. The data rate varies differ according to 6 different modes supported by the wireless M-bus (4.8 kbps, 100 kbps and 32768 kbps). The coverage area is 1 kilometer in the 868 MHz band. Data security is provided using the AES-128 encryption algorithm. In the wireless M-bus protocol, communication can be one-way or two-way. This protocol is used for remote monitoring of water, gas and electricity meters and for customer invoicing by public companies.
The physical and data link layers for the wireless M-bus are specified in the EN13757-4 standard. This standard refers about communication between the meter and other system components. System components consist of reading devices and data acquisition devices. These devices can be stationary or mobile.
For the physical layer, the EN 13757-4 standard has also set various performance classes depending on the maximum power to be transmitted and the lowest receiver sensitivity provided by the meter.
Wireless M-Bus Modes
Stationary Mode (S Mode)
This mode is for one-way or two-way communication between the meter and a stationary or mobile device. The meters send their data several times a day. The data collector can be a battery-powered device and can be optimized for stable operation. The communication can be one-way or two-way. It uses the frequency band of 868 MHz.
Frequent Transmit Mode (T Mode)
In this mode, the meters send data to collectors within range every few seconds. The communication can be one-way or two-way. The communication can be one-way or two-way. It uses the frequency band of 868 MHz.
Frequent Receive Mode (R2 Mode)
It prevents multiple measuring devices from interfering with each other by using separate frequency channels. The communication is one-way. It uses the frequency band of 868 MHz.
Narrowband VHF Mode (N Mode)
This mode is optimized for narrowband and long range. The communication can be one-way or two-way. Uses the frequency band of 169 MHz.
Frequent receive and transmit mode (F Mode)
This mode transmits and receives frequently on the 433 MHz band. It has a long range. Reading process takes place on demand. The meter listens every few seconds for the wake-up signal. Communication can be one-way or two-way.
Compact Mode (C Mode)
This mode is similar to T mode but can send more information using the same energy. Communication can be one-way or two-way. Uses the 868 MHz frequency band.
Wireless M-Bus Protocol Stack
RF Layer: Defines the frequency band and transmission spectrum mask to be used for wireless M-Bus products.
Physical Layer: Defines the maximum transmit power and the lowest receiver sensitivity of the meter.
Data Link Layer: Defines A and B frame formats. The frame carries the preamble, the link layer data payload, and the application layer data payload. Uses AES 128 CBC encryption for load data.
Application Layer: Defines the application protocol that makes devices from different providers interoperable in a single wireless M-Bus network.
