【Internet of Things Communication Technology】——M-Bus

Overview

M-Bus (Meter-Bus) is a European standard (EN 13757-2 for physical and link layers, EN 13757-3 for application layer) designed for remote meter reading of gas, electricity, or other types of consumption meters, such as those in heating systems or water meters. The M-Bus interface communicates over a two-wire line, making it cost-effective. The wireless radio variant, Wireless M-Bus, is also specified in EN 13757-4.

M-Bus belongs to the fieldbus family, consisting of an information transmission system based on a common transmission medium to which devices capable of receiving and sending information are connected. Information is encoded digitally and transmitted serially in the form of data telegrams. The transmission mode is asynchronous and half-duplex, controlled by a master device. The transmission medium is a simple two-core cable, with all devices connected in parallel.

M-Bus is an open system: its technical specifications and communication protocols are publicly available. Therefore, M-Bus devices from different manufacturers can be connected and exchange data on an M-Bus network. M-Bus is a master-slave system; communication is controlled by a single device (the master), which cyclically polls other devices (slaves) to collect information. Slave devices cannot initiate communication and must wait for interrogation by the master. In addition to data concentrator functionality, the Master typically provides other features such as data storage (data logging) and remote control via communication interfaces.

Development History

M-Bus was proposed by Dr. Horst Ziegler of the University of Paderborn in collaboration with TI Deutschland GmbH and Techem GmbH. The concept of the M-Bus is based on the ISO-OSI reference model, but M-Bus is not a true network in the conventional sense. Within the OSI seven-layer model, M-Bus only defines functions for the physical, link, network, and application layers. Since the ISO-OSI reference model does not allow upper layers to change parameters such as baud rate or address, M-Bus defines a management layer outside the seven-layer model, which can manage any layer without adhering to OSI model constraints. The proposal of the M-Bus met the needs of networking and remote meter reading for utility meters, while also accommodating special requirements for remote or battery-powered systems. The bus-type topology of the M-Bus serial communication method is well-suited for the reliable, low-cost networking requirements of utility meters, capable of connecting several hundred slave devices over distances of several kilometers.

Technical Features

• A single bus cable connects all meters to a central system, making it a very simple protocol.
• Bus nodes can optionally be powered directly via the two-wire bus.
• All data can be read electronically and remotely.
• Minimal reading errors, very fast reading speed, and subsequent processing is very easy.
• Devices from different manufacturers can be connected to the bus system, which does not lock users into a specific meter manufacturer.
• All meters can be addressed individually, allowing control of each energy consumption meter while using only a single cable for connection.

Application Areas

M-Bus can be used in industrial settings and is also convenient for use in private homes. According to the standard, an M-Bus master can read up to 250 slave devices.

These can be heat meters, water meters, electricity meters, or gas meters. M-Bus can also be used in applications such as alarm systems, flexible lighting installations, heating controls, etc. It can monitor different consumption meters and detect any leaks.

Related Links

Beijing Kehui Mingyuan Automation Technology Co., Ltd.: A range of M-Bus products, with many years of expertise in this technology.

M-Bus Standard

Modbus_Application_Protocol.pdf