The M-Bus was developed to fill the need for a system for the networking and remote reading of utility meters, for example to measure the consumption of gas or water in the home.
This bus fulfills the special requirements of remotely powered or battery-driven systems, including consumer utility meters.
An alternative method of collecting data centrally is to transmit meter readings via a modem.
Other applications for the M-Bus such as alarm systems, flexible illumination installations, heating control, etc.
The concept was based on the ISO-OSI Reference Model, in order to realize an open system which could use almost any desired protocol.
Since the M-Bus is not a network, and therefore does not - among other things - need a transport or session layer, the levels four to six of the OSI model are empty.
Therefore, only the physical, the data link, the network and the application layer are provided with functions.
M-Bus uses two-wire telephone cable (JYStY 1x2x0.8 mm or similar, 73 ohm/km, 120 nF/km) maximum length of 350 meters when using nominal transfer speeds 300 and 9600 baud.
Masters can provide type-dependent number of load units, and usually visually indicate overload.