The M-Bus (“Meter-Bus”) is a European standard for remote reading of heatmeters and it is also usable for all other types of consumption meters as well as for various sensors and actuators. With its standardization as a galvanic interface for remote readout of heat meters this bus wins a great importance for the energy industry as relevant users.

The remote reading of heat meters can take place in different ways, beginnig with the classical method - manual reading by the personnel of the providers - up to the remotely controlled collection of all the meter values for a complete housing unit. The latter is a logical continuation/extension of the technical development of consumption meters and is realizable with the help of the M-Bus.

Here some substantial characteristics of this interface are mentioned regarding their new possibilities:

• The data (e.g. heat consumption) are read out electronically
• At one single cable, which connects to a building controller all consumption meters of a housing unit can be attached
• All meters are individually addressable
• Apart from the availability of the data at the controller also a remote reading is possible

A set of advantages arise, both for the supply enterprises, and for their customers:

• The reading is fast and avoids reading errors
• The data being present in machine-readable form makes the further processing easier.
• A remote readout saves personnel expenditure, avoids unnecessary penetration into the private sphere of the inhabitants and permits to mount meters in places which are difficult to access.
• Short reading intervals are possible, which reduces the problems with tenant change or tariff amendments
• Due to the short reading intervals statistical data can be obtained, which can be used as a base for network optimization

The standardisation of the m-bus results in further technical possibilities. In particular devices of different manufacturers can be operated on the same bus; the users are free therefore in the choice of the manufacturer. On the other hand, a stimulation of the market can be expected, also regarding other m-bus based counters, so that with the very variable configuration options even difficult problems can be solved.

In the development of the m-bus also economic and technical aspects of the interface have been considered, that are relevant for everyday use. These are essentially:

• Large number of connectable devices
• Possibility for network expansion
• Fail-safe characteristics / robustness
• Minimum cost
• Minimum power consumption in the meters
• Acceptable transmission speed

None of the many already existing bus systems was able to fulfill all these constraints. Now with the M-Bus as a new standardized interface for the reading of consumption meters, an optimal compromise between price and performance can be offered.