Necessity is the mother of invention, they say but in the case of MBus, it was frustration that drove Professor Dr. Horst Ziegler of the University of Paderborn, who, in cooperation with Texas Instruments Deutschland GmbH and Techem GmbH. Developed the Meter-Bus or M-Bus protocol.
What is an M-Bus or Meter Bus?
The M-Bus concept was based on the ISO-OSI Reference Model, in order to realize an open system that could utilize almost any desired protocol. Today, M-Bus is ideal for sub-metering because it simplifies the communication between smart metering devices and the gateway or Data Collection Unit in the building allowing for the frequent collection of meter readings for energy management, or utility billing. This meter reading technology created in Europe is gaining popularity in North America with a wide variety of applications when it comes to submetering.
Let us take a closer look at what M-Bus is all about.
It is a serial communication system that uses a single pair of conductors that can tie up to 250 slaves, in this case, meters: to a single master, gateway, or in our case a Data Collection Unit. Every meter is then connected to the bus. The M-Bus string is exceptionally insensitive to external interference that may be caused by capacitive or inductive coupling. It can power the communication module on the meter, while electrically isolating it from other external sources, and it is a very cost-effective method for wiring in buildings, particularly when compared to Pulse-Output meters.
In addition to the savings in the initial installation costs, servicing the system is also easier, as any addition of a meter can be done without the need for reconfiguration of a daisy chain and there is further simplification because M-Bus incorporates protection against reversed polarity.
Role of MBus in the Metering System
Metering systems, in particular, those that meter flow, like water or Thermal Energy (heat)meters, use M-Bus to transmit energy consumption via a field bus (the Meter Bus) to a Master.
The communication is simple because the size of the information to transmit is small it can be transmitted up to one kilometer between the meter and the Data Collection Unit, provided the M-Bus voltage is maintained, once in operation; more than one meter can simultaneously and accessible on one common platform, making data available for energy-efficiency purposes.
How Mbus Improves Metering System Performance
M-bus systems have come a long way from manual reading methods where an employee from the metering company would have to read the data in hard-to-reach areas of the building - A previous time-consuming method that was often measured at long intervals. With M-Bus one, many or all the meters can be interrogated (polled) at any one time, or periodically, this is advantageous when tenants or occupants move in the middle of a billing period, and a partial period reading of the meter is required.
M-Bus can be programmed for multiple Baud rates from 300, to 38,400 Bauds, although most operators will settle with 9,600 Bauds.
MBus provides Fast and Accurate Remote Data
Mbus reads measurements electronically at shorter intervals, allowing landlords to have a more accurate view of tenant consumptions. The ability of MBus technology to read data faster from virtually anywhere eliminates manual reading errors made by field personnel.
Offers the Possibility of Expansion
While each master has a maximum of 250 slaves, there is no theoretical limit on the number of masters that can be installed this provides added benefits for future troubleshooting, for instance, in a large apartment building the water metering for Domestic Cold Water can be segmented from the Domestic Hot Water meters, allowing for additions to each of these systems at a later date. Another option is to retrofit and add another bus for another utility, like for Thermal Energy metering without disturbing the existing buses, and integrating all into a single reporting platform.
Get Reliable Electronic Readings
Compared to pulse-output meters, M-Bus is more accurate because it transmits the value of the actual read from the meter, and not the pulse count, avoiding using multipliers for conversion, which ensures the availability precise data. Additionally, the M-Bus wire-runs present higher immunity to noise and electromagnetic interference that may affect pulse transmission through non-shielded wiring.
Saves Costs
Unlike pulse output meters the MBus wiring is simpler and uses less cable.
