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About the M-Bus protocol
M-Bus stands for “Meter-Bus” and is a standardized communication protocol for remote reading and management of meters and sensors. The protocol is primarily used in energy and water metering systems, where it enables efficient and reliable communication between different types of meters and data collection devices. M-Bus is a communication technology used for measurement and remote reading of, for example, electricity, water, heat and temperature.
The M-Bus protocol is stable, clear and provides very detailed information. But it allows M-Bus in comparison to other technologies to be experienced slowly. M-Bus is therefore best suited for metrics that can be sent with less resolution, e.g. every quarter, hour or day. However, for charging, for example, water consumption or electricity, this is often more than enough.
M-Bus is a standardized open protocol developed in 1991 for the collection of meters in urban environments, but which today is mainly used for the collection of submetering in real estate. Despite its age and with tough competition from new technologies, M-Bus is one of the most common methods of meter reading.
M-Bus is available in two versions, wired and wireless. Wireless M-Bus shares many of the advantages of wired M-Bus, but with the difference that you avoid expensive cable installations. In our series of articles about M-Bus, we will return with an in-depth look at wireless M-Bus in a later post.
A wired installation is operated and controlled by an M-Bus master and since the M-Bus master supplies the meters (or loads as it is called in M-Bus terminology) with power, the number of loops is limited due to the power supply. The M-Bus masts come in various sizes and usually 256 meters (loads) can be connected, but expanded with extenders so that more can be collected.
M-Bus combines communication and power supply in two conductors. Since installations may look different and it can be difficult to pull pre-assembled connectors through electrical pipes, no standard connector is specified. In addition, the conductors are “polarity independent” which means that the installer does not have to think about the plus or minus, in other words, it does not matter how the two conductors are connected. The way the cables are pulled and connected is also flexible and can therefore be formed both in a star net or in a bus structure. Typically, one cabling can be used for 256 meters.
A common problem in networks is how to address meters. M-Bus has two possibilities for addressing: primary and secondary addressing.
In primary addressing, a digit between 1-250 is used which must also be unique on the loop, therefore each meter's primary address needs to be manually set upon installation.
In secondary addressing, one instead uses an 8 digit number preprinted on the meter, which is usually the same number as the meter number. This method does not require manual configuration and therefore has less risk of errors.
A secondary address is unique in most installations, but there is still a small risk that 2 meters from different manufacturers will be delivered with the same secondary address, therefore M-Bus uses an internationally unique identification in addition to the secondary address.
The unique identification consists of the meter's three-letter manufacturer code, the meter type, the meter generation and the secondary address. This is what an example of a unique identification might look like for an ABB electricity meter: ABB-12345678-Electrometer-Generation:1.
A major advantage of M-Bus over other protocols is that values sent in M-Bus are self-descriptive. For each value sent from the meter, the meter itself talks about what it is for greatness and unity. The advantage of this is that there is no need for a new driver for each new meter that one wants to collect. Unfortunately, this is somewhat lacking when it comes to slightly more complex meters and values, but we will return to this later in our series of articles.
M-Bus is a standardized protocol used for communication between meters and data loggers. This allows different manufacturers' meters and data loggers to communicate with each other, simplifying system integration.
As I mentioned earlier, values sent in M-Bus are self-descriptive, meaning that the meter itself indicates the magnitude and unity of each value sent. This makes it easier to interpret the measurement data.
M-Bus is designed to have low power consumption, making it an ideal solution for wireless submeter reading. This means that battery-powered meters can last for many years.
The installation of M-Bus based meters is relatively simple and usually does not require any special tools or expert knowledge.
Advantages of M-Bus in undermetering are its standardized protocol, self-descriptive values, low power consumption, and ease of confuguration and installation.