Smart Metering: M-BUS as a simple and elegant option to connect an energy meter to the LORAWAN network

Smart Metering: M-BUS as a simple and elegant option to connect an energy meter to the LORAWAN network

The Smart Metering, namely the remote measurement of meters (electricity, gas, heat) is one of the main areas currently under development of the Internet of Things (IOT). The objectives of Smart Metering are multiple:

  • Reduce the costs associated with collecting consumption data in order to bill the consumer more precisely, more quickly,
  • Increase the frequency of measurement in order to be able to analyse consumption more precisely and thus allow to provide energy optimisation advice, or even allow a differentiated billing according to the type of consumption, or the consumption profiles (to smooth peaks of consumption in the day, week or season)
  • Detect fraud (blocking counters), meter breakdowns (making the consumption record and its complex billing)
  • Detect related problems, such as leaks or suspicious consumptions (no occupant of a building).
  • Enable or disable the remote energy distribution, in case of start / stop of a supply contract, or in case of non payment of an energy bill for example.

Smart Metering: Automatic measurement of energy consumption

There are several solutions, thanks to The Internet of Things, to automate the remote reading of energy meters. It is possible to replace existing meters with smart and connected meters. This is the most expensive solution of course. These smart meters will generally use a type LPWAN (low flow, low energy consumption) network type LORAWAN, SIGFOX or NB-IOT. There are alternatives, such as:
  • Pulse counter for counters generating pulses, or for counters from which pulses can be extracted (“hall effect” with a rotating magnet). See the LORAWAN Pulse Counter
  • Or connect meters of water, gas, electricity or heat (“Utility counter“) via M-BUS, a standard set up for remote measurement of energy counters (utility counters).
M-BUS - Meter Bus (LORAWAN support)

M-BUS - Meter Bus

M-BUS is a European standard (EN 13757-2 for physical layers and EN 13757-3 for application layers) for remote reading of gas and electricity meters, also used for water or heat meters . In general, it allows the reading of any type of consumption at a lower cost, through a data bus composed of 2 wires.

Schematic diagram of the M-BUS topology with a Master (who does the reading) and Slaves (the energy counters).

The principle is that a Master (typically a battery-operated IOT MBUS sensor, and connected to a LORAWAN, SIGFOX, NB-IOT or M2M wireless communication network) can interrogate a set of counters (Slave) and return them. consumption data over the query period. These electricity consumption data / gas / heat are then reassembled, through the IOT network, to an application that will account for and analyze consumption.
The advantage of the MBUS technology is that it is possible to collect consumption data from several energy meters, through the same M-BUS communication bus. This makes each individual measurement of a meter very inexpensive!

The M-BUS to LoRaWAN Converter

The operating principle of the MBUS to LORA converter is that the LORA device, Master in the M-BUS architecture, can connect up to 10 energy meters (gas, electricity, heat, water), the Slaves, thanks to 2 wires. The Secondary Address of each connected counter is declared to the MBUS-LORA converter.

At a defined frequency (every hour, 6 hours, 12 hours or 24 hours), the SLAVE meters are queried, and the consumption data are transmitted through the LORAWAN network (or stored and transmitted later):

  • energy consumed in Wh (Watt-hour),
  • the volume of coolant,
  • the liquid temperature upstream and downstream,
  • the volume of liquid measured in liters / hour

M-BUS energy meters already supported by the M-BUS converter to LORAWAN

There are 2 modes of operation:
The Query mode, in which the energy counters (up to 10 counters!) Are declared in the LORA-MBUS Converter sensor (their secondary addresses) and where the Converter will automatically perform the queries at regular intervals, and send the decoded consumption data to an application server, through the LORAWAN network. The Danfoss Sonometer 500 and Kamstrup Multical 801 models are already integrated as standard. In this query mode, the internal battery of the LoRa Converter (Class A) allows a daily measurement of 10 meters, for 10 years!

Danfoss Sonometer 500
Kamstrup Multical 801

The second mode, called Transparent mode, allows the sending of an M-BUS command to a counter, from an external application, and the reception of the response, which must then be decoded. This transparent mode requires the passage of the MBUS-LORA Sensor in Class C and to operate it with a power supply.

Installation example of the M-BUS to LORWAN converter