(Meter-Bus) is a European standard (EN 13757-2 physical and link layer, EN 13757-3 application layer) for the remote reading of utility meters like electricity, water, heat, temperature, humidity and gas meters.
When interrogated, the meters deliver the data they have collected on two-wire-cable to a MBUS Master (IE), which in turn transmits the data on request to a remotely located data server (CS) via fixed Internet connection or a 3G/4G modem.
Topology - Bus Topology, Star Topology, mixture of Bus and Star but NOT Ring Topology
Cable- Any cable type suitable for 42V and 500 mA can be used EXCEPT for shielded cables. Recommended: 2 x 0,8 mm² alt. 2 x 1 mm²
Polarity independent, no need for line terminators at the end of the cables,
Maximum distance between Master/Repeater and Slave is 350 m at up to 9 600 Baud and 128 Slaves. Higher at lower Baud rate.
Total cable length 4 000 m at 2 400 Baud and 128 Slaves
Excerpts from M-Bus User Group description of the M-BUS system. See: http://www.m-bus.com/info/mbuse.php for the whole article.
- 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
- The reading is fast and avoids reading errors
- Short reading intervals are possible, which reduces the problems with tenant change or tariff amendments
- Devices of different manufacturers can be operated on the same bus
Economic and technical aspects:
- Large number of connectable devices
- Fail-safe characteristics / robustness
- Minimum cost
- Minimum power consumption in the meters
- Acceptable transmission speed
RS-485 supports inexpensive local networks and multidrop communications links over twisted pair. It is can be used with data rates up to 10 Mbit/sec and distances up to 1,200 m (not at the same time). RS-485 is used as the physical layer underlying many standards and proprietary automation protocols used to implement Industrial and Building Automation Systems, including Modbus and Profibus.
CompWell uses RS-485 technology in systems with require much higher transmission rates than M-BUS systems can provide (i.e. AMR combined with interactive Display Units and alarm/surveillance systems).
The Wireless M-Bus
standard (EN13757-4:2005 and 2012) specifies the RF communication link between water, gas, heat, and electric meters and the data collecting devices and is becoming widely accepted in Europe for smart metering or Advanced Metering Infrastructure (AMI) applications. Wireless M-Bus was originally targeted to operate only in the 868 MHz band, which gives a good trade-off between RF range and antenna size.
The Wireless M-Bus standard (EN 13757:2013) was expanded with the new N-mode (narrowband mode) at 169 MHz to take benefit of the newly freed band. The N-mode provides the best alternative for radio communication from water and gas meters installed in hard to reach places, such as basements and pits underground
The 169 MHz band was originally used for paging services in Europe, but when the cell phones were introduced as a mass market product, the frequency band was freed up for other services. First it was opened up for meter reading applications. The relatively low frequency (VHF band) combined with high transmission power (up to 500 mW), enables long range radio communication. In addition, narrow band radio (12.5 or 25 kHz) is used to get the best radio receiver sensitivity. A communication range of 3-4 km in urban environment has been demonstrated using ultra-narrowband radio modules at 169 MHz
CompWell provides Wireless M-Bus products communicating in 868 MHz and 169 MHz bands to cover the widest possible application the area of building automation.