M-Bus vs Wireless M-Bus: wired or radio meter reading?
M-Bus and Wireless M-Bus share a name and a data format. One travels on a pair of wires, the other by radio, and that changes where each belongs.
Metbox ·
Wired M-Bus
M-Bus (Meter-Bus, EN 13757-2 and -3) connects meters on a two-wire bus. The master — here a gateway — powers the bus and asks each meter for its values in turn, by its primary address (1 to 250) or by its longer secondary address, which is usually the serial number.
Because the gateway asks, readings come on demand and as often as needed, and meters on the bus draw their interface power from it. It suits buildings already wired in the riser, plant rooms and substations. A Metbox Pro polls up to 150 meters on one bus; see M-Bus gateway.
Wireless M-Bus
Wireless M-Bus (EN 13757-4) carries the same kind of data by radio at 868 MHz. Battery meters send on their own schedule, and a gateway nearby listens rather than asks. Nothing to cable, which is why it is the usual choice for apartment water meters and heat cost allocators. See What is Wireless M-Bus?.
Which to use
If a bus is already in the building, wired M-Bus is dependable and reads on demand. If there is no cable, or the meters are in individual flats, Wireless M-Bus saves the wiring. Many sites mix the two: a heat meter on the bus in the substation, water meters in the flats on radio.
The Metbox Pro reads both at once — wired M-Bus and Wireless M-Bus, plus Modbus — and the platform shows every meter the same way whichever route it came by.