
1 Introduction
M-Bus is a bus system, which is specially suited for reading of water, heat, cooling, gas and electricity consumption meters.
An M-Bus system consists of an M-Bus Master and a number of meters with M-Bus interface. A network can include different
meter types and brands. The cable type used will typically be twisted pair copper.
The connected meters are read either directly by the master with data appearing on the master’s display, or by a reading
program which is connected to one of the master’s communication ports.
The master powers the M-Bus slave modules in the meters. Battery supplied meters thereby achieve a longer battery
lifetime.
The maximum size of an M-Bus network using Kamstrup M-Bus Master MultiPort 250L is 250 meters. If a number of masters
are configured as repeaters and coupled in cascade and only secondary addressing is used, a total of 1,250 meters can be
connected, and the total cable length can be up to approx. 14 km.
If primary addressing is used, up to 250 meters can be connected.
Communication in the M-Bus network is asynchronous serial bit transmission in half duplex, which means that it is only
possible to communicate in one direction at a time.
Communication speed can be 300, 2400 or 9600 Baud.
It is not necessary to connect a PC to the master during installation, maintenance and troubleshooting in the M-Bus
network as the master itself includes the functions needed. Operation is carried out via display and front keys.
M-Bus is standardized according to EN 13757-2 and EN 13757-3.
1.1 Design
M-Bus Master MultiPort 250L is built into a solid cabinet, which complies with protection class IP 67.
The power supply is a switch mode type which enables you to connect the master to a power supply between 100 and 240
Volt. The frequency must be 50-60 Hz.
55121391_B1_GB_12.2013
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