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Kamstrup A/S • 5512853_C1_GB_01.2017
M-Bus Master MultiPort 250D
1 Introduction
M-Bus is a bus system, which is specially suited for reading 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 is typically 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 250D 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 250D is built into a solid cabinet, which complies with protection class IP 67.
The front consists of a backlit LCD, 6 keys, 4 status LEDs and an optical eye.
The power supply is a switch mode type which enables you to connect the master to a power supply between 100 and
240 volts. The frequency must be 50-60 Hz.