Bus Description - ABB A43 User Manual

Communication with M-Bus

10.1 Bus Description

M-bus is a 2-wire polarity independent bus, optimized for master-slave commu-
General
nication with gas, water, heat and electricity meters. Number of meters on one
physically connected bus is 1-250. A bus can be extended by using a repeater.
M-bus topology is flexible and star, line, tree topology or a mix of these can be
Topology
used, see figure below. Ring topology can not be used. Bus termination is not
required.
It is recommended to use non shielded twisted pair cable with wire area of 0.8
Cable
mm
shielded cable is used the shield must not be connected to any of the two bus
wires. Maximum total length of the bus is 1000 m. Maximum length between a
slave and a repeater is 350 m.
A43/A44
User Manual
2
, for example two-wire standard telephone cable JYStY N*2*0.8 mm
174
2
.
If
2CMC48001M0201
Revision: C