User Manual

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Building Technologies M-bus System CE1P5361en
HVAC Products 5 Engineering 08.02.2007
All bus topologies are permitted (with the exception of ring topology): Star, line, tree
and any combinations of them.
4
2370Z07
1 Line topology
2 Tree topology
3 Star topology
4 Ring topology
Using repeaters, an M-bus system can be subdivided into any number of segments in
order to increase the rate of transmission or to make system extensions.
5361Z22
N2
N2N2
N2
N1
S1.1
S2.1
S2.2
S3.2
S3.1
N1 M-bus master
N2 M-bus repeater
Sx.y M-bus segment x.y
 The cable required is a twisted 2-core cable
 The bus connections of the M-bus devices (slaves) are interchangeable
 The M-bus requires no bus termination
 The M-bus permits communication at 300, 2,400, 9,600 or 38,400 Baud. Different
Baud rates can be used on one and the same plant
 The OZW10 supports rates of maximum 9,600 Baud, the OZW111 2,400 Baud
 The maximum rate of transmission is dependent on the types of M-bus devices,
the distances, the number of M-bus devices and the types of cable used by the M-
bus system
 The rate of transmission can be increased through the use of repeaters
 For calculating the rate of transmission, refer to section 5.4.5 "Sizing"
 The M-bus permits cable lengths of more than 10 km (one M-bus device, 1.5 mm
2
cable). Recommended are cable lengths of no more than 4 km
 The maximum distance is limited by the number of M-bus devices, the rate of
transmission, cable routing and the types of cable used
 The M-bus network can be extended to almost any length through the use of re-
peaters
 For calculating the cable lengths, refer to section 5.4.5 "Sizing"
The M-bus uses 2 kinds of addressing: Primary addressing and secondary addressing.
They can be combined within a system.
Bus topology
Segments
Cable
Rate of transmission
Distances
Addressing