10
Smart Infrastructure
A6V10844290_en--_b
2019-10-21
M-bus
Address
M-bus uses two types of addresses to recognize devices:
●
Primary addressing: Up to 250 primary addresses can be assigned to a M-bus system.
The primary address is normally assigned during device commissioning. Pure primary
addressing is not possible if more than 250 devices are read.
●
Secondary addressing: Secondary addressing consists of 8 bytes and permits the
assignment of any number. In the default setting, the secondary address for a device
normally matches the serial number issued by the device manufacturer. The assignment
prevents address conflicts on the bus.
Bus expansion
Plant type
Maximum
distance
Total cable
length
Cable cross
section
Number of
devices
(slaves)
Max. transmission
rate
Small residential
buildings
350 m
1000 m
0.8 mm
2
250
9600 baud
Large residential
buildings
350 m
4000 m
0.8 mm
2
250
2400 baud
64
9600 baud
Small developments
1000 m
4000 m
0.8 mm
2
64
2400 baud
Large developments
3000 m*
5000 m
1.5 mm
2
64
2400 baud
Direct vicinity
5000 m*
7000 m
1.5 mm
2
16
300 baud
Point-to-point
connection
10000 m*
10000 m
1.5 mm
2
1
300 baud
*Shielded cabling required at a distance in excess of 1,000 m (see EN13757-2 appendix E).
Signal specification
M-bus
Condition
Minimum
Typical
Maximum
Measuring unit
Number simple
M-bus loads per
segment
WTV531-GA5060
0
60
Transfer rate
C
Segment
≤ 382 nF
300
2400
9600
baud
Bus power (Master)
WTV531-GA5060
30
39
40
R
Bus current (master)
WTV531-GA5060
0
90
mA
