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TECHNICAL DESCRIPTION Wired M-Bus • Water Meters flowIQ® 2101
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Kamstrup A/S · Technical Description · 55121944_A1_GB_08.2016
5.3.4
Wildcard search with break detection
The M-Bus water meter supports wild card search for an easy search for connected meters. Some or all digits of
the meters secondary and/or enhanced secondary addresses can be replaced with wild cards when searching for
meters in an M-Bus network. The integrated break detection functionality eases the meter search on the M-Bus
network.
The M-Bus water meter will not compare the wildcard characters with the equivalent digits in “its own” secondary
and enhanced secondary address, and the M-Bus water meter will be selected if the other characters match.
The 8 digits in the M-Bus ID number and the 8 digits in the ‘fabrication number‘ (= serial number) can each be
replaced by the wildcard character Fh.
The binary values ‘Manufacturer ID’ (2 bytes), ‘Version / generation ID’ (1 byte), and ‘Device type ID’ (1 byte) in the
secondary address may be replaced by the wildcard byte value FFh.
The values for DIF = 0Ch (for 4 bytes, 8 digit BCD) and VIF = 78h (for fabrication number) in connection with
enhanced secondary addressing cannot be replaced by wildcard values.
By means of wildcard characters (BCD Fh) and values (binary FFh), an M-Bus Master can, relatively quickly, search
the M-Bus for connected M-Bus water meters, without knowing the M-Bus water meters primary, secondary or
enhanced secondary addresses in advance.
5.4
M-Bus formats
The M-Bus protocol comprises following telegram / message format types:
Single character
Short frame
Control frame
Long frame
Ack. = E5h
Start = 10h
Start = 68h
Start = 68h
C-Field
L-Field = 3
L-Field = N + 3
A-Field
L-Field = 3
L-Field = N + 3
Checksum
Start = 68h
Start = 68h
Stop = 16h
C-Field
C-Field
A-Field
A-Field
CI-Field
CI-Field
Checksum
Userdata
Stop = 16h
(N = 0..252 bytes)
Checksum
Stop = 16h
The meaning of the C-Field
C-FIELD:
40h
SND_NKE
08h
RSP_UD
0Bh
RSP_SKE
49h
REQ_SKE
53h
SND_UD (FCB=0)
73h
SND_UD (FCB =1)
5Ah
REQ_UD1 (FCB=0)
7Ah
REQ_UD1 (FCB =1)
5Bh
REQ_UD2 (FCB=0)
7Bh
REQ_UD2 (FCB =1)
43h
SND_UD2
Note:
In the default application the FCB bit is not used and the M-Bus water meter accepts both FCB = 0 and FCB = 1.