User Manual
iM871A Wireless M-Bus
Module Firmware
iM871A_WMBus_UserManual.docx, Wireless Solutions, v1.2
Page 10
3.1.2
WM-Bus Modes
The iM871A supports all link modes according to EN 13757-4: S (stationary), T (frequent
transmit), R (frequent receive) and C (compact operation). These four main modes are
divided into further sub-modes for dedicated applications. All modes are described from the
meters view. Table 3-1 gives an overview over all WM-Bus modes and their physical
parameters.
Mode Direction
Data Rate Coding Frequency
Pr
Synchronization
S1
Meter => Other
32.768 kcps Manchester
868.3 MHz
582 chips
S1-m
Meter => Other
32.768 kcps Manchester
868.3 MHz
56 chips
S2
Meter => Other
32.768 kcps Manchester
868.3 MHz
56 chips
Other => Meter
32.768 kcps Manchester
868.3 MHz
56 chips
T1
Meter => Other
100 kcps
3 out of 6
868.95 MHz
56 chips
T2
Meter => Other
100 kcps
3 out of 6
868.95 MHz
56 chips
Other => Meter
32.768 kcps Manchester
868.3 MHz
56 chips
R2
Meter => Other
4.8 kcps
Manchester
868.03 MHz + n*60
kHz
104 chips
Other => Meter
4.8 kcps
Manchester
868.33 MHz
104 chips
C1
Meter => Other
100 kcps
NRZ
868.95 MHz
64 chips
C2
Meter => Other
100 kcps
NRZ
868.95 MHz
64 chips
Other => Meter
50 kcps
NRZ
869.525 MHz
64 chips
Table 3-1: Wireless M-Bus Modes
WM-Bus Mode S
Stationary mode
Mode S1 transmit only, unidirectional, long preamble
Mode S1-m unidirectional, transmission to mobile data collectors, short preamble
Mode S2 bidirectional, short preamble
Operation at 868.3 MHz, chip rate: 32.768 kcps, encoding: "Manchester"
Telegram Format A
WM-Bus Mode T
Frequent transmit mode
Mode T1 unidirectional, frequent operation
Mode T2 bidirectional, frequent operation
Transmission at 868.95 MHz, chip rate: 100 kcps, encoding: "3 out of 6"
Receiving (meter) at 868.3 MHz, chip rate: 32.768 kcps, decoding: "Manchester"
Telegram Format A
