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Introduction
This document describes features, parameters and setting possibilities of the WB169-SI2 module, which is used for
reading of either consumption meters with pulse output (water meters, electrometers, gas-meters. . . ), or two-state
sensors (e.g. door contacts, flood detectors, fire detectors, electronic seals...etc.) and for radio-broadcasting of the
data from connected meters/sensors to the superior remote reading system in form of Wireless M-BUS standard
messages. The WB169-SI2 module works either in unidirectional communication mode N1, or in the bidirectional
N2 mode. In both modes the module regularly broadcasts information messages of
”
User Data” type intended for
superior
”
master” device. In bidirectional N2 mode it is possible to use a back channel from master device, that
can be used for transfer of
”
Request” type of messages with remote configuration demands. In
”
alarm mode” the
module sends
”
Alarm from meter” type of messages based on the sensor status changes. These messages are sent
immediately, out of regular broadcasting interval.
1.1
Wireless M-BUS Communication Protocol
Wireless M-BUS is the communications protocol described by international standards EN 13757-4 (physical and
link layer) and EN 13757-3 (application layer), which is intended primarily for radio transmission of remote reading
values from consumption meters and sensors. Protocol Wireless M-BUS (hereinafter
”
WMBUS”) is based on a
standard M-BUS definition (uses the same application layer as M-BUS standard), but is adapted for data transfer
via radio signals.
Communications via WMBUS protocol works in Master-Slave mode, where
”
Master” is a collecting data device,
”
Slave“ is a providing data device. Slave device could be integrated or external radio module transmitting data
from the meter/sensor. The communications protocol WMBUS defines several communication modes (simplex or
duplex). If working in simplex mode a
”
Slave” device only transmits messages to
”
Master” that these messages
receives. If working in
”
bidirectional” mode, it is possible to use a back channel from
”
Master” device to
”
Slave”
device for
”
Request” type of messages, that can contain e.g. request for the change of slave’s configuration.
Wireless M-BUS communications protocol partially supports repeating of the messages. If receiving from some
”
Slave” device is not possible because of the low level of radio signal, the messages can be re-transmitted (repeated)
by appointed element of the radio network (repeater or slave with such functionality). Each repeated message is
marked as
”
repeated message” so as not to be repeated again.
1.2
Module usage
The WB169-SI2 module can be used either for remote reading of two consumption meters with pulse output, or for
transfer of alarm messages from two two-state sensors. It is possible to combine both type of usage.
When using for
remote reading of consumption meters
(water meters, gas-meters, electro-meters...), up to
two meters with standard pulse (”SI”) output can be connected to the module. The meters can be of different kind,
with different quantities and units and with different conversion rates. The module continuously registers incoming
pulses (generated by meters) into its internal counters, with using of preconfigured multipliers/divisors converts
current status of each counter into the required output units (m3, kWh, MJ...) and broadcasts info-messages with
current statuses of all connected meters as Wireless M-BUS
”
User Data” messages.
When using for
remote monitoring of sensor statuses
(door contacts, flood detectors, fire detectors, electronic
seals..), up to two two-state sensors with ”off/on” (”0/1”) outputs can be connected to the module. The sensors
can be of different kind, with different type of output and different logic of signaling. The module continuously
monitors status of each sensor and records all its changes. If the counter is switched into alarm mode, the module
immediately transmits alarm messages according to preselected rule. The module regularly broadcasts in each
info-message the number of
”
0-to-1” transitions, as well as current sensor status (”0” or ”1”). If the counter is
switched into the alarm mode, the module sends
”
Alarm from meter” message immediately at the change of sensor
status.
Each regular
information message
contains module identification, values of both counters, actual statuses of
all connected sensors in alarm mode and operational entries from embedded sensors (battery voltage, processor
temperature). Each
alarm message
contains only module identification and information about the actual status
of that port, on which the status was changed. Detailed information about the content and format of information
and alarm messages can be found in paragraph
Information and alarm messages are transmitted either in open mode (without encryption), or encrypted by AES-
128 encryption key. The messages are transmitted on the 169.4 MHz frequency with data rate from 2.4 kbps to
19.2 kbps (according to used frequency channel). Messages can be received either by WB169-RFE communication
WB169-SI2
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