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Introduction
This document describes features, parameters and setting possibilities of the WB169-RFG communication gateway,
which is used for receiving of radio messages from the devices for remote reading of consumption meters working
in the communication system Wireless M-BUS (hereinafter referred as WMBUS) in the 169 MHz band and for
transmitting of these messages over a standard IP network (Internet) to a central collecting system.
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 reverse 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-RFG module is intended for data transfer from the RF modules of remote reading in 169 MHz radio
band and a central computer application that receives and processes the data. The module receives radio messages
coded according to the Wireless M-Bus EN 13757-3 and EN 13757-4 standard for the 169 MHz band, checks
their correctness, encodes (
”
repacks”) them into IP/UDP frames and sends them to the configured IP address
and a central application port number. Wireless M-Bus messages are packed to the IP/UDP frames with using
of proprietary coding system ”NEP” by SOFTLINK. As the Internet access is provided through the mobile data
services, the module is equipped with the integrated GSM/LTE modem.
The WB169-RFG module works in
the N2 bidirectional communication mode
, where it can transmit Wireless
M-BUS messages of
”
Request” type
addressed to any subordinate module supporting N2 mode. These messages
can be used for remote changing of parameters of the subordinate
”
Slave” device. Broadcasting of the reverse-
channel message for a particular
”
Slave” device is under way during 500 ms long reverse-channel communication
window that opens immediately after transmitting of
”
User Data” message from the device. During this time period
the
”
Slave” activates its receiver so as to be able to receive a
”
Request” message (if transmitted). Receiving of the
reverse-channel message is confirmed by
”
Acknowledgment” type of message.
Management of
”
Request” type of messages must be implemented into the central application software. These
messages addressed to the particular
”
Slave” are transferred to the WB169-RFG module through the IP/UDP
protocol with using of
”
NEP” coding. WB169-RFG module stores the
”
Request” messages (that contain also the
lifetime period of each message) into its memory tables and after receiving of next
”
User Data” message from
the
”
Slave” device transmits the reverse-channel message within the communication window. If the message is
confirmed by receiving of
”
ACK” message from the
”
Slave”, the message is removed from the WB169-RFG memory
table. If
”
ACK” message does not come,
”
Request” is sent again during next window until its lifetime period is
elapsed. WB169-RFG module can keep just one message in the memory table, so if the module receives another
”
Request” message from the central application, stored message is replaced by new one so that only the last message
is transferred to the
”
Slave”.
”
Request” messages are coded by using of common M-Bus principles and the coding
system must be implemented in the central application as well as in the
”
Slave” device in a specular manner. The
WB169-RFG module performs just transferring of the messages.
1.3
Module features
The basis of the module is a microcomputer with one
10/100 Mb/s Ethernet
communication port, one
mini
USB
configuration port and an integrate GSM/LTE modem.
WB169-RFG
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