
1 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 1