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920MHz Band Wireless Device (Korea) USERS MANUAL EM-9121 Rev. 1
1. INTRODUCTION
M-System’s wireless devices configure a large-scale and highly reliable wireless multihop network system, which operates in the
920 MHz frequency band and complies with IEEE802.15.4g. The system can be used for various services such as BEMS, Smart
Metering, and M2M. There are two types of wireless devices: parent devices and wireless devices.
1.1 FEATURES
The wireless network system allows to collect data wirelessly from data acquisition devices and remote I/Os using Modbus protocol.
A wireless device (parent) communicates with the data acquisition device using Modbus/TCP protocol and with wireless devices
(child) using Modbus-RTU protocol. The parent device converts between Modbus-RTU and Modbus/TCP protocols.
1.1.1 BASIC CONFIGURATION
“Figure 1.1 System configuration example” shows a system where a PC side as Modbus/Master communicates with a child device
via a 920 MHz band wireless device using Modbus/TCP and RTU protocol, and also communicates with slave devices in multi drop
connection (RS-485).
LAN cable
(STP cable)
PC
Modbus /Master
Wireless gateway
(model: WL40EW2KR)
Wireless gateway
(model: WL40MW1KR)
Slave Device
Slave Device
Slave Device
MAX. 31
RS-485
Figure 1.1 System configuration example
1.1.2 CONFIGURATION INCLUDING LOW-SPEED MOVING DEVICES
A data acquisition device can collect data wirelessly from remote I/Os moving at low speed (4 km/h or less). The configura-
tion consists of a parent device, repeaters and child devices. Only the child devices move and do not function as repeaters.
In this configuration, it is possible to manage the devices moving at low speed within a specific range and collect data from them
through radio communication.
LAN cable
Wireless gateway
(model: WL40MW1KR)
PC
Modbus /Master
Wireless gateway
(model: WL40EW2KR)
Wireless gateway
(model: WL40MW1KR)
Wireless gateway
(model: WL40MW1KR)
Wireless gateway
(model: WL40MW1KR)
Wireless gateway
(model: WL40MW1KR)
Figure 1.2 System configuration example including low-speed moving device