SMG-5400 is an industrial Modbus Gateway which provides protocol conversion between Modbus/RTU (or ASCII) and Modbus/TCP, allowing Modbus devices with different interfaces to communicate with HMI (Human Machine Interface).
SMG-5400 provides IEEE802.11b/g wireless LAN and a universal serial port which can be selected to RS232, RS422 or RS485.
MODBUS is a communication protocol widely used for monitoring and controlling various industrial automation equipment represented by PLC (Programmable Logic Controller). It was developed based on serial, but it also has been expanded to network version for application in various communication environments. The serial (Modbus/RTU and Modbus/ASCII) and network versions (Modbus/TCP) are similar, but still different protocols.
You can set two adapters so that you get a wireless serial connection via WiFi. This application is described in the Technical Document under Serial Tunneling.
SMG-5400 requires a 5V power supply (not included).
More information is available on the website of Sollae Systems and Getting Started.