In any industrial environment, the plant data network is used to connect instruments and systems distributed across entire plant area. It allows central monitoring and control of the instruments very easy. With the advent of wireless sensor networking technology, few industries started adapting the wireless monitoring systems in phases. Gateway devices allow data communication between main plant data network and wireless field devices. It enables application level access to these field devices from central monitoring station. The gateways devices are used as protocol converter, command/data forwarder and also it can be used as Security Manager, Synchronizer in network. In this implementation, the Ethernet gateway has been designed to collect data from wireless sensor network and connect to the existing Ethernet network. This paper describes the design and development of Ethernet gateway and also describes the integration of this gateway with the computer centre wireless sensor network.