Well-suited for energy management, power distribution, building automation or factory automation, the gateway uses the Modbus TCP/IP protocol for fast, reliable communications. The “Power Over Ethernet”-enabled EGX100 eliminates the need for control power transformers, disconnects, and AC-DC power supplies, while reducing installation time and costs. The gateway hosts its own built-in Web pages so facility managers can configure the unit from any Web-enabled workstation. Additional features include a TCP/IP-filtering security capability that enables facility managers to specify the access level (read only, full access or no access) of each Modbus master device to slave devices. Additionally, the gateway allows a Modbus RTU or ASCII serial master devices, such as a PLC, to access devices across a TCP/IP network.