The term “Fieldbus” refers to a collection of communication protocols that were introduced to replace 4 to 20 mA analog signals. Fieldbus protocols include DF1, PROFIBUS, and Modbus for serial, and EtherNet/IP, PROFINET, and Modbus TCP for Ethernet. In this paper we concentrate on DF1 and EtherNet/IP, and how to convert between these protocols using a new generation of DF1 and EtherNet/IP communication gateways.