TCP/IP is a part of the Ethernet/IP protocol. So what is the difference between TCP/IP and Ethernet/IP?
EtherNet/IP (IP = Industrial Protocol) is an industrial network protocol that adapts the Common Industrial Protocol (CIP) to standard Ethernet.
EtherNet/IP performs at level session and above (level 5, 6 and 7) of the OSI model. CIP uses its object-oriented design to provide EtherNet/IP with the services and device profiles needed for real-time control applications and to promote consistent implementation of automation functions across a diverse ecosystem of products. In addition, EtherNet/IP adapts key elements of Ethernet’s standard capabilities and services to the CIP object model framework, such as the User Datagram Protocol (UDP), which EtherNet/IP uses to transport I/O messages.
EtherNet/IP classifies Ethernet nodes into predefined device types with specific behaviors. Among other things, this enables:
1) Transfer of basic I/O data via User Datagram Protocol (UDP)-based implicit messaging
2) Uploading and downloading of parameters, setpoints, programs and recipes via TCP (i.e., explicit messaging.)
3) Polled, cyclic and change-of-state monitoring via UDP.
4) One-to-one (unicast), one-to-many (multicast), and one-to-all (broadcast) communication via IP.