EtherNetIP

Ethernet/IP, short for EtherNet Industrial Protocol, is an industrial network protocol that uses standard Ethernet technology to exchange data between automation devices. Built on the Common Industrial Protocol (CIP), it supports real-time I/O data as well as configuration and diagnostics, enabling communication among controllers, sensors, actuators, drives, and operator interfaces in manufacturing and process automation environments. Its emphasis is interoperability and scalable integration across diverse vendor devices.

The protocol was developed by Rockwell Automation and is now standardized and promoted by the Open DeviceNet Vendors Association (ODVA). Ethernet/IP defines how CIP messages are transported over Ethernet networks, splitting communication into two main types: explicit messaging for non-time-critical data such as device configuration and diagnostics, and implicit (I/O) messaging for time-critical input/output data. In practice, explicit CIP messages typically use TCP port 44818, while implicit I/O data often uses a UDP-based channel, commonly on port 2222, to reduce latency.

Architecture and data model: Ethernet/IP relies on CIP’s object-oriented model. Devices expose objects and services that controllers can read, write, or invoke, using assemblies, instances, and attributes to represent device capabilities. This object-based approach supports a wide range of device profiles and allows scalable integration of different device types within a single network. The protocol runs over standard Ethernet switches and can leverage common network features such as VLANs, QoS, and security mechanisms.

Applications and extensions: Ethernet/IP is widely used for factory automation, process control, and motion systems. It supports extensions for safety (CIP Safety) and motion control (CIP Motion), and has a security-oriented extension (CIP Security) to address authentication and encryption. Its vendor-agnostic approach remains a key advantage, although some environments increasingly combine Ethernet/IP with other standards like OPC UA for broader interoperability.