EtherNet IP

EtherNet/IP (IP = Industrial Protocol) is an industrial network protocol that adapts the Common Industrial Protocol (CIP) to standard Ethernet.

EtherNet IP

STANDARDS BODY, TITAN AND PHILOSOPHY

Initially released in 2000, EtherNet/IP is an open industrial standard developed by Allen-Bradley (Rockwell Automation) and the ODVA (Open DeviceNet Vendors Association). The “Ethernet Industrial Protocol” is essentially a port of the CIP application protocol (Common Industrial Protocol), which was already used by ControlNet and DeviceNet, to the Ethernet data transfer protocol. EtherNet/IP is particularly well established on the American market and is often used with Rockwell control systems.

ARCHITECTURAL PHILOSOPHY: OPEN SOFTWARE/MODIFIED ETHERNET

EtherNet/IP is an application-layer protocol on top of TCP/IP. EtherNet/IP uses standard Ethernet physical, data link, network, and transport layers, while using Common Industrial Protocol (CIP) over TCP/IP. CIP provides a common set of messages and services for industrial automation control systems, and it can be used in multiple physical media. For example, CIP over CAN bus is called DeviceNet, CIP over dedicated network is called ControlNet, and CIP over Ethernet is called EtherNet/IP. EtherNet/IP establishes communication from one application node to another through CIP connections over a TCP connection, and multiple CIP connections can be established over one TCP connection. EtherNet/IP uses the standard Ethernet and switches, thus it can have an unlimited number of nodes in a system. This enables one network across many different end points in a factory floor. EtherNet/IP offers complete producer-consumer service and enables very efficient slave peer-to-peer communications. EtherNet/ IP is compatible with many standard internet and Ethernet protocols but has limited real-time and deterministic capabilities.

Ethernet/IP is the only one of the real-time methods described to be based entirely on Ethernet standards. In contrast to the other protocols, Ethernet/IP is not cycle-based but time-based, meaning that it merely requires that control commands are received by the field stations in time. This means the performance of the overall system can be made independent of network performance. Real-time delivery is safeguarded by three mechanisms which are all standards-based: UDP, Quality of Service (prioritization), and IEEE1588. To achieve real-time capability, accessible bandwidth is limited in order to avoid contention and latency. In other words, because EtherNet/IP is an application-layer protocol, it has a limited performance range that can deliver in real time.

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