You are probably familiar with Ethernet—a network protocol that allows computers (typically in office, school, or business environments) to share files, browse the internet, and access printers and other hardware connected to the network. Ethernet was developed for high-speed data transmission; it is efficient, simple, and flexible. Moreover, it is arguably the most widely adopted network protocol in the world. These factors, along with its low implementation cost, make Ethernet an attractive network technology for industrial environments.
However, a fundamental problem with using standard Ethernet in industrial settings is that the TCP/IP protocol used for routing and transmitting data does not inherently provide the real-time, deterministic (guaranteed) performance required in many automation and processing applications. The physical hardware used in Ethernet, however, can. Industrial applications necessitate a new real-time protocol designed to utilize Ethernet's physical layers, which also provide deterministic communication between machine controllers, sensors , actuators, and other devices. Industrial Ethernet was developed to address this need.
Ethernet is defined by the IEEE standard 802.3, which specifies the physical and data link layers for network functions. TCP/IP is a set of protocols used above the Ethernet data link layer for communication over Ethernet. TCP stands for Transmission Control Protocol, which ensures that data packets are transmitted completely without errors. IP stands for Internet Protocol, which routes data packets based on IP addresses.
A network protocol stack consists of multiple layers, each handling a specific aspect of data transmission and management. Industrial Ethernet is based on the physical and data link layers of standard Ethernet, with certain modifications, including—in some cases—different transport and negotiation methods.
Industrial Ethernet refers to a set of Ethernet protocols based on standard Ethernet hardware (physical and data link layers), Internet protocols (network and transport layers), and proprietary application layers. Application layer protocols ensure the correct transmission of data and guarantee data reception at the time and place required for a specific operation.
Just as standard Ethernet allows file sharing and access to networked devices in an office, the Industrial Ethernet protocol allows controllers to access data within drives, PLCs , workstations, and I/O devices on the factory floor.
Industrial Ethernet protocols employ one of three approaches to provide determinism based on Ethernet architecture. The first such architecture—called Standard Software/Standard Ethernet—uses standard Ethernet with TCP/IP protocols, but the top-level (application) layer has built-in mechanisms for real-time communication. Ethernet/IP is based on this architecture.
Another architecture—called Open Software/Standard Ethernet—uses the standard Ethernet layer and new (standard) protocols to manage access to the network and synchronize data sent from each node (device) to ensure that priority data is sent first. Ethernet POWERLINK uses this architecture.
The third architecture used by industrial Ethernet protocols—called Open Software/Improved Ethernet—is based on standard Ethernet hardware but uses new protocols and additional complementary hardware to ensure determinism. SERCOSIII and PROFINETIRT both use this architecture, but with different hardware and transmission mechanisms.
In addition to these architectural modifications, industrial Ethernet typically requires more robust hardware (such as cables and connectors) than standard Ethernet to withstand the harsh environmental conditions in most industrial environments. Many industrial Ethernet applications also require careful shielding, grounding, and filtering to handle electromagnetic interference (EMI or noise) commonly found in factory settings.
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