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Texas Instruments The Future of Robotics | 27 Figure 3: Selection example: time of flight. Industrial Ethernet: The Backbone of the Smart Factory In recent years, industrial Ethernet has demonstrated its value in highly automated factories, becoming the standard of choice in large field networks that include complex systems, PLCs and gateways to support intercommunication with external networks. Benefits such as high speeds, common interfaces and long connection distances have made Ethernet ubiquitous for data networks. In addition, industrial Ethernet uses a modified Media Access Control (MAC) layer to provide deterministic data delivery with low latency and support for time-triggered events. Support for ring and star topologies, as well as traditional in-line connection, ensure safety and reliability in the case of a disconnected cable. Industrial Ethernet is not a unique single specification but a large group of differing protocol implementations driven by various industrial equipment manufacturers for implementation in field- level applications. Popular protocols include EtherCAT, Profinet, Ethernet/IP, Sercos III and CC-Link IE Field, among others. The white paper "An inside look at industrial Ethernet communication protocols" compares these protocols and discusses older, non-Ethernet serial fieldbus protocols such Control Area Network (CAN), Modbus and Profibus. Two of the most widely used protocols, Profinet and EtherCAT, illustrate how the types of industrial Ethernet differ with each other and with IO-Link. Both are specified at 100Mbps transmission speeds and over distances up to 100m. Profinet requires power to be supplied independently of the data cable power, while EtherCAT offers a version (EtherCAT_P) that includes power and data in the same cable. Profinet supports full duplex traffic and is capable of sending packets to each node on the network. The protocol also offers three classes that allow the user to match the level of performance required to the network. By contrast, EtherCAT sends a shared frame in one direction on the network that all slaves place their data in—a scheme that supports extremely fast forwarding times. Both Profinet and EtherCAT have faster cycle times than IO-Link with much less tolerance. Both base timing on network synchronization rather than from the start of communication, as with IO-Link. Additional protocols provide functional safety for connections. Industrial Ethernet protocols in general offer a number of services to simplify integration within an automation environment. Although most sensors do not need the robust set of features offered by an industrial Ethernet connection, an important exception is visual sensing. The massive data created by a video camera is itself a sufficient reason for a higher data-rate connection than what IO-Link can offer. Visual and sometimes other types of sensing can provide essential inputs for real- time process control, thus requiring the deterministic delivery of industrial Ethernet. For example, time-of-flight applications track and anticipate the three-dimensional movement of an object. A typical response would be a robot arm that moves to intercept the object. IO-Link can provide sufficient speed and resolution for limited sensing of presence in these applications, but industrial Ethernet offers sufficient bandwidth and low-enough latency to determine some characteristics of the object and its surrounding space. Even higher levels of identification might be possible using camera feeds via Gigabit Ethernet, but the industrial Ethernet protocols discussed here have not yet been specified at these speeds. TI Technology for Smart Factory Communications Many possibilities exist among the competing industrial Ethernet protocols to serve cameras, motors, robots, PLCs, and other complex systems; and even simple sensors and actuators need to operate effectively within a larger industrial Ethernet environment. With so many options for communication among