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Real-Time Industrial Ethernet Protocols

Every Second Counts

Demand for Ethernet as a real-time control network is growing as manufacturers and other companies discover the advantages of a single network technology throughout the enterprise (from the office floor to the factory floor). This kind of vertical integration offers many benefits in terms of administration and support for IT. Lower product costs combined with the potential for overlap in training and maintenance costs for information, field, control, and possibly device networks, are expected to reduce costs significantly.

Ethernet offers many advantages over existing approaches at the real-time control level. As a control network, it offers a bandwidth of 10Gbps (and higher), which is almost 1,000 times faster than comparable fieldbus networks. However, distributed applications in control environments require tight synchronization to guarantee message delivery within defined cycle times. Conventional Ethernet and fieldbus systems are unable to meet the timing requirements of less than a few milliseconds, but real-time Industrial Ethernet enables cycle times of just a few microseconds.

Ethernet also promises less complexity with all the features required for a field, control, or device network. Moreover, Ethernet devices support TCP/IP stacks, allowing Ethernet to connect to the Internet without problems. This feature is attractive because it enables remote diagnostics, control, and monitoring of an industrial network from any device connected to the Internet.

Real-Time Systems

Various organizations like IEEE and ISO define standards and guidelines for real-time systems that can vary by context and application, but real time generally can be defined as the operation of a computing system in which programs for processing incoming data are constantly ready for immediate execution, enabling the system to process data and produce outputs within a strict, predefined time constraint.