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Ethernet Protocols' Flexibility A Boost For Manufacturing
The ability of Ethernet to carry multiple protocols enables innovation in communication for effective manufacturing efficiency.
Packaging Corp. of America (PCA) saves a lot of money by reclaiming wood chips that were once lost during the production of container board and corrugated packaging. Though it was easy for executives to see the potential savings, potential problems loomed large in the outlook of engineers tasked with stacking and reclaiming the waste material.
Foremost among them was the task of getting all the equipment at the facility in Valdosta, Ga., to work together. The stacker-reclaimer at the heart of the project has to communicate with log handling cranes, debarkers and conveying systems that don't all use the same communication schemes. They all need to work together to gain the greatest benefits.
“The reclaimer's design is similar to that of a giant chainsaw, with a massive boom that rotates and then rakes wood chips back from the stockpile to load onto conveyors,” says John Lewis, engineering vice president at Fulghum Industries Inc., a Wadley, Ga., forestry equipment producer. PCA's reclaimer uses variable frequency drives regulated by Allen-Bradley controllers that communicate with the woodyard chipper and debarker, as well as two truck dumps, he adds.
EtherNet/IP (a standard from ODVA, formerly known as the Open DeviceNet Vendors Association) is the protocol for PCA's reclaimer, but gear from Fulghum and others uses Ethernet TCP/IP (for Transmission Control Protocol/Internet Protocol). Two separate control systems had to work together seamlessly with response times that were quick enough to sound alerts when safety issues or other problems arose. That was addressed by implementing a programmable automation controller (PAC) system that included EtherNet/IP as one of the many protocols it handles.
This ability to link many protocols together—whether they're variations of Ethernet or legacy fieldbus protocols—remains one of the biggest advances that has occurred over the past decade. Ethernet is becoming the dominant physical medium for networking, enabling communication systems to carry a number of protocols.
“Ethernet's been popular for 10 years or so, but not everyone's bought in yet,” says a spokesperson for Opto 22, a Temecula, Calif.-based automation vendor. “When they do, most customers want to bring everything together under one umbrella so they can move data around the enterprise, using something like EtherNet/IP in one facility and communicating with another building that uses another protocol.”
These protocols let users accomplish a broad range of tasks with few communication worries. The TCP/IP schemes widely used on Ethernet address a number of common tasks, making it possible to move many different types of data around simultaneously.
These protocols let users accomplish a broad range of tasks with few communication worries. The TCP/IP schemes widely used on Ethernet address a number of common tasks, making it possible to move many different types of data around simultaneously.
“With Ethernet, a lot of multitasking happens. Control, diagnostics and management data all ride on one network,” says Marty Jansons, network consultant for vendor Siemens Industry Inc., in Norcross, Ga.
More Speed
Initially, Ethernet made its way onto the factory floor because it provided more compatibility with front-office networks while also creating a flat hierarchy that reduces complexity and simplifies maintenance. But continued advances driven by the need to move more data in less time has given it another weapon that helps it compete with legacy industrial networks. The Institute of Electrical and Electronics Engineers (IEEE) committees that manage the standard continue to drive the speed of its wired and wireless versions upward.... Read
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Watch Your Ethernet Definitions
If I mention the word “Ethernet,” what's the first thing that comes to mind?
Well, you're probably wrong. Ethernet technically describes only the physical layer of the network. It encompasses the cable, connector and the lowest layer firmware needed to effect an electrical connection. When I took my first networking classes around 1987, Ethernet was barely discussed, even though it did exist at the time. It was almost a surprise when, as it seemed, Ethernet suddenly became the personal computing and client/server network almost everywhere.
We use the term in this magazine in a way reflecting general usage. We not only refer to the physical layer, but also to the whole host of transmission, addressing and application layer protocols that have grown up over the years. Many grew because the early Web browsers supported the application protocols. The hypertext transfer protocol (http) that enables Web page loading and the file transfer protocol (ftp) that enables transmitting large files are a couple of examples.
The beauty of Ethernet and the standards and practices that have grown up around it lies in the network's openness and flexibility. The way it is designed, it can carry all of the protocols at the same time on the same wire—and the messages don't become garbled... Read more
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