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.

“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.

“The biggest issue regarding Ethernet is bandwidth,” says Bill Wotruba, director of networking and connectivity products for Hirschmann, an industrial Ethernet component supplier in Chambersburg, Pa. “We’re at 100 Mbaud (megabits per second), compared to 2 to 5 Mbaud for Profibus. With wireless Ethernet, you drop down to 54 Mbaud, depending on the version, so you’ve still got a lot more bandwidth than with many other networks.”

Ethernet’s bandwidth and its ability to carry many different protocols provide a huge array of options for users. Being able to connect devices that use fieldbus technologies such as Modbus, DeviceNet and Profibus makes it easy to connect legacy equipment and inexpensive products such as sensors that don’t need Ethernet’s capabilities.

At higher levels, a number of different protocols have emerged to address the disparate requirements of different automation environments. Profinet, EtherNet/IP, Modbus TCP, EtherCat and Ethernet PowerLink are among the protocols available to industrial suppliers. For the most part, they don’t employ any significant changes that impact networking switches and other communication products. “Most folks don’t require switches to do anything special to send messages back and forth,” says the Opto22 spokesperson. “We’ve steered away from technologies that do things in a different way.”

However, the protocols offer a few little changes that can help plant floor managers improve efficiency. For example, Profinet mandates some protocols such ...