Whether networks are being expanded or being repaired when inevitable problems arise, one of the big benefits of Ethernet is that the tools and skill sets of the people who use them are far higher than with alternatives.“There are a lot of debugging tools for Ethernet,” Stricker says. “You can use them and a consumer PC (personal computer) to debug your network, you don’t need special tools.”

Though some large plants may link a number of Ethernet systems together, Ethernet can also reduce the number of networks within a facility. The network has enough bandwidth to handle safety and motion—functions that have typically used dedicated communications schemes. That provides a big benefit. “If you put motion products or safety networks on Ethernet, you really simplify your architecture, eliminating dedicated motion and safety networks completely,” Harris says.

Vendors are coming up with new ways to reduce complexity, which often means lowering costs. In networking, varied topologies can be structured to meet the wide-ranging requirements of the industrial world. Those configurations continue to evolve.

ODVA Inc., formerly known as the Open DeviceNet Vendor Association, completed documentation for a topology called the device level ring (DLR) last year. This linear scheme lets multi-port Ethernet devices work in ring topologies. That simplifies layouts and lowers costs, while also improving uptime by detecting breaks and reconfiguring communications around them. “With a DLR, customers don’t have to buy a number of switches to go to the device level. They can create a linear daisy chain,” Hannah says. “That’s not new, but using a device level ring lets you have a ring master that can recognize breaks in the cable and route communications the other way to minimize downtime.”

Conventional networking architectures used for years are used in different ways depending on user requirements. In some applications, suppliers recommend using a star architecture with a central hub surrounded by devices operating under its control. That can save a lot of wiring. “With Ethernet, you can make one machine a hub and have a few devices around it connected directly to the hub,” Stricker says. “That’s much easier than networks that force people to go back and forth with cables.”

That may be the most effective approach in some environments. But in others, the star topology is less desirable. Multi-port devices let companies build long strings of devices. “People are installing switches with two ports so they can use linear topologies instead of a star,” Henning says. “Stars don’t work as well in the factory as in the office. If you use a central switch, you need an individual wire running to each device.”

Regardless of the architecture used on the plant floor, Ethernet boasts far better remote access than alternatives such as fieldbuses. When the network is used throughout the facility, an operator sitting at home or in a plant halfway around the world can communicate directly with the actuators on a specific piece of equipment.

“When you’ve got Ethernet at the I/O level, you have better access to diagnostics information and alarming. That also means you can take corrective action from a remote site when those alarms are sent,” says Marty Jansons, a networking consultant at vendor Siemens Energy & Automation Inc., of Alpharetta, Ga.

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