Ethernet Takes Over
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Ethernet Takes Over
The ubiquitous network is moving down to the I/O level.
The huge pricing benefits of commodity technologies continue to expand their usage, often taking them into areas far distant from those they were built for. Ethernet is no exception. The ubiquitous network—which started out in the office—is today extending deeper into manufacturing environments, connecting sensors and other input/output (I/O) points to more sophisticated modules.
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Advanced Measurement Inc. uses Ethernet to link sensors in remote oil fields in northern Canada to ruggedized systems that send data to distant offices. The application has millisecond communication requirements as well as demanding environmental specifications. But those hurdles weren’t enough to offset the benefits of Ethernet.
“We like the ubiquitous nature [of Ethernet], and we’ve got tons of experience with it,” says Steve Conquergood, chief executive officer of the system integrator, in Calgary, Alberta, Canada. But it’s pricing that drives him away from proprietary fieldbuses. “Ethernet’s so dirt cheap, we use it everywhere it’s practical.” That reasoning is shared by a growing number of developers who focus on more traditional industrial applications. While Ethernet may still be rare in the wilds of Canada, it’s becoming the norm in many factories around the globe. “Material handling is one of many fields that are pushing very hard to standardize on this,” says Helge Hornis, intelligent systems manager at automation components vendor Pepperl+Fuchs Inc., of Twinsburg, Ohio. Managers who use Ethernet for higher level communications are extending the technology down to simple devices such as sensors. All types of dedicated buses are moving to Ethernet. “We’re seeing more activity with safety, putting itinto the Ethernet I/O rack instead of laying out a separate safety network. The real value in that is that safety becomes an I/O function. Instead of wiring special safety relays and safety networks, you wire everything as an I/O point, the same as if it were a motor,” says Jeremy Bryant, networking technology specialist at Siemens Energy & Automation Inc., the Alpharetta, Ga.-based automation supplier.
WHY SWITCH?
The price of Ethernet chips, or more often, of the central processing units (CPUs) that include Ethernet “for free,” is a critical factor behind the adoption of Ethernet I/O. Prices for proprietary fieldbus chips are relatively fixed, but the price of an Ethernet peripheral on a CPU continues to fall from its already low price point.
But the ubiquity of Ethernet brings other benefits. Equipment providers cite a number of additional reasons for the broader adoption of the network. “We’re seeing a desire for a single, flat network, with one media structure,” Bryant says.
“People move to Ethernet for the commonality or because they want additional functionality. There are basic restraints in the proprietary fieldbuses that Ethernet solves, like node count and data packet size,” he adds.
The pricing benefits of Ethernet extend beyond the cost of purchasing controllers. Eliminating proprietary fieldbuses simplifies maintenance, even though the communication protocols for these lower-level links may well be different than the Internet Protocols used at higher levels. Everyone understands the basics of the network. “The reason for the increasing acceptance is, amongst others, fast start-up because everybody is familiar with Ethernet,” notes Hornis, of Pepperl+Fuchs.
This familiarity, coupled with success stories throughout the industry, is eliminating concerns that once prohibited the use of Ethernet in demanding applications. “Customers aren’t afraid of Internet Protocol networks any more. They may not understand them, but now they trust their suppliers,” says Digi International’s Young.
They can also put their faith in the Institute of Electrical and Electronics Engineers (IEEE) to continue pushing performance upward. Gigabit Ethernet chips and boards are inching into the ruggedized industrial world, providing a path beyond the 100 megabits per second (Mbps) speeds that are in broader use. The IEEE’s High Speed Study Group recently set the stage to push transfer rates up to 100 ...
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