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Ethernet's Reach Grows In Manufacturing
More applications extend Ethernet down to the I/O level of the automation control system.
One key to success in injection molding is to make plastic walls as thin as possible without compromising strength and durability requirements. Reducing material consumption requires close attention to every detail, precisely monitoring every sensor and actuator with a speedy network. Manufacturers can see significant benefits by using faster networks.
“The pressure curve was very wavy with the old system,” says Chris Choi, chief technology officer for plastics machine vendor Husky Injection Molding Systems Ltd., of Bolton, Ontario, Canada. “With faster sampling time, pressure tracking becomes much closer to ideal. That lets us control the melting point more precisely, which results in much thinner walls.”
The mainstay in shortening those sampling times is a faster device-level network. Husky is one of a growing number of companies that's using Ethernet as its only network. Though some vendors argue that existing fieldbuses are better suited for input/output (I/O) device level communications, engineers such as Choi feel that the benefits of Ethernet far outweigh the downsides. “Profibus and proprietary connections are slower,” he says. “With Ethernet, we don't have any latency, so the whole system goes faster.”
That speed is the key to letting its customers save money and reduce waste with thinner walls, he explains. In a volume production run of 55 million parts per year, trimming just two grams from a 22-gram package can save $180,000. To make that happen, Husky employs one of the real-time Ethernet technologies, EtherCat, throughout the system. However, Choi muses that customers couldn't care less what architecture the equipment uses so long as they can save materials, which also helps them win sales in this environmentally conscious era.
The equipment designers who help companies such as Husky do need to think about every aspect of their designs. Networks are a key element in the full systems architecture, touching on both performance and cost. Though Ethernet's speed improvements may seem minor, they can make a big difference.
“EtherCat's bandwidth is very important. If you're sensing and actuating, and you get back or send signals using a faster network, you can gain 2 percent to 5 percent without changing anything else,” says Graham Harris, president of Beckhoff Automation LLC, of Burnsville, Minn. Gaining a few microseconds on activities that occur thousands of times each day adds up to significant improvements over time, he adds.
Cabling made easy
One of the reasons that industrial users are extending Ethernet down to the lower levels of their systems is to simplify cabling. Using a single medium at all levels can reduce complexity and give installers more freedom. At the same time, many consumers find this approach also saves them money ...Read more
Many Ways to Cut the Cord
Wireless communications are still a small niche market in the industrial world, but interest levels are high, and development programs are many.
In often-changing automation facilities, being able to reconfigure lines and floor plans without worrying about cable runs is a huge benefit.
Many companies have already installed wireless networks, helping erase the reliability concerns that were once expected to bar wireless links from the factory. ARC Advisory Group Inc., Dedham, Mass., predicts that wireless products for process manufacturing will grow 32 percent per year, hitting $1.1 billion in 2012. Products are emerging rapidly, prompting many to tout wireless as a way to cut costs and headaches.
“One of the best ways to eliminate wiring costs and problems is not to use any [wiring],” says Carl Henning, deputy director of the Profibus Trade Organization, in Scottsdale, Ariz. “Wi-Fi and Bluetooth both come along with Profinet for free because it's Ethernet.”
Industrial Bluetooth?
That Ethernet compatibility has made Wi-Fi (for Wireless Fidelity) a key player in the market. Wireless Hart, ZigBee and proprietary schemes are all challenging Wi-Fi. Bluetooth is also expected to extend beyond its huge cell phone base, gaining a role in industrial facilities. “It's simpler than Ethernet. Ethernet is more costly in dollars, power consumption and its software footprint,” Henning says. The small amount of memory in phones makes it attractive for industrial equipment designers who want to keep storage requirements low. Henning expects to see a document for an industrial Bluetooth specification later this year. It will focus on the protocols needed to ensure reliable communications in harsh environments, he explains.
Another specification that was completed last year, WirelessHart, is expected to gain solid acceptance for the many devices that don't require much bandwidth. At the sensor level, “the completion of WirelessHart is a major milestone,” Henning adds. That network complements Ethernet protocols, providing a way to integrate the networks without compatibility problems. Network proxies will be a critical aspect of this integration, he says.
The availability of more protocols will probably boost the usage of wireless. Alternatives often mean that users can select a technology that's well-suited to their needs. Still, most suppliers feel that it's prudent to move slowly. Wireless can serve as a useful tool for prototyping before a network is deployed widely.
“Using wireless in a pilot project can be an effective, low-cost way to provide proof of concept for a project before investing in costly, permanent wiring runs or making an enterprise-wide commitment to wireless,” says David Crump, marketing manager at vendor Opto 22, in Temecula, Calif ...Read more
Opening the Door
The idea of networking automation control is getting on to 20 years old.
And it was just about 20 years ago when the chief controls engineer for an automotive component manufacturing plant told me that he would never run a wire from a programmable logic controller (PLC) to anything. In those days, input/output modules were in the chassis of the PLC and wires just went to sensors, motor starters and other assorted devices. Actually, I think he used a little Modbus or Modbus Plus for limited communication. When I started learning about DeviceNet, I didn't bother pitching it.
Visionaries at about the same time (early 90s) began experimenting with the network that was just about to take over the general networking environment-Ethernet. It was not a done deal back then that darn near everything would become Ethernet
Here we are in 2009 and Ethernet is everywhere. Any kind of device you can think of that communicates either has an Ethernet port or access via its wireless cousin WiFi. Engineers used to think that it was just a chintzy office network that would never make it in the factory. They were wrong. The genius of Ethernet-simplicity and adaptability-lent itself to adoption by automation suppliers and engineers.
One of our most popular Webcasts of all time was our first one from several years ago about taking Ethernet to the I/O. It still remains a popular topic. We'll have more on it later this year. As Terry Costlow discovered in researching his article this month, engineers are becoming more comfortable with the technology and finding more ways to use it ...Read
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