| Time-Synchronized Ethernet
 As Ethernet penetrates the factory floor, at least two issues regarding connectivity and devices are active—and both pertain to time.
One is continued implementation of the Institute of Electrical and Electronics Engineers’ IEEE 1588: Standard for a Precision Clock Synchronization Protocol for Networked Measurement and Control Systems. The other is convergence of manufacturing and enterprise networks, using new IEEE 1588-supporting switches.
The most important recent development in Ethernet connectivity devices, according to Brian Tutor, product marketing manager in the industrial-networking group within Moxa Americas Inc. (www.moxa.com), a Brea, Calif.-based automation vendor, is continued IEEE 1588 implementation. “Timing control between devices is becoming more sensitive as new technologies emerge to improve monitoring and control of devices related to industrial automation.”
Under a microsecond
But Tutor quickly notes that even though IEEE 1588 was published in late 2002, “vendors are still integrating the required hardware and protocols, especially in Ethernet networking equipment.” And although there are other timing/synchronization standards, “IEEE 1588 is needed to bring synchronization down to the sub-microsecond range.” That’s done by integrating real-time clocks and IEEE 1588’s protocol into Ethernet devices, he explains...
Doing that requires a network time server, network switches and end devices with 1588 support to allow latency to be determined and passed to the end device, Tutor states...
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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... Read more
Controlled Motion for Packaging
Fifteen years ago, I was a packaging industry neophyte.
My background was primarily assembly, but I had a customer who was chatting with me one day and mentioned that he had a problem with a packaging machine. Changeover from one package size to another was time-consuming and painful.
A team from my company and an integrator whose expertise was machines, but not specifically packaging, evaluated the situation and recommended putting servo motion control on all the movable sections that related to changing the machine—in order to handle different package sizes. I didn’t know that was revolutionary until seven or eight years later, when I started sitting in on the OMAC Packaging Workgroup meetings... Read more
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