Ethernet's Reach Expands in Manufacturing

Compatible Networks

First there was Ethernet. Bob Metcalfe, working at the Xerox Palo Alto Research Center (PARC), sketched a network architecture over lunch (so the story goes).

Eventually, Ethernet and its basic protocols—transmission control protocol/Internet protocol (TCP/IP)—came to dominate business networking, and the company Metcalfe founded to exploit the technology—3Com—made him wealthy.

Meanwhile in the manufacturing world, visionaries began to explore how digital networking could benefit plants and factories. After an original dream of one network that would serve all purposes (sort of like the physicists' dream of a Unified Field Theory), technologies and markets settled around a few networks designed especially for manufacturing. These were owned, not by individual companies, but by “open” organizations. Thus were born ControlNet, DeviceNet, Foundation Fieldbus, Interbus and Profibus, among others. In Japan, eventually, a network called CC-Link was developed and recently became an open standard as well.

The fieldbuses have served manufacturing well, but many dreamed of Ethernet as the Unified Field Theory for manufacturing networking. Some companies have used Ethernet alone as a fieldbus, but most of the current fieldbuses have an Ethernet implementation... Read more

Still Playing the Field - Fieldbuses remain viable architectures to augment Ethernet.

The full color printing presses that print the high precision photos and text to create hundreds of thousands of magazines and newspapers in short timeframes are extremely complex devices. For the printer that produces some of Italy' s leading publications, a key aspect of keeping them running efficiently was to build a network to manage all the sensors, actuators and controllers of its huge presses.

Officine Meccaniche Cerutti (Cerutti' s Mechanical Workshops) handles prominent Italian weekly magazines “L'Espresso” and “Panorama,” a version of “National Geographic,” and Italian daily newspapers “La Repubblica” and “Famiglia Cristiana.”

“The local area network at Cerutti's facility in Casale Monferrato has nearly 500 nodes and 13,000 input/output (I/O) points. That requires a complex scheme that includes a set of sub-networks. The flexographic machines used to print daily papers require a combination of very different devices featuring heterogeneous communication protocols. A single machine can incorporate no fewer than seven types of networks.

Writing software and making sure these networks communicate efficiently is an ongoing challenge. “Cerutti is doing an important job concerning the product engineering of software applications and the optimization of data exchanges among devices and interconnected systems,” says Paolo Di Santo, director of packaging machine software at Cerutti.

While Ethernet is increasingly being used for all of these networks, many systems rely on time-tested fieldbuses to handle I/O, sensors and some real-time tasks. Though they're often viewed as fading technologies, these fieldbuses remain viable in many applications, operating as sub-networks that usually feed into Ethernet backbones... Read more

Sidebar: Fieldbuses Adapt to Wireless World - The success of wireless networks might be viewed as another nail in the coffin for fieldbuses.

But many observers feel the wireless boom may breathe new life into some architectures. Though these fieldbuses have been around for a long time, they are adapting to the new world of wireless communications.

While fieldbuses are often phased out for newer technologies such as industrialized Ethernet, wireless is providing a new channel for the protocols. Many of the input/output (I/O) points that remain a bastion of fieldbus usage could benefit from the ease of installation provided by wireless technologies.

The organizations that oversee the various fieldbuses are moving to ensure that their technologies adapt to the rapidly expanding usage of wireless communications. “All the fieldbus consortia are looking at ways to ensure that their protocols operate over wireless networks,” says Cliff Whitehead, Mayfield Heights, Ohio-based strategic applications manager at vendor Rockwell Automation Inc.

Which wireless scheme they tap is an open question. A range of proprietary networks and standards such as ZigBee are vying for acceptance. Wi-Fi has gained acceptance because it's compatible with Ethernet backbones. Even Bluetooth, normally associated with cell phones, is getting some interest.

“Wireless is not a solution, it's a range of solutions,” says Greg Dixson, Automation Systems marketing manager at Phoenix Contact Inc., Middletown, Pa.-based automation supplier. “We can embed Bluetooth into the backplane along with a fieldbus and industrial Ethernet. Communications can occur in under 10 milliseconds. Bluetooth offers high speed, low costs and short range.”

Ease of installation is a key benefit of wireless links, which give engineers the ability to install sensors or other products in locations that would be difficult to wire. "A customer had a rotating table that made it impossible to connect though hard wires. We used a Wireless Adapter to connect a CPU (central processing unit) on the rotating table with the main CPU," says Stephan Stricker, product manager at vendor B&R Industrial Automation Corp., in Roswell, Ga... Read more

Industrial PC Brings Controls Benefits to High-speed Tray Former/Sealer - Ethernet connectivity simplifies the acquisition of data about machine operating conditions.

Introduced recently at the Worldwide Food Expo in Chicago, the Model R 535 thermoforming machine from Multivac forms and seals trays of food and other products at speeds to 600 packs/min. It's equipped with a Beckhoff CX1020 DIN rail-mounted embedded PC that centralizes control by handling PLC, motion control, and HMI functions in a single device. The industrial PC controller provides a direct backplane connection to Beckhoff I/O terminals, which in Multivac's case are networked via Ethernet as the system's fieldbus. According to Multivac's Michael Krieger, this represents a significant controls improvement.

“We used to use a proprietary system more or less tailored for us,” says Krieger. “It kept cost down and worked well enough, but this off-the-shelf solution we have now is much better. It eliminates the need to have one controller for HMI and a second for machine functions.”

Measuring 96 x 112 x 99 mm, the CX 1020 controller helps Multivac keep the size of the controls cabinet to a minimum. The controller runs Windows' XP embedded operating system and Beckhoff's TwinCat NC PTP (Point-to-Point axis positioning) control software. Beckhoff adheres to OMAC guidelines and incorporates the PackAL function-block library into the TwinCat software environment.

“We see more customers asking for OMAC compliance,” says Krieger. “When the machines that we build adhere to such guidelines, it makes it easier to integrate them with other machines from other OEMs on a fully networked basis”... Read more

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