Ethernet: The Promised Land?

Networking Nirvana Is Just Over the Horizon. Ethernet and Digital Fieldbus Are the Compass. Here's How to Make the Trip

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By Jim Montague, executive editor

Knowing where you’re going can be harder than it looks. Because industrial networks are everywhere, but slightly invisible due to their supporting roles, it can seem like not much is happening, even though many changes are underway. Sure, Ethernet and wireless continue to move toward dominance, fieldbus organizations are hurriedly cooperating, intelligence and control functions keep migrating into the field, and everyone keeps trying to improve network safety and security. However, beneath these surface events, there are several unusual trends developing and gaining momentum.

“Everyone’s trying to move to Ethernet and wireless, but they don’t want to throw out all the networking they’ve already got,” says Martin Michael, business solutions VP at Advanced Automation LP, a CSIA-certified system integrator in Exton, Pa.  “Users don’t want to make huge moves, and would rather upgrade as they go. That’s why plant engineers,  IT, and management need to sit down, and decide who owns what part of their networks.”

Comfortable Users Taking Over

Perhaps the most significant industrial networking trend is that users are getting more comfortable and even cozy with Ethernet, fieldbuses and other digital networks. Though still just a quarter to a third of the overall installed base of 4-20 mA and other hardwired networks, digital communications are making their way into larger, more complex and more technologically diverse applications.

Figure 1

Italy-based Officine Meccaniche Cerutti used EtherNet/IP to reduce the number of networks and achieve 10 msec speeds on their flexographic printing presses.
Photo by: ROCKWELL AUTOMATION AND  Cerutti

“All the fuss now is about wireless, but the real work is going on in the wired world. People finally are accepting the fieldbus concept, and it only took 10 years,” says Dick Caro, digital networking consultant for CMC Associates and co-chair of ISA 100’s user working group. “At this point, fieldbus is what’s being mostly implemented in new installations and major revamps, but not for the original reason we thought, which was to reduce installed costs. The primary reason is that users are finding that diagnostics with smart instrumentation lets them improve maintenance and do preventative maintenance. This is very valuable, but it can’t be done with instruments that don’t have the intelligence to analyze causes of instrument failure, and they need digital fieldbuses for communication. All this goes along with monitoring devices in the field for better asset management.”  

Brian Oulton, Rockwell Automation’s networks marketing director, adds: “We’re seeing people put together really large networks on the plant floor and in their enterprises. Fieldbuses were limited to 100 nodes or less, but Ethernet allows 250 nodes or more, and people are comfortable with it. It’s a big, wide pipe. Some have up to 800 nodes, but the biggest we’ve heard about has 3,400 nodes, including drives, controllers, robots, HMI and even telephony.” Oulton reports, for example, that Italy-based Officine Meccaniche Cerutti recently reduced the number and variety of previous networks on its flexographic printing machines by installing 600 nodes of CIP-based EtherNet/IP (Figure 1).

Recombining Combinations

Though it might be expected that initially reluctant end users would wait for suppliers to tell them how to use fieldbuses, Ethernet and wireless, many users just take these new networking solutions and run with them, sometimes outstripping their officially intended uses.

“People using wireless to replace hardware in their applications that were never considered before,” says Caro.

“For example, a typical chemical plant could have 200 control valves, each with a fieldbus connection, and four to 12 shut-off valves, as well as isolation, shut-off and bypass valves around the pumps. Now, nobody thought about having a limit switch around each valve before because it would have been prohibitively expensive.

However, you can add a wireless sensor to each valve to indicate if it’s open or closed, so you don’t have to send an operator to check valve because you can now look at a valve diagram on your HMI for each valve, and it’s affordable to do.”

Ian Verhappen, industrial networks director, at MTL Inc., says his former company, Syncrude, already uses digital, IP-enabled cameras in its oil sands processing applications. These cameras take live video on the plant floor and convert it to a 4-20 mA signal that Syncrude can transmit over its network.

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