Ethernet Gearing Up
If theres one place in the enterprise where Ethernet has failed to gain ubiquity, its on the factory floor. But that is changing rapidly, according to a study released last week.
ARC Advisory Group Inc. found in its study, "Ethernet at the Device Level Worldwide Outlook," that at the lowest level of the factory automation hierarchy, shipment of Ethernet interfaces grew 57 percent per year over the last two yearswhile other segments of the factory automation market, such as small programmable logic controllers, actually shrank.
ARC is projecting that Ethernet interface shipments at the device level will grow 84.1 percent annually over the next five years, according to author Harry Forbes, senior analyst at the Dedham, Mass., market research company.
Although Ethernet, which goes hand in hand with TCP/IP in factory automation equipment, is the network of choice for the upper hierarchies of factory automation, some 27 different networking schemes are still in use at the device level, according to Eric Byres, research manager at the British Columbia Institute of Technologys Internet Engineering Lab, in Vancouver.
"Its a long-running joke. There is no standardization in field-level devices. But only four of those  have a snowballs chance in hell," Byres said.
Field-level devices can range from automated welders and robots to pressure transmitters and limit switches. The typical network technologies used for those devices include DeviceNet, Foundation Field Bus or Profibus, among others.
Ethernet has been shunned at the factory floor because of its nondeterministic nature. But the technology has evolved to overcome those types of limitations. And despite the fact that the industrial automation world is slow to change, a new generation of automation devices is being shipped with Ethernet interfaces across a wide spectrum of equipment suppliers.
GE Fanuc Automation, a joint venture between General Electric Co. and Fanuc Ltd., in 2000 announced its intention to use Ethernet in all its offerings, and it has delivered on that consistently in the last two years.
Not everyone agrees with the blistering growth rate projected by ARC, and its easy to grow faster when the graphing starts at 287,000 nodes for 2002, according to Forbes estimates. His forecast projects that there will be 6.06 million Ethernet nodes at the device level by 2007.
One of the obstacles to Ethernets acceptance at the device level is the lack of standards at the application level.
"We decided not to use Ethernet at the I/O [device] level. There is no real standard yet. You cant take a GE Ethernet controller and hook it up to someone elses device," said Jan Lindstrom, vice president of technology for printing press manufacturer KBA North America Inc., in York, Pa.
Lindstroms company uses Profibus to connect drives, I/O racks and server systems, but it uses Ethernet as a peer-to-peer network linking programmable logic controllers.
Economics, of course, is driving manufacturers to use Ethernet interfaces in their automation equipment.
"Ethernet cards are $50. A foundation field bus card is $2,000," said Byres. But devices can range from single- function limit switches to complex industrial-waste scales. And as a more complex protocol than typical device-level networking schemes, Ethernet cant really be justified on simple devices.
"Were probably four or five years away from Ethernet on a $1,000 control valve and 10 years before we see Ethernet on a limit switch," said Byres.
But as Ethernet with TCP/IP and other traditional IT technologies make their way down to the plant floor, IT will see increasing opportunities to extend its reachalong with a new set of challenges.
"Its going to become important for [the factory floor] to adapt their companys best practices in network management," said Forbes. "But the networks will be more heterogeneous than [those] in the IT world with different requirements. For example, when power fails, you want everything to come back just the way it was."
Security is one area ripe for misunderstanding and conflict between IT and factory automation technicians. For example, a password policy that locks out access after three failed attempts could be disastrous if implemented on the factory floor.