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

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.

Remote Intelligence Takes Over

Similarly, some sources indicate that far flung I/O and control devices with added intelligence—usually in the form of software-based algorithms—now are being organized into groups coordinated around a distributed hub, taking on even more of the functions that used to be sent back to traditional control rooms.

“Clusters of intelligent devices now can work together and make more decisions involved in running processes and machines. They still send reports back to control rooms, but not as much as before,” says Jeremy Bryant, Siemens Energy & Automation’s industrial networking specialist. “The master controller that communicates via a fieldbus to remote-controller slaves has evolved into what we call component-based automation, in which Ethernet and Profinet enable devices to simply sit on a network and talk to each other as needed.”

Caro adds that increased use of remote I/O also generates cable savings because I/O processing units that used to be in a control room now are in the field, so the wires that used to travel between them now only run from the instruments to a remote I/O block house that’s also in the field. “A lot of major control tasks are being done in the field, and the I/O and remote controller are making the decisions,” says Caro. “These devices are still in constant contact with operators, and the data displayed on their HMIs still reflects all it did before. However, instead of this information coming from a local controller, it now comes from the network, and the backbone for all these field networks is Ethernet.”

Have Control Room, Will Travel

Control rooms and distributed intelligence are well known terms, but did you ever hear of a distributed control room? Dave Stock, of Innovative Control Inc. (ICi), Crystal Lake, Ill., says his CSIA-certified system integration firm uses wireless, Internet server-based handheld PCs and GE Fanuc’s Proficy iFix software to take process control-room tasks onto the plant floor at several of Valspar’ Corp.’s paint and coating facilities. If an operator on the floor needs 1,000 gallons of material for a process, he no longer uses a pushbutton station, but instead uses one of the handheld PCs to link a wall-mount barcode via Foundation fieldbus to the plant’s SCADA system and PLCs, which send his order to the plant’s motor control center. “This allowed us to remove 30 pushbutton stations at $1,000 each from one facility, and these savings helped the project go forward,” says Stock.

How to Build a Solid Ethernet Network

Bryan Singer, professional services vice president at Wurldtech Security Technologies (wurldtech.com), has several suggestions for building a reliable Ethernet network:
  • Examine your entire network or planned network for all the devices communicating on it.
  • Find out the theoretical maximum for traffic capacity on your network.
  • Use managed switches.
  • To find out what devices you want to put on your network will require, ask the supplier’s network services administrators. They should also be able to help design network strategies for that device.
  • Keep control traffic at home. Don’t layer vision, security, VoIP, and business applications without first isolating your control communications.
  • Thoroughly commission your network at start up. Check all physical media. Analyze line lengths and the noise on them. Test systems and evaluate their performance before startup.

Eric Westerman, senior engineer in  Valspar’s intermediates division, adds that, “One of the coolest parts is that ICi wrote a program that crosses over to our Oracle system, so we’ve been able to add a quality assurance step to our application. For example, when we’re unloading solvent, we can check refractory indexes, and enter the data right there via the handheld. This helps us verify, align, and start our process faster, which means more batches and less waste.”

Oulton adds, “I don’t think we’ve scratched the surface of what these technologies can do for control and automation. I mean, what’s it worth to be able to walk your plant floor, and have your data at your fingertips? I think it’s worth a lot to manufacturers because it lets them increase the quality of their processes and gives them the peace of mind that comes with an immediate response.”

Surprise, Ethernet Rules

Alright already, if there’s a common thread to today’s industrial networking trends, it’s still Ethernet. Its strength and momentum remains paramount in industrial networking, and the proof is that it’s the driving force behind most, if not all, of the other networking trends.

As if Ethernet-based networking wasn’t powerful enough, the Internet Engineering Task Force that administers most Internet standards is expected to release Internet Protocol Version (IPV) 6 shortly. Everyone has been using IPV 4 for several years, but IPV 6 will make twice as many web addresses available to users.

Oulton adds there have been three notable technological advances that allowed CIP-based EtherNet/IP to be widely deployed on plant floor, including moving from 10 Mbps to 100 Mbps, from half-duplex to full-duplex operations and from hubs to routers and switches to avoid data collisions and achieve determinism. This also let users set up subnet-based addressing schemes, which kept some nodes and devices in a private space and establish virtual local area networks (VLANS). “Users now can deploy networks the way they want to, rather than being limited by a network, or limited by a vendor’s devices,” says Oulton. 

Bryant is starting to see the real power of Ethernet in products and applications and what users start to do with them. “For instance, a web browser in an Ethernet-enabled PLC lets users get diagnostic data without specialty programming software,” he says. “All you need is an IP address and Internet Explorer to look at the diagnostics buffer. This also shows the value of having IP addresses in devices because they can be seen symbolically, too.”

All of this means fewer barriers to data that users need. In fact, adds Bryant, people are using the Internet because they didn’t implement OPC before, and now they don’t have to. “Ethernet is opening up standards for users that need a protocol that fits their application’s requirements, and its security and safety is helped by intelligent switching and addressing,” he concludes. “Of course, the next piece is how to do all this with wireless.”

OK, Wireless Too

Perhaps the true attraction of wireless is that it delivers the benefits of a hardwired fieldbus, and also provides the installation savings that fieldbus originally promised. “With fieldbus, there are incremental cost savings in hardware, but getting them means going through procedural changes that are unacceptable to many user companies,” says Caro. “With wireless, you get real installation cost savings.”

Steve Toteda, Dust Networks’ marketing vice president, adds that, “As wireless replaces wire, we see more wireless in places where there simply couldn’t be any sensors before. Now, users can put in wireless sensors that self-form into a mesh, and the maintenance technicians are freed from having to dig into a rat’s nest of wiring.

“As a result, we’re seeing growth in wireless sensors for machine health monitoring, such as checking vibration with GE Energy’s wSim solution. This can help preventive maintenance because motors below 4-5 hp usually aren’t monitored, even though the resulting downtime can cost a lot. Likewise, wireless sensors also are moving into the IT world. One customer, Federspiel Controls, uses them to monitor its mainframe computing data center’s temperature, and estimates they can save 1.4 million kilowatt-hours with better monitoring.” 
Toteda adds that wireless mesh eventually can be viewed as an almost biological, nervous system-like “real-time, real-world web” that allows users to build an intranet of their plant and its processes with a sophisticated network linking all applicable sensors. “The challenge then is synthesizing the resulting data, and using it to make better decisions,” he says. 

Protocols Playing THE Same Tune

Faced with the looming presence of Ethernet and wireless, more traditional networking standards and their organizations adopted Ethernet-based flavors and are undertaking increasingly closer degrees of cooperation—even on wireless.

Following the joint agreement by the Profibus Trade Organization, Fieldbus Foundation, and HART Communication Foundation to standardize on Electronic Device Description Language (EDDL), HCF released its Wireless HART protocol earlier this year. Most recently, ISA and HCF agreed to integrate Wireless HART and the upcoming ISA 100 standard, which is scheduled to release details of its protocol in January 2008. The agreement calls for accommodating the HART 7 wireless protocol in Release 1 of the ISA 100.11a standard via a dual-gateway architecture.

Caro explains that ISA 100 takes a ZigBee wireless chip and extends the protocol by adding multi-channel, direct-sequence, spread-spectrum frequency hopping. In fact, ISA 100 and Wireless HART both hop the same 15 channels, which increases signal reliability and security.

In addition, now that wireless Ethernet appears to be leaning toward settling on Wi-Fi and Bluetooth technologies, the focus appears to be moving wireless down closer to the sensor level, according to Carl Henning, PTO’s deputy director. In fact, FF, HCF and PTO agreed to form a cooperative team to seek and evaluate the best solution for wireless at the sensor level. This will be similar to the team that helped the organizations draft their EDDL agreement. “This team will help prevent a divergence of standards from occurring over sensor-level wireless,” says Henning.

Also, FF’s technical director, Dave Glanzer, says the foundation’s board approved a wireless specification development project earlier this year, and is forming a team to develop gateways connecting Wireless HART and other protocols to its Foundation fieldbus High-Speed Ethernet protocol in early 2008. A second phase will develop wireless field devices for Foundation’s function blocks and distributed control capabilities. 

Safety and Security

Though users often worry whether wireless devices are safe and secure, Caro says that if suppliers make their wireless instruments correctly and conform to intrinsic safety guidelines, then the resulting instruments will be inherently safe because they’ll be battery-powered. And, Toteda adds, those batteries can last five to seven years or more because time-domain network synchronization methods allow network devices to wake up and work when called on.

Toteda adds that most wireless mesh networks and Wireless HART have good security based on 128-bit AES encryption, encrypted key distribution, packet-by-packet processing, and provisions that the whole network won’t be affected if one device is compromised.

Also, Robin McCrea Steele, of Invensys-Premier Consulting Services, reported at the recent Triconex Technical Conference that fours sites are presently testing FF Safety Instrumented Functions (FF-SIF) for partial-stoke testing, and that registered products will likely be available by November 2008.

In addition, some hardware suppliers such as Hirschmann offer Layer 3 Ethernet switches with Internet addressing of TCP/IP protocols. Bryan Singer, professional services vice president at Wurldtech Security Technologies, says these switches can provide some benefits of larger, more costly network routers to smaller local area networks (LANs). “IT administrators design capabilities for choking off communications when there’s too much network traffic, and these port throttling devices probably will be in industrial network switches soon,” says Singer. “Many users buy cheap switches, and don’t plan for industrial network traffic.”

Likewise, a traditional security and safety aid is users simply being aware that not all networks are the same and then selecting the right one for the job at hand, says Verhappen.

To pick the most appropriate networking method, Verhappen adds that users must consider the response time their application needs, the network’s compatibility with lower-level networks, and the environment where it will be installed. Once a network is in place, users need to seek and find any holes in it.

“Users often think their network isn’t connected to the outside—when it actually is,” says Verhappen. “They think all they need to do is protect themselves from the Internet, but colleagues can connect unauthorized devices accidentally or make remote virtual private network (VPN) connections, too.”

The Social Scene

Though not traditionally part of industrial networking, a few of the more social aspects of digital communications are showing up as Ethernet and wireless drag the Internet into the plant. This progression might unfold as naturally as other communications evolved, such as television migrating from broadcast to digital cable and satellite, or telephones shifting from landlines to cellular wireless and Voice over Internet Protocol (VoIP).

Many printed instruction manuals and schematic drawings have been converted into digital documents such as PDF and PowerPoint files for display on laptops and handhelds. However, this electronic format also lets users add audio and video content to enhance an instructional message, and these files can be copied from the originating PC and distributed online as needed.

In fact, instructional control and automation videos by users already are appearing on content-sharing websites such as youtube.com and elsewhere. For example, some use on-screen presentations about how to build ladder logic software or supervisory control and data acquisition (SCADA) applications.

Likewise, early chat rooms and their text-based discussion threads evolved into website-based blogs and profiles on facebook.com, where users ask questions, present problems to their online groups, and seek solutions from those same communities. Even the briefest exploration of these groups and their members shows that the give-and-take isn’t simply fueling improvements in industrial networking, but is inspiring and distributing innovations of all kinds, and it’s happening between communities that usually were unaware of each other until just recently.

“Everybody’s screaming for one network and one network technology,” adds Oulton. “However, the future isn’t going to be just saving on deploying technologies, but providing a better mix of all existing ones, such as voice, video, web and wireless, and we’ll end up with even better ways to solve business problems.”