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p11 Wire Termination: Simple but Critical
p18 A Path Through the Fieldbus Jungle
p22 Area Classifi cation Impacts Network
Selection
When It Comes to Protecting Your Network Against Intruders, You Can’t Afford to Fall Down on the Job
Q1 • 2011Q1 • 2011
IN11Q1_01_Cover2.indd 14 1/27/11 12:46 PM
Our STRIDE family of industrial grade unmanaged Ethernet switches and media converter is specifically built for industrialenvironments. Install Stride switches and your Ethernet control network will maintain more consistent cycle times even under heavy I/Oand data exchange. The aluminum-housed models offer a wider operating temperature range (-40 to +85 deg. C).
Product Description STRIDE PLASTIC MODELSPrice/Part Number
CHECK OUT PRICES ON ETHERNET SWITCHES
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5-port Ethernet switch with five 10/100BaseTRJ45 Ethernet ports
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$ 162.00SE-MC2U-ST
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1102-IndustrialNetworking-Communications-MAG:Communications 1/13/2011 6:34 PM Page 1
Where Do I Go for Wireless Transmitter Products?
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© COPYRIGHT 2011 OMEGA ENGINEERING, INC. ALL RIGHTS RESERVED
*PATENT PENDINGFor Sales and Service, Call TOLL FREE
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INW_0211_Control Design 1/24/11 12:03 PM Page 1
IN11Q1_FPA.indd 2 1/27/11 12:49 PM
Our STRIDE family of industrial grade unmanaged Ethernet switches and media converter is specifically built for industrialenvironments. Install Stride switches and your Ethernet control network will maintain more consistent cycle times even under heavy I/Oand data exchange. The aluminum-housed models offer a wider operating temperature range (-40 to +85 deg. C).
Product Description STRIDE PLASTIC MODELSPrice/Part Number
CHECK OUT PRICES ON ETHERNET SWITCHES
AutomationDirect prices are U.S. published prices as of October 2010. Prices subject to change without notice.
5-port Ethernet switch with five 10/100BaseTRJ45 Ethernet ports
8-port Ethernet switch with eight 10/100BaseTRJ45 Ethernet ports
Ethernet-Fiber converter with one 10/100BaseT RJ45Ethernet port and one 100BaseFX fiber optic port
5-port Ethernet switch with four 10/100BaseT RJ45Ethernet ports and one 100BaseFX fiber optic port
$ 99.00SE-SW5U
9-port Ethernet switch with eight 10/100BaseT RJ45Ethernet ports and one 100BaseFX fiber optic port
AutomationDirectSTRIDE METAL MODELSPrice/Part Number$ 199.00
SE-SW5U-WT
$ 172.00SE-SW8U
$ 259.00SE-SW8U-WT
$ 172.00SE-SW5U-ST
$ 259.00SE-SW5U-ST-WT
$ 242.00SE-SW9U-ST
$ 339.00SE-SW9U-ST-WT
$ 162.00SE-MC2U-ST
Advanced Industrial Hardware• All 10/100BaseT RJ45 ports are auto-detecting,
auto-crossover and auto-polarity• Redundant power inputs with surge and spike protection• Optional 100Mbps multimode fiber optic port for
distances up to 4km
Real-time Performace• Store and forward wire speed switching - no delays• Full-duplex operation with flow control (no collisions!)• Auto crossover (MDI/MDIX) and auto polarity
True Industrial Design• Ethernet Isolation -1500 VRMS 1 minute• Spike protection - 5,000 watts (10x for 10 uS)• UL (CUL) listed and CE certified• Hazardous locations rated for Class 1, Div. 2
www.automationdirect.com
1-800-633-0405
Go online or call to get complete information,request your free catalog, or place an order.
www.automationdirect.com/ethernet
Shielded Cat5e cablesstarting at: $5.00
Also Available
1102-IndustrialNetworking-Communications-MAG:Communications 1/13/2011 6:34 PM Page 1
Where Do I Go for Wireless Transmitter Products?
Your single source for process measurement and control products!
© COPYRIGHT 2011 OMEGA ENGINEERING, INC. ALL RIGHTS RESERVED
*PATENT PENDINGFor Sales and Service, Call TOLL FREE
omega.com, of Course!
© Nadejda Degtyareva / Dreamstime.com
New Horizons®
in WirelessCommunications
FREE!
DPG409-W$695
Very High Accuracy Digital Pressure Gauge 316 SS Body, Analog Output and Optional Wireless Transmitter
Monitor and Control Your Process with Wireless Products
Wireless Receiver forWeb-Based MonitoringUWTC-REC3
$235
DP24-E meter, $195,sold separately
*UWTC-REC6Starts at
$69
Universal WirelessTransceiver Module
Wireless DINRail Receiverwith 4 AnalogOutputs and Alarms
UWTC-REC4$275
Shop Online at For Complete Product Details Visit omega.com/wireless
Visit omega.com to order yourFREE copy of The BLUE CAT®
New Horizons in WirelessCommunications Version No.26
Digital RTDThermometer316 SS Enclosurefor Sanitary, Wash-Down, andMarine Applications
DTG-RTD100-WSeries
Starts at$495
Non-Contact InfraredTemperature SensorWith Wireless Transmitter
UWIR-2-NEMA$285
UWTC-REC1$225
Wireless Connector/Transmitter Receivers
INW_0211_Control Design 1/24/11 12:03 PM Page 1
IN11Q1_FPA.indd 3 1/27/11 12:49 PM
reddot designaward winner 2009
IN11Q1_FPA.indd 4 1/27/11 12:49 PM
7 FIRST BIT No Help for Naked Turtles
8 PACKETS Wireless Networking Finally
on the Rise
11 BUS STOP Totally Terminal, Man
22 PARITY CHECK Area Classi� cation Matters
25 PRODUCTS
27 TERMINATOR Future Fieldbus Trends
COLUMNS & DEPARTMENTS
COVER STORY
INDUSTRIAL NETWORKING is published four times annually to select subscribers of CONTROL and CONTROL DESIGN magazines by PUTMAN MEDIA INC. (also publishers of CHEMICAL PROCESSING, FOOD PROCESSING, PHARMACEUTICAL MANUFACTURING and PLANT SERVICES), 555 W. Pierce Road, Suite 301, Itasca, IL. (Phone: 630/467-1300; Fax: 630/467-1124.) Address all correspondence to Editorial and Executive O� ces, same address. ©Putman Media 2011. All rights reserved. The contents of this publication may not be reproduced in whole or part without consent of the copyright owner. INDUSTRIAL NETWORKING assumes no responsibility for validity of claims in items reported. Single copies $15.
For additional information, please contact Foster Printing Service, the official reprint provider for Industrial Networking.
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Call 866.879.9144 or [email protected]
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Custom REPRINts INDUSTRIAL NETWORKING
Q1 • 20115
Adapting to ChangeThe Number of Network Protocols Is Not Decreasing, Necessitating Gateways and Adapters That Can Help Devices Communicate With One Another
R E S E A R C H 2 3
The Fieldbus JungleAn Experienced Integrator Examines the Benefits Claimed for Fieldbus and Their Relationship to Industrial Reality
BY P. HUNTER VEGAS, AVID SOLUTIONS
E V A L U AT E 1 8
Do Not Slip Up on Security
When It Comes to Protecting Your Network Against Intruders, You Can’t
A¥ ord to Fall Down on the Job
BY JIM MONTAGUE, EXECUTIVE EDITOR
D E S I G N 1 2
18
IN11Q1_05_TOC.indd 5 1/27/11 12:48 PM
PAN110 Hilscher Full Page ad Pub: Automation W
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SYCON.net• Configuration and Diagnostic
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The netTAP 100 is the most flexible and cost effective ProtocolConverter available to interconnect traditional Fieldbus systems,Real-Time Ethernet and/or serial protocols.
To learn more about flexible and cost effective solutions, visit our website at www.hilscher.com/usa6 or call 1.630.505.5301.
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IN11Q1_FPA.indd 6 1/27/11 12:49 PM
7
Is there a draft In here? I’ve been reporting and writing about network security for a few years, but I never felt exposed, scared or ill—probably because I’m not personally responsible for a large factory-floor production line or a potentially volatile process.
however, my concern started to ramp up when I began learning about new viruses like stuxnet that can lodge themselves and hide in PLCs and
dCs-based systems, and then launch “man-in-the-middle” attacks that can damage equipment, while at the same time making it look like the network and its components are running normally. I began to get that twinge behind the knees that us parents get when they see their kids start to fall off a jungle gym on the playground.
My worry only increased as I researched this issue’s “do not slip Up on security” cover story (p12) because many folks seem so uninformed about the capabilities of these viruses. for instance, there were lots of statements that stuxnet was only focused on Iran’s nuclear fuel centrifuges (mostly true), that it can only invade via Usb sticks (mostly false, because it can get in through laptops and file transfers), and that Microsoft has already issued software patches (true, but more may be needed). There was little or no discussion that other viruses using similar methods are inevitably on their way.
Consequently, if I were a plant manager, I think my first impulse would be to cut all ties with ethernet-based networking and the Internet. business-level reporting and remote troubleshooting be damned.
Unfortunately, I’m told that plant-floor turtles no longer can pull their heads in, so to speak, and that their noggins will get stuck or lopped off if they try it. The links that enable remote monitoring and enterprising reporting are just too important because the whole lean-and-mean, just-in-time manufacturing infrastructure that has grown up in recent years depends on them. Of course, many statements that you can’t sever ethernet-based networking ties come from people who sell security systems and services, and so they have a conflict of interest, but they’re probably right.
still, in my usual search for unbiased information, I repeatedly called and emailed several branches of the U.s. government because it’s supposed to
have so many folks working on “cyber security.” These included the U.s. department of homeland security’s Industrial Control systems Cyber emergency response team (ICs-Cert), the national Institute of standards and technology (nIst), Idaho national Laboratory (InL) and the non-government north american electric reliability Corp. (nerC). Unfortunately, though I got through to a few receptionists and people who promised to set up
interviews, no one called back or communicated any advice on network security. now, I’m sure they’re all very busy with high-level security projects, but again I’m just glad I wasn’t a plant manager with a disabled network.
several other suppliers and end users reported running into the same brick wall, too. even most of the best security practices on the ICs-Cert website are five or six years old, as if someone set up the site and then let it grow stale.
I think my situation is even more ridiculous in light of the recent Washington Post series on the huge federal security bureaucracy that grew up since 9/11, which apparently scours vast amounts of Internet traffic to generate reports that no one reads (http://projects.washingtonpost.com/top-secret-america).
so, if your slender amphibian neck is on the line and it’s getting cold, what to do? are there any security blankets out there? Well, the basic advice so far is to deter and mitigate. This means inventory your network and equipment; account for all data pathways into your application and facilities; enable and routinely update complex passwords; turn on and maintain existing antivirus software; identify and prioritize vulnerable points in your network; segment it into functional zones and subzones, perhaps using duPont’s reference model; isolate those zones with firewalls that only allow well-defined, crucial communications; don’t allow the use of unchecked Usb data sticks, laptops or other data storage devices in your facility; update your company’s security and software patching policies, and train all employees to follow them; require plant-floor and It staffs to cooperate on security issues; regularly back up essential data and software to an isolated setting; and have some replacement equipment and software available and ready to go in case an intrusion disables some of your devices.
No Help for Naked TurtlesDespite repeateD
calls anD emails to
DHs’s ics-cert, nist,
inl anD nerc, none
calleD back witH
input on security.
lucky i wasn’t a plant
manager witH a
DisableD network.
f i r s t b i t
Jim montagueexecutive eDitor
7inDustrial networking
Q1 • 2011f i r s t b i t
IN11Q1_07_FirstBit.indd 7 1/27/11 12:50 PM
IndustrIal networkIng
Q1 • 20118 p a c k e t s
Wireless Networking Finally on the Rise
After yeArs of hype, wireless industriAl networking solutions Are expected to see some actual significant growth this year in purchase orders, shipments and revenues, according to the latest report from Vdc research group (www.vdcresearch.com). wireless networking product shipments overall will exceed 25% cAgr through 2015, details tim shea, senior analyst at Vdc.
research for its latest industrial networking report—highlighting the top 10 trends for the industrial networking solutions market in 2011—found that standards development, as well as improved technology (e.g., isA 100 and wirelesshArt) and security (e.g., mesh networking and wpA2) remove some of the major barriers to wireless adoption and relieve security and reliability concerns that traditionally have stood in the way of wireless success.
“standards development initiatives among a number of the primary automation suppliers, end users, oeMs and other relevant stakeholders is a major driving factor beyond the continued technical enhancements made in response to reliability and security concerns,” shea says.
According to survey respondents who use wireless networks, the family of 802.11 networks will play an increasingly dominant role as the technology improves and continues to edge out narrow-band proprietary networks. wireless users indicated particularly strong future demand for 802.11n, isA sp-100.11 and wirelesshArt, shea says. “technical considerations aside, the reason for expected future demand resides primarily among the number and type of suppliers designing products for these networks, and the legacy presence as fieldbus derivatives,” he adds.
real-time ethernet capabilities are expected to dominate the wired side of industrial networking, according to Vdc. The bent there is toward ethernet/ip and profinet for discrete industrial automation applications, and Modbus tcp for process automation applications, shea notes, adding, “Based on respondent data, our outlook for wireline industrial networking infrastructure product shipments will exceed 20% cAgr through 2015.”
industrial networking will be no stranger to mergers and acquisitions this year, also. Vdc expects increased M&A activity, and predicts that a large it player will acquire an industrial networking solutions provider.
Bits & Bytes
Belden (www.belden.com) agreed to acquire GarrettCom (www.garrettcom.com). this acquisition solidifies Belden Hirschmann’s brand “as one of the top two dominant players in the wireline networking component products segment for use in industrial facilities,” notes tim shea, senior analyst at Vdc research (www.vdcresearch.com).
Emerson Process Management (www.emersonprocess.com) joined the FDT Group AISBL (www.fdtgroup.org) on its executive committee and board of directors.
the Ethernet Powerlink Standardization Group (epsg, www.ethernet-powerlink.org) made the opensafety standard available for profinet, making opensafety available for all major real-time ethernet protocols.
the Fieldbus Foundation released designMate software tool for planning, validation and documentation of Foundation fieldbus H1 segments. It automatically audits segment layouts for conformance with the Foundation physical-layer spec based on the Iec 61158-2 (type 1) standard.
GarrettCom (www.garrettcom.com) shipped its 100,000th Magnum 6k Managed switch. the line of managed ethernet switches is designed for demanding industrial ethernet applications on the factory floor, in power plants and substations, transportation and industrial security and surveillance.
perceived Benefits and drawbacks of wireless Industrial networks % of respondents
wireless provides solutions where wireline Impossible or Impractical 52%
wireline More reliable (noise Immunity, etc.) 48%
wireless easier/Quicker to Install 40%
More Familiar with wireline (easily understood, known technology) 35%
wireline More secure 35%
wireline Has wider Bandwidth and Is Faster 29%
wireless allows Mobile applications 18%
wireless More suitable for remote locations 18%
wireless More Flexible (easier to Modify, etc.) 16%
wireline easier to configure/specify 12%
wireless performs poorly in adverse weather (e.g. rain, etc.) 12%
wireless not suitable for control applications 12%
wireless easier to Maintain 8%
note: percentages sum to over 100% due to multiple responses
Vdc
rese
arch
IN11Q1_08_09_Packets.indd 8 1/27/11 1:10 PM
9 INDUSTRIAL NETWORKING
Q1 • 2011
With the Spectris acquisition of N-Tron in October, and again with Belden’s acquisition of GarrettCom in November, Shea noted in VDC’s blog the expectation for continued M&A activity, including a prediction that RuggedCom will be acquired soon.
Shea also noted a trend toward convergence within the networking products themselves. As VDC notes in its latest industrial networking report, automation suppliers are driving down costs, providing space savings and
reducing wire interface by embedding switch port capability into products such as network I/O adapters, PLCs and drives. Embedded switch capability is on the rise to capture growing demand for Ethernet capability.
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arch
OPC Program Recognizes UA Growth
THE OPC FOUNDATION WWW.opcfoundation.org) introduced the OPC Unified Architecture (OPC UA) Test and Certification Program for products from its corporate members. The program recognizes increasing adoption of OPC UA technology, and efforts toward interoperability and ease of use.
Certification of an OPC UA product ensures that the product is fully compliant with OPC UA specifications, and provides assurance that tested products can successfully interoperate with other OPC Foundation member products, according to the foundation. The move “solidifies OPC Unified Architecture as the de facto industrial communications standard,” says Thomas Burke, president and executive director of the OPC Foundation.
The number of OPC UA products tested will be in accordance with a company’s type of membership. All testing will be conducted in the North American Test Lab in Scottsdale, Ariz., and will begin in the second quarter of 2011.
“Products awarded the Lab Certification logo will not only be tested for function and performance, but will also be tested against other OPC Foundation products to ensure interoperability,” says Nathan Pocock, director of compliance.
Get more information about the OPC Test Lab process and procedures at www.opcfoundation.org/compliance.
IN11Q1_08_09_Packets.indd 9 1/27/11 1:10 PM
IN11Q1_FPA.indd 10 1/27/11 12:49 PM
11
John [email protected]
11IndustrIal networkIng
Q1 • 2011F I r s t B I t 11
IndustrIal networkIng
B u s s t o P
The “TerminaTion” of a wire—really The continuation of a circuit—is among the simplest, but extraordinarily critical, components in our control systems. how many vexing hours have been burnt, often by high-priced help, by issues ultimately traced to a loose wire? when even a rudimentary factory has thousands of field and oem-landed conductors, it’s remarkable we don’t suffer more from termination defects. Choices,
compromises, and errors from the specification and construction phase of a project might go unnoticed for years before they create issues for the plant dwellers who have to fix them.
my electrical foreman always seems to be testing my resolve by using a butt splice when a conductor breaks. i suppose he feels obliged to offer the cheap and quick alternative to pulling in all new cable or, at a minimum, adding a junction box. one of the reasons butt splices are taboo in plants is their tendency to become troubleshooting nightmares in the future.
if you’re shameless enough to document it on a markup, maybe your unfortunate successors will stand a chance of finding the ubiquitous conduit fitting it’s tucked away in. Unfortunately, these are repairs done in haste or even in secret. when the plant is waiting on you to get the wiring back together after an outage, it’s hard to tell the boss he has to wait another shift while you round up and pull in some new cable. a junction box—even if it’s a GUa or similar fitting—is the standard compromise. Be sure to update the drawing.
The complex where my plant operates is populated by users who favor the traditional rising-clamp screw terminal. available in an enormous variety of sizes, combinations, ratings, colors and capabilities, most projects specify them without a second thought. although loose wires are not unknown, these terminations seem to hold up well. after years, a random tug-test seldom reveals a loose wire. Some installers advise a cursory retightening of screw terminals after a year, or even on an ongoing (e.g., every two years) basis. over-tightening can be as bad as under-tightening, and companies are known to specify that torque screwdrivers be used to ensure the proper tightening is applied to each field-installed termination. Screw terminal users can check
their manufacturer’s specifications to learn the recommended torque for a specific terminal. Some routine or random inspection/quality control of terminations is wise, especially oem assemblies that have been on a long, bumpy ride to the site.
higher-vibration environments increase the possibility that screw terminals will loosen over time, and there’s a significant contingent of oems, integrators, installers and end users who have found
happiness with the spring-clamp terminal. instead of a screw clamp, the wire is locked in place by a relatively strong little spring. The principle is the same as the shepherd’s-hook-shaped connections you might have used back in the day for your old model railroad. i’ve had a few oem devices that used spring clamps for customer wiring, and loose wires were never an issue—they are in there and they’re not coming out. Sometimes a specialized tool is supplied to release a wire, or open the clamp for a wire to be inserted. others can be opened with the same screwdriver blade you use for traditional blocks. you might need to be more cautious when specifying spring clamps, because the range of wire gauges that can be reliably landed is typically narrower than what’s accommodated by screw clamps. it’s also more challenging to land multiple wires under the same terminal. Some installers like using ferrules with screw clamps, but i like the secure feeling of all the strands trapped by the spring.
radicals have been exploring the insulation displacement connection (iDC) terminal for a number of years. Some swear by them and others swear at them. The more sophisticated (and expensive) offerings have improved security and longevity, and have proven themselves in hazardous and corrosive environments such as in sulfur plants. The beauty of the iDC is that no wire stripping is needed. But multiple wires in a terminal are verboten and the connection can be made and unmade only a limited number of times. Because each terminal contains an engineered mechanism to ensure a secure connection, they are bulkier and take up more room in your panels.
Best advice i’ve seen is to get samples from a number of suppliers and styles, and try them out. and make sure your installers like them. The savings promised by the latest innovations will likely be lost if your craftspeople aren’t on board.
Totally Terminal, Manone oF the reasons
Butt sPlIces are
taBoo In Plants
Is theIr tendency
to Become
trouBleshootIng
nIghtmares In the
Future.
IN11Q1_11_BusStop.indd 11 1/27/11 12:55 PM
PAY ATTENTION. THAT’S THE FIRST THING.Icy pavement, dark alleys, newly mopped fl oors, biker bars, Wall
Street, banana peels and industrial control networks all demand caution—or expect bruised backsides or worse. Your choice.
Likewise, anyone can kick in your front door or break a window, but that doesn’t mean locking them is a waste of time or that you never can leave the house. Common-sense barriers prevent most residential break-ins, and keeping cash and other valuables in a bank lessens the losses from the few intrusions that statistics show must happen eventually. Both deterrence and mitigation mean never having to say you made it easy for the bad guys. Your choice again.
� ese physical analogies hold equally true for industrial network security. It also demands attention and focus because some intrusions might occur, but ongoing and evolving deterrence and mitigation can prevent most break-ins and limit those that do happen.
THE NEED TO PREPARE“Our end users aren’t making drastic changes because of viruses like Stuxnet, but they’re certainly aware of it,” says Steve Goldberg, industrial
systems division director at Matrix Technologies (www.matrixti.com), a system integrator in Maumee, Ohio. “Most of our larger end users in oil and gas and food products feel like they’re on top of their network security because they know they have to learn as they go. � ey already have their own security policies, but now they’re telling their independent contractors that they must use the end user’s laptops to access their system.”
Tom Lycans, Matrix’s senior engineer, adds, “One adverse incident would show some end users how they could prepare their network security and the worth of doing it, but it’s still hard for many of the smaller ones to justify it ahead of time. For instance, one client has its whole plant and corporate offi ce on the same network, but just doesn’t have the manpower to divide it yet. � at’s why we’re helping them to prevent exposing the control layer to the business layer by only allowing communications across a fi rewall, which defi nes what data can go to the control layer, or by only letting data go one way from the PLC to business level. For example, we typically deploy two separate IP ranges on one PC with two NIC cards.”
Matrix helps its users defi ne and understand their specifi c network security needs, such as how much outside contact their users and
BY JIM MONTAGUE, EXECUTIVE EDITOR
When It Comes to Protecting Your Network Against
Intruders, You Can’t A ord to Fall Down on the Job
IN11Q1_12_17_cvrstory.indd 12 1/27/11 2:17 PM
13 INDUSTRIAL NETWORKING
Q1 • 2011
applications require and how much they can do without, Goldberg and Lycans add. Next, they review what type and level of security is needed in each area of the organization, such as how much access is allowed to the corporate VPN, or if machines on the plant fl oor need to be locked down. Based on these studies, Matrix helps users pick and apply equipment that satisfi es the security level required for each area.
“We still want basic antivirus software on each PC, so it helps that it’s been learning to play nicer with our HMI/SCADA and controls software over the past fi ve years,” Lycans says. “I think Microsoft, Norton and McAfee got enough complaints about antivirus software identifying HMIs as viruses, so they added more-intelligent software engines, and stopped putting on the broad and indiscriminate threat masks they used to put on. We also have a couple of users that maintain ideal images of just the operating system software they need to run their PCs, and then ghost them to each new PC at installation or when needed. � ey also back up their data and software, so they can restore it during a recovery. � ese are tasks that can’t be ignored. We and our users have to be as vigilant as we can, and these eff orts have to be ongoing, and then evolve as needed.”
HOW BADLY STUXNET BITESDespite these logical security steps, some of the always-simmering panic over network security boiled over last summer when Stuxnet offi cially emerged on July 14. � e violently destructive Trojan-style virus used a security breach to exploit all versions of Microsoft Windows and infect Siemens Industry’s Simatic WinCC SCADA software, PCS 7 distributed control system (DCS) and S7 controllers.
Symantec (www.symantec.com) reported that Stuxnet can steal code and design projects, hide using a Windows rootkit, use programming software to upload its code to PLCs monitored by SCADA systems, and then hide these code blocks, too. As a result, Stuxnet isn’t just a rootkit that hides itself on Windows, but is the fi rst publicly known rootkit that is able to hide injected code located on a PLC, according to Symantec. It adds that Stuxnet contains 70 encrypted code blocks that appear to replace some “foundation routines,” which take care of simple yet common tasks such as comparing fi le times, and others that are custom code and data blocks. By writing code to a PLC, Stuxnet potentially can control or alter how a system operates.
Although Stuxnet seems to have been coded specifi cally for Siemens products, other products could be just as vulnerable to similar viruses or attempted intrusions, according to John Cusimano, security services director at exida (www.exida.com). “WinCC is by far the largest SCADA HMI package. It’s embedded into everything. Whether you know you’re buying it or not, it might be embedded in your system. � at’s probably why it was the target.”
After Stuxnet was created and initial versions started circulating in June 2009, its developers created a second, more powerful iteration, which allowed it to spread among USB devices with virtually no intervention by victims. � ey also used encryption keys belonging to chipmakers Realtek and JMicron, and digitally signed the malware, so antivirus scanners would have a harder time detecting it. � is allowed Stuxnet to defeat multiple-factor authentication.
One of the worst aspects of Stuxnet is its ability to use a man-in-the-middle attack. � is means its software lets it appear to be just another PLC on a network, and deliver indications that everything is fi ne on a network, while doing damage behind the scenes.
Some early reports indicated that Stuxnet was developed by a U.S. intelligence organization to disrupt or damage nuclear fuel centrifuges in Iran. More recent evidence indicates that it was tested in Israel.
RUN AWAY OR BE RESILIENT?How do you handle viruses such as Stuxnet and other network threats? Microsoft issued four patches to prevent further infections, and Siemens developed fi xes for its devices. Most experts warn users not to plug unexamined USB data sticks or laptops into their networks, which is Stuxnet’s preferred entry method, even though it also can get in via fi le transfers and other pathways (Figure 1). However, now that Stuxnet’s software and method have been revealed, other similar viruses are likely just a matter of time.
Your fi rst impulse in response to Stuxnet might be to make like a turtle and pull your head
in—sever your application and plant from all Ethernet-based and Internet-enabled connections to the outside world, tell your CEO and accountants to come get their production data manually, and tell any remote troubleshooters to get used to fl ying and visiting in person again. A reasonable impulse, especially if you haven’t yet linked your plant to any Ethernet that connects to the business level and beyond.
Unfortunately, going standalone isn’t exactly practical these days. Too many basic production and even critical systems now depend on Ethernet-based links to other systems, often because there are few staff left to tend many processes.
“It’s not possible to put the genie back in the bottle at this point,” says Eric Cosman, engineering consultant at Dow Chemical (www.dow.com) and ISA-99 committee co-chair. “Machines and processes can be infected by USB sticks or other data fi le transfers, so there’s no way to guarantee that an industrial network won’t be impacted by Stuxnet or another virus. We just have to try and prepare our networks to be as resilient as possible, just like when we back up data fi les to be ready for hard disk crashes. � is is what Dow and everyone else is doing. We’re developing contingency plans for when an incident happens, such as adopting zone-prudent practices to reduce or mitigate our risk and
D E S I G N
“WE STILL WANT BASIC
ANTIVIRUS SOFTWARE ON
EACH PC, SO IT HELPS THAT
IT’S BEEN LEARNING TO PLAY
NICER WITH OUR HMI/SCADA
AND CONTROLS SOFTWARE
OVER THE PAST FIVE YEARS.”
IN11Q1_12_17_cvrstory.indd 13 1/27/11 12:56 PM
INDUSTRIAL NETWORKING
Q1 • 201114
reduce any damage that does occur. For instance, we only allow process control to be done on PLCs for process control, and we typically don’t allow unfettered access to the Internet from the plant fl oor. Now, this doesn’t eliminate all risk, but it does reduce it a lot. It helps to think of security as a risk-management exercise.”
FIND AND FIX VULNERABILITIES Fortunately, there are many ways to avoid and blunt intrusions, and dilute and mitigate them when they happen. � is begins by inventorying and characterizing all the devices and applications on a given network, and then identifying all the security vulnerabilities on them. Many experts report that most plant-fl oor networks have many more paths to the outside world than they realize.
“Windows and Ethernet-based networking gave us standardized, open systems, and allowed companies to optimize their processes,” says Eric Byres, CTO of Byres Security (www.tofi nosecurity.com). “Even 10 years ago, you could order a shipment of paper in Japan, and 15 minutes later, a pulp and paper application in Vancouver would start setting up to produce it. All kinds of just-in-time manufacturing depend on these networks, so I don’t think it’s possible to go back to standalone systems. � is is why it’s so important to know where and how data fl ows in and out of your plant.”
For example, Byres says, a couple of years ago he was asked to examine the network security of an oil and gas application. “� ey thought they had one Ethernet pathway with a fi rewall, but we found they had 17 pathways between the plant and the corporate level,” he recalls. “� ere also was no accounting for serial links between the plant and the business. � ey didn’t know that several of their PCs
had networking capabilities via dual-homed cards. And there were
pathways via laptops and USB sticks, too.” Typically, a dual-homed PC, server or other device has two network interface cards (NICs), which can be located between two diff erent networks, such as the untrusted Internet and a trusted corporate network, and so serve as a fi rewall and help provide more secure access.
So, users must document data fl ow and interface connections in their operations and facilities, build a threat model and risk assessment for each data source, and separate their network into isolated zones with fi rewalls that limit communications to essential data only, Byers says.
Cosman reports that users can begin to assess network security on their own, but adds it’s often worthwhile to hire an expert to help fi nd network vulnerabilities that need to be fi xed. “Once a network’s vulnerabilities are identifi ed, there usually are many simple ways to help mitigate those risks,” he says. “� ese include keeping software up to date and installing patches, and making sure your controls vendors certify those patches before you implement them. Many suppliers such as Honeywell, ABB and Invensys have been working hard to reduce this time from months to days, and Dow is benefi ting from it. Also, it helps to design control systems with elements that can be taken down for patching without taking down the whole system. For example, if your application needs three HMIs, then it might be good to install a fourth, so they can be patched one at a time without disabling the system.”
COMMON-SENSE SEGMENTS AND FIREWALLSHow do you decide how to segment your networks, where to locate your fi rewalls, and how much to restrict the data allowed to pass through them? Or do you establish white lists that defi ne permitted data sources and recipients ahead of time?
“Critical areas must be managed diff erently than regular or support areas,” Cosman explains. “You’ve got to ask, ‘If we lose one computer, what will happen? But, if we lose another computer, then what will happen to it?’ If what happens is diff erent on each, then they probably need diff erent levels of security. � is is the fundamental basis for the zone concept as described in the ISA-99.01.01 standard.”
For example, a large, multi-unit petrochemical plant in South Africa discovered in December 2009 that the Win32/Sality virus had infected its DCS. � is virus deletes many executable fi les, copies itself to removable fi les, ends processes and lowers security settings by modifying the registry. In this case, it shut down two OPC servers that were critical to the front end of the plant’s process, and which could have halted the entire plant’s operations, according to exida’s Cusimano, who presented its case study at the Industrial Control Systems Joint Working Group (ICSJWG) conference this past October.
One of the OPC servers handled control-to-safety system communications, while the other handled control-to-electrical automation traffi c. It’s believed the virus came from an infected USB stick or from some software in new equipment that had been added to the servers recently or from the plant’s business level. � is uncertainty drove the plant’s engineers to seek both immediate protection and a long-term evaluation of how to make their network stronger.
Initially, because the servers were inoperable, the petrochemical plant operators ran the unit partially blind for about eight hours
D E S I G N
ALL ABOUT STUXNETThere’s been a lot of coverage of the Stuxnet virus since it emerged last summer. Two of the three best stories are in Control magazine and the third in the New York Times. Here’s where they can be found:
• N. Bartels, “Worst Fears Realized,” Control, October 2010, p. 40, www.ControlGlobal.com/malware.
• R. Langner, “How to Hijack a Controller,” Control, January 2011, p. 47, www.ControlGlobal.com/hijack.
• W.J. Broad, J. Marko� and D.E. Sanger, “Israeli Test on Worm Called Crucial in Iran Nuclear Delay,” New York Times, Jan. 15, 2011, www.ControlDesign.com/stuxnet.
IN11Q1_12_17_cvrstory.indd 14 1/27/11 2:25 PM
15IndustrIal networkIng
Q1 • 2011
using manual controls and radios, while their engineers wiped and reinstalled the two servers’ software from scratch, and updated their access control list. The plant recovered without losing production, but the event was still an unnerving wake-up call.
“The engineers immediately updated the lockdown process for their safety instrumented system (SIS) and deployed new antivirus software, but they also called us in a few months later to assist their root-cause analysis and help re-architect their system to protect it better,” Cusimano says. “They also implemented several policy and procedural changes, including a configuration management policy for IT switches, new third-party software policy, antivirus management policy, a prohibition on remote access, and an updated portable-media policy. We found network connections were not well-documented, insufficient separation between the business LAN and control system VLANs and ACLs, boundaries were unclear and had no boundary devices, several computers had hundreds of established network connections, and there were several dual-homed servers to manage.”
Consequently, exida drafted nine
critical recommendations and 48 other recommendations for the plant, including segmenting its network with firewall devices between its business zone, process information and electrical information subzones in its demilitarized zone, and the DCS, electrical, vibration and safety system subzones in its process control zone (Figure 2). To further harden its network, the plant was advised to remove all unnecessary applications and services, apply the vendor-recommended or NIST hardening settings to all workstations and servers, remove any unnecessarily shared devices, disable or lock any unused ports, and use physical devices to lock cables into used ports and block access to unused ports.
“The client learned that network segmentation is critical, antivirus software must be used per supplier recommendations, portable media can be dangerous, awareness and training is important, and that systems should be hardened and patched per supplier recommendations,” Cusimano says. “However, we also learned that, while the ANSI/ISA-99.02.01 standard provides a good security structure, it can’t be used as a checklist, and that zone and conduit
Internet
USB DriveServer Services
Shared Printer
Shared Drives
S7 Program Files
WinCCSQL
RPC Server
RPC Server
InfectedLaptop
Main StationPLCPLCPLC
EngineeringStation
ProgrammingStation
SQLServer
HMI Station
Figure 1: Stuxnet and other viruses can spread through multiple pathways, such as USB data sticks, infected laptops and other kinds of file transfers.
How Stuxnet can Spread
Byre
s Sec
urity
IN11Q1_12_17_cvrstory.indd 15 1/27/11 2:25 PM
IndustrIal networkIng
Q1 • 201116
modeling works, suppliers’ reference architectures need to be adjusted for real applications, and that data collection must be performed very carefully on a live control system.”
Besides employing ANSI/ISA-99 and other standards to help them segment their networks and prioritize their communications, some international end users also work with the International Instrument Users’ Assn. (WIB, www.wib.nl) in the Netherlands and its 72 members to develop security requirements for its suppliers. The three-part organization includes Evaluation International, WIB and Exera.
“End users want a guarantee that vendors supply secure systems and services at all stages of the lifecycle,” stated Ted Angevaare, Shell’s global DACA manager and chair of WIB Plant Security’s working group, during its seminar in March 2010. “We need fit-for-purpose security based on best practices of the WIB members, an affordable
way for both large and small vendors to gain security certification, and a minimum standard freely available for everyone.”
Good Security = evolvinG SecurityNot only is eternal vigilance the price of freedom, but it’s also good for network security. “There’s no free lunch on security,” Cosman says. “You might want to just complete a checklist to know you’re secure, but that’s not possible. You can take steps to lower the probability of an infection, but you have to assume that you’ll be impacted eventually, and so you have to back up files and data, create a disaster recovery plan, and perform drills based on it. Network security is a lot like an arms race because better solutions will evolve, but the threats evolve too. So, instead of just trying to prevent incidents, we also have to measure and improve how quickly we can recover.”
d e s I g n
BUSINESS ZONE
DEMILITERIZED ZONE (DMZ)
PROOCESS CONTROL ZONE
Electricalinformation
zone
Electrical zone Safety system zone
Process information zone
DCS zone
Vibrationzone
Core
Dist
Access
AV
SCADA 1 SCADA 2
Op(s)
OPC 2 Controller 1
Server 1 Server 2 Mon 2
Com 1 Com 2 Mon 3
Controller 2 Controller 3 Controller 4 Controller 5 Controller 6
SIS eng
SIS op SIS SIS SIS
OPC 1
Vibrationcon�g OP
Vibrationmonitoring
Eng Sprvsr Plant mgr Boardrm OptimizeEng server
Alarm HistoryAssetmgmt
Access Access
Dist
Figure 2: using the duPont reference architecture, the process control network at a large petrochemical plant in South Africa was protected by dividing it into zones separated by firewalls at potentially weak boundary locations. these zones include business, demilitarized/operations management, process control, safety and various subzones.
PRACTICAL NETWORK SEGMENTATION
exid
a
IN11Q1_12_17_cvrstory.indd 16 1/27/11 12:57 PM
In fact, several developers say that firewalls and other network gateways soon will perform data authentication at the switch level, which should make it easier to weed out and prevent potentially destructive traffic. Ben Orchard, applications engineer at Opto 22 (www.opto22.
com), reports that its PAC controller is adding SSL encryption to some of its communication methods in the near future, and is looking at extending similar functionality to other areas of the controller. Similarly, Rockwell Automation (www.rockwellautomation.com) uses digital signature checking in its ControlLogix L7x to authenticate its firmware, and this method likely will be used in the future to check software-based communications, network connections and individual data packets.
“People want to put security systems in place that will protect them, but what we haven’t come to grips with yet is that our new security reality needs a cultural change, too,” says Ernie Rakaczky, portfolio program manager for control systems and cybersecurity at Invensys Operations Management (www.invensys.com). “This will have to be similar to the change by which everyone came together on process safety, took self-ownership, and helped each other be responsible. Likewise, besides looking at security’s tactical side of surrounding and protecting code, we also have to look at security’s strategic side by learning to write code that is itself stronger and less vulnerable in the first place.”
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“They ThoughT They had
one eTherneT paThway wiTh
a firewall, buT we found
They had 17 paThways
beTween The planT and The
corporaTe level. There also
was no accounTing for
serial links beTween The
planT and The business.”
IN11Q1_12_17_cvrstory.indd 17 1/27/11 12:58 PM
INDUSTRIAL NETWORKING
Q1 • 201118
FIELDBUS CAN BE GOOD. FIELDBUS CAN BE BAD. AN EXPERIENCED INTEGRATOR EXAMINES
THE BENEFITS CLAIMED AND THEIR RELATIONSHIP TO INDUSTRIAL REALITY
The Fieldbus Jungle
THERE HAVE BEEN COUNTLESS ARTICLES THAT TOUT SUBSTANTIAL savings generated by fi eldbus networks. Most claim greatly reduced wiring, marshalling panel and I/O space, reduced commissioning time, and extensive savings from putting control out in the fi eld devices.
� ese all are mostly true statements. However, when you consider the larger picture, those benefi ts and savings can be off set by other factors rarely mentioned. It is important that the automation professional considers all of the relevant factors before choosing a technology.
In this article the word “fi eldbus” refers to digital networks in general. � e scope of this discussion is limited to the instrument-level fi eldbuses: Profi bus-PA, Foundation fi eldbus, AS-i and DeviceNet.
THE REAL ECONOMICSDoes fi eldbus save wiring cost and reduce installation cost? It depends.
Fieldbuses replace multiple I/O cards and individual instrument wires with a single card and a single wire running to the area and then split off to the instruments. � e amount of reduction is dependent on the fi eldbus used, how it is installed, and the area electrical classifi cation. On average, it is fair to say that fi eldbuses will reduce wires and/or terminations by at least a factor of 4, and some fi eldbuses can save a great deal more than that.
It is also true that there can be some engineering reduction because the marshalling panel sizes are reduced or eliminated and fi eld junction boxes are no longer used. However, those savings are often off set—even overwhelmed—by other factors.
Fieldbus I/O hardware is signifi cantly more expensive than a standard I/O card, and the fi nal hardware cost is at best break even. On average, the control hardware of a single, non-redundant AS-i port costs about the same as the DI and DO cards associated with 20-25 on/off valves with two limit switches each. Some vendors make dual-port cards, others single. � ese values are on a per-port basis. If
you install fewer than 20-25 valves per port, the AS-i hardware likely will cost more on a per-instrument basis. An AS-i card also requires a power supply and might require power conditioners and repeaters.
A single, non-redundant, non-IS Foundation fi eldbus (FF) network card with power supply costs about the same as the analog input I/O associated with 15 transmitters or valves. Most segments will not carry that many devices, so the Foundation fi eldbus hardware actually costs more than standard analog I/O hardware for the same number of points.
Price comparisons with Profi bus-PA are more diffi cult because the cost of the segment depends on how the DP/PA couplers and DP communication cards are implemented. However, in a typical installation, the cost of a single, non-redundant, non-IS channel of Profi bus-PA is about the same as the I/O cards associated with 5-10 valves or transmitters. � is puts the cost of Profi bus-PA hardware on par with standard analog I/O.
Fieldbus wire is much more expensive than regular 4-20 mA wire. Although theoretically almost any shielded pair can be used, the specifi c fi eldbus wire will allow maximum network lengths with minimum communication problems. Prices vary, but fi eldbus wire is
BY P. HUNTER VEGAS, AVID SOLUTIONS
E V A L U A T E
� is is Part I of a two-part article. Part II will appear in the Q2 2011 issue of Industrial Networking. You can read both parts now at www.industrialnetworking.net/fi eldbus11q1. Part 1 discusses fi eldbuses in general and outlines the true costs of fi eldbus installations. Part II discusses advantages/disadvantages of individual fi eldbus technologies.
ON AVERAGE, IT IS FAIR TO SAY THAT FIELDBUSES WILL REDUCE WIRES
AND/OR TERMINATIONS BY AT LEAST A FACTOR OF 4, AND
SOME FIELDBUSES CAN SAVE A GREAT DEAL MORE THAN THAT.
IN11Q1_18_21_Featr2.indd 18 1/27/11 12:59 PM
19 INDUSTRIAL NETWORKING
Q1 • 2011
typically 3-5 times more expensive. � at price diff erence can jump signifi cantly if it includes the cost of special connectors, whip cords, etc., which are required in most fi eldbus installations.
Fieldbus fi eld devices are almost always more expensive than traditional I/O devices. � e diff erential is shrinking, but still exists. Lead times can be longer as well.
Foundation fi eldbus and Profi bus-PA can eliminate fi eld junction boxes, but they often replace them with some kind of segment coupler or block that must be installed in the fi eld to allow the local devices to connect to the network. � ese blocks are vital because they usually protect the network from shorts in individual transmitters. � e total cost of these segment blocks as well as the fi ttings, terminators, etc., can approach or eclipse the cost of the original junction box.
Fieldbuses eliminate engineering associated with junction boxes and marshalling panels, and replace it with the engineering of the network itself. � is cost can be very signifi cant, since it often requires knowing—within a few feet—where the devices are located before the facility even exists. As the process design changes and equipment is relocated, the network design must be re-checked. A 4-20 mA wiring scheme is very forgiving. It doesn’t matter if the cable is 10 ft or 1,000 ft, it still will work. Few fi eldbus installations allow changes of that magnitude without a revisit to the design.
Fieldbus installations often require additional software and/or software licenses that are not required for standard I/O. � ese costs can be very signifi cant, especially if they are priced on a per-tag basis. � is additional software often is overlooked during the initial cost evaluation phase.
Be wary of savings calculators provided by automation vendors. These calculations can make unrealistic installation assumptions and use labor and material costs very different from those of your plant. Take the time to do your own calculations.
REDUCED COMMISSIONING TIME?Can fi eldbus reduce instrument commissioning time dramatically, as many claim? Yes. It also can make a startup a complete nightmare. You just don’t hear much about the nightmares.
A 4-20 mA installation is pretty easy to troubleshoot. If the transmitter doesn’t work, you ring out the wires with a cheap multimeter, fi nd the swapped or broken wire, and go on your way.
Troubleshooting a fi eldbus installation is rarely so straightforward. Until recently, there were few devices that could aid the network diagnostic process and the team was reduced to disconnecting segments and shooting them with oscilloscopes and meters to detect and correct errors. Recent introductions of network analysis devices make this process easier, but at added cost.
� e key determinant between success and failure rests heavily on the technical capabilities of the project design team. Don’t assign your fi eldbus project to a team that has no experience with the technology.
� e team must ruthlessly evaluate the fi eld devices to ensure they work as advertised. Plug-and-play devices often fail to live up to their name. � e team also must ensure the network design is complete and correct. � is is no small task and
might require multiple visits if device locations change during project design and/or construction.
Another key success factor is the capability of the electrical contractor installing the equipment. � e wiring and terminations are much more sensitive, and installation requires a knowledgeable technician. If not, network startup can be a very long, painful process.
REDUCED LIFECYCLE COSTS?It’s said that fi eldbuses reduce lifecycle costs by speeding troubleshooting, and their advanced diagnostics eliminate work requests to fi x instruments that aren’t actually broken. � is claim rarely is backed up with real numbers.
A fi eldbus makes a tremendous amount of diagnostic data available to a knowledgeable user. But even the most knowledgeable technicians often lack access to the programming
levels of the distributed control system (DCS) required to use the information. When a 4-20 mA device fails, a technician armed with a loop drawing and a multimeter can usually identify and resolve the problem quickly. If the transmitter is at fault, he can replace it with any transmitter of similar range and material of construction.
Consider that same scenario for a fi eldbus transmitter. If the control system does not provide integrated, direct access to the device, the technician needs a laptop or specialized fi eldbus communicator to access the device. If it requires replacement, he needs an exact replacement, then has to get the transmitter communicating on the network, and download the confi guration fi le for it. If the transmitter software revision is not the same, the system might not recognize the transmitter at all
BE WARY OF SAVINGS CALCULATORS PROVIDED BY AUTOMATION
VENDORS. THESE CALCULATIONS CAN MAKE UNREALISTIC INSTALLATION
ASSUMPTIONS AND USE LABOR AND MATERIAL COSTS VERY DIFFERENT
FROM THOSE OF YOUR PLANT.
IN11Q1_18_21_Featr2.indd 19 1/27/11 12:59 PM
INDUSTRIAL NETWORKING
Q1 • 201120
and could require an updated device fi le to be downloaded to the DCS. If the problem is network-related, it will require a highly skilled technician with a network analyzer to troubleshoot and isolate the problem. � e net result is that a failed fi eldbus device requires an elevated or engineering skill set to do the work that originally could be done by a reasonably trained technician. � is costs the plant time and money.
� e ability of advanced diagnostics of a fi eldbus device to eliminate many maintenance requests must be considered carefully. � e failure rate of fi eld instrumentation is very low. When a device provides bad readings, the problem is rarely hardware-related and is usually associated with wiring, process fouling, or plugged sensors. Advanced diagnostics usually won’t detect this type of failure nor will it reduce its frequency.
Another lifecycle cost issue is that fi eldbuses introduce obsolescence into the fi eld devices. A 4-20 mA transmitter from 20 years ago will function perfectly on a 4-20 mA control system today. Fieldbus devices undergo constant technical upgrade and improvement, and existing instruments and spare parts might not operate on the latest control networks.
MORE PROCESS INFO, BETTER ALARMSYou’ll hear that fieldbus provides much more process information and alarm features. This is absolutely true. It also can be a double-edged sword.
Fieldbus devices can provide hundreds of pieces of information beyond the single process variable value of a 4-20 mA transmitter. � e volume of data can be overwhelming, and it has minimal value unless presented to the right person in a timely and meaningful way. Production operators generally receive far too many alarms as it is. Burying them with more alarms every time an instrument thinks it detects a problem can be counterproductive. Suppressing the alarms and logging them to a fi le that never is monitored is equally pointless. It takes time and money to engineer the HMI to eff ectively take advantage of the additional information. Add the per-tag software licensing costs, and the total price can be signifi cant. Is that additional information worth the cost?
A large percentage of existing fi eld devices have HART communications and can provide a great deal of additional process and diagnostic information. However, few companies actually take advantage of that information even today.
INCREASED UPTIME AND RELIABILITYDepending on the system the fi eldbus installation is compared against, improvements in uptime and reliability are achievable. If you compare a new, carefully designed fi eldbus installation against an aging, poorly documented and poorly maintained control system, there can be little doubt the fi eldbus installation will be more reliable. If you draw that same comparison against a new, carefully designed traditional I/O installation, the diff erence will be minimal.
There are a number of issues to consider; single point of failure is one of them. A 4-20 mA transmitter has a single pair of wires leading to a single I/O card. Wire failure likely will impact only one transmitter. Card failure could take out a single channel or at worst all the channels on that card.
Wire failure on a fi eldbus might take out the device or it could take out all the network devices. Card failure likely will take out the entire segment (or two if it is dual-port). Power supply failure also will take out the segment. Redundant fi eldbus cards and/or power supplies are
available, but costly. Segments can be made smaller to reduce exposure, but at a much higher installed cost.
If a new 4-20 mA transmitter is being added, it almost always can be added without impacting production. If a new fi eldbus transmitter is added, the network often will require a complete download. � is takes the segment offl ine as the information is transferred. Some processes accommodate this easily. Other systems don’t shut down for weeks, months, or even years. An outage in this case might be diffi cult, if not impossible.
OUTSTANDING IN THE FIELDA system with control in the field devices is touted to be better than control in the DCS because it provides higher uptime, faster control and better response.
� e logic is not convincing. Improved control response is based on extremely fast processes run on a laboratory simulation. It ignores the real-world eff ects of actuator speed and saturation limits. It also compares fi eld-device control response to the control response of a typical DCS/fi eldbus installation. A true analog response would be much faster than any fi eldbus—regardless of the location of the control—if it runs directly to a DCS and will be even faster with a dedicated analog loop controller.
E V A L U A T E
A 4-20 MA INSTALLATION IS PRETTY EASY TO TROUBLESHOOT.
IF THE TRANSMITTER DOESN’T WORK, YOU RING OUT THE WIRES
WITH A CHEAP MULTIMETER, FIND THE SWAPPED OR BROKEN WIRE,
AND GO ON YOUR WAY.
IN11Q1_18_21_Featr2.indd 20 1/27/11 1:00 PM
21 INDUSTRIAL NETWORKING
Q1 • 2011
Perhaps the most important omission is that fi eld device control has an unknown failure mode. Historically, most analog instruments fail in a small number of ways: downscale, upscale or, very occasionally, mid-scale. Fieldbus instruments have a larger number of failure modes, but their advanced diagnostics generally can indicate this. However, if control is performed in the fi eld devices and the fi eldbus
communication card goes down, now we have fi eld devices that might—or might not—be operating. � ey might continue to feed reaction materials to an out-of-control process reactor, and there is no way to know.
Consider that there is a reason very few people employ this technology.
In the next issue of Industrial Networking, I’ll take us through a look at the advantages and disadvantages of specifi c fi eldbus systems.
P. Hunter Vegas is senior project leader at industrial process control system integrator Avid Solutions (www.avidsolutions.com), based in Winston-Salem, N.C. Vegas and his colleagues have engineered and installed many fi eldbus systems in many diff erent industries. He spent a great deal of time interviewing engineers and technicians in end user fi rms. � is article is the result of that work.
A S I A PA C I F I C | A F R I C A | E U R O P E | M I D D L E E A S T | L AT I N A M E R I C A | N O R T H A M E R I C A
OPERATORS GENERALLY RECEIVE FAR TOO MANY ALARMS AS IT IS.
BURYING THEM WITH MORE ALARMS EVERY TIME AN INSTRUMENT
THINKS IT DETECTS A PROBLEM CAN BE COUNTERPRODUCTIVE.
CONSIDER THAT THERE
IS A REASON VERY FEW
PEOPLE EMPLOY THIS
TECHNOLOGY.
IN11Q1_18_21_Featr2.indd 21 1/27/11 1:00 PM
f i r s t b i t
Ian Verhappeniverhappen@
industrialautomationnetworks.com
industrial networking
Q1 • 201122
f i r s t b i tp a r i t y c h e c k
Last year this coLumn discussed different types of network topologies (www.industrialnetworking.net/topology). now let’s take a look at the impact of area classification on network selection.
area classification is predominantly a field/continuous process issue, although there are parts of a factory where it is also a consideration. if you use an explosion-proof enclosure as your method
of protection, then there are no limits on your equipment—except for parts such as antennas that extend outside the enclosure. you have to select the right enclosure, taking into consideration heating or heat dissipation for the electronics; select and properly install the appropriate seals; and implement the correct hot work practices and procedures. you then should be good to go.
on the other hand, if you want to be able to perform live work on your system, then a variety of options are available. Let’s start with fieldbus alternatives.
The original live-work alternative, intrinsic safety (is), relies on the entity concept, meaning all the components need to be considered as a single entity. unfortunately, in the case of fieldbuses with multiple drops on a single network, the number of components for which the concept needs to be verified expands exponentially (power supply connection to device a, power supply connection to device B, device a to device B, etc.). in addition, is has an approximately 80 ma current limit that severely limits the number of nodes/field devices.
as a result, most process fieldbus systems support the fieldbus intrinsically safe concept (Fisco). unlike is, Fisco is based on experimental measurements of the equipment placed in the hazardous gas environment, where the energy is increased until an explosion occurs. appropriate safety factors then are applied and the results submitted to the iec. The iec 60079-27 ed2.0 2008 standard describes the limitations and documentation requirements for these sorts of installations.
all Fisco installations follow the star/tree/chickenfoot configuration with a trunk and multiple spurs, although all the spurs need not be located at the far end of the trunk. you can have one barrier at 50% of the trunk length, another at 80%, and two others at the far end with the terminator
(remember, a trunk is defined by the terminators at either of its ends). Because Fisco is limited to outlet voltages of about 12–13 V and currents of 120–360 ma depending on the gas group for which it is designed, many Fisco systems can be used as repeaters to extend the network. repeaters normally are installed in series, but they can be installed in parallel to increase the number of devices connected to a single fieldbus interface port.
The third commonly used alternative is the high energy trunk (het), also known as the Fieldbus Barrier concept. het, as the name implies, uses much higher voltages and current levels than Fisco, but the trunk is not live workable because it is an ex ‘e’ classified installation. This higher voltage and current make fully loaded networks at long distances possible—the trade-off for not being able to do live work on the trunk and for having active electronics (transformers and is circuitry) in the barriers themselves. The barriers are mounted in the field, compared to the Fisco units that normally reside in the interface room, but they normally are designed for the field, so this shouldn’t be an issue. This year, the Fieldbus Foundation plans release of a specification for what they call active device couplers.
Because all the options provide both power and communications over the same cable, providing the same capabilities of power and signal via one cable becomes more desirable and common with ethernet products, as well via Power over ethernet (Poe), which has extra benefits in an industrial setting where cable installation costs are significant.
The majority of industrial ethernet suppliers provide one or more products with Poe capability, and a number of them supply the Poe intermediaries to inject power at other than the end device. in addition, there are options available for installations of ethernet in classified areas with intrinsically safe isolators. There is not yet a standard in place for is ethernet, so these products are not all interoperable.
ian Verhappen is an isa fellow, certified automation professional, recognized authority on industrial communications technologies, and principal at industrial automation networks. read his blog at www.controlglobal.com/kanduski.
unlike intrinsic
safety (is), fisco
is based on
experimental
measurements of the
eQuipment placed
in the hazardous
gas environment,
where the energy is
increased until an
explosion occurs.
Area Classification Matters
IN11Q1_22_ParityCheck.indd 22 1/27/11 1:01 PM
One fOr ManyEL67xx EtherCat master and slave terminals provide a direct interface to EtherCat I/O nodes for all Profibus (EL6731), DeviceNet (EL6752) and CANopen (EL6751) devices. The terminals channel each fieldbus signal type through the EtherCat protocol with full availability of the respective network’s features and functions. PCI cards in PCs are no longer required.Beckhoff Automation; 952/890-0000; www.beckhoffautomation.com
all in OneFL mGuard products provide stateful firewall, router and VPN functionalities in a single device in RS DIN rail-mount style for
industrial Ethernet and PCI card versions for integration into industrial computers. For applications that need a modem, but might later need to migrate to a VPN connection, it includes an optional integrated modem that can serve as a backup connection.
Phoenix Contact; 800/586-5525; www.phoenixcon.com/mguard
SiMplify SafetyENX AS-Interface Gateways support Modbus TCP and EtherNet/IP for communication with standard and safety networks in a single gateway with diagnostics retrieval. The gateways handle 992 I/O asynchronous to the Ethernet
traffic and scan every AS-i node in 150 µs, which enables up to 62 safety e-stops, magnetic switches, and safe outputs in one safety program. Pepperl+Fuchs; 330/486-0001; www.pepperl-fuchs.us
tap in tO prOtOcOlSnetTAP 100 has master and slave protocols for CANopen, DeviceNet, Profibus, CC-Link, EtherCat, EtherNet/IP, Modbus TCP, Powerlink,
Profinet, Sercos III, MB/RTU, MB ASCII RS-232, RS-422, and RS-485 for Real-Time I/O data exchange. The configuration software for the master is an enhanced version of Sycon.net, an FDT/DTM-based tool. Development tools allow third parties to develop custom protocol gateways using any of the stacks and
gateway applications to their own protocol.Hilscher North America; 630/505-5301; www.hilscher.com
can DO ethernetAnybus X-gateway CANopen enables transfer of I/O data between devices on EtherNet/IP and CANopen. The 24 V, standalone gateway mounts to a standard DIN rail and functions as a slave on EtherNet/IP network and as a master on the CANopen side. CANopen master functionality is configured with a Windows-based configuration tool, after which it passes up to 510 bytes of I/O data transparently. HMS Networks; 312/829-0601; www.anybus.com
The Number of NeTwork ProTocols Is NoT DecreasINg, NecessITaTINg gaTeways aND
aDaPTers ThaT caN helP DevIces commuNIcaTe wITh oNe aNoTher
adapting to change
IN OUR LATEST INDUSTRIAL EThERNET SURVEy, WE FOUND that our readers use a wide array of protocols. EtherNet/IP and Modbus TCP/IP figured most prominently at 70% and 62%, respectively; but standard Ethernet and Profinet were also high on the list at 28% and 21%. Add to those the currently lesser-used EtherCat, Foundation fieldbus hSE, Powerlink and Sercos III, and it’s no wonder users need devices that will help their various protocols communicate with one another.
Wireless protocols also should be figured into the mix. Of those surveyed, 37% planned to deploy wireless Ethernet within the next year, with usage expectations spread between 802.11b/g, 802.11n, WirelesshART, 802.11a, and proprietary protocols.
In a separate survey conducted this year about wireless networking, respondents told us that their wireless networks need to communicate with a wide range of Ethernet variants, plus Modbus, Profibus and Foundation fieldbus.
23INDusTrIal NeTworkINg
Q1 • 2011r e s e a r c h
IN11Q1_23_24_Research.indd 23 1/27/11 2:39 PM
IndustrIal networkIng
Q1 • 201124 r e s e a r c h
Gateway to ModbusEKI-1221D and EKI-1222D gateways provide transparent connectivity between Modbus serial devices and Ethernet-based
Modbus TCP equipment. They have built-in Ethernet switches for cascading/daisy-chain connectivity that offers flexible cabling. Cascading connections support Ethernet auto-bypass to prevent accidental power failure in the event one of the Modbus gateways unexpectedly shuts down.
Advantech Industrial Automation; 800/205-7940; www.advantech.com/ea
safety via GatewayBihl+Wiedemann Gen. 2 safety gateways integrate AS-i safety monitors and slaves, allowing two Safety at Work networks and up to 16 release circuits to be monitored through each gateway. Two independent AS-i networks can be powered by a single power supply, providing diagnostic data to the higher-level controller. The gateways are available for EtherNet/IP, Modbus TCP, Profinet, Profibus-DP and EtherCat.Turck; 800/544-7769; www.turck.us
etherNet/iP to df1MGate EIP3000 has one or two EtherNet/IP-to-DF1 ports for connecting DF1 devices and EtherNet/IP devices to A-B PLCs for remote maintenance. It uses ProCOM, which generates four extra virtual serial channels for Ethernet data pass-through and maximum network flexibility, without modifying
the existing system, and it supports two IPs—one for each serial port—so EtherNet/IP devices can communicate with two DF1 devices simultaneously.Moxa; 714/528-6777; www.moxa.com
dual Gateway750-352 ECO Ethernet Fieldbus Coupler carries dual Ethernet ports that function as gateways between Modbus TCP (or UDP) and EtherNet/IP. It can communicate simultaneously via Modbus TCP or EtherNet/IP out of both onboard Ethernet ports (10/100 Mbps) to serve different devices and minimize system components. It has an onboard DIP switch for IP address assignment and web-based management system.Wago; 800/din-rail; www.wago.us
CoNvert aNd iNteGrateXcenet Ethernet expansion card for Data Station Plus isolates machine-
level network traffic from the enterprise-level network for communication on separate networks. Supporting 10 simultaneous Ethernet protocols and three serial protocols, Data Station Plus and Modular Controllers provide protocol conversion and device integration. A second Ethernet port for communication increases bandwidth and allows communication on two
distinct Ethernet networks simultaneously.Red Lion Controls; 717/767-6511; www.redlion.net
Preserve the leGaCyEServ series for legacy serial communications in industrial environments aids the integration of legacy mission-critical components with newer network technologies by bridging the gap between older serial and contemporary Ethernet and Modbus Ethernet protocols. Connectivity options for 10/100Base-TX and multimode fiber applications are available in each series.N-Tron; 251/342-2164; www.n-tron.com
versatile ProIndustrialPro wireless gateway provides 3G or 2G cellular connectivity, one Ethernet port, one serial port and support for ac or dc power. It supports
IPSec or SSL VPN, port forwarding and support for network address translation (NAT), OSPF and RIP. It also offers a local web-based management interface managed by SixView Manager software.
Sixnet; 518/877-5173; www.sixnet.com
Cool hot sPotsRLXIB-IHxN series of 802.11n Industrial Hotspot radios provides plant-wide network integration and easy deployment in the field using a single web page setup. The radios use multiple input, multiple output (MIMO), which uses up to three antennas to enable data rates to 300 Mbps. The radios can operate in the 5 GHz band with 23 non-overlapping channels.ProSoft Technology; 661/716-5100; www.prosoft-technology.com
CoNvert to ProfibusPanda PUP-550 Profibus to RS-232/422/485 converter for Profibus-DP slave devices is equipped with Hybrid COM1 port design to easily choose one type of COM port to integrate serial devices into Profibus. Devices such as remote I/O, drives, motor starters, weighing and dosing systems, HMIs and energy systems can be connected.Ethernet Direct; +886/29235918; www.ethernetdirect.com
IN11Q1_23_24_Research.indd 24 1/27/11 2:39 PM
f i r s t b i t 25industrial networking
Q1 • 2011p r o d u c t s
AnAlog SignAl ConverterIO-Link analog plugs with 14-bit high resolution are for systems
with limited instances of analog signals. They have IP67 enclosure rating, a space-saving housing, are connected directly to the sensor, and convert the analog signals into IO-Link signals before transmission. They are available with 4-20 mA current input and output, voltage of 0-10 V or PT 100, and a voltage output of 0-10 V.Balluff; 859/727-2200; www.balluff.com
enCApSulAted ConneCtorS Homac multi-tap connector blocks and splices are encapsulated in PVC and accommodate cable sizes from 14 AWG to 750 kcmil in configurations of two to eight conductors. Made from high-conductivity aluminum alloy, they are dual-rated for aluminum or copper cable, pre-filled with oxide inhibitor, rated at 90 ºC/600 V, UL-listed, and meet or exceed ANSI C119.4 specifications.Thomas & Betts; 800/816-7809; www.tnb.com
CAn doCAN bus modules interface network sensors and actuators to high-performance control systems. IP560 Industry Pack ANSI/VITA-4 card plugs into VME, CompactPCI and PCI bus mezzanine
carrier cards or single-board computers in embedded systems. IOS-560 models are for use in Acromag’s I/O Server industrial PC. Both interface modules feature
two channels with optional isolation and an NXP SJA1000 CAN controller with a TJA1041 transceiver.Acromag; 248/295-0310; www.acromag.com
prepAred for HAzArdSJBBS junction bricks for AS-interface networks are FM-approved for Class I, Div 2, Groups A, B, C and D hazardous locations. They include options with four, six or eight short-circuit protected ports that can be shut off via integrated dip switches located under the cover. IP69K-rated JBBS junction bricks are available with M12 or 7/8-16UN connectors in stainless steel or nickel-plated brass.Turck; 800/544-7769; www.turck.us
2011 updAted CAtAlogThe 300-pg 2011 Industrial Electronics product catalog provides up-to-date information and specifications for line of signal conditioning, data acquisition, and data communication products and introduces the 6.2 mm slim-line DSCP family of signal converters and ReDAQ Shape software for the 8B isoLynx SLX300 data acquisition system.
Dataforth; 800/444-7644; www.dataforth.com
flexy CAbleSBelden Infinity C-TC+ and FCC cables with high-performance Belflex jackets have flexing capabilities, resistance to sunlight, oil and abrasion, and withstand temperature ranges of -40 to 90 ºC (cold impact) and -50 to 90 ºC (cold bend) for use in C-track systems, robots, automated assembly systems, material handling systems, multi-axis machine tools, wind turbines, etc. They are UL-approved for direct burial, suitable for Class I and II Div 2 hazardous locations, meet the requirements of NFPA 79 for industrial machinery, and are CE- and RoHS-compliant.Belden; 800/belden1; www.belden.com
extend tHe WireiCON-3344 with IP30-rated housing and M12 Ethernet connector can extend Ethernet connectivity over existing coaxial cable to 200 m at 85 Mbps and 2,600 m at 1 Mbps. It complies with IEEE 802.3/802.3u 10/100 Mbps Ethernet standard and supports full duplex transmission. The Ethernet port provides auto-MDIX and auto-negotiation. The extender is compliant with IEC
61000-6-2 EMC for industrial environments and has front-facing LED indicators for continuous status reports on network speed.Axiomtek; +886-2-29174550; www.axiomtek.com
dnp diSCoveryKepServerEX v.5.3 adds DNP3.0 Ethernet and DNP3.0 serial drivers to KepServerEX v5 Suite. Automatic device discovery for SNMP and Ping drivers lets KepServerEX scan a network, detect devices, and select devices and their associated tags for import. Enhancements to the DNP drivers include improved optimization for low-bandwidth and noisy communication channels, and diagnostic messages for better management of errors, alarms and general notifications. Kepware; 888/537-9273; www.kepware.com
IN11Q1_25_26_Products.indd 25 1/27/11 1:02 PM
It’s a LockHan-Yellock connectors with integral locking system incorporate a pushbutton technology. Pre-wired modules can be installed into the connector body from the front or back and without fixing screws. The ability to combine potentials and contacts is integrated into the connector, and it has a single gender crimp contact design that eliminates the need for inventory and processing of male and female contacts.Harting; 847/717-9289; www.harting.com
Push ItTerminal blocks with push-in technology (PIT) reduce insertion forces, are available in a 2.5 mm2 cross section, and accept 22 AWG and 14 AWG ferrules. An actuation button opens the spring to the maximum wiring space of 14 AWG, and the universal button is compatible with any type of tool, including a pen.Phoenix Contact; 717/944-1300; www.phoenixcontact.com
FLex ‘emSeries XM flexible control cable in 18 to 8 AWG, 600/1,000 V range for medium- to high-
flex applications has an oil-resistant construction, and shielded or unshielded versions for ranges of -30 to 90 °C (static) and -5 to 90 °C (dynamic). It meets NFPA Standard 79 for industrial machinery.Alpha Wire; 800/52-alpha; www.alphawire.com
Process aPPIndustrial Hotspot radios with Sweet William Automation’s ScadaMobile app for the iPhone/iPod platform can provide access to live process control variables, and the ability to modify the data from an iPhone. The application creates a secure wireless interface between an iPhone and an existing 802.11 wireless network to read Modbus TCP/IP and EtherNet/IP process control variables from PACs and PLCs.ProSoft Technology; 661/716-5100; www.prosoft-technology.com
comPact Is connectIonsUp to 16 fieldbus devices per segment can be connected to compact, intrinsically safe fieldbus barriers. The 8-channel barriers can be combined with various standard enclosures and cable glands; the IS clamps are detachable, and with an aluminium, stainless steel or GRP housing, the coupler can be installed on DIN rails. R. Stahl; +49 7942 /943 0; www.stahl.de
2626
a d i n d e x
Advertiser pAgeno.
automationdirect .................................................... 2
CC-Link Partner assn. ............................................10
GarrettCom ...............................................................15
Hilscher north america .......................................... 6
HMS industrial networks ....................................... 9
Moxa Technologies .................................................. 4
Omega engineering ................................................ 3
ProSoft Technology................................................21
Sealevel Systems.....................................................17
Transition networks...............................................28
ContACtus555 W. Pierce Rd., Suite 301, itasca, illinois 60143
630/467-1300 • Fax: 630/[email protected]
editoriAlteAm editor in Chief Joe Feeley executive editor Jim Montague Managing editor aaron Hand digital Managing editor Katherine Bonfante Senior Technical editor Walt Boyes Senior Technical editor dan Hebert Contributing editor John Rezabek Contributing editor ian Verhappen editorial assistant Lori Goldberg
design&produCtionteAm art director derek Chamberlain
publishingteAm Group Publisher/VP, Content Keith Larson ad Traffic Supervisor anetta Gauthier director of Circulation Jack Jones Group art director Steve Herner
subsCriptions888/644-1803
sAlesteAmnortheasternandmid-Atlanticregionalmanager
dave Fisher • [email protected] Cannon Forge dr., Foxboro, Massachusetts 02035
508/543-5172 • Fax: 508/543-3061
midwesternandsouthernregionalmanagerGreg Zamin • [email protected]
555 W. Pierce Rd., Suite 301, itasca, illinois 60143630/467-1300 • Fax: 630/467-1124
WesternregionalmanagerLaura Martinez • [email protected]
218 Virginia, Suite 4, el Segundo, California 90245310/607-0125 • Fax: 310/607-0168
insidesalesmanagerPolly dickson • [email protected]
630/467-1300 • Fax: 630/467-1124
reprintsFosterreprints
Jill Kaletha • [email protected]/879-9144 ext.168 • www.fosterprinting.com
induSTRiaL neTWORKinG
Q1 • 201126 P R O d u C T S
IN11Q1_25_26_Products.indd 26 1/27/11 1:03 PM
27
P. Hunter [email protected]
27IndustrIal networkIng
Q1 • 2011F I r s t B I t 27
IndustrIal networkIng
t e r m I n a t o r
Along with my fieldbus Articles in this magazine, i’m predicting future trends in the technology in this column.
we automation professionals in a plant environment are a cautious, conservative lot who are slow to adopt new technologies unless the benefits are concrete and the risks low. Therefore, these predictions might be a bit less rosy (but hopefully more accurate) than those espoused in
the glossy, color marketing brochures and the flashy articles written on the hottest technology du jour.
Fieldbuswhen foundation fieldbus and Profibus-PA first were introduced in the early 1990s, they were expected to revolutionize industrial control and render 4-20 mA instrumentation obsolete within a few short years. nearly 20 years later, fieldbus devices still make up a small fraction of the installed base and well fewer than 50% of new installations.
one of the reasons for slow adoption has been addressed. The major organizations finally are at work on a common standard with similar device files, etc. however, the rapidly increasing cost of fieldbus hardware and licensing software, especially for foundation fieldbus and Profibus-PA, is stifling future growth. The increases are not the result of manufacturing cost hikes, but mainly because people are willing to pay the difference and automation vendors are looking to capitalize.
At this point, fieldbus solutions equal or exceed the cost of traditional i/o and the touted savings simply are not there. hopefully, recent attempts to adopt a common device definition file and falling control chip costs should allow the vendors to create a single device that can operate on either foundation fieldbus or Profibus-PA systems. when that happens, competition should drive down fieldbus device costs significantly, and the rate of adoption will increase.
Wirelesswireless instrumentation will grow, but not nearly as fast as the current predictions suggest. fundamentally, wireless has value in tank farms and similar monitoring applications. but control over wireless for a process plant simply makes no economic sense. in a plant of any size, one outage
caused by lightning, radio interference or a failed battery will often pay for all the wire saved in the original installation. wire installation is a one-time cost, and when considered over the life of a 15-year instrument, it is a small part of the total lifecycle cost.
HigH-sPeed netWorksethernet will continue to grow, and i expect many of the current high-speed communication protocols
(Profibus-dP, controlnet, etc.) will migrate in some manner toward the ethernet hardware layer. some might argue about the need for determinism, but as the network speeds increase, the response is becoming so quick that the issue of deterministic data transfer is nearly moot.
Power over ethernet (Poe) is going to play an increasing role in automation and control. in the long run, i could see the low cost of switches and high-speed communications pushing the industry toward some kind of common high-speed field network with self-healing rings and power available straight off the network. field devices will be assigned addresses as they plug in and the control system will query the field device and pull up a configuration menu straight off the device—finally eliminating the needless pain of chasing down the latest gsd/eds/cff file.
All of these changes will happen slowly. with millions of 4-20 mA instruments in reliable, trusted and supportable service today, the risk of changing to the new technology will need to be more than offset by the benefits to the plant’s bottom line. As such, the industry as a whole will be in no hurry to migrate in a new direction. Plants will continue to try new technologies in small projects, and gradually will adopt those that offer intrinsic value and payback.
in the meantime, magazine articles will continue to be written hawking the latest trend and promising global acceptance “in a few short years.” i feel pretty certain about that last prediction.
P. hunter Vegas, Pe, is senior project leader at industrial process control system integrator Avid solutions (www.avidsolutions.com), based in winston-salem, n.c. Vegas and his colleagues have engineered and installed many fieldbus systems in many different industries.
Future Fieldbus Trendscontrol over
wIreless For a
process plant
sImply makes no
economIc sense.
In a plant oF any
sIze, one outage
caused By lIghtnIng,
radIo InterFerence
or a FaIled Battery
wIll oFten pay For
all the wIre saved
In the orIgInal
InstallatIon.
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C
M
Y
CM
MY
CY
CMY
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