PROCESS CONTROL

B Y JACKIE COX,ASSOCIATE EDITOR

FIELDBUS:A revolution in the

INDUSTRYIthas been demonstrated at tradeshows and discussed in professional publications. It's been de-

scribed as the next generation of industrialinstrument communication standards,and itsdevelopment has seemingly moved at asnail's pace.

It's Foundation fieldbus, the ability tobuild a process control system in the fieldcomposed of devices frommultiple vendorson a single twisted pair ofwires that are fullyinter-operable with one another.

And now thewait for commercially avail-able fieldbus products is over. In late July,John A. Pittman, president of the Austin,Texas-basedFieldbus Foun-dation, told Pa-permaker, "Weare at a key turn-ing point in thedevelopment ofFoundationfieldbus technol-ogy. We havecompleted thespecifications.The Found-ation's physicallayer is compli-ant with both theInstrument Soci-ety for Measure-ment and Control(ISA) and the In-ternational Electrotechnical Commission(lEC) specifications. Our data link layer andapplication layercomply with proposed ISAspecifications and both layers are now outfor vote by the national committees of thelEC. Communications software (the 'stack')is under test by the Fraunhofer Institute inKarlsruhe, Germany, and we expect to an-nounce byAugust 31 that several stacks have

passed the conformance test.Interoperability testing will begin inAugustand we plan to announce the availability ofa number of field devices by late August."

BEYOND BETAFor the pulp and paper industry, the

promise of fieldbus became a reality onJune S, 1997,when DaishowaAmerica Co.Ltd.'s PortAngeles, Wash.,mill installed an"unofficial" fieldbus system in its refinerbleachingoperations. It was "unofficial" be-cause the equipment had not yet passed theFieldbus Foundation's conformance andinteroperability tests.

Yee Tak Ngan, left, and Jason Mangano, process control engineers atDaishowa America's Port Angeles mill, show the wiring in the junction boxconnected to the fieldbus.

Pittman explained that the Foundationwill not register any devices until they con-form to all Foundation fieldbus specifi-cations as evidenced by successfully pass-ing both the conformance andinteroperability tests. A device with a com-munication stack that has passed the con-formance test and is registered with theFoundation will then be submitted for

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interoperability testing by the Foundation."This rigorous process ensures that end-users have plug and play capabilities," saysPittman, "which allows them to choose thebest device for that specific measurementor control action in their control systemregardless of manufacturer."

Still, Daishowa is the first mill in thepulp and paper industry to install anon-beta fieldbus system that demon-strates interoperability among vendorswith closed loop control in the field.Daishowa's suppliers are confident thattheir devices will pass the Foundation'stests as the tests become available.

Dan Dumdie, Daishowa's process engi-neering and control supervisor, explains thatNational Instruments inAustin, Texas, sup-plied theWindows-based software for sys-tem control configuration and operator in-terface, and the utility software including abus monitor for maintenance troubleshoot-ing and a fieldbus dialog system for diag-nostic work. National Instruments also pro-vided a personal computer (PC) card, giv-ing the PC access to the fieldbus.

Smar International Corp. in Houstonsupplied all the transmitters and redundantpower supplies; and Releom Inc. of ForestGrove, Ore., provided a power multiplexerfor redundancy,power conditioning, bus ter-mination and instrument termination.

Dumdie was quite candid about the factthat Daishowa had no desire to be the firstin the pulp and paper industry to installfieldbus. "We chose fieldbus because wewanted to be vendor independent and wewanted the best transmitter for our needs.And we chose to install fieldbus in ourgroundwood mechanical pulp mill's refinerbleaching operation because it was low riskand low cost. Wehad a fall-back position incase this new technology didn't performproperly."

PROCESS CONTROL

Amanually controlled bleaching systemwas in place prior to fieldbus, says JohnBoyd, utilities and mechanical pulping su-pervisor. "We had a peroxide skid that hadsome electronic controls, but we had to gooutside and manually adjust the chemicalpumps and dosages from the skid. Now thefieldbus system controls four chemicals andadjusts dosages to meet brightness specifi-cations," Boyd notes. Mill officials explainthat they do not use the peroxide bleachingsystem on a continuous basis, "and sincefieldbus is so new, this was a good way totrain our people on the technology withoutimpacting a critical area of our operations,"says Boyd.

If the mill didn't opt for the closed loopfieldbus system, it would have selected adistributed control system (DCS). Butfieldbus proved to be a major cost savings.

MAJOR COST BENEFITSFieldbus installation at Daishowa took

three months from system approval to op-erability, said Jason Mangano, process andcontrol engineer at the mill. "We collectedand read information on fieldbus starter kitsinAugust 1996,ordered the kits in Septem-ber, received them in October, and selectedvendors inNovember.Westarted theprojectin March 1997and brought the fieldbus online in June," he says.

The entire system is operated via amouse connected to an off-the-shelfPC, andall the data is in one control room, saysBoyd. Everything, including the PC, fieldtransmitters, valves, and power supplies, isconnected via one single pair of twistedwires.

"We realized a 55 percent cost savingsoverDCS in control hardware, software, en-gineering, installation and startup," saysDumdie, "and it is a much moreuser-friendly interface than what we wouldhave had with a DCS."

Don Holley, industrial automation mar-keting manager for National Instruments,notes that, with Foundation fieldbus, thereis a lot of opportunity to retrofit existingcontrol systems to enhance production ca-pabilities. Mills can use their existing wir-ing and upgrade components both in thefield and in the control room.

However, the real savings in wiringcomes in greenfield operations, notesMarjorie Ochsner, senior product definitionmanager for Honeywell IAC in Phoenix. "Itis easier to put in and optimize new wiringthan to change what is already in place,"she adds.

Fieldbus can also open the door for a

The transmitters are connected to spurs off these fiefdbus segments.

lot of smaller incremental projects thatmills previously found cost prohibitive,saysWade Stewart, fieldbus consultant forFisher-Rosemount Industry Solutions."For example, say a mill wants to replaceor add some valves and transmitters to aprocess area. Having to run new cables andjunction boxes for one or two items addsexpense. But with fieldbus, the mill sim-ply ties into the existing cable segmentsrather than running separate wires back tothe control room," Stewart notes.

Pittman remarks that "a great deal ofattention ispaid to the cost savings achievedbyhaving fewerwires, cable trays andjunc-tion boxes. Installations are done quickerand with fewermistakes because ofthe abil-ity of the devices to 'self identify' them-selves to the other devices on the network.However, more important is the fact thatmills now have the opportunity to get muchmore information about the instruments andtheir status than they could get with the con-ventional 4-20 milliamps (rna) system-such as whether the data is current or stale,the device's calibration status, serial num-ber, etc.Weare particularly intrigued by theprospect that manufacturers are going tobuild new capabilities into instruments andthat these capabilities will be easily avail-able to Foundation fieldbus users withoutretrofitting or modifying their system oreven taking the system off line to add thenew instrument."

Holley adds that, in today's regulatoryenvironment, companies are required togather more information about their pro-cesses and the instrumentation connected

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to the processes. "Traditionally," Holleysays, "4-20 rna analog instrumentationprovides only one value, the process value.On a digital network, instruments can pro-vide maintenance and diagnostics infor-mation for better tracking of instrumentperformance."

And this is real-time information, so ifa problem develops, such as a sticky valve,maintenance can take care of it before itdeteriorates into a costly and possibly un-safe situation, adds Paulo Garrone, gen-eral manager of Smar.

Another benefit of Foundation fieldbusis its ability to free up the mill's primaryDCS for more high level control. Fieldbusenables the new generation of smart fielddevices to communicate directly with eachother so that basic control loops can bepushed down and out into the field, saysH. Len Walton, marketing director forFisher-Rosemount.

"Finally, since Foundation fieldbusis an open communication system con-sisting of instrumentation with standardprotocols, devices from many supplierscan co-exist on the same network andcommunicate with one another, therebygiving the end user a choice of equip-ment and manufacturers," says Holley.

WIRING CONCERNSWhile fieldbus has so far performed

up to or better than expectations,Ochsner noted that it is still in its in-fancy, and people are playing it safe."Fieldbus is making its debut largely inpilot plants, in wastewater operations,

PROCESS CONTROL

and (as in the case of Daishowa) in ar-eas that are low risk to the overall manu-facturing process."

Some mills have raised the concernabout fieldbus' single twisted pair ofwires, or, under adverse condi-tions, the single point of failure.Where this is a concern, Waltonsuggests putting in redundantwires as a backup or running aconduit protected cable just asmills would with conventionalwiring.

Another issue that millsshould be aware of is product re-liability. As Dumdie says, "If de-vices don't have the FieldbusFoundation's registration markconfirming that they have passedall testing, then mills should thor-oughly test the equipment beforeinstalling it."

Ochsner brings up the fact that,as more experience is gained withfieldbus devices, more bugs will bediscovered and specifications maychange. "Be sure that your equip-ment vendor will support youthrough the whole fieldbus grow-ing process."

MOVING FORWARDFoundation fieldbus is grow-

ing, and with growth comes theneed for education and training."This is not the same technologyas DCS," says Pittman. "It is amajor shift, a major move for-ward, and end users must be thor-oughly educated and trained toget the most from fieldbus."

Dumdie and Mangano agree, statingthat, while Daishowa's operators have beentrained and are quite comfortable usingfieldbus, they would have opted for invest-ing more time in system training. "TheFieldbus Foundation,National Instruments,and Smar all contributed to our training onthe new system," says Mangano. "Most ofour engineers and instrumentmechanicshadeight hours of basic and eight hours of ad-vanced classes, and Dan Dumdie also tooka three-dayoutside course from the FieldbusFoundation that included their introductoryand advanced training class."

Pittman adds that the Fieldbus Foun-dation and ISA are coordinating efforts tobegin teaching on-site, one-day end userclasses on fieldbus technology.

"Over the next year," says Walton,"there will be a lot of fieldbus-based

education and a lot of opportunities forend users to take advantage of this edu-cation, to understand how fieldbus canimpact their conventional technologiesand processes. Equipment manufactur-

Transmitters connected to fieldbus using quick disconnectsreduce the time needed for installation.

ers will work toward training custom-ers in handling the complexities offieldbus installations."

Since full compliance Foundationfieldbus products first came on the marketonly this year, Ochsner sees fieldbus catch-ing on more in 1998. "Fieldbus has been along time coming," she says, "and next yearwe should see its installation starting in alot more critical process control loops."

Indeed, saysDumdie, "Wewill definitelyconsider fieldbus for all our future projects,and right now we are adding another closedloop to our current bleaching system so bythe end of the yearwewill have two fieldbussegments in operation."

In another application, said by Waltonto be the first commercial application ofproducts conforming to the FieldbusFoundation's final specification, a majorchemical company's plant in Fort

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Saskatchewan, Alberta, has been usingFoundation fieldbus-based architecture ona furnace application since last April.

Walton says that fieldbus technologyhas not only lowered this project's wiring

costs, but also significantly re-duced the amount of time and ef-fort needed for installing, commis-sioning and starting up the system."Instead of spending weeks string-ing wires to every device, ringingout every connection, configuringeach device in the field and track-ing down problems," explains amember of the project team, "wejust plugged everything together,verified device status from a PCin the control room, and down-loaded configurations from thesame PC. Everything worked as itwas supposed to--and startup tookonly 15man-hours instead of200."

Interest in fieldbus is by nomeans limited to North America."Fieldbus is being looked at notonly in Europe and the PacificRim, but there is a lot of activityin Latin America as well," saysOchsner.

"A lot of benefits are going tobe realized by people in greenfieldoperations because they can opti-mize the wiring and not worryabout any need for retrofittingequipment," she explains. "Andmost of the greenfield mills are inLatin America and Asia. Whilenothing has been implemented yet,there are a lot of requests for test-ing in these regions."

Holley noted several pilot installationsgoing on in power generation facilities inJapan and Europe, and Pittman says thateven though Europe has its own fieldbusprotocol from Germany (Profibus), endusers there are and will continue evaluat-ing the benefits and advantages of Foun-dation fieldbus technology. "Profibus wasdeveloped by a single company, not by agroup of 120 global member companiesoffering ideas and solutions as the Foun-dation fieldbus protocol was," saysPittman.

The Fieldbus Foundation already hasabout 40 members in Europe and anequal number in the Pacific Rim. "Weare at the early stages of putting a newand powerful tool in users' hands," saysPittman. "Fieldbus is one of the mostexciting things that has happened to pro-cess automation." ~