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Automatisierungs-technische Praxis
2004
SPECIAL EDITION
Three ways to automation solutionsmatched to users’ needs
Foreword
In the discussion on innovati-ons in process automation, theterms Fieldbus and Remote I/Oand the related achievablecosts savings, simplificationsand the information obtainedare constantly the focus of re-
porting. The characteristics ofthese installation concepts andcommunication concepts arediscussed and wide-ranging vi-sions developed. The real soluti-ons implemented are however,
weighted by application areaand “outlook”, always in the con-text of all the technologies cur-rently available. Only a com-mon approach in mechanicalengineering, electrical enginee-ring and modern informationtechnology will permit furtherinnovative steps to be taken.
During the discussion on the introduction of fieldbustechnologies, it is therefore necessary to give greater consideration to three aspects:
a) The frequently quotedexample of factory automa-tion with its rapid accep-tance of fieldbus technolo-gy cannot be transferred di-rectly to process automati-on. The reasons for this si-tuation are the very diffe-rent characteristics of thesetwo application areas, seeTable 1.
b) Along with the two “new”communication concepts al-ready mentioned, fieldbusand Remote I/O, the “classic”4–20 mA signal in conjuncti-on with the point-to-pointconnection is in practice by
far the most frequently applied standard for thetasks in process automation.This situation is predomi-nantly due to very long ser-vice life of process plant(15–20 years) compared tothat in factory automation,and the intensive standardi-zation efforts undertaken bythe German chemical in-dustry. Today 4–20 mA tech-nology has been proven mil-lions of times over inworldwide use.
c) The three communicationconcepts have a technologi-cally and commercially justi-fiable right to co-existence.The times of technologicalpreferences are over; cost-effectiveness alone definesthe use of the technologies.On this topic see Figure 2,which shows the three con-cepts as segments of a port-folio with the axes Costreduction and Informationobtained. However, this isonly a snapshot as theboundary conditions for au-tomation projects are verycomplex and it is only rarelythat one project can be di-rectly compared with ano-ther. In an illustration withvariables such as “System-compliant expansion of oldplants” or “Limited require-ments on the maintenancepersonnel”, for example, the4–20 mA segment wouldhave a stronger position andthe fieldbus segment a wea-ker position.
Three ways to automation solutions matched to users’ needs
Table 1. Reasons for the varying acceptance of fieldbus in factory and process automation.
Factory Automation Process Automation
The service life of the plant is limited and similar to The service life of the plant is 15–20 years and morethe cycles for information technology and thus much longer than the IT cycles
No specific standard signals available The 4–20 mA standard signal has been and continuesto be familiar and used worldwide
The size of the investment and thus the significance The size of the investment and thus the significance ofof protection of investment per plant is limited protection of investment per plant is high
Explosion protection tasks have no high priority Explosion protection tasks as well as availability andsafety of the plant are very important due to the possible consequences and result in conservativebehavior on the part of the operating organizations [2]
For signal transmission, speed plays the Speed does not play a dominant role on signaldominant role transmission
Consequence ConsequenceRapid and complete acceptance Hesitant and step-by-step acceptanceof fieldbus technology of fieldbus technology
Step 1: Retention of 4–20 mA technology,possibly with use of HART technology
Step 2: Combination of 4–20 mA technologyand fieldbus via RIO technology
Step 3: Use of fieldbus technology
Figure 2: Communi-cation concepts forprocess automationwith related pro-duct lines from aninterface manufac-turer. The user defi-nes the technologyfor the signal pro-cessing.
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Figure 1: Modern communication concepts for process automationwith related product lines (example Pepperl+Fuchs GmbH). The userdefines positioning and technology for the signal processing.
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The K-System – the firewall for analog signals
Table 2. Product lines for point-to-point connections(Pepperl + Fuchs).
“Point-to-point” interface technologyE-System K-System HiD2000 System
Interface modules Interface modules Interface modulesas Eurocards in as compact modules as plug-in modules
19’’ racks on rails on the motherboard
Suitable for Ex i
HART communication
SIL categorization as per IEC 61508
PACTwareTM Graphic User Interface (GUI)
Design preferred by Extremely versatile, Optimized forthe chemical industry highly veriable connection to control
for many years systems
For the user, innovations areboth necessary and required toremain competitive, but basedon the motto Everything ingood time and within the bo-unds of the feasible, the usershould be given the opportuni-ty to realize innovations for hisplant's systems based on hisspecific situation and expectati-ons (timing, concept and re-sources). For the user, technolo-gy segmentation is a good de-cision aid.
For an equipment manufac-turer, the segmentation is achallenge and a burden at thesame time! On the one handthe manufacturer must satisfy,with his developments, the re-quirement of some users in thefieldbus segment for digitaliza-tion and obtaining information
so that manufacturer can secu-re competitive advantage. Onthe other hand the manufactu-rer is under pressure not to ig-nore the already establishedsegments and the customergroups in them. This situationresults in an increase in thenumber of device variants withthe concomitant developmenteffort and costs. The balancingact is made more difficult bythe fact that fieldbus technolo-gy, despite its standardizationin IEC 61158, does not comprisea single standard. There are cur-rently no less than 18 fieldbussystems [1] listed as covered byIEC 61158.
As a result the equipmentmanufacturers have varyingproduct presences in the seg-ments and the one or the
other equipment manufactu-rer will not cover all segmentsfor commercial or technical re-asons.
As a market leader and spe-cialist for interface technology,Pepperl+Fuchs has the clearobjective of serving and sup-porting all three segmentsequally with highly innovativeproduct lines, and also creatingtransitions between the seg-ment technologies (see illustra-tion in Figure 1). In this way theuser can, like on a roundabout,“turn off” into one of the seg-ments without hindrance whenthe user considers the changeopportune. This situation helpsachieve the best possible pay-back periods for both new in-vestments and investments al-ready made.
In this three-part article,the three segments and theirrelated concepts, technologiesand properties are discussed,the possible methods of tran-sition between the segmentsexplained and examples ofcurrent equipment technolo-gy given. It is the authors' ob-jective to assist users in ma-king decisions about how, un-der specific boundary conditi-ons, an existing plant can bemodernized or extended, or anew plant can be optimallyautomated.
In this respect the reader isalso referred to FuRIOS Studyby Infraserv GmbH [3], which isclosely related to this series ofarticles. Extracts from this studycan be requested from the au-thors of this article.
The most frequently used com-munication method in processautomation is still analog trans-mission with its focus on the4–20 mA current signal.
The classic plant structurehas now been derived from this technology for more than30 years: sensors and actuatorsin the field, control system andsignal conditioning using inter-face assemblies in the controlroom and in between the di-rect point-to-point connectionswith their distributors and con-trol cabinets.
Worldwide acceptance anduse
Over 30 million field devices,that is approx. 75 % of the volu-me installed worldwide, todayutilize the 4–20 mA current sig-nal (with or without additionalHART functionality). This tech-nology represents not only thecurrent standard in process au-tomation, but at the same timemakes it clear that it will conti-nue to retain this status forconsiderable time to come. Asomewhat unusual finding in
the age of aggressively marke-ted and rapidly adopted field-bus technology. This strong po-sition can be traced back to thefollowing reasons, amongothers:� As early as the 60’s the che-
mical industry pushedextensively for the introduc-tion and for the nationaland international accep-tance of this standard.
� Due to the high service lifeexpectancy of process plant,this standard is to be foundin all plants set up in recentdecades. In this period ofcontinuity, unachievable formodern technologies, the
4–20 mA analogue signalhas become established andproven as a fixed constant inplant planning.
� With HART technology, the4–20 mA analog signal hasobtained its modern linkupto the world of digital datatransmission. This linkup isprovided without changeto the existing plant con-cepts and with the reten-tion of the existing cableroutes.
Finding the right way
Today, 4–20 mA technology(point to point K-System in Fi-
Classic signal transmission is performed using 4–20 mA analogue sig-nals and “point-to-point connections”. This technology impresseswith its signal integrity, its resilience and its worldwide acceptance.(Example Pepperl +Fuchs).
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gure 2) has features that, givencorresponding boundary conditi-ons for the automation task inhand, render the new or conti-nued use of this technologynot only appropriate for theuser, but also attractive. “Field-bus may be in, but the 4–20 mAsignal remains very resilient”, onthis basis every user should, aspart of his decision analysis,identify the most cost-effectiveand efficient solution depen-ding on the task, size of theplant, costs, opportunity formaintenance, plant reliability,payback period and similar cri-teria.
For the new construction oflarger plant with flexible pro-cesses, in future a completefieldbus installation will veryprobably be the first choice.Batch plants with their chan-ging recipes and processes arejust one example of many. Thetechnology of the point-to-point connection will, however,also continue to be consideredfor new plant as soon as theplant have fixed processes andthe focus is on long paybackperiods defined by cost-effecti-veness.
In the following we wouldlike, together with the articleson the segment “point to busRemote I/O – the gateway tothe fieldbus” and the segment“bus to bus FieldConnexTM –power for the fieldbus” to support the user during such a decision process.
The 4–20 mA plus points ata glance
� The 4-20 mA interface is inuse worldwide and is to befound on nearly all fielddevices from any manufac-turer.
� The 4–20 mA signal is pre-sent continuously and theinformation (= the measu-red value to be transmit-ted) thus has high availabi-lity.
� Installation and mainte-nance require neither newtools nor special skills.
� The separately wired meas-uring circuits with their fewcomponents are easilyunderstandable and easethe proof of intrinsic safety.
� Additional information istransmitted with the aid ofthe HART concept.
� Up to 400 mW can be sup-plied to the field devices in ahazardous area with intrinsicsafety.
� Modern interface modulesprovide the user a variety ofmonitoring and evaluationfunctions that can be usedto significantly increase per-formance. These modulesare much more than justconnection modules.
Simple technology incre-ases plant safety
Plant safety is always a key issue, not least due to the esta-blishment of the internationalstandards IEC 61508 andIEC 61511 in large parts of theworld.
On the aspect of relevanceto safety, the transmission andevaluation of signals using con-ventional interface modules isin some areas superior to bustechnology. One reason is theintegrity of the signals withpoint-to-point wiring. The wi-ring is very reliable and hashigh availability. Moreover, theuse of devices that are as sim-ple as possible and the relatedsimple transmission of the sig-nals are of particularly high re-levance to safety considerati-ons. The failure behavior of
such devices is stable and kno-wn, unlike the behavior of morecomplex devices. Conventionalmodules such as analog trans-mitters, electrical isolators orisolating amplifiers often donot require software and thusavoid the recurring subject ofsoftware updates with their re-levance to safety and their vali-dation.
“Firewall” against inter-ference
The integrity and the availabili-ty of all signal levels is an impe-rative requirement for the effi-
ciency of the plant, and also forthe plant safety. No signal is al-lowed to affect and/or changethe measured values from ano-ther measuring circuit due to awire-break or a short-circuit, asimportant process variablessuch as product quantities,quality features, costing varia-bles and similar are derivedfrom the measured signals. The4–20 mA signal meets this re-quirement provided moderninterface modules are used forits transmission, modules thatprotect against signal loss andat the same time monitor allmeasuring circuits in the field.
Figure 3: Screenshot from the Graphic User Interface PACTwareTM.
to the Field
to the control system
Power
Fault
warning
signal
24 V DC
Centralised fault
indication
24 VDCredundant
Figure 4: The modular K-System with rail mounting.
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Thus, e.g., the electrical isolati-on of the measured signals isthe best means to reliably pre-vent from impairing the electri-cal isolation within complexplants and for signal sources ofunknown origin. High-quality,non-interacting isolating mo-dules ensure maximum immu-nity to interference here andthus provide a sort of “firewall”functionality for conventionalautomation technology, similarto the firewalls familiar from IT.
4–20 mA: intelligent due toHART
HART (“Highway AddressableRemote Transducer”) is a vari-ant of the digital field commu-nication that already containsmuch of the functionality offieldbus technology. The undis-puted advantage is that theclassic 4–20 mA technologywith the infrastructure of thepoint-to-point connection isused for the signal transportwithout change. Here a digitalsignal is modulated onto theanalog signal using the FSK(Frequency Shift Keying) me-thod. This digital signal trans-mits information on, e.g. valuesfor limits or diagnostics toge-ther with the measured value,without affecting the analogfunctionality. In addition, usingthe HART protocol it is alsopossible to integrate the fielddevices in engineering tools ormaster systems. The communi-cation with the HART device isperformed over the existingcabling, an invaluable advanta-ge on the modernization ofexisting plants.
The online communicationbetween process control sy-stem/PC and the field devicesthat support HART is perfor-med using HART multiplexers.Here information such as me-asuring range, calibration sta-
te and status, tag number, ma-nufacturer's ID, etc. cannotonly be read from the intelli-gent field devices, but alsochanged and saved again inthe device. HART multiplexersare located in the measuringroom (or in the switch room)and are connected in parallelwith the 4–20 mA wiring the-re. Due to the modern designof the multiplexers, bi-direc-tional links to up to 7936 fielddevices (maximum configura-tion) can be established in ex-pansion steps of 16 or 32using one RS 485 connection.
Interface modules, morethan just connections
The interface modules availabletoday feature both wide-ran-ging coverage of the applicati-ons and compliance with therelated plant concepts.
An example of the conside-ration of different plant conceptsis shown in Table 2. Here the re-quirements of the “point-to-point” segment are excellentlycovered with three product li-nes. The upgrading of oldplants is considered, as are thedemands for the latest techno-logy. Both Eurocards and com-pact modules on rails (the K-System) or the motherboardvariant (the HiD2000 system)are available. Many compo-nents in these three systems,with their mechanical diffe-rences, comply with current re-quirements in relation to IEC61508 (characteristics for riskreduction, Safety Integrity Le-vel, SIL), in relation to the explo-sion protection method Ex-i (in-trinsic safety) in accordancewith ATEX and provide digitalcommunication via HART. Mo-reover, they can be operated ina uniform manner using thePACTwareTM software appli-cation (Figure 3).
Some examples from the K-System (Figure 4) demonstratethe versatility and practicalityof the design of current inter-face technology:� Due to the latest microcon-
troller technology, manydevices are multifunctional.This feature reduces thewiring effort and the controlcabinet space.
� The uniform and self-expla-natory menu layout easesmanual adjustment, the gra-phic display indicates alldevice settings both on ini-tial commissioning and onmaking changes to parame-ters. In addition, the majorityof devices have a serialinterface for setting parame-ters using a PC.
� Speed sensors monitor rota-tional speeds or frequenciesand at the same time signala wire-break or short-circuiton the signal wires. Relaysare available to monitor thelimits; the relays can be usedas either MIN or MAX con-tacts. A further input is usedfor startup bridging. Usingthis input shutdown functi-ons can be cleared and tem-porarily bypassed.
� Frequency-current conver-ters monitor, along withtheir task as measurementtransducers, also the inputfrequencies for limits andsignal when limits are rea-ched using a relay contact.
� Transmitter power feeddevices can, along with theirpower feed function, alsoevaluate 0/4…20 mA sensorsignals. Active sources, 2 and3-wire transmitters can beconnected to the inputs.Analog current outputs andlimit relays are available asoutputs.
� Valve control modules sup-ply power to solenoid val-ves. Here the current con-
sumption of the field circuitis monitored for a wire-break or short-circuit andthe status signaled to thecontrol system. At the sametime, on the input side theuser has various means ofaccess for choosing bet-ween “manual” and “automa-tic”.
� Isolated switch amplifiersuse the 2:1 method to trans-mit two binary signals overone pair of wires. Thismethod reduces the fieldwiring by 50 % and makessubsequent extensions tothe system possible despitecables without any spare co-res.
� Almost 80 % of the interfacemodules in the K-Systemprovide modern safety tech-nology in accordance withthe international aspects ofIEC 61508/IEC 61511 – in thelow cost device standard.
Conclusion
“Point-to-point” remains topicalnot only due to the number ofplants instrumented and opera-ted using this technology, butalso because it is technological-ly justified for certain planttasks. Modern interface modu-les are to be thanked for thissuccess; these modules notonly amplify, convert, isolate orlimit the signals, but also un-dertake monitoring functionsand communicate with the hig-her-level control system.For setting up large new plantswith a free choice of topologyand transmission technology,the alternatives of Remote I/Oor fieldbus could be the moreappropriate solution. Thesetechnologies and the possiblemethods of transition betweenthe individual technologies willbe covered in two further arti-cles.
tinue to be transmitted as analog signals. The field signalsare then digitized in the remoteI/O.
Remote I/O systems can beinstalled in the safe area in acontrol cabinet or on-site inthe field in a distribution box.For applications in the chemi-cal industry, on-site installati-on often means areas withzone 1 or 2 potentially explo-sive atmospheres. The signalcircuits in the RIOs are predo-minantly designed in the pro-tection method intrinsicallysafe (Ex i) and are thereforecompletely suitable for hazar-
dous areas. With the characte-ristic of decentralized installa-tion in the field, RIOs bring thefieldbus to the field level wi-thout changing the conven-tional field devices and theirconnector technology! Usingthe RIOs the analog signalsare obtained far out in thefield, digitized at an early sta-ge and then fed to the pro-cess master system over a buspath. This configuration is ad-vantageous both for the planttopology (installation of thedistributors near the field de-vices) and on the costs sidefor the wiring.
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Introduction
Unlike factory automation, in-novations in process automati-on take place at a measuredpace and in steps. The reasonsfor this situation are the longservice life and the large invest-ment required for processplants, which prevent short-term changes to the plant onthe occurrence of a technologi-cal advance. The pronouncedsafety requirements of the sec-tor also act against rapid chan-ge. Don't reject the proven overhastily and introduce the newcautiously: this is the principleused in process technology tosuccessfully address the pressu-re for increased efficiency in re-cent years. Particularly in thecommunication between fielddevices and master system, mi-gration models between con-ventional and new technologyhave not only grown but alsolastingly proven themselves.“Remote I/O” is the term for theconcept that connects the clas-sic 4–20 mA technology withthe new fieldbus technology.
However, in the meantime ithas become clear that RemoteI/O is more than just a prelimi-nary stage on the way to field-bus technology. Along with, onthe one hand, the proven andtechnically unchanged 4–20 mAtechnology employed and, onthe other hand, the innovativefieldbus technology, RemoteI/O is today a third indepen-dent segment that can repre-
sent the best solution for manyapplications with certain boun-dary conditions. Here the sizeand the expected life of theplant play just as much a roleas the physical situation or the“proven in use” that is so im-portant in many cases.
Purpose and expectations
Remote I/O as fieldbus node
In conventional technologywith the widespread use of the4–20 mA signal, the field devi-ces in a plant are individuallywired to the control system orthe master system based onthe principle of the point-to-point connection with isolatingcabinets and terminal blocksinserted in between. This confi-guration requires both wiringeffort and space, however forcertain tasks it is also certainlyadvantageous and offers inte-resting characteristics.
Remote I/O (RIO) are circuitsthat retain the 4–20 mA devicesand their individual connectionwithout any change in the field,but replace the complex indivi-dual wiring to the control sidewith a single bus connection.RIOs are thus bus nodes for afieldbus system with all the rela-ted advantages and possibili-ties. Technologically, however,there is a major difference tofieldbus: the field signals are nottransmitted to the remote I/Osystem purely digitally, but con-
I/O modules
Fieldbusmodule (Gateway)
Power feed module
Space for expansions
DIN-Rail
Power Rail for supply andbus communication
Interface for setting parameters
Figure 5: Modular structure of a Remote I/O system based on theexample of RPI.
Field wiring canbe further used
Experiences canbe further used
Low-costdevices
Devices remainunchanged
Operation usingFDT/DTM
Integration inPROFIBUS
Central deviceaccess
Only one cableto the PLC
Co
nve
nti
on
al 4
-20
mA
tech
no
log
y
Fieldb
us tech
no
log
y
Hot SwappingGateway Technology
Hot SwappingGateway Technology
Volle Nutzungvon HART
Full utilizationof HART
Special developments for RIO
Remote IOtechnology
Figure 6: Attractive technology mix for remote I/O.
Remote I/O, more than a gateway to the fieldbus
Modern communication concepts for process automation with rela-ted product lines, in this case remote I/O.The user defines positioningand technology for the signal processing.
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The expectations of the user
With increasingly widespreaduse of the RIO concept, specificuser expectations have arisenthat change to suit ongoingtechnical development. This si-tuation speaks for the high le-vel of acceptance of the RIOtechnology among users.What the user expects from aRemote I/O system:� Modular structure as fle-
xible as possible for adapta-tion to the characteristics ofthe plant and type of field-bus
� Wide range of solutions forsignal conversion, fieldbusinterface (gateway), redun-dancy, transmission charac-teristics, auxiliary powersupply, etc.
� Interaction-free replace-ment/addition of compo-nents during operation
� Electrical isolation betweenthe field circuits as well asbetween fieldbus and auxili-ary power
� Use also in potentiallyexplosive atmospheres and
processing of intrinsicallysafe signals as well as sig-nals with increased safety
� Availability of communica-tion with the devices for set-ting parameters and confi-guration in parallel with thesignal transfer, if possiblefrom a central point
� Monitoring facility for wire-break, short-circuit and fielddevice failure
� Full utilization of HART com-munication
Numerous manufacturershave taken up this wish list andoffer corresponding products.Pepperl+Fuchs as a specialist forinterface technology complete-ly addresses the requirementsof the market with its RemoteI/O systems RPI and IS-RPI.
Modular structure
Remote I/O systems are as arule of highly modular structu-re and, depending on the I/Omodule used, provide connecti-ons for up to 8 analog field de-
vices and actuators and up to16 binary senors. Several mo-dules form an “RIO Station”,which in the majority of caseshas a fieldbus module (gate-way) with a dedicated fieldbusconnection and thus representsa fieldbus node. Several stati-ons can be combined to forman “RIO System” with furtherdistribution across the plant.The range of modules available(differentiation by functions) isvery large and also meets spe-cial user requirements, see Fi-gure 7.
RIO with attractive technology mix
Attractive key position
RIO technology profits signifi-cantly from its central positionbetween conventional tech-nology and fieldbus, see Figu-re 6. It adopts characteristicsfrom both 4–20 mA technolo-gy and from fieldbus techno-logy and is becoming evenmore powerful due to manu-
facturer developments especi-ally for RIO.
Gain due to conventional 4–20 mA technology RIO benefitsfrom� The unchanged field instal-
lation comprising devicesand their point-to-pointconnections to the RemoteI/O,
� The continued use of low-cost 4-20 mA devices
� The continued use of theexisting know-how, e.g.during commissioning,maintenance and service.
Gain due to fieldbus technologyRIO provides� Low-cost and space-saving
wiring from the Remote I/Oto the control room
� The possibility of centralaccess to all devices, e.g.from a maintenance system
� Depending on the interfacemanufacturer, operationusing the advancedFDT/DTM concept
Gain due to special develop-ments available for RIO are� Extensive diagnostics featu-
res due to access to the fullHART functionality of thefield devices using the inte-grated HART multiplexertechnology
� Dedicated, channel-specificdiagnostics informationfrom the RIO modules(limits, short-circuit, wire-break, …)
� The possibility of the non-interacting replacement ofcomponents during opera-tion (“hot swapping”)
� Flexibility for adaptation todifferent fieldbus systemsusing “gateway technology”
� The facility for full integra-tion in PROFIBUS using the“RIO for PA” and “HART onPROFIBUS” profiles.
The central position alsocontributes to the simple and“seamless” design of the transi-tion from conventional techno-logy to fieldbus technology onupgrades, extensions or moder-nizations of plants:
At stage 1 the 4–20 mA fielddevices in a conventional sys-tem are interfaced to an exis-ting or newly installed fieldbus
Isolation switch amplifier Transmission of digital input signals from thehazardous area to the safe area
Frequency converter
Transmission of frequencies of digital input signalsfrom VORTEX sensors, magnetic transducers andproximity sensors from the hazardous areaincluding signal processing (frequency meter,flowmeter, rev counter, standstill monitor...)
Valve control moduleSupply and triggering of valves and positioncontrollers in the hazardous area, bi-directional HART communication
Transmitter power feed devicePower feed to 2 and 3-wire transmitters in thehazardous area, transmission of the analogsignals, bi-directional HART communication
Temperature transducer Signal transmission from resistance temperaturesensors, thermocouples and mV signals
Transducer Power feed to transmitters and transmission ofanalog measured values
Output isolating transformer Transmission of current signals to the hazardous area
Gateway PROFIBUS DPConnection of conventional binary or analogsensors to the automation device over PROFIBUS DP
Gateway PROFIBUS PAConnection of conventional binary or analogsensors to the automation device over PROFIBUS PA
Gateway MODBUS Connection of conventional binary or analogsensors to the automation device over MODBUS
Gateway MODBUS/Ethernet Connection of conventional binary or analogsensors to the automation device over MODBUSusing Ethernet transmission technology
Gateway ControlNet Connection of conventional binary or analogsensors to the automation device over ControlNet
Module racks, power rail bus, redundant powerfeed modules, power supplies, bus couplers,segment couplers, etc.
System accessories
I/O modules
Gateways
Module Function
Figure 7: Typical module range for an RIO system (example Pepperl+Fuchs).
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system using RIO systemsmounted near the applicationin compact switch boxes (Figu-re 8). In this way it is alreadypossible to realize a large porti-on of the potential for reducingcosts from simpler wiring andless switching. In addition, withthe aid of the HART technologyit is also possible to collect di-agnostics information on thefield devices from a centralpoint and to set parameters.
At stage 2, if necessary, the4–20 mA devices are replacedby fieldbus devices and the de-vices connected to the bus.Field devices that are only avai-lable in 4–20 mA versions forreasons related to the manufac-turer, can continue to be opera-ted on the fieldbus without li-mitations using the existingRIO systems.
HART, only fully exploited byRIO
HART (Highway AddressableRemote Transducer) is a variantof the digital field communica-tion that has been familiar forsome time and that has beco-me the industry standard. It al-ready includes much of thefunctionality of fieldbus tech-nology, it differs however, inthat the analog measured sig-nal is used for the transport ofthe digital information. For thispurpose the measured signal ismodulated with a further sig-nal. The two different frequen-cies of this signal, 1.2 kHz and2.2 kHz represent the bit con-tents 1 and 0. In this way addi-tional information can be trans-mitted without affecting theanalog signal and using theexisting wiring. This informati-on can originate from the fielddevice and be destined for theprocess management systemor maintenance (limits, diag-nostics data, information onmanufacturer, device identifica-tion, measuring ranges, tagnumber, among others), howe-ver it is also possible to writeinformation – acyclically – tothe field device, for instance forsetting parameters or configu-ration.
The HART protocol is a stan-dard feature in the current ge-neration of 4–20 mA devicesand is therefore potentially
available in all newer plants.The HART information can beutilized with either the classicaccess via hand-held terminalson-site at the devices or viaHART multiplexers.
HART multiplexers are usedto tap the digital HART infor-mation. HART multiplexers areconnected to the 4-20 mA wi-ring and thus form an underly-ing, independent service layerthat can be used to collect digi-tal information including theprocess value (this value is alsoavailable in digital form) trans-mit the information digitally tothe process master system oran operating tool. The analogsignal transmission and theprocessing of the measured va-lue by the PLC are not affectedin any way!
The HART multiplex systemsHIS, MUX 2700 and KFD2-HMM16 manufactured by Pep-perl+Fuchs make it possible todigitally access configurationand diagnostics data from upto 7,936 HART field deviceswith the aid of software packa-ges such as PACTwareTM. Themultiplexers are connected tothe automation device via anRS485 interface.
The functionality of theHART multiplexers is integratedin the Pepperl+Fuchs remoteI/O systems RPI and IS-RPI andmakes it possible to utilize thecomplete range of functions ofthe HART technology.
By means of the digital andparallel transmission of theHART information for severaldevices, faster processing of theHART information is achieved.Process values can now also becyclically transmitted “purely di-gitally” more quickly usingHART, and therefore also usedfor control tasks.
Integration in fieldbus systems (PROFIBUS)
Remote I/O are nodes in a field-bus system and devices on afieldbus system are typicallycharacterized by uniform beha-vior independent of manufac-turer (device model, operatingconcept). It is thus understand-able that with increasingly wi-despread use, the market is alsorequiring such standardizationalso for RIO devices. PROFIBUS
has addressed this desire anddeveloped an Application Profi-le “RIO for PA” (PROCESS AUTO-MATION) that, following therealization of this profile in thedevices, will result in the devi-ces behaving the same for im-portant functions and thereforemake the devices interchange-able to a certain degree.
The profile takes into ac-count both the detailed mo-dular structure of the RIOsand also the pressure for in-novation that requires roomfor maneuver for the manu-facturers in the related de-signs. A basic profile has beenspecified that concentrates ondefinitions for interchangeabi-lity in relation to standardterms for parameters with thesame semantics.
The device model is basedon an RIO structure comprisingheader station and moduleswith varying functionality that
realize the actual channels forthe connection of the field de-vices. Here a channel is consi-dered a logical component,which provides an input valuefor the cyclic communicationover the PROFIBUS MS0 chan-nel and accepts an output va-lue from there. A key aspect ofthe profile is the definition ofuniform data formats for the in-put and output values for thechannels.
For the integration of thedifferent RIO devices in thefield bus system, standard func-tions, e.g., for identification ormaintenance, have a high prio-rity. The definitions made forthis purpose have been mat-ched with other PROFIBUS pro-files and contain both informa-tion to be defined both by themanufacturer during device de-velopment and by the user du-ring device operation (datasets).
Figure 8: IS-RPI in the switch cabinet.
KFD0-HMS-16 KFD0-HMS-16
KFD2-EB2
4 AT
789 10 1112 13 14 15
1 23 4 5 6
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KFD2-HMM-16
ON
13 14 1519 20 21
16 17 18
ON
24 VDC
Up to 15 mux slaves per master
Signals from 16 Hart field devices per master/slave
RS 485connection
Up to 31 HART mux masters
RS-232RS 485
Converter
Modular HART multiplexer KFD2-HMM 16
Figure 9: HART multiplexer.
10
Uniform device manage-ment with FDT/DTM
The access to the digital infor-mation can only be used as ef-fectively as possible if suitabletools are available. For this pur-pose the new FDT/DTM conceptfor device management develo-ped for fieldbus technology andconsidered to have a very pro-mising future has also beenadopted in RIO technology:� A DTM (Device Type Mana-
ger) is a specific descrip-tion (similar to a datasheet) of a device in soft-ware from the devicemanufacturer. This softwarealso contains the so-calledFDT interface.
� FDT (Field Device Tool) is anew standard that is used asan interface between thedevice-specific DTMs andcorrespondingly equipped
operating tools or enginee-ring tools with FDT support.In this way, various tools canbe used for the digitalaccess to the configurationand diagnostics data on theHART devices, such asPACTwareTM, as is thecase with fieldbus techno-logy.
Process interface with “HARTon PROFIBUS”
In view of the large number ofHART devices installed, theirimplementation in existing ornew fieldbus systems is an ur-gent task for the majority ofusers. The application profile“HART on PROFIBUS” has beenspecified as an open solutionfor this purpose on PROFIBUS.The profile is additionally im-plemented in the PROFIBUS
master and slave (above layer7) to represent the HART "Cli-ent-Master-Server" model onPROFIBUS. The HART client ap-plication is integrated in thePROFIBUS master and the HART
master device integrated in aPROFIBUS slave. This slave, as amultiplexer, takes over thecommunication with the HARTdevices. The HART messagesare transmitted using an inde-
Device catalogNavigationwindow
Planttopology
MonitoringTrend indication
Diagnostics
Device operation,setting parameters
Figure 10: PACTwareTM screenshot. Figure 12: RIO system at the application.
PROFIBUS master
HART clientapplication
HART profile HART profile HARTcomm
HARTcomm
HARTmaster
HARTserver
PROFIBUS slave
PROFIBUS DP
HART device
HART communication
7
2
1
7
2
1
Figure 11: HART on PROFIBUS communication. Figure 13: RIO system in central arrangement.
11
pendent communication chan-nel, however, PROFIBUS mecha-nisms (protocol, services) re-main unchanged (Figure 11).
Flexibility in the installationand topology
Every plant is different, both inrelation to its physical size orthe number and position of thefield devices as well as in thepossibilities for the installationof switch boxes or cable ducts.The prerequisite for the cost-optimized installation of RIOsystems is therefore flexibilityin the number and arrange-ment of the RIO components inrelation to the field devices in-stalled.
Here there are basically twoalternatives (with any numberof intermediate solutions):� Connecting a few field devi-
ces very near to the applica-tion to a small RIO station(Figure 12) with very shortpoint-to-point connectionsand longer fieldbus cable
� Coupling a larger number offield devices over longerpoint-to-point connectionsusing a more centrally posi-tioned, larger RIO station(Figure 13).
The common RIO systemsprovide complete freedom toadopt any of these variants.
Product coverage meetsuser's expectations
Many of the users' require-ments mentioned at the start,e.g. modular structure, suitabili-ty for hazardous areas, hotswapping, compatibility withdifferent fieldbus types and ac-cess to HART are met by theRIO products available today. Inthe context of cost-effectiveutilization, with RPI and IS-RPIPepperl+Fuchs offers two sys-tems that differ in structure andsome functions. Figure 14 sho-ws a matched product rangewith identification of the cha-racteristics supported by each.
PACTwareTM is a soft-ware application for the uni-form setting of parametersand/or configuration of fielddevices, remote I/O systemsand communication assemb-lies in fieldbus systems inde-pendent of manufacturer.PACTwareTM has a commu-nication interface as per theFDT standard and is therefore also termed an FDTframe application. WithPACTwareTM it is possible toaccess all HART field devicesand RIO modules, providedtheir technical descriptions areavailable in the form of a DTM.PACTwareTM also includes aso-called generic HART DTMthat can be used for settingthe parameters of field deviceswith HART support for which aspecific DTM is not availablefrom the manufacturer. Thegeneric DTM supports the uni-versal commands and stan-dard commands as per theHART specification, which arealso used by the majority of
HART devices on the market.PACTwareTM provides versa-tile functions, also includingstatus monitoring and messa-ges, interactive functions andgraphic objects such as trendcurves, echo curves, graphsover time or device-specificonline help integrated in therelated DTM (see Figure 10).
Conclusion
The remote I/O technology,originally conceived and de-veloped as a transition and“gateway” from 4–20 mA tech-nology to the fieldbus, hasachieved more than this ob-jective. It exactly meets theneeds of a market focused onthe retention of value andsafety, a market that onlywants to adopt new technolo-gies cautiously and with lowrisk. Today this technology re-presents more than a transiti-on technology. It is the middlesegment of three technologysegments.
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Product line Product characteristic
RPI Remote Process Interface RPI
IS-RPI Intrinsically safe RPI
KFD2-HMM 16 HART multiplex system
HIS MUX 2700 HART multiplex system
PACTwareTM Tool for device management
Product features
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17
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Figure 14: HART multiplexers and RIO product range (example Pepperl+Fuchs).
12
Introduction
In the discussions on the cha-racteristics and benefits offieldbus technology for pro-cess automation, it has beco-me clear, perhaps surprisingly,that despite all the positiveexperience with this newtechnology, the existing alter-natives of “4–20 mA” and “Re-mote IO” continue to be of in-terest and continue to beused. This fact does not con-tradict the justified expectati-
on that with the passage oftime, fieldbus is the technolo-gy of choice for the majorityof plants. This situation, howe-ver, takes into account the factthat conventional 4–20 mAtechnology currently repre-sents a realistic alternative formany applications and willalso do so in the future due tothe very large installed base,the long service life of processplants and also due to com-plementary developmentssuch as HART and RIO.
As a consequence, plant auto-mation and the communicati-on technology used for thispurpose has been segmentedinto “point-to-point” (4-20 mAwith HART),“point-to-bus”(RIO with HART) and “bus-to-bus” (fieldbus), see Figure 2.This situation offers the userthe opportunity to select sui-table technology for his speci-fic task, his environment andhis cost situation. During thisselection process the user alsohas the opportunity to realizea transition from one techno-logy to another without a sys-tem discontinuity. On theother hand, this segmentationforces the manufacturers ofinterface technology to deve-lop and support more pro-duct lines.
This article deals with theconnection technology bet-ween the field devices and thehost (master system or controlsystem) as is necessary for field-bus solutions. Figure 15 showsthat this connection technolo-gy can be divided functionallyinto the stages power sup-ply/segment coupling, field dis-tribution/bus termination andintegration of conventional signals. The sections that
follow are based in this division.
The article is based on theFieldConnexTM system (manu-factured by Pepperl+Fuchs) asan example; this system provi-des various components for thefieldbus systems PROFIBUS PAand FOUNDATION Fieldbus H1for the design of optimal topo-logies. A detailed overview isgiven in Figure 20.
Segment coupling andpower supply
In process plants the proximi-ty of areas with potentially ex-plosive atmospheres, mostlydesigned in the explosionprotection method intrinsical-ly safe (in the field), and safeareas (e.g. the control room) isa reality. Fieldbus installationsmust take this situation intoaccount, an aspect that has re-sulted in the division of thefieldbus topology into intrinsi-cally safe and not intrinsicallysafe segments.
Segment Coupler
On the PROFIBUS, the seg-ment coupler forms the inter-face between a PROFIBUS DPnetwork and the PROFIBUS PAsegments. With FieldConnexTM
this device is implemented inthe modular Segment CouplerSK2. The Segment Coupler SK2converts the digital messageswithout affecting the fieldbuscommunication, adjusts theBaud rate, provides the powersupply for the PROFIBUS PAsegment and enables up to 20PROFIBUS PA segments to beconnected to a PROFIBUS DPspur.� The Segment Coupler con-
nects the field device MBPtransmission technology(Manchester Coded, BusPowered as per IEC 61158-2, transmission rate 31.25kBit/s) used on PROFIBUSPA with the PROFIBUS DPphysical RS 485 with atransmission rate of up to12 Mbits/s using the SK2Gateway module. The Seg-ment Coupler is “transpa-Figure 15: Topology concepts for fieldbus communication based on the example of FieldConnexTM.
Power for the fieldbus
Modern communication concepts for process automation with related product lines, in this case FieldConnexTM. The user definespositioning and technology for the signal processing.
13
rent” in relation to dataconversion and it is there-fore not necessary to confi-gure it in the master sys-tem. The master directlyaddresses each slave viathe Segment Coupler andthe total volume of I/Odata of 244 bytes for eachslave is available withoutrestrictions.
� The Segment Coupler pro-vides the power feed forthe field devices using theSK2 Power Link modules.The Power Link modulesare available both in theprotection method “intrin-sically safe” and also wi-thout explosion protection.On installation in the safearea and on the usage ofFieldBarriers in the explosi-on protection method en-capsulated Ex me, very po-werful plant topologies areproduced; see the sectionon FieldBarriers.
Figure 16 shows, as an exam-ple, the Segment Coupler SK2using which a gateway can be
combined with up to 20 Po-wer Link modules. Here onemodule is responsible for onePROFIBUS PA segment andprovides max. 400 mA powerfeed to the segment. In thiscase all modules are centrallyfed via the Power Rail.
Fieldbus Power Supply,Power Conditioner and Power Hub
The Fieldbus Power Supplies,Fieldbus Power Conditionersand Power Hubs supply fielddevices with power via theFOUNDATION Fieldbus H1network. They couple the po-wer onto the two-wire field-bus cable without disturbingthe communication signals.
Power Conditioners providea power supply current of up to1 A over the fieldbus cable tothe field devices connectedand enable two redundant po-wer sources to be connected.
Power Hubs provide, in addi-tion, a very flexible power supplyconcept with fully redundantsegment power feed and electri-
cal isolation. Power Conditionersand Power Hubs support alarmsand indication of the failure ofthe power source, low voltage,short-circuit and overload. CREST(Crosstalk Resonance Suppressi-on Technology) prevents reso-nances and crosstalk betweenthe fieldbus power supply andthe internal power supply.
Power Repeater
Power Repeaters supply fielddevices via the signal cable ona PROFIBUS PA or a FOUNDA-TION Fieldbus H1 networkand improve the digital com-munication signal within thesystem, particularly in physi-cally large installations. Inde-pendent of the load and theinput voltage, the Power Re-peater provides a constantvoltage for supplying the fielddevices connected to the bussegment. On the field side therepeater has a fixed integra-ted bus terminating resistor,on the host side the bus ter-minating resistor can be ena-bled as required.
An important application forPower Repeaters is the expansi-on of a fieldbus network.
Field distribution andbus termination
The fieldbus trunk is not inpractice, as is often shown forsimplification, fed directlythrough the field devices, butdistributed to the field devi-ces using “fieldbus distribu-tors” using the T-distributionprinciple. In this way the plant
availability is optimized andthe isolation of individual de-vices from the fieldbus simpli-fied. The fieldbus topologyproduced in this way must sa-tisfy the numerous require-ments on the plant, with clearand safe structures for all am-bient conditions as well assimple expansion of existingsegments or the integrationof conventional signals. Field-ConnexTM provides a widerange of field distributors forthe numerous tasks. The fielddistributors permit flexibleplanning of the topology toexactly suit the requirementsof the related plant.
Junction Box
The Junction Box enables afieldbus trunk to be distribu-
Figure 16: Segment Coupler SK2
Figure 17: FieldBarrier in harsh environment in an oil and gas plantin Hungary.
Figure 18: Pneumatic Interface.
Figure 19:„Mini-RIO“ for instal-lation in zone 1.
14
ted to up to eight spurs forthe connection of field devi-ces to the fieldbus segment.This device has a trunk inputas well as a trunk output andthus permits the trunk to belooped through. Various cableglands and connector variantsare available for this purposeand for the outputs of thespur channels. A fieldbus ter-minating resistor is integratedand can be enabled as requi-red. A high level of flexibility isalso ensured by the differentscreening and explosion pro-tection methods available,and the varying numbers ofoutputs.
Segment Protector
Segment Protectors are fielddistributors with an additionalprotection function. They con-vert a fieldbus trunk into se-veral spurs for the connectionof field devices to the fieldbussegment. In addition to thecharacteristics of the junctionbox, each spur is individuallymonitored for short-circuitand overload such that a faulton a spur does not have anynegative effect on the com-
munication in the rest of thefieldbus segment. Each outputis designed for the connectionof a field device. The trunk canbe looped through; an inte-grated bus terminating resis-tor can be enabled as required.
FieldBarriers
In general the issue is to pickup the signals in the plant asclose as possible to the sen-sors and actuators (Figure 17).As these are in general instal-led in the Ex zones 0 or 1 andintrinsically safe operation isrequired, it is appropriate toonly realize the power supplyin explosion protection me-thod “intrinsically safe” in thefield distributor box (insteadof from the Power Link on).For this task the FieldBarriertechnology was developed.The input to a FieldBarrier is fedwith a relatively high power inexplosion protection method Exe (increased safety). Currentlyvalues of up to 400 mA are pos-sible with PROFIBUS, with theFOUNDATION Fieldbus up to 1A. The individual outputs on theFieldBarrier are in explosionprotection method Ex i with 40
mA output current each. For re-asons of clear structuring andreliability, only one field deviceshould be connected per out-put. In this way it is ensured thata failure in a field device willonly affect this device and willnot have any effects on neigh-boring device, or in the worstcase bring the complete field-bus to a halt. The 40 mA are suf-ficient to feed high power loadssuch as valve circuits.Further characteristics ofFieldBarriers:� The individual outputs on
the FieldBarriers are desig-ned so that they are not
mutually interactive suchthat the failure of a device,even in the case of a short-circuit, cannot affect theother devices or even cau-se the complete collapse ofthe entire segment.
� The FieldBarriers electricallyisolate the outputs in rela-tion to the bus trunk. As aconsequence it is not ne-cessary run the legally sti-pulated „durable and safeequipotential bonding” outof the hazardous areathrough the plant. This sig-nifies a considerable costsaving particularly for the
Use 10987654321 11 12 13 14 15 16 17
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Fieldbus Terminating Resistor
PROFIBUS PA
FF FoundationTM Fieldbus
Segment CheckerSurge Protectors
Fieldbus Pneumatic Interface
Mini-RIO
FieldBarrier
Sensor Interface
Valve Coupler
Fieldbus Pneumatic Interface
Power Hub
Temperature Multi Input
FieldConnexTM- systemcomponent
Valve Coupler
Segment CouplerFieldbus Power SupplyPower Conditioner
Power Repeater Junction BoxSegment Protector
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Figure 20: Interface components with application and functionality based on the example of FieldConnexTM.
FISCO
is a concept to plan, install, modify and extend intrinsically safe fieldbusinstallations in zone 1
• Without comprehensive calculations
• Considering only the supply data of the supply device and thefield devices
• Using the maximum number of devices and cable length accordingto IEC
• Without special approval procedures
in a straightforward manner.
FNICO
Is a concept which uses FISCO procedures and rules on fieldbusinstallations in zone 2
long-term operating costs,as such equipotential bon-ding is subject to ageingdue to the contact resis-tance and therefore requi-res regular inspection.FieldConnexTM makes itpossible to use a hardearth at one end of thefieldbus cable and a capa-citive earth at the otherend. In this way the effortfor running the equipoten-tial bonding from the safezone into the zones withpotentially explosive atmo-spheres can be reduced.
� The technology used in theFieldBarriers makes it pos-sible to operate each in-trinsically safe output forthe connection of the bususers with up to 120 m ofcable without a fieldbusterminating resistor.
� Due to the high power pro-vided by the Power Link,when the Ex e trunk is con-tinued several FieldBarrierscan be connected in series.The number of FieldBar-riers is limited on the onehand by the amount ofcurrent available and onthe other hand by the ma-ximum of 32 bus users thatcan be connected to a bussegment.
Connecting conventionalsignals
Even in new plants there willalways be conventional sig-nals that must be integratedin the fieldbus communicati-on. The Fieldbus Process Inter-faces are used for this purpo-se. These are devices for con-necting a wide variety of sen-sors or mechanical contactswithout fieldbus support [7].
Sensor Interface and ValveCoupler
The Sensor Interface enablesup to 12 binary sensors or me-chanical contacts to be con-nected to a single fieldbus ad-dress.
The Valve Coupler is desig-ned for the connection of four
low power solenoid valves alsoto one fieldbus address. Thisdevice converts the fieldbussignal into a binary signal forvalve control and integrates the eight feedback signals from the end position sensorson the valve into the field-bus message.
Temperature Multi Input
The Temperature Multi-Inputenables up to eight resistancetemperature sensors, thermo-couples, resistance signals andmillivolt signals to be connec-ted to the FOUNDATION Field-bus. The module makes possi-ble the effective configurationof the relevant parameters forthe temperature measure-ment. Sensor diagnostics aresupported.
Pneumatic Interface andMiniRIO
The Pneumatic Interface com-bines valve couplers and pilotvalves in one functional unitin one housing with pre-as-sembled connections for field-bus and compressed air sup-ply, see Figure 18. For morecomprehensive installations, itis also possible to integrateFieldBarriers in the housing,which makes possible thecontrol a large number ofpneumatic valves using a sin-gle fieldbus cable.
The MiniRIO combines a lar-ge number of conventionalsignals, such as binary andanalog inputs and outputs aswell as temperature and fre-quency inputs with one field-bus address. Here all featuresof RIO technology can be utili-zed, an aspect that offers signi-ficant possibilities in conjuncti-on with HART communication.With HART technology, meas-uring points can be straight-forwardly and cheaply connec-ted to the fieldbus using theRIO. Power supply and pre-assembled connection pointsare combined in one housinghere, which can be installed in the field in zone 1, see Figure 19.
FNICO, FISCO and Entity
During the design of the field-bus topology, the ambientconditions play a crucial role.These conditions range fromsafe areas through zone2/class I, div. 2 to zone 1/class I,div. 1. The components for sig-nal transmission must satisfythe requirements of the rela-ted safety zones in the sameway as the field devices
FieldConnexTM provides vari-ous versions for this purpose:� Versions for applications
outside hazardous areas� Versions in accordance
with FNICO (Fieldbus Non-Incendive Concept) for in-stallation in zone 2/class I,div. 2; explosion protectionmethod “n”
� Versions in accordancewith FISCO (Fieldbus Intrin-sic Safety Concept, [3]) forinstallations in zone 1/classI, div. 1; explosion protecti-on method “i”
� Versions in accordancewith Entity for installationin zone 1/class I, div. 1
Product portfolio meetsusers' expectations
At an early stage fieldbususers employed their practicalexperience to indicate theneed for additional connecti-on technology [4, 5]. The ma-nufacturers have reacted andas a consequence suitablecomponents are availablefrom various manufacturers.An example of a particularlycomprehensive product rangeis the FieldConnexTM system[6] that makes it possible forthe user to cost-effectivelyand homogeneously instru-ment from a single source.
Figure 20 shows the compo-nents included in FieldConnexTM
with their functions.
Conclusion
As easy as it is to connect fielddevices to a fieldbus systemhost in principle, the connecti-on technology used for thispurpose must be versatile and
powerful. Efficient supply ofpower, field distribution tomatch the topology, and ef-fective safety mechanisms arenecessary among other as-pects to fully utilize the per-formance of fieldbus systemson the automation of processplant. Various manufacturersoffer appropriate devices andcomplete, matched product li-nes and are thus helping field-bus to obtain wider accep-tance.
Authors:Gerhard Jung,
Marketing ManagerPepperl+Fuchs GmbH
Process Automation Division
Thomas Westers,Marketing Manager
Pepperl+Fuchs GmbHProcess Automation Division
Bibliography
[1] Max Felser, Bulletin SEV/VSE9/2002
[2] atp 45 (2003) issue 3, p. 26 ff
[3] atp 44 (2002) issue 12, p.61ff
[4] Baltus, Ch.: Installationskon-zepte für EEx (i)-Feldbussyste-me. atp – Automatisierungs-technische Praxis 43 (2001),issue 9, p. 29–34
[5] Schmieder, W., Tauchnitz, Th.,Seintsch, S.: FuRIOS: Feldbusund Remote I/O – ein System-vergleich. atp – Automatisie-rungstechnische Praxis 44(2002), H. 12, p. 61–69
[6] Kasten, Th.,: Die Anwendbar-keit der FuRIOS Studie. atp –Automatisierungs-technischePraxis 45 (2003), issue 3,p. 51–54
[7] G. Kegel, J. George, T. Kasten:Fieldbus Installation practicein hazardous and non-hazar-dous areas. atp International(2004), issue 2, p. 78–82
Pepperl+Fuchs GmbH, Königsber-ger Allee 87, D-68307 Mannheim,Tel. (06 21) 776-22 22, Fax (06 21)776-27-22 22, Internet: www.pepperl-fuchs.com
15
www.pepperl-fuchs.com
Subject to reasonable modifications due to technical advances • Copyright PEPPERL+FUCHS • Printed in Germany • Part. No. 182 964 10/04 00
Worldwide HeadquartersPepperl+Fuchs GmbH · Königsberger Allee 8768307 Mannheim · GermanyTel. +49 621 776-0 · Fax +49 621 776-1000e-mail: [email protected]
USA HeadquartersPepperl+Fuchs Inc. · 1600 Enterprise ParkwayTwinsburg, Ohio 44087 · Cleveland-USATel. +1 330 4253555 · Fax +1 330 4 25 46 07e-mail: [email protected]
Asia Pacific HeadquartersPepperl+Fuchs Pte Ltd. · P+F Building18 Ayer Rajah Crescent · Singapore 139942Tel. +65 67799091 · Fax +65 68731637e-mail: [email protected]
Comprehensive Interface Technology – including sensors for level measurement
Point-to-point – single standardsignal lines transmit field signalsconventionally to the controlsystem.Two systems are available forconventional instrumentation.The K-System for mounting onDIN rail and the motherboardsolution with plug-in moduleson the system circuit board.
Point-to-bus – conventionalpoint-to-point connections forthe process and bus connec-tions for the control system.For applications in explosionprotection zone 2 the remote I/ORPI System is used, whilst fordirect installation in zone 1 IS-RPI is the first choice –including of HART transfer.Configuration can be carried outusing the FDT-compatiblePACTwareTM software with theappropriate DTMs.
Installing – connecting – isolating fieldbus systems withbus-to-bus technology. Mutuallycompatible components special-ly developed for the demands ofprocess technology allow you tospeedily plan and commissionyour fieldbus system and tooperate your plant safely andefficiently. FieldConnexTM, thefieldbus installation technologyfrom Pepperl+Fuchs – forPROFIBUS and FOUNDATIONFieldbus.
Practical sensors to measure levels in liquids and solids.Sensors from Pepperl+Fuchs are
widely used in thechemical and petro-chemical industries,in bulk materialsand waste waterapplications. Yourapplication can benefit from ourextensive productrange.
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