FIELDBUS By: Stuart McAllister 11/30/2007
What is a Fieldbus? • A Fieldbus is an industrial computer network for real-time distributed control. • A complex automated industrial system usually needs an organized hierarchy of controller systems to function. • Human Machine Interface (HMI) at the top, Programmable Logic Controllers (PLCs) in the middle, and the Fieldbus at the bottom. • The Fieldbus links the PLCs to the components which actually do the work such as sensors, actuators, electric motors, console lights, switches, valves, and contactors.
What is a Fieldbus? • Fieldbus is a generic term that describes a new digital communications network that is being used in industry to replace the existing 4-20 mA analog signal standard. • The network is a digital, bi-directional, multi-drop, serial-bus communication network used to link isolated field devices, such as controllers, transducers, actuators and sensors. • Bi-directional means it is a duplex port; the data can be transmitted in two directions at the same time. • Multi-drop is also referred to as multi-access and it can be interpreted as a single bus with many nodes connected to it. • Serial-bus means the data is transmitted serially according to RS232 or RS485 protocol. Profibus uses RS485 protocol.
What is a Fieldbus? • Fieldbus works on network structures such as daisy-chain, star, ring, branch, and tree network topologies. • Previously computers were connected using RS-232 by which only two devices could communicate. • This is the equivalent of the currently used 4-20 mA communication scheme which requires that each device has its own communication point at the controller level • The fieldbus is the equivalent of the current LAN-type connections, which require only one communication at the controller level and allow multiple (100's) of analog and digital points to be connected at the same time. • This reduces both the length of the cable required and the number of cables required.
History & Current State • In 1999 a committee formed the IEC 61158 standard with eight different protocol sets: • FOUNDATION Fieldbus H1 • ControlNet • PROFIBUS • P-Net • FOUNDATION Fieldbus HSE • Interbus • SwiftNet • WorldFIP
History & Current State • Recent additions or planned additions to IEC 61158 include but are not limited to: • PROFINET IO • EtherCAT • Both FOUNDATION Fieldbus and Profibus technologies are now commonly implemented within the process control field, both for new developments and major refits. In 2006, China saw the largest FF systems installations at NanHai and SECCO, each with around 15,000 fieldbus devices connected
Those who plan complex automated industrial systems Who uses Fieldbuses?
In complex automated industrial systems where an organized hierarchy of controller systems is needed. In manufacturing plants where many instruments need to be connected. Where are Fieldbuses Used?
What are Fieldbuses Used For? • When fieldbuses work in the factory, the purpose has been to reduce installation cost by moving the I/O interface from the programmable logic controller (PLC) to a remote I/O unit mounted close to the machine on the factory floor. • Factory automation fieldbuses are fast and deterministic. (Deterministic means the maximum worst-case time to obtain data across the fieldbus is accurately predictable and is not subject to chance.)
When are Fieldbuses Used? • When the advantages of Fieldbuses, discussed on the next slide, are needed • When the disadvantages of Fieldbuses, on the slide after that, do not hinder use
Advantages of Fieldbus • A major advantage of fieldbus is the capital expenditure (CAPEX) savings associated with cable elimination; multiple devices share wire-pairs in order to communicate over the bus network and savings are also available through speedier commissioning. • Ongoing maintenance and process control system performance are significantly enhanced through fieldbus systems, which results in operations expense savings (OPEX).
Disadvantages of Fieldbus • Disadvantages of fieldbus compared to the 4-20 mA analog signal standard: • Fieldbus systems are complex, so more training needed • The price of fieldbus components is higher • Fieldbus test devices are more complex • Device manufacturers have to offer different versions of devices due to different fieldbus standards. This can add to the cost of the devices and increases the difficultly of device selection. • Standards may predominate or become obsolete, increasing the investment risk.
Costs • (CAPEX) Savings • (OPEX) Savings • Cost of Devices • Investment Risks • Engineering costs • Equipment costs • Installation costs • Commissioning costs • Maintenance costs • Operating costs • Inventory costs • Retooling costs Figure 1. Typical Modern Industrial System
Requires Supporting Technology? • YES • Fieldbus Components: • Bus Terminal • EtherCAT • Fieldbus Box • Lightbus • PC Fieldbus Cards • Switches • And more … http://www.beckhoff.com/english.asp?embedded_pc/cx1000_2.htm
References • http://en.wikipedia.org/wiki/Fieldbus • http://www.isa.org/InTechTemplate.cfm?Section=Article_Index1&template=/ContentManagement/ContentDisplay.cfm&ContentID=60680 • http://www.us.profibus.com • http://www.easydeltav.com/video/product/foundation_fieldbus.asp • http://www.fieldbus.org/images/stories/newsroom/newsletter/200702/ • http://www.beckhoff.com/english.asp?embedded_pc/cx1000_2.htm • http://ethernet.industrial-networking.com/articles/articledisplay.asp?id=79
Use in Industry • Fieldbus continues to be an important element of the automation industry. InTech magazine conducted a Market Study • 80% of manufacturing facilities use fieldbus • Manufacturers use more than one fieldbus protocol in their process • Fieldbus connected to the Internet? No - 82%, Yes - 18%
Primary Vendors of Technology • Acromag, Inc. • RTD Embedded Technologies, Inc. • Contemporary Controls • RM Michaelides Software & Elektronik GmbH • Interface Concept • Steinhoff Automation & Fieldbus-Systems • Hilscher Gesellschaft für Systemautomation mbH • PTO • Beckhoff • http://www.eg3.com/search411.cgi?query=fieldbus&case=on&engine=VENDORS
Existing or Evolving Standards? • Ethernet-based industrial communication systems recently established, and have extensions for real-time communication. • Will potentially replace traditional fieldbuses in the long run. • Currently the issue stopping most Ethernet fieldbus implementations is the availability of device power. Measurement & control devices need power from the bus and Power-Over-Ethernet (PoE) does not deliver enough. • Here is a partial list of the new Ethernet-based industrial communication systems: • EtherCAT • Ethernet Powerlink • SERCOS III • PROFINET IO • ETHERNET/IP • VARAN • SafetyNET • Industrial Ethernet • IEC 61158 is an evolving standard with a 5-year maintenance cycle.
Application Example • Quest Separation Technologies | Food & Beverage • Needed new facility • The typical timeline for design, construction, and startup of a facility of this scale is 9 to 12 months. • Wanted plant to start production in less than five months. • Emerson Process Management's PlantWeb digital plant architecture, based on the FOUNDATION fieldbus communications protocol, intelligent field devices, and the DeltaV digital automation system met this project's daunting challenge. • Reduced capital and engineering expenditures • Reduced operations and maintenance effort • Reduced regulatory compliance effort • Reduced variability of plant and processes • Designed plant to be scaleable in future • Fieldbus technology, the DeltaV system, and PlantWeb architecture saved Quest many man-hours in installation time. The breakthrough automation solution also saved Quest 10 percent in installed material costs, and it reduced both space and process control equipment by up to 43 percent. As a team, Quest and Emerson met the deadline in record time.
Application Example • Valley Record Distributors - Woodland, CA • Automated conveyor system installed • By Dorner Manufacturing Corporation • Thousands of dollars were eliminated by not having to hard wire the I/O devices back to the main computers. The PLCs and PROFIBUS made that benefit possible. The line operates very efficiently, increasing production substantially. Less warehouse space is consumed by the machine layout. If the machinery has to be moved to another location, its modular design makes this much easier than previous designs. Speed and efficiency of the new sortation line exceeded that of the first-installed system.
Summarize Technical Paper • Title: With 20 million nodes, Profibus says it's mainstream.Source: Control Engineering, 54 (9): 31, September 01, 2007. ISSN: 0010-8049Publisher: Reed Business InformationDocument Type: JournalPublication Country: United States, Language: English
Summarize Technical Paper • The Profibus Trade Organization (PTO) commemorated 20 million installed nodes world-wide (as of April 2007). • Profibus digital industrial network and fieldbus technology are mainstream for general applications. • Examining fieldbus platforms at the end of 2006, Profibus claims a 46% market share by node count. • The organization projects the 30 million node milestone could be passed as early as March, 2009. • PTO estimates that when all the instrumentation and peripheral equipment to support those networks are included, the total market value for those 20 million nodes exceeds $50 billion. • These numbers should tell an end user that fieldbus technology is mainstream. It is operating today in all types of plant environments.
Profibus • Profibus is a vendor-independent, open fieldbus standard for a wide range of applications in manufacturing, and process automation. Devices configured by different manufacturers can communicate without special interface adjustments. Profibus can be used for both high-speed, time-critical data transmission and extensive complex communication tasks. • Profibus family consists of three compatible versions: • Profibus-FMS (Fieldbus Message Specification) • Profibus-DP (Decentralized Peripherals) • Profibus-PA (Process Automation) • PROFIBUS (Process Field Bus) is the most popular fieldbus today
Video • http://www.easydeltav.com/video/product/foundation_fieldbus.asp • http://www.easydeltav.com/video/product/index.asp
Class Application • There is a section in the textbook on fieldbus ... T / F • IEC 61158 is the fieldbus standard … T / F • Ethernet-based industrial communication systems could potentially replace traditional fieldbuses … T / F • PROFIBUS is not the most popular fieldbus today … T / F
Summary • Presentation Evaluation Form • ME 486 – Automation • Presenter Stuart McAllister Grade (total pts)__100__ • Heading? __10_(10) • Title of Topic, Presenter Name, Date ___X___ • Overview? __30_(30) • Define current state? ___X___ Where used? ___X___ Who uses, what used for, when used? ___X___ Costs? ___X___ Requires supporting technology? ___X___ References? ___X___ • Discuss use in industry? __20_(20) • Discuss application rules, limitations? ___X___ Primary vendors of technology? ___X___ Existing or evolving standards? ___X___ • Application examples? __25_(25) • Summarize and include technical paper? ___X___ How integrates? ___X___ Video and/or slide shorts? ___X___Class application? ___X___ • Summary? __15_(15)