Fieldbus Products

Fieldbus products are industrial automation products used in industrial network communications on factory floors. They link programmable logic controllers (PLC) to devices such as sensors, switches, actuators, motors, controllers, contactors, and transducers. Fieldbus is a generic term for a digital communications architecture designed to replace the 4 - 20 mA analog standard. Fieldbus products require less wiring than conventional bus networks and offer improved reliability and reduced cost. The International Electrotechnical Commission (IEC), the Instrument Society of America (ISA), and other standards organizations have defined physical, data link, application, and user layers for fieldbus products. IEC/ISA SP50 is just one of the standards supported by the Fieldbus Foundation (FF), a non-profit group of suppliers and end-users who are dedicated to developing fieldbus digital communications.

Fieldbus products are designed for fieldbus networks such as AS-i, BITBUS® (Intel Corp.), CANbus, DeviceNet, and the FOUNDATION fieldbus. The AS-interface (AS-i) is a network system for the lower field range of the automation level. It is suitable for networking binary actuators and sensors. BITBUS or IEEE 118 is based on standard technologies such as RS485 and synchronous data link control (SDLC). Controller area network bus (CANbus) is a high-speed serial data network designed for harsh electrical environments and real-time control applications. DeviceNet uses the CAN protocol to connect industrial devices such as limit switches, photoelectric cells, valve manifolds, motor starters, drives, and operator displays to programmable logic controllers (PLCs) and personal computers (PCs). Fieldbus products for the FOUNDATION fieldbus use a serial, all-digital, two-way communications system that serves as a local area network (LAN) and uses a tree topology.

Fieldbus products are also used in fieldbus networks such as INTERBUS® (Phoenix Contact GmbH & Co), HART® (HART Communication Foundation), PROFIBUS® (PROFIBUS International), and P-NET. INTERBUS is a fieldbus network based on the cyclic, serial transmission of input/output data between a master and slave. The highway addressable remote transducer (HART) protocol uses 1200 baud frequency shift keying (FSK) based on the Bell 202 standard to superimpose digital signals on conventional 4-20 mA analog signals. The process fieldbus (PROFIBUS) is a popular, open communication standard used in factory automation, process automation, motion control, and safety applications. PROFIBUS is standardized in IEC 71158 and IEC 61784 and is suitable for both fast, time-critical applications and complex communication tasks. P-NET fieldbus products use a digital communication standard for connecting distributed process components via a common two-wire cable. P-NET is both a European standard (EN 50170, Vol. 1) and part of the international fieldbus standard (IEC 61158, Type 4).

• Tales from the Front: Applying Fieldbus at Genzyme, Part 1
  By William T. Dolan, P.E., Genzyme Corp. It has been said that most pharmaceutical companies fail to capture and use more than 10% of the information coming from the instruments already installed in...
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• The Ups and Downs of Taking the Bus
  By Gary Forrest, PhD, Wyeth Research In June of 2002, ground was broken for a new Bioprocess Development Facility at the Wyeth site in Pearl River, N.Y. Primary applications for the new building...
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• The Ups and Downs of Taking the Bus
  By Gary Forrest, PhD, Wyeth Research In June of 2002, ground was broken for a new Bioprocess Development Facility at the Wyeth site in Pearl River, N.Y. Primary applications for the new building...
  (read more)

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