ISA50, Signal Compatibility of Electrical Instruments

Scope

1. To develop standards for signals used in process measurement and control, to transmit information between subsystems or separated elements of systems. Such signals may be analog or digital. However, data highway and other time-shared transmission paths, such as those within the scope of ISA72, are excluded.

2. To continue to serve as the U.S. Technical Advisory Group for IEC-SC65A/WG4: Interface Characteristics.

Purpose

To define a common interface between components of electronic measurements and/or control systems.

A Word from the Chairman

Richard Caro, Chairman of ISA50 since 1993, and Cullen Langford, Chairman from 1987 to 1993, wish to thank everyone who participated in the development of the ISA-50.02 Fieldbus standards. The standards were administratively withdrawn as ANSI standards and have now also been withdrawn as ISA standards as they are no longer in use due to the issuance and acceptance of a more current IEC 61158 standards series.

ANSI/ISA-50.00.01-1975 (R2002), Compatibility of Analog Signals for Electronic Industrial Process Instruments is one of the most widely used standards in industrial automation (print and downloadable versions are available), specifying 4-20 mA as the signaling range for analog data transmission of instrumentation and control signals. The standard document is simple, and the technology is very mature. All ANSI standards must be either withdrawn or re-certified every five years. There have been no technical innovations in this area since 1972, and the trend is to move gradually to digital fieldbus transmission, however, the annual volume of instruments sold with an ISA-50.1 conforming analog signal is still much larger than all fieldbus instruments combined.

There have been some proprietary additions to the 4-20 mA implementations, particularly to use the band below 4 mA but above zero to signal a specific system malfunction, and likewise to use a small band above 20 mA as well. There has been no general call to standardize on these small additions, however. No new work is planned.

Although the ISA50.4 subcommittee had been inactive for several years, ISA-TR50.02, Part 9, Fieldbus Standard for Use in Industrial Control Systems: User Layer Technical Report (downloadable version available), was published in 2000. The document is a valuable tutorial that captures the knowledge of a unique expert along with the analysis of a complete synthesized digital control system. Former ISA50 Chair Cullen Langford was integral in converting the text, almost 1000 pages, into a workable electronic format. The subcommittee and ISA50 thank him for his remarkable efforts.

List of Standards for Committee

Contacts:

Robert Adamski Information Member RA Safety Consulting LLC Phone: (865) 458-3455	Chuji Akiyama Voting Member Yokagawa Electric Corp Phone: +81 42 2 52 5534 Fax: +81 42 2 55 6492
William Baker Information Member KML Inc Phone: (619) 695-9468	Eliana Beattie Staff Contact ISA Phone: (919) 990-9228 Fax: (919) 549-8288
Lawrence Beckman Information Member Safeplex Systems Inc Phone: (713) 983-8410 x303 Fax: (713) 983-8428	Miguel Borges Information Member Petrobras Cenpes Supen Diprom Phone: 55 21 598 6228 Fax: 55 21 598 6244
Romilly Bowden Information Member Fisher-Rosemount Ltd Phone: +44-1 243-845 Fax: +44-1 243-845	Stuart Boyer Information Member Iliad Development Inc Phone: (403) 271-8032
Rolf Breithaupt Information Member Siemens Schweiz AG Phone: (411) 495-4823 Fax: (411) 495-4732	Patricia Brett Information Member Honeywell Inc Phone: (215) 641-3373 Fax: (215) 641-3850
Peter Burton Information Member Holwell Consulting Phone: +44 1462 813620 Fax: +44 1462 816718	Richard Canfield Voting Member Square D Co
Antony Capel Information Member Comgate Engineering Ltd Phone: (613) 235-4778 Fax: (613) 235-6214	Richard Caro Voting Member Chair CMC Associates Phone: (978) 635-9449 Fax: (978) 246-1270
Bruce Casner Information Member Miller Electric Mfg Co Phone: (920) 954-3869	Salvatore Cavalieri Information Member Universita' degli studi di Catania Phone: +39 095 738 2362 Fax: +39 095 338280
Si Chang Information Member Hana Co Ltd Phone: (822) 558-7476 Fax: (822) 558-7479	Robert Crowder Voting Member
Emmanuel DelaHostria Voting Member Rockwell Automation Phone: (440) 646-7324 Fax: (440) 646-7327	Udo Doebrich Voting Member Siemens AG Phone: +49 7 21 595 2550 Fax: +49 7 21 595 6728
Bernard Dumortier Voting Member Schneider Electric Phone: +33 1 74 13 87 31 Fax: +33 1 39 16 38 84	Thomas Feindel Information Member R Stahl Inc Phone: (603) 870-9500 X615 Fax: (603) 870-9290
Ferrill Ford Information Member Emerson Process Management Phone: (512) 832-3270 Fax: (512) 832-3199	Mauro Giraudi Information Member Private Consultant Phone: +39 1 980-2918 Fax: +39 1 980-2918
Maris Graube Information Member Relcom Inc Phone: (503) 357-5607	Paul Griem Information Member
Ben Gross Voting Member General Motors Corp Phone: (810) 947-0609	Ashok Gupta Voting Member Aniotek Inc Phone: (732) 274-2648 Fax: (732) 274-2332
Hans Hasler Information Member Adelcontrol Phone: 34 9 0192 337 355	Douglas Heiss Information Member Shaw Stone & Webster Inc Phone: (856) 482-3594
Toru Ito Information Member Fuji Electric Phone: 81425 84430 Fax: 81425 810400	Vince Jacobson Information Member
James (Jim) Jamison Voting Member EnCana Corporation Ltd Phone: (403) 463-6112	Ken Kakizakai Information Member Fuji Electric Co Ltd Phone: 04257 36111
Robert Ketcham Voting Member PAS Inc Phone: (281) 334-6749 Fax: (281) 286-6767	Kenneth Krivoshein Information Member Fisher-Rosemount Systems Inc Phone: (512) 418-7400 Fax: (512) 418-7505
Yasuo Kumeda Information Member Yamatake Corp Phone: +81 466 20 2430 Fax: +81 466 20 2431	Timo Kuusisto Information Member Phone: +358 3 3446883 Fax: +358 3 12668324
Thierry Laine Information Member Alstom Technology Phone: +33 1 46 29 12 59 Fax: +33 1 46 31 75 45	Halvor Landet Information Member Fieldbus International Phone: 4722067963 Fax: 4722067320
Richard Lasher Voting Member	Arthur Lesh Information Member AMP Inc Phone: (717) 592-6274 Fax: (717) 592-6179
Patrizio Leviti Information Member Alstom Power Italia SpA Phone: +39 02 26232 783 Fax: +39 02 26232 293	Klaus-Peter Lindner Voting Member Endress+Hauser Process Solutions AG Phone: +41 61 715 7348 Fax: +41 61 715 2802
Timothy Madden Voting Member Exxon Mobil Development Co Phone: (281) 654-4238 Fax: (262) 314-0837	Giorgio Mazzola Information Member Enel Phone: +39023015257 Fax: +390223015675
Albert McCauley Information Member Chagrin Valley Controls Inc Phone: (216) 831-8069 Fax: (216) 831-8069	Francis McKenna Voting Member Catena Associates Phone: +44 1525 712100 Fax: +44 1525 712277
Rick Meeker Information Member Process Controls Solutions Inc Phone: (850) 385-5100 Fax: (850) 385-5200	Dale Merriman Information Member MerTech Inc Phone: (713) 978-7765 Fax: (713) 978-6230
Orazio Mirabella Information Member Univ di Catania Phone: (399) 573-2361 Fax: (399) 533-8280	Donald Modell Information Member Phone: (410) 628-1460
Ashu Mukherji Information Member Systems Automation Intl Inc Phone: (856) 772-6078	George Nachev Information Member Isomatic Lab Phone: +359- 2-774-596 Fax: +359- 2-774-556
Lewis Natiello Voting Member Covex Phone: (267) 960-5100 Ext 303 Fax: (267) 960-5105	Lee Neitzel Voting Member Emerson Process Management Phone: (512) 418-4663 Fax: (512) 418-7500
H. Michael Newman Information Member Cornell Univ Phone: (607) 255-4630 Fax: (607) 255-5377	Patrice Noury Voting Member Alstom Transport TIS Phone: +33 1 46 29 13 93 Fax: +33 1 46 29 12 65
Evan Pageler Voting Member Fisher-Rosemount Systems Inc Phone: (512) 832-3072 Fax: (512) 834-7313	P. Patel Information Member V Automation Phone: (214) 243-3246 Fax: (214) 243-1626
Tom Phinney Information Member Phone: +1.602.938.3163	Axel P�schmann Information Member
Deon Rae Information Member Chevron Energy Tech Co Phone: (713) 372-7324 Fax: (713) 372-7300	Ronald Reimer Information Member Rockwell Automation Phone: (262) 388-1978
Francesco Russo Information Member MGR Automazione Phone: +39 2 266 4013 Fax: +39 2 266 4013	Karlheinz Schwarz Information Member Schwarz Consulting Co Phone: 49 72 1 684 844 Fax: 49 72 1 679 387
Edward Sederlund Voting Member Dow Chemical Co Phone: (989) 636-1111	William Shaw Information Member Cyber SECurity Consulting Phone: (443) 517-9427 Fax: (443) 705-0677
Yoh Shimanuki Information Member The Soc of Instrument & Ctrll Engrs (SICE) Phone: +81 3 3814 4121 Fax: +81 3 3814 4699	Edward Skabowski Voting Member Tendent Consulting Phone: (925) 944-7167
Jiri Slavinsky Information Member Czech Standards Inst Phone: 422-2 62251 Fax: 422-2 65795	Daniel Sniezek Information Member Lockheed Martin Federal Svces Phone: (607) 751-6235 Fax: (607) 751-6920
James Sprague Information Member Saudi Aramco Oil Co Phone: +966 3 874 6414 Fax: +966 3 873 0037	Robert Squires Information Member
Herman Storey Voting Member Phone: (281) 743-3944	Ronald Szanyi Voting Member ExxonMobil Research Engineering Phone: (703) 846-1160 Fax: (703) 846-1086
Peter Thiessmeier Information Member Klockner-Moeller Phone: 49 22 8 602 568 Fax: 49 22 8 602 724	Nathan Tobol Voting Member Ronan Engineering Phone: (818) 883-5211 Fax: (818) 992-6435
Alain Tresset Information Member CEGELEC Phone: +33-1 -46-29-16-30 Fax: +33-1 -46-31-7545	Ashish Umbarkar Information Member Praxair Inc Phone: (716) 879-2120
Chai Vaidya Information Member Sun Microsystems Phone: (408) 774-8711 Fax: (408) 544-0240	Clyde Van Haren Voting Member James River Corp Phone: (920) 494-7830
Ian Verhappen Information Member Industrial Automation Networks Inc Phone: (780) 842-4722 Fax: (780) 628-7352	Robert Webb Voting Member ICS Secure LLC Phone: (360) 394-3692 Fax: (360) 930-0546
Joseph Weiss Information Member Applied Control Solutions LLC Phone: (408) 253-7934 Fax: (408) 253-7974	Christopher Williams Voting Member ITT Phone: 585 269 7764
Gregory Winchester Voting Member Natl Electrical Mfrs Assn Phone: (703) 841-3299 Fax: (703) 841-3399	Graeme Wood Voting Member Graeme Wood Consulting Phone: +44 1 883 62 7797 Fax: +44 1 870 135 1131
David Wroblewski Information Member Bailey Controls Co Phone: (216) 585-6635	Marty Zielinski Voting Member Managing Director Emerson Process Management Phone: (952) 828-3230 Fax: (952) 828-3299