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.


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 The standards were administratively withdrawn as ANSI standards and have now also been withdrawn as ISA standards as they are no longer in use due to the issuance and acceptance of a more current IEC 61158 standards series.

The technical report ISA-TR50.02, Parts 3 & 4, Fieldbus Standard for Use in Industrial Control Systems, Parts 3 & 4, TR1: Technical Report for Fieldbus Data Link Layer - Tutorial, under the coordination of Patrizio Leviti, is still in use. This tutorial explains the "why" and "how" relevant to "what" has been included in the Data Link Layer standards. This document addresses those who have not had any contact with the Data Link Layer Standards, now a part of the IEC 61158 standards series.

The tutorial eases the initial review of the Data Link Layer Standards by 1) presenting the particular reasons why some of the features have been included; 2) describing its main features; and 3) making simple examples or graphic representations of these features. The tutorial goes into further detail by 1) linking separate parts of the standards relevant either to the same subject or to related items; and 2) making detailed examples of this Data Link Layer mechanism.

Ashok Gupta 
ISA50.3 Chair

For more information, please contact

Eliana Brazda
ISA Standards Administrator
(919) 990-9228