Fieldbus technology in industrial automation Jean-Pierre Thomesse To cite this version: Jean-Pierre Thomesse. Fieldbus technology in industrial automation. Proceedings of the IEEE, Institute of Electrical and Electronics Engineers, 2005, 93 (6), pp.1073-1101. 10.1109/JPROC.2005.849724. inria-00000807 HAL Id: inria-00000807 https://hal.inria.fr/inria-00000807 Submitted on 21 Nov 2007 HAL is a multi-disciplinary open access L’archive ouverte pluridisciplinaire HAL, est archive for the deposit and dissemination of sci- destinée au dépôt et à la diffusion de documents entific research documents, whether they are pub- scientifiques de niveau recherche, publiés ou non, lished or not. The documents may come from émanant des établissements d’enseignement et de teaching and research institutions in France or recherche français ou étrangers, des laboratoires abroad, or from public or private research centers. publics ou privés. > REPLACE THIS LINE WITH YOUR PAPER IDENTIFICATION NUMBER (DOUBLE-CLICK HERE TO EDIT) < 1 Fieldbus Technology in Industrial Automation Jean-Pierre Thomesse solutions in a given sector. These companies realized the Abstract— Fieldbus technology in industrial automation strategic importance of the fieldbus in the industrial is not only relatively complex because of the number of automation systems. Once their products were developed, solutions possible, but also, and above all, because of the they pushed to have them standardized, and hence we have variety of applications. Ironically, these in turn are responsible for the multitude of solutions available. If the the current vast range of standards, de facto and de jure. analysis of the basic needs is relatively standard, as they will This paper will try to establish the origins and current always involve connecting sensors, actuators, and field status of the fieldbus technology, including technical and controllers with each other, the options in architecture are scientific analysis, and standardization. Taking into account numerous and can impose the need for certain services. The the number of systems and the number of contenders, the required performances themselves and the quality of service expected fundamentally depend on the applications. history of the fieldbus is long and the different episodes are This article traces this technology from its beginnings, numerous. Because of this, a lot of details will not be which go back to the first industrial networks in the 1970’s. included, and we will simply focus on the essential steps in The principal stages of development are recounted, from the its evolution. initial requirement specifications to the current state of There are two main parts to this paper. The first focuses international standardization. The diverse technical solutions are then analyzed and classified. In particular, we on the origin of the concept of the fieldbus and on the study the temporal aspects, the medium access control requirements which led to the beginning of fieldbuses, protocols and application relationships. ending with the current state of standardization. The second part is dedicated to the technical aspects, the services, the protocols, and then the quality of services, ending with Index Terms—Application relationships, Architecture, some communication architecture considerations. The Client – server, Cooperation models, Fieldbus history, Medium Access Control, Protocol classification, Publisher – conclusion will focus on perspectives and future possible Consumer, Real-time, Standardization. evolutions. I. INTRODUCTION II. FIELDBUS CONCEPTS: ORIGIN AND REQUIREMENTS OR about 20 years now, the word "fieldbus" has been A. How the fieldbus concept began Fvery widely used. Its common meaning is a network for connecting field devices such as sensors, actuators, The fieldbus concept has several origins, but they can be field controllers such as PLC’s, regulators, drive classified into two main groups: the end-user needs and the controllers, etc., and man-machine interfaces. But this is technological capabilities. only an informal definition and needs more in-depth 1) Functional end-users needs analysis. Fieldbus technology represents a wide domain of a) Needs for standardization problems which are similar, but not exactly identical in nature. Fieldbus technology involves a variety of solutions It is appropriate to start with the history of fieldbuses, in and techniques which, although frequently seen as closely order to understand the differences in approaches. As with related, are different from each other. Fieldbus technology is most histories, this one has a prehistory. The fieldbus a kind of technical, political and human adventure, which ancestors which stood out the most in industrial automation for more than 20 years has led to a lot of articles in were Modbus from Modicon (Modicon Bus) [62], [63] and journals, a lot of announcements, a lot of so-called scoops, WDPF from Westinghouse (Westinghouse Distributed a lot of conferences and workshops, and a lot of products Processing Family) [140] [112] because of their seniority, and standards. their functionalities, and their worldwide acceptance. Other There are many standards. Why? networks, were already in existence, but did not go beyond • The need for a fieldbus technology identified by a few specific applications or domains. For example, the a number of different end-user companies in a network ARCNET (Alliance Research Centre Network) number of different sectors. started in 1977 and primarily covered office communication • The variety of possible hosts to be connected needs [114], before being used in data acquisition [19]. (the variety of sensors, of actuators, of Another network which was highly used in avionics and controllers). aerospace applications was the Military Standard 1553, Initially, there was no existing standard so each IT [56], [133]. In the nuclear instrumentation domain, the (Information Technology) provider developed their own CAMAC [28] network, created in the 60s, is considered as > REPLACE THIS LINE WITH YOUR PAPER IDENTIFICATION NUMBER (DOUBLE-CLICK HERE TO EDIT) < 2 the first instrumentation network. Several proprietary networks were in use at the end of the 70s to connect PLCs Fig. 2 Operational Architecture (Programmable Logic Controllers) (Allen Bradley Data HighWay and Tiway – Texas Instrument Way), [126] as In Fig. 2, a TOP network is situated between the well as in the process industry [158], [136]. enterprise and the factory control levels, a MAP network is between the latter and the cell control level, Mini-MAP or b) MAP and TOP projects sometimes Proway (Process Data Highway) [52], [81] just The integration of heterogeneous systems was difficult below that, and then finally the fieldbus network between due to the lack of standards, and was expensive on account the machine control and the sensor-actuator levels, leading of necessary gateways, adaptors, and protocol converters. It to the operational architecture. Mini MAP [58] or was at this moment that two US companies started two MAP/EPA (MAP - Enhanced Performances Architecture) projects, aim of which was “the definition of a standard [108], [125] was added, based on the FAIS (Factory communication profile”. Boeing Company launched the Automation Interconnect System) specification [115] TOP project (Technical and Office Protocol) [26], [36], and developed in Japan. General Motors the MAP project (Manufacturing This notion of hierarchical architecture was also Automation Protocol) [41], [145], [48], [79]. The main developed in process industries, [159], [11] but with a objective of the MAP project was the definition of a difference in functions. Indeed, the following layers were standard communication profile suited for communication most often considered: a first layer for reflex automation, a between the design offices and factories, and inside the second for the supervision and a third for optimization. factory, between workshops and machine tools or robots. General Motors wanted a communication profile for d) Wiring simplification needs manufacturing applications that could allow all devices to At the lowest level of communication, before the communicate without having to develop specific hardware fieldbus era, a lot of standards reigned, for example, the 4- and/or software. Boeing’s idea with the TOP project was 20 mA standard for analog sensors or the 0 – 24 V for similar but concerned another issue, namely communication digital inputs, etc. These standards led to a cabling of 2 between business and technical offices. wires for each analog point and for each Boolean point (true, false), or each binary digit in a number. The result c) The concept of CIM and hierarchical was the need for a great number of cables in the factories. architecture The design and installation of the wiring were expensive Computer Integrated Manufacturing refers to automated operations, and maintenance or evolution was difficult. This manufacturing, automated transport of pieces and materials, was one of the reasons why end-users requested a solution using computer technologies at all the stages of a product for simplifying these operations: the fieldbus was an answer from its design to the manufacture and the quality control. to this request. This need had already been stated in 1971 The idea of structuring applications in a hierarchical way by [80]. abstracting levels has been used for decades to simplify their design. Fig. 1 shows the five levels model of 2) Technological capabilities (enabling technologies)