This article is reprinted from:

Chair for process computers

Technical University of Munich

Professor Dr. Dr.-Ing. George Faerber

Arcisstr. 21

80333 Munich

Winter semester 1994/95

Field bus systems – Interbus-S

by:

Tobias Einsele

1999-03-16

Introduction

The Interbus s manufactured by Phoenix Contact 1987 as simple actuator/sensor bus at the market one introduced. The user organization Drivecom registered association, in which manufacturers and users united, anxious, the standardized design DIN 19,258 is to be let fix as International Electronical Commission international standard.

Areas of application

The actuator/sensor bus Interbus s is thus required particularly begun in environments, where time-critical applications must be operated, by the bus a deterministic system time behavior. With Interbus s the cycle times are unique calculable. This succeeds only, because only “dumme” {components without “intelligence”) actuators and sensors, thus without micro CONTROLLERS, are used, which indicate static load behavior. Actuators and sensors must define thus a fixed number of control or measured values. As example of simple in- or output devices, which can be attached at the Interbus s, temperature sensor, valve islands, serves light barriers, protractor etc.. [ BEN90 ]

Features

A set of specific features make interesting for the Interbus s as actuator/sensor bus in the manufacturing industry. Small link costs and simple interface development result from the fact that it concerns a very simple and efficient log. Peripheral devices can be attached without larger expenditure, i.e. without software development etc. immediately. Log-caused also the utilizable data efficiency rises at rising number of actuator/sensors. The master/server bus can address max. 256 users, the standard data transmission rate amounts to 500 kBit/s. Furthermore also rates of 125 can kBit/s (for non-time-critical applications) and 2 Mbit/s (already reserved for future applications) with a total bus length by up to 13 km to be adjusted. Regarding data security the Interbus s a Hammingdistanz indicates those of 4, among other things in a RCC CHECK TOTAL is achieved [ BEN91 ].

OSI layer 1:

Physical medium As physical medium Interbus s uses the copper two-wire line (R-S 485) or the fiber-optic cable (LWL). The two-wire line enable signal transmission floating with the type of modulation to NRZ (Non Return to of zero) and reduces thus sensitivity in relation to electromagnetic irradiations. The bus is from the outside as line structure with remote bus recognizably, of out over bus coupler branch lines to local or further remote penalties branches. It actually concerns itself with the Interbus s however around a ring topology with active user linking [ BLO92 ].

OSI layer 2:

Sum framework log The rising utilizable data efficiency at rising number of users arises as a result of the sum framework log, which functions in the procedure time division multiple ACCESS (TDMA): A fixed time framework of the length T divided with n users into n time-tutor. Per user a certain number of bit locations is reserved, on which process data will transfer cyclically and time-equidistantly. From it guaranteed and unique calculable cycle times result. Additionally a-cyclic parameter data for the network management or for other Schicht-7-Dienste can be transmitted [ BAG94 ] for non-time-critical applications at certain bit locations.

OSI layer 7:

Applications The Interbus s designates already also services for Schicht-7 applications, which enable it to make producer-independently information exchange between the users. Thus actuators and sensors of the most different manufacturers can be bound into the network, if they take PMS (Peripherals the Message up of Specification) services. Basically one can classify these services in three groups [ BAG94 ]:

Application services: Reading and writing of communication objects, start and stop of programs

Civil services: Exchange of information about communication relations of the users among themselves, reading of the object directories

Network management services: Sicherstellung {safety/security} of the bus operation, Auf-und reduction of communication relations

Literature / sources

BAG94

A. Baginski, M. Mueller: ``InterBus s, bases and practice ' ', Huethig, Heidelberg, 1994

BEN90

Roland Bent: ``Ganz down interlaces ' ', in: electro-technology, special edition, number 7-8/90, Franzis, 1990

BEN91

R. Bent, W. Schnurbusch, W. Wiele: ``Viele field penalty for all applications ' ', in: Electronics 7/1991

BLO92

Wolfgang Blome: ``Feldarbeit, the Interbus s in automation ' ', in: Electronics practice, special edition, NR. 11/1992, Franzis, 1992

BUR91

Christof Burmann: ``Durchgaengig opened ' ', in: iee, special edition, number 12/91, Huethig, Heidelberg, 1991

DIN19

DIN 19,258

MUEL91

M. Mueller: ``Steuerungsaufgabe flexibly solvable ' ', in: HLH heating ventilation/climate heating technique, special edition, Bd. 42 (1991) NR. 1, VDI, 1991

NOTE:

This article was translated into the English language by "Alta-Vista - Babelfish". We wish to apologize for any mis-useages or mis-translations that may have occured.