Software Quality and Productivity Improvement Techniques for Process Computer Systems at Mizushima Works, Kawasaki Steel Corporation

Copyrighl © IFAC Aulomation in Mining. Mineral and MClal Processing. Beijing. PRC. 1992

SOFTWARE QUALITY AND PRODUCTIVITY IMPROVEMENT TECHNIQUES FOR PROCESS COMPUTER SYSTEMS AT MIZUSHIMA WORKS, KA W ASAKI STEEL CORPORATION R. Owaki, H. Torikoshi, I. Toda, E. Nagayama and T. Iwamura Plant Control Technology Scction, Mizu.,hima Works, Kawasaki Steel Corporation, Kurashiki, Okayama, Japan

Abstract. Process computers have a long history of use in the steel industry. where they have made a remarkable contribution to product quality and production efficiency. Moreover. process computer functions have become increasingly sophisticated and complex in response to the requirements of high-level line automation . making the improvement of software quality and productivity an essential task. Since 1987, Kawasaki Steel has actively promoted the development of techniques for the improvement of software productivity, The main software techniques developed are as follows : Autonomous distributed systems An autonomous distributed system was put into practical application in the steel industry for the first time at Mizushima Works, resulting in improved software portability, which had been inadequate with process computer systems in the past. (2) Reuse of software Better efficiency was achieved in software design and production by the use of parts management practices developed for software specifications and programs on the basis of improved software portability. (3) Improved development environment A network system is essential as infrastructure for the reuse of software; a high-speed! highcapacity FDDI was introduced for this purpose. A multi-vendor development environment was constructed by linking process computer systems, workstations, and personal computers.

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These techniques were applied to a CGL system and to two continuous annealing line systems. The results include a reduction in software bugs and a two-fold increase in productivity. This paper presents an outline of software techniques developed by Kawasaki Steel Corporation .

Keywords. Process computer; Software development; Computer software; Reuse of software; Network; Steel industry.

Inlroduction

complex and larger in scale. and improvement in techniques for achieving higher productivity and better quality in software at the time of PC development has become an increasingly critic;!1 requirement.

Kawasaki Steel has consistently endeavored to improve yield. upgrade product quality, and reduce energy consumption with the aim of producing highquality. economically-priced steel products and thus supporting a wide range of industrial activities. Recent changes in the structure of consumption have brought about a shift from quantity to quality, so that greater importance is now attached to high product quality than in the past. Accordingly. s teelworks automation systems have tended to become increasingly sophisticated. Software for process computer (PC) systems, which are a key element in automation , have likewise become more

In addition to new software development as s uch, heavy weight is also given to the maintenance factor. Figure 1 shows the volume of software currently available at Mizushima Works . As these figures suggest. the appropriate development and maintenance of software with limited human resources requires measures for improved efficiency; this has become a major task of the I'nn t Con trol Technology Department.

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With the aim of achieving a qualitative leap forward in software quality and productivity, the authors began experiments with software reuse techniques in 1987. The software reuse environment thus developed covers software architecture and external computer interfacing, and has as its most important aim a higher level of portability. Conventional functions and program parts are also included in the structure of the environment.

devices, resulting in greater complexity of the equipment/PC interface . (4) The most efficient means of increasing software productivity is the use of software developed in similar processes. In practice, however, this is difficult, since the overall structure of software differs in each system. (5) Software assets are held and used locally in each shop, making it difficult to apply particular items of software on a works-wide basis.

This paper describes techniques developed to date at Mizushima Works for the enhancement of PC software quality and productivity.

Improvement of Software Portability and Autonomous DisLribuLed SysLem

Hierarchical Structure of Computer Systems at Mizushima Works

A design which only conventional functions and program parts is inadequate for software reuse. For this reason, software portability was the authors' prime consideration. This philosophy was realized in a new PC software architecture called the autonomous distributed system, which was developed and put into practical use jointly by Kawasaki Steel and i1itachi, Ltd. The fundamental concept of the autonomous distributed system is shown in Figure 3. The system is discussed with reference to this figure.

Mizushima Works is a large, modern steelworks with an exceptionally high level of computerization . The Works comprises more than twenty major shops, where computers of all sizes are used . As shown in Figure 2, these computers form a hierarchical structure consisting of central computers (CCs), on· line computers (OCs), process computers (PCs), and direct digital controllers (DDCs), which are organically linked and exchange information in real time. The functions allocated to each level of this hierarchy are as follows:

Features of Autonomous Distributed System In the autonomous distributed system, the computers and the application prograins which they contain are linked by a broadcast network called a data field, the basic principle of which is data flow. In the broadcast method which characterizes the data flow, da ta transmissions are made not made between specific system uni ts. Informa tion transmissions i ni tia ted by the recei ver side a re decoded a nd on ly the neccssa ry information is retained. The data flow information transmitted by computer A is called FC (Function Code) and has the structure shown in Figure 4. Computers Band C check the classes of information included in the FC transmission and determine whether it is to be retained in the computer or not. Accordingly, it is not necessary for computers Band C to know the configuration and status of the entire system, since these units are capable of identifying and retaining information appropriate for local use. In other words, the link between computers is not strong. and individual computers hnve a high degree of independence .

Central computers: Works-wide functions such as quality planning, production planning, manufacturing instructions, and production progress management. On-line computers: Operation control functions affecting individual shops or groups of shops with related processes. Prepares daily instruction sheets for line operation and supports the operationadjustment function . Process computers: Automatic control functions such as on-line control using formulas which model processes and tracking covering the total processes, based on the linkage of information and actual materials in process. DDCs: Automatic control function for individual units of equipment in each process. Generally, this level is comprised of the electrical system and the instrumentation system.

SofLware DevelopmenLlMainLenance Problems with Currently Existing PCs

Features of Operating System As shown in Figure 3, ench PC is controlled by an operating system called nn ACl' (Autonomous Control Processor). The ACP provides the npplicntion progr;J1ll with two interf:1cc modes (tran s miss ion, rccei v ing). and thus controls data communication.

Some of the principal problems in software development and maintenance are as follows: With conventional PCs, the scale of software with a si ngle system is limi ted to about 70-80K steps (lines of code) per system. With the continuation and synchronization of production facilities, however, the required scale has increased to 200K steps. (2) It is necessary to promote new development in parallel with maintenance and operation of PCs. Thus early development must be undertaken with limited manpower resources.

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Features of Applicntion Program Structure Figure 5 shows a compnri son of the fil e system in thc conventional system and the autonomou s di stributed system . The design concept in the conventionnl sys tem emphasized centralized datn nnd the common use of computer resources in nn effort to crente n unified dilta base. Conversely , port:lbility was n problcm. With the autonomous distributed system, however, ilpplication

(3) Progress in equipment automation has meant an increase in the number of smaller automation

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programs do not use common files. The data flow system is applied, and each application program establishes its own files. Because program units are "closed" with respect to the data flow, program independence is enhanced and the transfer of program blocks to other computers is easy.

7, a tree structure is used to unify and control software specification sheets. Sheets and folders are represented on the screen by icons, making it possible to select desired items from wi thin the standardized specification sheet. The features of the software development process are summarized below.

Although the great advantages of the autonomous distributed system software architecture in terms of portability and transferability have been mentioned, other advantages include improved expandability and reliability. These topics are discussed In detail elsewhere.' 1),12)

As shown in Figure 8, the development process for application programs has been standardized for all systems. First, the softwar e development proc ess was clarified, reference parts were established for each process, and the results to be achieved are reduced to rules. This means that the same set of development procedures is used for all systems and, at the same time, software products are of a common type.

Unified Interface with

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In the past, the design of common application programs and the creation of program parts was difficult because of heavy dependence on la devices. Expansion of the concept of the autonomous distributed system to include the la devices used with PCs, as shown in Figure 6, has solved this problem. By applying this concept, for example, the auth ors developed a utility tracking program for cold rolling processes. 1\ package for use with the autonomous distributed system was developed by unifying the processing of PlO (Process Input Output) signals for weld point detection , coil length sampling, and other functions under the data flow method. The main functions of this package are as follows:

Software specification sheets are expressed in hierarchical form by the classification keywords shown in Figure 7. In this method both graphics and text are controlled by parts. Functional division keywords are standardized for all systems so as to permit common design regardless of the system. This facilitates the reuse of software in all systems. With programs, a s with the software specification sheets , keywords have been decided for each classification , and program reuse is facilitated by parts control. The characteristics of the autonomous distributed system ensure that test results are not affected by the overall structure of the system. Test data can be easily reused by securing private files.

Control of coil length flnn information change points using signals from weld point detectors Backup control for weld point detector signals Control ofliming of information setup at sensors Control of information relating to up -and downstream material handling equipment Control of information revisions

Automatic programming tools are used lo improve the efficiency of the two-step operation of drafting detailed program flow charts and recording source codes. I\lthough these flow charts perform satisfactorily at workstations, their quality as documents is poor and they have not yet reached the stage of general use. Test operation has recently begun.

Data transmission control procedures for PCs were developed using an RS-232C interface in the data transmission line and are applied in connecting such sensors as the thickness and width meters.

Software portability and the standardization of products has improved th e level of reuse.

Company standards for the CC and OCs were established in 1983 and are now in general use. In the current project, efforts were therefore made to develop common communication procedures consistent with existing standards using an autonomous distributed interface for sensor-related microcomputers.

Realization of Multi-Vendor Environment lhrough Use of Network System One requirement for improved efficiency in software development is an adequate basic component comprising workstations, personal computers , and a network system, as shown in Figure 9. The following measures were implemented for this purpose.

As the first step in software reuse, the autonomous distributed system was applied to internal PC application programs to enhance portability. Standardization of interfacing with the external environment also improved the application program reuse ratio.

Construction of Network System

Application Software Parts and Reuse A flexible communication environment for workstations, PCs, and personal computers was constructed on the basis of an industry-standard FDDI (Fiber Distributed Data Interface) and "IEEE802.3." Features are as follows:

In software development, specifications are clarified at an early in the life cycle and recorded in specification sheets. To maximize software reuse, it is essential that existing software be incorporated into the development process in the up-front. A hierarchical method of document control was adopted using the basic unit "sheet," which is also the minimum unit of the specification sheet, and "folders." As shown in Figure

Planning was predicated on a multi-vendor capability. A high-speed, general-purpose open network was adopted.

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(4) Adoption of the parts methodology for software specifications and programs improved the efficiency of maintenance work after startup. (5) The time required for system development was reduced and an early startup was achieved.

File transfer and virtual terminal functions make possible free communication among workstations, PCs, and personal computers. The software development environment was shifted from the PC target machine to the distributed development environment based on workstations and personal computers.

Fu ture Tasks The following tasks are considered necessary in achieving higher levels of efficiency in software development in the future.

Document Workstations Document workstations are provided with functions which support high-efficiency preparation of fixedform documents such as software specifications. Support features include icons and multi-windows, which facilitate the preparation of graphics, tables, and text. Past document assets can be transferred between workstation windows. Numerous other functions also support document reuse efficiency.

(1) Introduction of a CASE (Computer-aided Software Engineering) tool with the aim of improving efficiency in upper-phase activities such as needs analysis. (2) Establishment of a reverse-engineering techniques for preparing up-to-date specification sheets the current format from information on systems already developed and in use, with the aim of improving maintenance efficiency. (3) Expanded application of already-adopted measures for productivity and quality improvement in the developmen t of future systems. (4) Improvement of parts data base management capabilities to further improve the use ratio for software parts. (5) Study and research in connection with security measures from the viewpoint of system protection , in response to the increasing size of LAN (Loca I Area Network) systems.

Personal Computers Personal computers are used in a variety of fields and now offer an abundance of processing functions. In this system an easy-to-use environment is created by linking personal computers in a network system, taking advantage of the outstanding costJperformance features of these machines. Program reuse was realized by adopting the Japanese language wordprocessing capabilities of personal computers as a cutand-paste function for programs.

Conclusion Engineering Workstations (EWs) With the aim of improving software productivity and quality, the authors introduced an autonomous distributed system, conducted development work related to such new technologies as software reuse and LANs, and developed new high-productivity, highreliability systems. In addition to new development activities, the authors intend to study CASE applications and the improvement of software control techniques in order to support high productivity in such tasks PC refurbishment, which is expected to assume increasing importance in the future.

Engineering workstations are used mainly in the capacity of test environment and file server. The structure created by the authors makes it possible to execute single tests in an EW environment. Notable features adopted include the pseudo-interface tool and debugging tool of the autonomous distributed system. The fact that software from other systems can be used as desired by way of the network system is a major advantage in software reuse. PC Software Development Machine

References The PC development machine is used mainly in integration testing for the final software check. It is also used in on-line simulation tests for maintenance purposes.

Mori, K., and 0 the I' s ( 1984) . Aut 0 nom 0 u s Decentralization Concept. Trans. IEEE of Japan, 104-c, No. 12. Mori, K., and others (1986). Autonomous Decentralized Software Structure And Its Application. Fall Joint Computer Conference, pp. 1056-1063(AClvI and IEEE) .

Results of Implementation The trend in software development productivity at Mizushima Works is shown in Figure 10. The results are summarized in the following in comparison with conventional technology. Software productivity is approximately twice as great as with conventional techniques, as shown in Fig. 10. (2) Software reliability, as evaluated by the incidence of errors in the trial operation of object systems, was almost twice as great with the new system. (3) Software portability was enhanced by adoption of the autonomous distributed system, eliminating duplication in the development of various systems.

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