WO2000020934A1

WO2000020934A1 - Method for designing/testing industrial control systems

Info

Publication number: WO2000020934A1
Application number: PCT/EP1999/007790
Authority: WO
Inventors: Guido Ceiner; Massimo Danieli; Lucas Ferrarini; Claudio Maffezzoni; Giuseppe Scafati
Original assignee: Abb Research Ltd
Priority date: 1998-10-06
Filing date: 1999-10-05
Publication date: 2000-04-13
Also published as: IT1302613B1; ITMI982149A1

Abstract

A method for designing and testing industrial process automation and control systems comprising the steps of: defining, on the basis of process data, modules of control functions of a plant; writing said control functions in a functional manner, independently of the control system platform in which the functions are to be implemented; and automatically converting said control functions into a language that can be executed by a given control system platform.

Description

METHOD FOR DESIGNING/TESTING INDUSTRIAL CONTROL SYSTEMS DESCRIPTION

The present invention relates to a method for designing and testing industrial s control systems. More particularly the present invention to a method for designing control systems, generally used for automation of industrial plants. It is known that the activity for designing and testing systems such those used for controlling industrial plants is quite laborious and entails a sequence of different phases which is described in the following. in In basic engineering phase, the paper and/or computerized files that comprise the input information for the configuration of the control systems are prepared. These documents, often called "Process and Instrumentation Diagrams" ( P&IDs), are produced by using both integrated computerized tools, sharing common databases, and tools, individually dedicated to the production of a i ^ specific document.

The information arriving from basic engineering is then processed in order to produce the paper documents that describe the control logic systems from a functional point of view. In practice functional aspects, like the plant regulations and structure, the input/output points to be connected to the control

2o system (the latter being also available in electronic form), are taken in consideration and designed.

In order to produce the documents related to the functional description of the plant, CAD (Computer Aided Design) tools are often used in which the only final product consists of the paper documents that the programmer must use to

2^ provide the control functions described by the designer.

The documents that functionally describe the control system are employed for providing the detailed configuration. Configuration engineers use these documents to implement the logic systems and the adjustment on a specific control system platform, using one the known languages to those skilled in the art. In practice the programming of the adopted logic controls is performed in this phase. Once the control system has been configured, it is factory-tested. The testing phase consists of hardware tests of the control system and of tests

5 of its software configuration (databases and/or logic controls and/or graphic pages and the like).

The control system is then shipped for installation at the site of operation and, once assembly has been completed, the control system is field-tested and calibrated, ending with the release of the apparatus. i n Many drawbacks can be observed in the current phase sequence of the design and testing of industrial process control. The main ones are described in the fol lowing.

First, the study of the control functions of the plant occurs without the aid of a tool, which allows designing them before their implementation according to a

\ *> specific representation standard.

By working in this way, the quality of the structure of the control functions is entrusted exclusively to the sensitivity and experience of the engineer who develops them. Editing the control functions of the plant by means of a CAD tool which, for its

20 nature, is only capable of providing paper documents requires a second operation for re-editing the same information on the specific control platform to be configured. This duplication of work of course entails lower efficiency of the entire workflow and adds another useless source of error. Moreover, the inevitable configuration and editing error and the functional errors made during

25 control function engineering cannot be easily traced to a given step of design. It is therefore necessary to recheck the entire workflow carried out up to that time. Moreover the presence of many manual steps makes very difficult the re-using of control solutions already adopted and tested in previous control system's. The control functions, edited functionally by means of the CAD tool, are not subject to formal verification by means of a suitable software tool before they are re-edited on a specific control platform. As a consequence of this, when the control functions are tested the operator has to handle simultaneously both functional problems (for example logic errors in the implementation of the control functions) and programming-related problems linked to the specific control system platform (for example the functional block scanning order). The possibility of refining and correcting the implemented control functions is assigned to the field testing step, where the control system is actually connected to the process to be controlled. Any errors in implementation and any inefficiencies of the control system directly affect the real process, with all the consequent risks and costs. In fact the customer generally requires heavy penalties if the designed control system is not capable of operating correctly and entails undesirable plant stoppages.

In order to improve this situation, some computerized design tools, that allow performing a functional approach to the implementation of the control system, have been introduced recently. Unfortunately these tools are dedicated to a specific control system platform. In practice, the operator who defines the control strategies must also take into account, while he is implementing said strategies, specific programming problems related to the particular operation of a specific computerized machine, comprised in the adopted specific platform. The aim of the present invention is to provide a method for designing and testing industrial control systems which allows improving the current sequence of phases, eliminating redundant steps and sources of errors.

Within the scope of this aim, an object of the present invention is to provide a method for designing and testing industrial control systems in which the control functions are highly orientated to the process being controlled, so as to facilitate reuse of prepared and tested solutions.

Another object of the present invention is to provide a method for designing and testing industrial control systems, which allows designing plant control strategies independently of the type of hardware and software of the control system used.

Another object of the present invention is to provide a method for designing and testing industrial control systems, which allows testing the defined controlled strategies by emulating the control logic systems.

Another object of the present invention is to provide a method for designing and testing industrial control systems, which allows automatically obtaining the program code that can be executed by a specific control system starting from the functional description of the plant control strategies.

Another object of the present invention is to provide a method for designing and testing industrial control systems, which allows improving the efficiency of the control system testing activity. This should be obtained not only by means of the emulation of the control logic systems but also by means of the simulation of the process in a single integrated environment.

Thus the present invention provides a method for designing and testing industrial control systems, characterized in that it comprises the steps of: defining, on the basis of process data, modules of control functions of a plant; writing said control functions in a functional manner, independently of the control system platform in which said control functions are to be implemented; and automatically converting said logic control functions into a language that can be executed by said given control system platform.

Further characteristics and advantages of the present invention will become apparent from the following detailed description of a preferred embodiment of the method according to the invention, illustrated only by way of non-limitative example in the accompanying drawings, wherein:

Figure 1 is a conceptual block diagram of the steps that compose the method for designing and testing automation and control systems according to the present invention;

Figure 2 is a general block diagram of the portions of program for performing the method according to the present invention; and

Figure 3 is a more detailed block diagram of the implementation of the method according to the present invention.

With reference to the above figures, and initially with reference to Figure 1 , the method according to the present invention comprises a first step (reference numeral 2 ) i n which process data, designated by the reference numeral 1 , are employed to define the control systems structure. The control system structure is preformed in a strictly functional manner, i.e., entirely independently of implementation problems related to the use of a specific control system platform but strictly oriented to the control problems.

Process data 1 can for example be comprised in the P&IDs that are generally used. The functional data obtained from step 2, designated by the reference numeral 3. are used (step 4), at this point, to automatically generate code for implementing the functions of the control system provided previously.

Moreover, the plant configuration data, produced by step 4 and designated by the reference numeral 5, are used to perform an emulation of the control system, not directly in the field, as occurs in the prior art, but in the laboratory

(step 6).

The sequence of steps described, provided by the method according to the present invention, is particularly advantageous because it allows eliminating some direct sources of mistakes, due to manual editing operations.

With reference now to Figure 2 and 3 (where identical reference numbers indicate equivalent elements), two computerized environments, which allow providing preferred embodiments of the method according to the invention, are illustrated schematically. The computerized environments, designated by the reference numerals 10a and 10b, can be comprised suitably configured computerized systems. The computerized environments internally integrate a plurality of modules.

As illustrated in figure 3, they can be provided with a video interface 20 and databases 2 1 .

Specifically, the module 1 1 provides project management (PM) functions.

Such PM functions can be quite various: l o - the opening of a project number; and/or

- the definition of control function modules; and/or

- the organization of the control modules by means of a file manager; and/or

- the management of the links between the control modules; and/or

- the management of libraries of control modules; and/or i - the copying and deletion of control modules.

The reference numeral 12 instead designates an editing module, which allows to perform the step 2 of writing the control functions in a strictly functional manner, i .e.. independently of implementation problems linked to the use of a speci fic control system. Advantageously, this phase is performed using the

2o project management functions above described.

I n particular, the module 12 for editing the control system function allows the operator to edit, by using recognized representation standards such as for example DIN/VGB or SAMA or ISA. The module 12 makes available a library of graphic symbols, which conforms to the adopted representation standards.

25 The control functions are written by means of a CAD-based graphic tool, which is capable of offering a complete series of low- and high-level editing options. During the writing of a logic system or of a plant adjustment, a structured text is compi led in a fully operator-transparent manner; said text describes, according to an appropriate language, the semantics of the control flow entered by the operator by means of functional blocks and their links.

Preferably, the phase of writing the control functions in the module 12 provides the steps ( defining a set of control functions by the operator and/or functional diagrams 22 which contain the representation of the control functions for a very speci fic portion of the process.

This representation can be made available to the operator on different levels of interaction. For example: - on a graphic level, on which the operator works; and

- on a text level, which is written automatically by the module 1 2 and converts into a structured text the logic system information described by means of the functional block language, an example of which is designated by the reference numerals 23, 24 and 25 of figure 3; and/or - on a documentation level which represent a portion of the functional diagram which corresponds to the printed page in the output documentation. During editing, the module 12 allows the operator to write his control strategies without worrying about how the implemented data will be documented on paper. Advantageously, during editing, the operator can be presented with a dashed-line grid of sheets, which compose the functional diagram being edited. The module 12, during documentation (i.e., sheet printout), organizes the printout according to the sheets used and automatically manages the links between the sheets; and/or

- on a connection level where connections to the functional diagram, which provide information exchange between logic and adjustment portions are represented:

- on a signal level where signals, which constitute the information that arrives from the field, i.e., the data 1 shown in Figure 1 , are represented. The reference numeral 13 designates a code generator module, which allows performing the automatic conversion into executable code of the control functions described functionally in module 12 (step 4 of figure 1 ). The code generator module 13 allows having an automatic conversion of the functionally described control strategies into a code, which can be executed by a speci fic control system platform. The code generator 13 converts the text representation of the functional diagrams 22 and the corresponding database of signals and information exchanged into the executable code and into the corresponding platform database for the specific control system. The reference numeral 14 designates a control function emulator module by means of which it is possible to perform the preferred additional step of testing the formal correctness of the implemented control functions by executing them within the operating environment 10 itself (step 6 of figure 1 ). The reference numeral 15 designates a module, which allows, in a preferred embodiment of the method according to the present invention, defining the architecture of the control system as a function of the structure of the process. I n practice this module can comprise an automatic tool, which help the operator lo logically decompose the process flow in a plurality of elementary portions and manage these portions in a structured manner. Once the information regarding the process has been structured, the operator can easily design the control functions in a manner strictly related to the process. The reference numeral 16 designates a process simulation module, which al lows, in another preferred embodiment of the method according to the invention, simulating the dynamics of the controlled process on the basis of equations that describe said process.

This simulation step, together with the emulation step performed in module 14, allows effectively testing the control functions, defined for the management and control of the plant. It has been proven that the method according to the present invention allows reaching the intended aims.

In particular the method according to the present invention is highly process- orientated, improving the qualities of the control functions and allowing to

5 reuse the prepared solutions in subsequent processes which require similar strategies for particular steps. These characteristics represent a relevant i mprovement given the fact that, on the contrary, conventional control function design methods are highly orientated to the control system platform on which said strategies must be implemented rather than to the process to control.

10 In this way the control functions can be subsequently reused in most cases. Reusing solutions prepared and tested for a particular type of plant entails a drastic reduction in the time required to configure and test control systems. Moreover, the functional design of the control functions independently of the type of hardware and software of the control system platform adopted entails a i better design of said strategies. This fact is possible because during editing the designer needs to take into account only functional aspects, without considering at all the programming issues related to a specific control system. The automatic generation of the executable code starting from the functional description of the plant control strategies allows avoiding to duplicate the

2o control system design steps, consequently saving time and reducing the human errors that inevitably occur.

Finally, the possibility of simulating and emulating process control directly during the creation of the control system allows to avoid unwanted errors which in the case of conventional engineering methods would be detected only

2 once the control system is installed in the field.

The method thus conceived is susceptible of numerous modifications and variations, all of which are within the scope of the inventive concept; all the details may also be replaced with other technically equivalent elements.

Claims

1 . A method for designing and testing industrial control systems, characterized in that it comprises the steps of:

- defi ning, on the basis of process data, modules of control functions of a plant: and

- writing said control functions in a functional manner, independently of the control system platform in which said control functions are to be i mplemented; and

- automatically converting said control functions into a language that can be executed by a given control system.

2. The method according to claim 1 , characterized in that it comprises an additional step of testing said control functions by emulating them, before the control system is installed in the field.

3. The method according to claim 1 or 2, characterized in that it comprises a step of designing said control functions on the basis of the characteristics of said process provided in said plant.

4. The method according to one or more of the preceding claims, characterized in that it comprises a step of simulating the dynamics of said process, on the basis of equations that describe said process.

5. The method according to one or more of the previous claims, characterized in that said step of writing the control functions comprises the definition of said control functions by means of a graphic language.

6. The method according to claim 5, characterized in that said graphic language is converted into a text representation according to a formal language which is suitable to be translated autonomously into code which can be executed by a control system.

7. The method according to one or more of the previous claims characterized in that said step of writing the control functions comprises the steps of;

- defining a set of control functions by the operator; and/or

- defining functional diagrams containing the representation of the control functions for a very specific portion of the process. S. The method according to claim 5, characterized in that said representation of the control functions is made available to the operator on different levels of interaction.

9. A computerized system for designing control systems for an industrial plant, characterized by the fact of comprising a computerized environment for performing a design method according to one or more of the preceding claims.

1 0. A computerized system according to claim 9 characterized by the fact that said computerized environment comprises the following modules:

- a module providing project management functions; and

- an editing module, which allows writing the control functions in a strictly functional manner: and

- a code generator module, which allows performing the automatic conversion into executable code of the written control functions.

I 1 . A computerized system according to claim 10 characterized by the fact that said computerized environment comprises the following additional modules:

- a control function emulator module which allows testing the formal correctness of the implemented control functions; and/or

- a module, which allows defining the architecture of the control system as a function of the structure of the process;

- a process simulation module, which allows simulating the dynamics of the control led process on the basis of equations that describe said process.

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