WO2000041046A1

WO2000041046A1 - Method for performing control system functional design

Info

Publication number: WO2000041046A1
Application number: PCT/EP1999/007794
Authority: WO
Inventors: Guido Ceiner; Giuseppe Scafati; Massimo Danieli; Luca Ferrarini; Claudio Maffezzoni; Luciano Arrighi
Original assignee: Abb Research Ltd.
Priority date: 1998-12-31
Filing date: 1999-10-05
Publication date: 2000-07-13
Also published as: ITMI982871A0; ITMI982871A1; EP1075674A1; IT1304077B1

Abstract

The present invention discloses a method for performing a functional design for an industrial process/plant control system, characterized in that it comprises the steps of: using a data model adapted to define the control strategies related to said control system in a purely functional manner; and using a design interface to edit the functional diagrams related to said control strategies on the basis of said functional data model; and using an output interface for providing a representation of said functional diagrams according to predefined syntax and semantics.

Description

METHOD FOR PERFORMING CONTROL SYSTEM FUNCTIONAL

DESIGN DESCRIPTION

The present invention relates to a method for performing a functional design of control systems used for industrial automation. More particularly, the present invention relates to a method that can be used for editing the functional diagrams related to control strategies of distributed control systems for industrial processes/plants. It is known that, generally, the design of control systems for industrial processes/plants comprises a phase in which the functional design is performed. With the term "functional design" it is meant a design of the control strategies related to the control system which is related to the functionality of the process/plant to be controlled. This phase is then followed by the phase of programming the control system, using a language proper of the HW/SW control platform.

An important task in the functional design phase is represented by the task of editing said control strategies on a suitable computerized support. For accomplishing this task, common methods of the art allow the designer to use a set of libraries and graphic objects. These graphic objects are generally inspired, in their form, semantics and syntax, by recognized international standards well known to those skilled in the art such as, for example, DIN/VGB or SAMA.

The graphic objects and the libraries are managed by a hardware/software platform, which is used to implement the control system. In particular, the graphic objects are constituted by logic blocks which have input and output pins.

The pins are substantially of two kinds: - pins required to define the functions of the control strategies to be implemented; and - pins required for correct interfacing with the hardware/software platform being used. In known control system editing methods, a certain number of blocks is entered in the worksheet and the various pins are appropriately connected to each other in order to define the control function to be implemented. Known control system editing methods have several drawbacks, particularly due to the fact that they depend on the particular hardware/software (HW/SW) platform used. During the editing process, the designer must take into account both functional aspects and implementation problems linked to the particular HW/SW platform used. This necessarily entails less efficient and accurate design, since the designer must be expert both in the functional problems linked to the process and in the problems related to the particular HW/SW platform used. Moreover, reuse of already-edited and tested control strategies is compromised, since the editing process is closely tied to the particular HW/SW platform used. This entails that since the description of the control strategies is not purely functional, it cannot be used to control the same type of process or can be used only after readjustments that are highly onerous in terms of time and resource allocation.

The aim of the present invention is to provide a method for performing a functional design, particularly for industrial plant control systems, wherein the task of editing the functional diagrams is independent of the particular hardware/software platform used. Within the scope of this aim, an object of the present invention is to provide a method for performing a functional design, which allows obtaining documentation, which is structured and essentially functional, i.e., substantially tied to the nature of the control strategies to be implemented. Another object of the present invention is to provide a method for performing a functional design, which allows to feed, using a structured text complying with a well-defined semantics, a code generator which is capable of producing software which can be executed by any control platform. Another object of the present invention is to provide a method for performing a functional design, which allows to easily reuse strategies that have been already edited, tested and validated.

Another object of the present invention is to provide a method for performing a functional design, which allows performing a cheaper, more rapid, efficient and structured plant control system design.

Thus the present invention provides a method for performing a functional design for an industrial process/plant control system, characterized in that it comprises the steps of:

- using a data model adapted to define the control strategies related to said control system in a purely functional manner; and

- using a design interface to edit the functional diagrams related to said control strategies on the basis of said functional data model; and

- using an output interface for providing a representation of said functional diagrams according to predefined syntax and semantics. 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 schematic view of the steps of the method according to the invention;

Figure 2 is a schematic view of the functions into which said data model used by the method according to the invention is structured;

Figure 3 is a schematic view of the functions into which the design interface used by the method according to the invention is structured;

Figure 4 is a schematic view of the structure of the output interface used by the method according to the invention;

Figure 5 is a schematic view of the data flow in the method according to the invention;

Figure 6 is a schematic view of an electronic worksheet used by the method according to the invention.

With reference to Figures 1 and 2, the method according to the invention uses, for functionally designing the control strategies of said control system, a data model (block 2) which has a precisely defined structure suitable to be used subsequently by said design interface. Every functional diagram of control strategies is described by using elements, whose structure is defined in the data model. Said elements comprise information, which is closely correlated to the industrial process to be controlled. Preferably, the data model comprises at least one of the functions as in the following. a) Performing a first representation of the signals and the devices managed by the control system (block 5). Said representation of the signals and devices managed by the control system can comprise at least one of the descriptive fields as in the following. a. 1 ) A first field representing the external signals can be included. This field describes the signals exchanged between the control system and the plant

(block 1 2). Preferably, this first field comprises at least one of the following attributes: - an identifier which can be, for example, a name, a description, a suffix and a suffix description;

- a comment, ad example, for describing the aim of this first field;

- the type of external signal, which can be, for example, analog or digital; - the direction of the data flow, which can be in input or in output;

- an application attribute, which can be used to quickly understand the type of measurement to which the external signal relates;

- an instrument type, which is the type of the instrument from which the signal 5 is comins;

- the unit of measure associated with the external signal;

- an indication flag, which can be of the logic type and used to understand whether the signal is to be displayed;

- a logging flag, which can be of the logic type and used to understand whether 10 the signal is to be logged.

Preferably, the first field also comprises attributes, which depend on the type of the external signal. In particular, if the external signal is of the digital type (e.g. of the ON/OFF type), the attributes comprised in the field are:

- an alarm flag, which is a logic value suitable to detect when the value of the 1 external signal is not normal;

- a value attribute, which is the value of the corresponding analog component that determines the transition of the digital external signal;

-a normality flag, which is the value assumed by the signal in normal conditions. 2 If the external signal is of the analog type (continuous-type signals), advantageously the attributes comprised in said field are:

- a variability range, which comprises the maximum and minimum values assumed by the analog external signal;

- a threshold list, which comprises, for each item of the list, secondary

~> attributes such as identifier, value, type, indication flag, logging flag, and alarm flae. a.2) A second field which represents the internal signals (block 13) can be included. This second field describes the internal signals of the control system, exchanged for example between the operator and the control system. The block 1 3 preferably comprises the following attributes, similar to those used for the first field:

- identifier; - comment;

- type, which can be analog or digital;

- direction of the data flow;

- unit of measure;

- indication flag; - logging flag.

Preferably, if the internal signals are of the digital type, the block 13 also comprises the following attributes:

- alarm flag;

- normality flag. If the internal signals are of the analog type, then the block 13 can also comprise the following attributes:

- variability range. a.3) A third field which represents the devices of the plant (for example motors, pumps and the like) managed by said control system (block 14) can be included. The block 14 comprises advantageously the following attributes:

- identifier;

- comment;

- list of external signals coming from the devices of the control system;

- list of references (for example to a functional diagram or to a macro function). b) Performing a second representation of said functional diagrams (block 6). This second representation constitutes the representation of a control function in a project. In practice, it represents a control function of a significant part of a plant. Preferably, said representation comprises at least one of the descriptive fields as in the following. b.1 ) type of said functional diagram; b.2) identifier for identifying the part of diagram; b.3) general information on said functional diagram; b.4) comment; b.5) description of plant area: it can be a comment describing the plant area; b.6) description of plant functional group: it can be a comment describing the functional group; b.7) list of variables: in practice they represent the I/O signals exchanged by the selected area; b.8) list of terminals: they represent the I/O terminals proper of the selected area; b.9) list of elementary units that are the functional blocks used inside the diagram.

Preferably, the functional diagram can be of one of the following types:

- sequence type: a diagram of this type represents plant sequences which can concern, for example, the activation or shutdown of a plant portion;

- control type: a diagram of this type represents the analog regulation, typically implemented by means of an industrial controller;

- device type: a diagram of this type represents the control, actuation and protection functions of a device of a plant such as for example a pump, a valve, and the like;

- logic type: a diagram of this type represents the classical control and interlock logic systems;

- free type: a diagram of this type represents a non-standard functional diagram in which the designer can implement an ad-hoc control function. c) Performing a third representation of the (analog or digital) control variables. This representation can comprise the following descriptive fields (block 7): c. l ) name; c.2) comment; c.3)unit of measure; c.4)domain, which represents the range of the comprised control variables. d) Performing a fourth representation of the interface (terminals) among the functional diagrams or the functional diagrams and the signals or the functional diagrams and the devices managed by said control system (block 8). The fourth representation preferably comprises the following descriptive fields: d. 1 ) functional diagram corresponding to the terminal; d.2) interface name; d.3) comment; d.4) data flow direction; d.5) list of variables (each one defined, for example, by name and signal); d.6) external connection: wherein the terminal is connected. e) A fifth representation of elementary units used in said functional diagrams (block 9) can also be considered. Preferably, said representation comprises the following descriptive fields: e.1 ) functional diagram to which the block belongs; e.2) identifier; e.3) name of a function performed by the block; e.4) type (for example, analog or digital or sequence); e.5) list of pins required to establish an external connection. Each item is defined for example by a name, a type, a direction, and an external connection; e.6) parameter list. Each item is defined, for example, by a name, a type, a range, a value, a variable and a threshold number; f) Performing a sixth representation of blocks and connections used to control a given device (block 10) can also be included. Substantially they can be SW procedures (i.e SW macros), providing a SW interface level for a given device. The descriptive fields that can be used are preferably similar to those used for said fifth representation: f. 1 ) functional diagram to which the device belongs; f.2) identifier: f.3) name of a function performed by the device; f.4) type (for example, analog or digital or sequence); f.5) list of pins required to establish an external connection. Each item is defined for example by a name, a type, a direction, and an external connection; f.6) parameter list. Each item is defined, for example, by a name, a type, a range, a value, a variable and a threshold number; f.7) Description: the behavior of the macro is described. g) Performing a seventh representation of blocks and connections used to speed up editing operations (block 11). They are substantially groups of blocks that can be used for managing the control, for example, of a set of devices or of a device with the connected accessories. The following descriptive fields can be present: g. l ) identifier; g.2) comment; g.3) list of blocks and connections comprised.

With reference to Figures 1 and 3, the method according to the invention uses a design interface for editing functional diagrams (block 3). Said interface can be implemented by a configured computer system. The design interface is characterized in that it comprises a series of functions, which allow editing the functional diagrams rapidly and efficiently. Additionally, by using libraries and archives, it allows to advantageously reuse the information already available or validated. The interface preferably comprises at least one of the following functions suitable to allow to edit functional diagrams: h) editing of said functional diagrams pertinent to the control of a certain plant portion (block 20). i) basic editing (block 21). This function preferably allows the following operations:

- simultaneous opening of said functional diagrams;

- initialization of elementary units of the functional diagrams;

- placement of elementary units of the functional diagrams (for example placement, parameter attribution); - movements of elementary units of the functional diagrams;

- connection between elementary units of the functional diagrams;

- deletion of signals and connections between elementary units of said functional diagrams;

- deletion of elementary units of the functional diagrams; - management of cross-references between the functional diagrams or among different pages of a functional diagram (node management, navigation); j) editing of control sequences. This editing can occur by means of a standard language and preferably comprises:

- consistency verification operations; - "cut and paste" operations between elementary units of the functional diagrams;

- "copy and edit" operations between elementary units of the functional diagrams;

- graphic object zooming operations; - print preview operations;

- signal conditioning management, comprising the management of branch-off nodes and crossed procedures; k) advanced editing (block 22). This function preferably comprises the following operations:

- revision management (for example by indicating page, modification, deletion, insertion):

- modification of the representation of blocks and connections used to speed up editing and automatic propagation thereof;

- "search" and "search and replace" operations (for example search by page, by elementary unit, by signal, by name);

- saving operations;

- printing operations; - page management operations (for example adding, moving, removing a page);

- operations using "wizard" functions (for example sequences and macro functions);

1) management and use of libraries containing solutions which have already been implemented, verified and validated (block 23). This function preferably comprises the following operations:

- management and use of system libraries containing the know-how of the operators who engineer the control system;

- management and use of project libraries which contain the basic elements for designing a control system of a certain type. Said basic elements can be sequences already written according to an international standard or macro functions or typical adjustment and control logic system portions; m) management and use of archives (block 24). Preferably, this function comprises the following operations:

- management and use of project archives containing the preceding revisions of functional diagrams and copies, even if related to other projects;

- management and use of user archives containing the material developed during the project.

With reference to Figures 1 and 4, the method according to the invention comprises the use of an output interface (block 4). The interface also allows, by means of a computer system, to convert the information generated during the editing of the functional diagrams of the control systems into code, which can be executed by the hardware/software platform used by the control system. The interface allows rendering the method according to the invention independent of the particular hardware/software platform used. Said interface advantageously allows obtaining paper documentation, which is closely correlated to the controlled process and therefore which can be reused in other control systems. Preferably, the output interface comprises the following functions: o) performing an eight representation of the functional diagrams in the form of paper documentation in a manner which is strictly functional and independent of the hardware/software platform used by the control system (block 5); a) performing a ninth representation of the functional diagrams in the form of code which can be executed by a predefined syntax and semantics (block 6).

Said executable code can be used as input for the hardware/software platform used by the control system.

With reference to Figure 5, the data flow in the editing and printing method according to the invention is shown schematically. The designer receives in input, for example from plant basic engineering, the process information (block 40), the instrument database (block 41), the process and instrument diagrams (block 42) and the descriptions of the controlled processes (block 43). Advantageously, the designer composes the logic structures in a strictly functional manner, using for example the available libraries or archives and providing the appropriate connections.

Through the output interface, the method according to the invention allows to obtain both a code which can be processed by the hardware/software platform used by the control system (block 45) and paper documentation of the project (block 44 of Figure 5).

The method according to the invention can be implemented by a computer system (for example a computerized system, which is independent of the hardware/software platform used by the control system). In particular, editing of the functional diagrams by means of the design interface can occur by means of an electronic sheet shown by way of example in Figure 6. The output interface can be implemented by the same computer system or by another computer system. In practice it has been observed that the method according to the invention allows achieving the intended aim and objects. In particular, the fact that the method is substantially independent of the hardware/software platform allows optimizing the steps of the design of control systems, allowing effective reuse of data that has already been validated and tested. It has also been observed that the method according to the invention allows a considerable reduction in the time and cost required by control strategy design. The method thus conceived is susceptible of numerous modifications and variations, all of which are within the scope of the same inventive concept; all the details may also be replaced with other technically equivalent elements.

Claims

CLAIMS 1 . A method for designing control strategies for industrial process control systems, characterized in that it comprises the steps of: -using a data model adapted to define the control strategies related to said control system in a purely functional manner; and

-using a design interface to edit the functional diagrams related to said control strategies on the basis of said functional data model; and -using an output interface for providing a representation of said functional diagrams according to predefined syntax and semantics.

2. The method according to claim 1, characterized in that said data model comprises at least one of the following functions: a) performing a first representation of the signals and the devices managed by said control system; b) performing a second representation of said functional diagrams; c) performing a third representation of the control variables; d) performing a fourth representation of the interface among said functional diagrams or said functional diagrams and said signals or said functional diagrams and said devices managed by said control system; e) performing a fifth representation of elementary units used in said functional diagrams; f) performing a sixth representation of blocks and connections used for the control of a certain device; g) performing a seventh representation of blocks and connections used to speed up editing operations.

3. The method according to claim 1 , characterized in that said design interface comprises at least one of the following functions: a) editing said functional diagrams; b) basic editing; c) editing of control sequences d) advanced editing; e) library management and use; f) management and use of archives.

4. The method according to claim 1, characterized in that said output interface comprises at least one of the following functions: a) performing an eighth representation of said functional diagrams in the form of paper documentation; b) performing a ninth representation of said functional diagrams in the form of code which can be executed by a predefined syntax and semantics.

5. The method according to claim 2, characterized in that said first representation of the signals and devices managed by said control system comprises at least one of the following fields: a.1 ) a first field representing the external signals; a.2) a second field representing the internal signals; a.3) a third field representing the plant devices managed by said control system.

6. The method according to claim 5, characterized in that said first field which represents the external signals comprises at least one of the following attributes:

- identifier;

- comment;

- type;

- data flow direction; - application;

- instrument type;

- unit of measure;

- indication flag; - logging flag.

7. The method according to claim 6, characterized in that said external signals are digital signals and in that said first field also comprises at least one of the following attributes: - alarm flag;

- value;

- normality flag.

8. The method according to claim 6, characterized in that said external signals are analog signals and in that said first field also comprises at least one of the following attributes:

- variability range;

- threshold list.

9. The method according to claim 5, characterized in that said second field that represents the internal signals comprises at least one of the following attributes:

- identifier;

- comment;

- type;

- data flow direction; - unit of measure;

- indication flag;

- logging flag.

10. The method according to claim 9, characterized in that said internal signals are digital signals and in that said second field also comprises at least one of the following attributes:

- alarm flag;

- normality flag.

1 1.The method according to claim 9, characterized in that said internal signals are analog signal and in that said second field also comprises at least the following attribute:

- variability range.

12. The method according to claim 5, characterized in that said third field that represents the devices managed by said control system comprises at least one of the following attributes:

- identifier;

- comment;

- list of external signals; - list of references.

13. The method according to claim 2, characterized in that said second representation of said functional diagrams comprises at least one of the following fields: b. 1 ) type of said functional diagram; b.2) identifier; b.3) general information on said functional diagram; b.4) comment; b.5) plant area description; b.6) description of plant functional group; b.7) list of variables; b.8) list of terminals; b.9) list of elementary units.

14. The method according to claim 13, characterized in that the type of said functional diagram comprises at least one of the following typess: - sequence type;

- control type;

- device type;

- logic type; - free type.

15. The method according to claim 2, characterized in that said third representation of said control variables comprises at least one of the following fields: c.1 ) name; c.2) comment; c.3) unit of measure; c.4) domain.

16. The method according to claim 2, characterized in that said fourth representation of the interface among said functional diagrams or between said functional diagrams and said signals or between said functional diagrams and said devices managed by said control system comprises at least one of the following fields: d. l ) functional diagram; d.2) name; d.3) comment; d.4) data flow direction; d.5) list of variables; d.6) external connection.

17. The method according to claim 2, characterized in that said fifth representation of elementary units used in said functional diagrams comprises at least one of the following fields: e.1 ) functional diagram; e.2) identifier; e.3) name of a function; e.4) type; e.5) list of pins; e.6) list of parameters.

1 8. The method according to claim 2, characterized in that said sixth representation of elementary units used in said functional diagrams comprises at least one of the following fields: f. 1 ) functional diagram; 5 f.2) identifier; f.3) name of a function; f.4) type; f.5) list of pins; f.6) list of parameters; i o f.7) description.

19. The method according to claim 2, characterized in that said seventh representation of elementary units used in said functional diagrams comprises at least one of the following fields: g. l ) identifier; 15 g.2) comment; g.3) list of blocks and connections.

20. The method according to claim 3, characterized in that said basic editing function comprises at least one of the following operations:

- simultaneous opening of said functional diagrams; 0 - initialization of elementary units of said functional diagrams;

- placement of elementary units of said functional diagrams;

- movements of elementary units of said functional diagrams;

- connection between elementary units of said functional diagrams;

- deletion of signals and connections between elementary units of said 5 functional diagrams;

- deletion of elementary units of said functional diagrams;

- management of cross-references;

- editing of control sequences; - consistency verification operations;

- "cut and paste" operations between elementary units of said functional diagrams;

- "copy and edit" operations between elementary units of said functional diagrams;

- graphic object zooming operations;

- print preview operations;

- signal conditioning management.

21 . The method according to claim 3, characterized in that said advanced editing function comprises at least one of the following operations:

- revision management;

- modification of said representation of blocks and connections used to speed up editing and automatic propagation thereof;

- "search" and "search and replace" operations; - saving operations;

- printing operations;

- page management operations;

- operations using "wizard" functions.

22. The method according to claim 3, characterized in that said library management and use function comprises:

- management and use of system libraries;

- management and use of project libraries.

23. The method according to claim 3, characterized in that said archive management and use function comprises: - management and use of project archives;

- management and use of user archives.