JPH04332001A - Process control device - Google Patents

Abstract

PURPOSE:To prevent the operation of the whole control system from being influenced by a local change by sequentially executing control drawings and function blocks in each control area in accordance with the definition of each execution control table. CONSTITUTION:Each control drawing 2 is constituted of combining plural function blocks and attains an integrated control system. Each control area 3 is a group of plural control drawings 2 and attains a control system. A drawing execution control table 4 prepared in each control area 3 specifies the execution order of control drawings 2. Plural function block execution control tables 5 are linked with the table 4 and each table 5 specifies the execution order of the function blocks 1 in its corresponding drawing 2. Thereby local maintenance such as the addition, deletion, etc., of function blocks 1 can be executed without exerting influence upon other drawings 2.

Description

[Detailed description of the invention]

0001

[Field of Industrial Application] The present invention relates to a process control device that uses a computer to construct a control system by combining a plurality of functional blocks that execute predetermined control functions using software. The present invention relates to a process control device that allows the execution order of functional blocks to be partially changed without affecting desired control characteristics as a whole.

0002

[Prior Art] Process control equipment that uses a computer to construct a control system by combining multiple functional blocks that execute predetermined control functions using software has been put into practical use as a distributed control system. . Examples of multiple functional blocks include blocks that function as control instruments that perform feedback control, functional blocks that function as sequence control instruments that perform sequence control, and calculation function blocks that perform various calculations. A large control system (loop) is constructed by combining them as appropriate depending on the process to be carried out. Ideally, a computer that executes these various functional blocks should be capable of parallel execution, but as far as current digital computers are concerned, they are executed sequentially in some order. At this time, the dynamic characteristics of the control system generally differ depending on how the execution order is selected.
In the worst case, desired control characteristics may not be obtained. Therefore, in a process control device realized by a computer, it is necessary to be able to execute functional blocks in any order in order to obtain the control characteristics desired by the user. 5 and 6 are conceptual diagrams showing a conventional method for controlling the execution order of functional blocks in this type of process control device. FIG. 5 shows a definition order execution method, and as shown in the figure, the function blocks BK1, BK2, . FIG. 6 shows an execution order definition table method, in which each functional block is assigned a number representing the functional block as shown in the figure, and a definition table TL defining the execution order is prepared. This method executes in the order of definition.

0003

[Problem to be Solved by the Invention] However, although the definition order execution method shown in FIG. , the following problems arise. (a) The newly added functional block becomes the last functional block that already exists. For this reason, it is almost impossible to obtain the execution order desired by the user. (b) If you really want to change the execution order, you will have to go through the complicated process of sequentially changing the block numbers assigned to each functional block and inserting the additional functional blocks. In this case, by sequentially changing the block numbers, it becomes necessary to change definition information in other control loops that use those functional blocks, and partial corrections will affect others. (c) In order to avoid this kind of influence, when initially allocating functional blocks, it is possible to insert an appropriate empty block number for expansion, but in this case, it is necessary to prepare unnecessary functional blocks in advance. This results in a waste of software resources. The execution order definition table method shown in FIG. 6 allows function blocks to be executed in any order, so even function blocks added later can be freely inserted between existing function blocks. Problems can be resolved. However, when the scale of the control system increases, the following problems occur. (a) Even when it is desired to change the execution order very locally, the execution order definition tables of all functional blocks must be replaced. Since modification of the execution order table affects the execution processing program of the functional block, execution must be stopped at least immediately before loading the table. Therefore, even a local change affects the control operation of the entire control system. (b) When a control system becomes large-scale, users no longer recognize the entire control system uniformly. The reason for this is that grouping is performed according to the separation of target processes, and local maintenance for one process area and global maintenance for the entire control system can be distinguished and recognized. The execution order definition table that manages the entire system at once changes the configuration of the entire control system. For this reason, local maintenance operations for one area may interfere with maintenance for other areas. The present invention has been made in view of these points, and when constructing a large-scale control system by combining functional blocks,
Local changes do not affect the operation of the entire control system, and operations using local maintenance can be controlled even for users who take a hierarchical maintenance approach consisting of global maintenance and local maintenance. It is an object of the present invention to provide a process control device that can minimize interference with maintenance of other areas within the system.

0004

[Means for Solving the Problems] The present invention achieves the above objects in a process control device that constructs a control system by combining a plurality of functional blocks that execute predetermined control functions using software. A control drawing that realizes a control system by combining a plurality of control drawings, a plurality of control areas that realize one control system by aggregating a plurality of the control drawings, and a control drawing that is prepared for each control area and that is It is equipped with a drawing execution control table that defines the execution order, and a function block execution control table that is linked to this drawing execution control table and defines the execution order of the functional blocks in the drawing. This process control device is characterized in that control drawings and functional blocks are executed sequentially according to the definitions of each execution control table.

[0005]

[Operation] A plurality of control areas are prepared within the control device. Within these control areas, a control system is set up in units of control drawings. Furthermore, each control drawing is formed by combining a plurality of functional blocks. Control drawings and functional blocks within each control area are executed sequentially according to the definitions of the drawing execution control table and the functional block execution control table linked to this table.

[0006]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Examples of the present invention will be described in detail below with reference to the drawings. FIG. 1 is a conceptual diagram showing an embodiment of the apparatus of the present invention. In the figure, CS is a process control device,
Process signals PV from each sensor installed in the field
These process signals are input to a control system constructed by combining a plurality of functional blocks within a control device to obtain a control output MV, which is then output to a valve or the like. This includes functional blocks with feedback control calculation functions, functional blocks that perform sequence control,
A plurality of functional blocks 1, such as functional blocks that perform numerical/logical operations, etc., are prepared. Process control device CS
2a, 2b, 2c, . . . are control drawings for realizing a control system by combining a plurality of functional blocks 1. This control drawing is the smallest collection of functional blocks that can be considered as a control unit, and is defined as "equipment (Equipment)" defined in process control.
It is assumed that the control system is about the size of a "equipment module". 3a, 3b... are control drawing 2
This is a control area where multiple units are assembled to realize one independent control system. This control area consists of several "devices" (Uni
t) or area (
It is assumed that the scale will realize a control system in the range of "Area)". 4 is a drawing execution control table prepared for each control area 3a, 3b and defines the execution order of control drawing 2; 5 is a drawing execution control table 4;
and is linked to function block 1 in drawing 2.
This is a functional block execution control table that defines the execution order of the functions. The control drawings 2 and functional blocks 1 in each control area 3 are configured to be executed sequentially according to the definitions of the respective execution control tables 4 and 5.

FIG. 2 is a conceptual diagram showing the relationship between the control drawing 2 and functional blocks. Here, an example of a control system is shown in which the temperature of the polymerization pot as shown in (a) is controlled by adjusting the flow rate of the heating fluid supplied to the outer pot. In order to construct such a unified control system, one control drawing 2 is constructed by combining a plurality of functional blocks 1 as shown in (b). In this control drawing 2, 11 (tag name TIC102) is a functional block that functions as a temperature controller that receives the temperature signal (T1IN) inside the pot, and 12 (tag name
) is a functional block that functions as a computing unit that inputs the signal from the functional block 11 as a temperature controller and the flow rate signal (F1IN) of the raw material introduced into the pot;
are the heating fluid flow rate signal (F2IN), pressure signal (PIN
), a functional block that functions as an arithmetic unit that inputs a temperature signal (T2IN). Also, 14 (tag name FIC1
01) is a functional block that functions as a flow rate controller to which a signal from the functional block 12 that functions as a computing unit is applied as a set value SV, and a signal from the functional block 13 that functions as a computing unit is applied as a process signal PV. , the output MV (VOUT) from here is output to an operating end such as a valve. The control drawing 2 formed by such a control system is, for example, a control unit for controlling the heating of raw materials put into the pot.

In FIG. 1, each control drawing included in the control area 3a executes such a group of controls. For example, the control drawing 2a
The control drawing 2b executes heating control, for example, the control drawing 2b executes stirring control of the material in the pot, and the control drawing 2c executes control, for example, to discharge the stirred material from the pot. By executing each control drawing within these control areas, one system of process control is realized. In Figure 3, each area 3a, 3b
... and the process control system that each of these areas is in charge of. Area 3a is in charge of process control of the first system, area 3b is in charge of process control of the second system independent of the first system, and each control area is
Each is executed asynchronously.

FIG. 4 is a conceptual diagram of the structure of each table that manages the execution order of control drawings and functional blocks in each control area. The control drawing execution control table 4 specifies the processing order of control drawings, and the processing order is determined by the first drawing number (first DR
W#) Processing is started from the control drawing pointed to by the pointer, and when all processing in one drawing is completed, the drawing specified in the primary link direction is specified next. The functional block execution control table 5 specifies the execution order of functional blocks.The processing order starts from the functional block pointed to by the first block number pointer, and when the processing in that functional block is finished, the processing starts from the secondary functional block. The next functional block is configured to be processed according to the link (block link). Various databases used by each functional block are constructed for each control area.

Next, the operation of the apparatus configured as described above will be explained separately into the operation when executing control and the operation when changing the order of execution of functional blocks. (Operation during control execution) The programs that execute the functional block processing of each control area operate as independent tasks. Furthermore, the program that executes the functional block processing periodically starts processing from the control drawing pointed to by the first drawing number (first DRW#) pointer shown in the drawing execution control table 4. In each control drawing process, the process starts from the functional block pointed to by the first block number pointer of the primary link node. When the processing of that functional block is completed, the secondary link (block link) of the functional block execution table 5 is
Process the next functional block in sequence according to the following. When processing of all functional blocks in a certain control drawing is completed, the next control drawing is designated according to the primary link (drawing link) of the drawing execution control table 4. When the processing of all control drawings connected to the primary link is completed, the control area processing for that cycle ends.

(Operation when changing the functional block execution order) When changing the functional block execution order, the contents of the functional block execution control table 5 are changed. Such changes can be made in the builder that constructs the control system.The builder specifies the control area number and control drawing number indicating the control area, and then writes the function block execution control table 5.
The correction data (list data in which block numbers are listed in accordance with the execution order in the control drawing) is transferred to the control device CS. The control device CS that has received such list data modifies the secondary link (block link) of the control drawing of the corresponding control area in accordance with the modification data. When adding or deleting a functional block (when changing the configuration of a control drawing), this can also be accomplished by sending modification data of the functional block execution control table 5 from the builder to the control device in the same manner.

In this embodiment, it is assumed that the program that performs control area processing is a separate task for each control area, but it is possible to make the same task function equally well by, for example, time-sharing scheduling. Is possible. Furthermore, regarding the control drawing execution control table 4 and the functional block execution control table 5,
In both examples, links are bidirectionally linked, but bidirectional linking has the advantage that elements within the link can be specified and added, deleted, and searched at high speed. However, if such an advantage is not desired, the secondary link (block link) may be a unidirectional link, for example.

[0013]

[Effect] As explained in detail above, the present invention provides a control drawing execution control table that specifies the execution order of control drawings in the control area for each control area, and also provides an independent control table for each control drawing. A function block execution control table has been prepared that allows you to add a function block to a certain control drawing,
Local maintenance such as deletion or change of execution order can be performed without affecting the configuration or execution of other control drawings.

[Brief explanation of drawings]

FIG. 1 is a conceptual configuration diagram showing an embodiment of the apparatus of the present invention.

FIG. 2 is a conceptual diagram showing the relationship between control drawings and functional blocks.

FIG. 3 is a diagram showing the relationship between each control area and the process control system that each of these areas is in charge of.

FIG. 4 is a conceptual diagram of the structure of each table that manages the execution order of control drawings and functional blocks in each control area.

FIG. 5 is a conceptual diagram showing a conventional method for controlling the execution order of functional blocks.

FIG. 6 is a conceptual diagram showing a conventional method for controlling the execution order of functional blocks.

[Explanation of symbols]

CS Process control device 1 Functional block 2 Controlled drawing 3 Control area 4 Drawing execution control table 5 Function block execution control table

Claims (1)

[Claims] 1. A process control device that constructs a control system by combining a plurality of functional blocks that execute a predetermined control function using software, comprising: control drawing that realizes a control system by combining a plurality of functional blocks; , a plurality of control areas for realizing one control system by collecting a plurality of the control drawings, a drawing execution control table prepared for each control area and specifying the execution order of the control drawings, and the drawing execution control table. It has a function block execution control table that is linked to the table and specifies the execution order of the function blocks in the drawing, and the control drawings and function blocks in each control area are executed sequentially according to the definition of each execution control table. A process control device characterized in that: