JP2722851B2 - Process control equipment - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a process control apparatus using a computer to construct a control system by combining a plurality of functional blocks for executing a predetermined control function by software. The present invention relates to a process control device capable of partially changing the execution order of functional blocks without affecting desired control characteristics as a whole.

[0002]

2. Description of the Related Art A process control apparatus using a computer and constructing a control system by combining a plurality of functional blocks for executing a predetermined control function by software has been practically used as a distributed control system. . The plurality of functional blocks include, for example, a block that functions as a control instrument that performs feedback control, a functional block that functions as a sequence control instrument that performs sequence control, and an arithmetic function block that performs various calculations. The large control system (loop) is constructed by appropriately combining according to the process to be performed. The computer that executes these various functional blocks is
Ideally, those that can be executed in parallel are desirable, but as long as they are implemented on a current digital computer, they are executed sequentially in any 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, the desired control characteristics may not be obtained. Therefore, in a process control device realized by a computer, in order to obtain a control characteristic desired by a user,
It is necessary to be able to execute the functional blocks in any order. FIG. 5 and FIG. 6 are conceptual diagrams showing a conventional method of controlling the execution order of functional blocks in this type of process control device. FIG. 5 shows a definition order execution method. As shown in FIG. 5, the function blocks BK1, BK2
.. Are executed in the order of arrangement (if numbers are assigned, in numerical order). FIG. 6 shows an execution order definition table method. Each function block is assigned a number representative of the function block as shown in the figure, and a definition table TL defining the execution order is prepared. This method is executed in the order of definition.

[0003]

However, the definition order execution method shown in FIG. 5 has the advantage of simplicity. However, after constructing an initial control system, if an attempt is made to add a functional block according to the operating situation. The following problems arise. (a) The newly added functional block is the last of the existing functional blocks. Therefore, the execution order desired by the user is hardly obtained. (b) If it is absolutely necessary to change the execution order, it is necessary to change the block numbers assigned to the respective functional blocks sequentially and insert a functional block to be added, which is complicated. In this case, since the block numbers are sequentially changed, it is necessary to change definition information in other control loops using those function blocks, and the partial correction affects others. (c) In order to avoid such an effect, when assigning function blocks initially, it is sufficient to insert an empty block number appropriately for expansion, but in this case, prepare unnecessary function blocks in advance. This is a waste of software resources. In the execution order definition table method shown in FIG. 6, since the function blocks can be executed in an arbitrary order, the function blocks added later can be freely inserted between the existing function blocks. The problem can be solved. However, when the scale of the control system is increased, the following problem occurs. (a) Even when it is desired to change the execution order extremely locally, the execution order definition tables of all functional blocks are replaced. Since the modification of the execution order table affects the execution processing program of the functional block, it is necessary to stop the execution at least immediately before loading the table. For this reason, even a local change affects the control operation of the entire control system. (b) If the control system becomes large-scale, the user will not recognize the entire control system uniformly. The reason is that grouping is performed in accordance with the division of the target process, and local maintenance for one process area and global maintenance for viewing the entire control system are distinguished and recognized. The execution order definition table that collectively manages the whole changes the configuration of the entire control system. For this reason, a local maintenance operation for one area may interfere with maintenance for another area. The present invention has been made in view of these points, and when a large-scale control system is constructed by combining functional blocks,
Local change does not affect the operation of the entire control system, and local maintenance operation is controlled even for users who take a hierarchical maintenance approach consisting of global maintenance and local maintenance. An object of the present invention is to provide a process control device capable of minimizing interference with maintenance of other areas in a system.

[0004]

SUMMARY OF THE INVENTION In order to achieve the above object, the present invention provides a process control apparatus for constructing a control system by combining a plurality of function blocks for executing a predetermined control function by software. A control drawing that realizes a single control system by combining a plurality of the control drawings; a plurality of control areas that realize a single control system by collecting a plurality of the control drawings; and A drawing execution control table that defines an execution order; and a function block execution control table that is linked to the drawing execution control table and that defines an execution order of the function blocks in the drawing. Control drawings and function blocks are executed sequentially according to the definition of each execution control table. A process control device being characterized in that so as to be line.

[0005]

The control device has a plurality of control areas. In each of 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. The control drawing and the function block in each control area are sequentially executed according to the definition of the drawing execution table and the function block execution control table linked to this table. Here, the technical meanings of the functional block, the control drawing, and the control area are as follows. Function block: The function block is a basic element that is a minimum unit of the control function, and is configured to calculate an output signal by software based on data read from an input terminal and output a calculation result from an output terminal. I have. As the operation, a feedback control operation, a sequence control operation, a numerical / logical operation, and the like are performed. Each function block is assigned identification information such as a tag name for specifying the function block. The technique of forming a control circuit by combining such functional blocks is a known matter, for example, as disclosed in Japanese Patent Application Laid-Open No. 55-127607. Control drawing: Control drawing is composed of a minimum collection of functional blocks that can be regarded as a unit of control by a user, and each control drawing is assigned identification information such as a drawing number for identifying the control drawing. Can be There is no restriction on the number of functional blocks included in the control drawing, and the size is freely determined according to the user's requirements. "Equipment module (Equipm) defined in the process control production model
It is convenient to make a range corresponding to "ent Module)" correspond to one control drawing. Each function block included in one control drawing is continuously processed without being interrupted by a function block included in another control drawing. By introducing such a concept of control drawing, it is possible to engineer the control drawing as one block (unit),
The user can efficiently organize and manage the control system. Control area: The control area is constituted by a set of control drawings that can be regarded as an independent control system. The size of the control area can be freely determined according to a user's request. However, the "train (Line)" including several "devices" or "area (A)"
rea) ”is assumed to be expressed in a control system degree in a range called“ rea ”. By introducing such a concept of the control area, a theoretically independent control system can be allocated to each control area, and each control area is
They function independently without affecting each other, so that engineering work (construction / generation / test / execution / maintenance of control systems, etc.) can be easily performed in a distributed manner for each control area. The English process control term shown in parentheses is "Batch System Standard (ISA / SP8
8) ”.

[0006]

Embodiments of the present invention will be described below in detail with reference to the drawings. FIG. 1 is a conceptual view showing the configuration of an embodiment of the apparatus of the present invention. In the figure, CS is a process control device,
Process signal PV from each sensor installed in the field
The control output MV is obtained through a control system constructed by combining a plurality of functional blocks in the control device with respect to these process signals, and the control output MV is output to a valve or the like. Among them are a function block having a feedback control calculation function, a function block performing sequence control,
A plurality of functional blocks 1 such as functional blocks for performing numerical and logical operations are prepared. Process control device CS
, 2a, 2b, 2c... Are control drawings for realizing a group of control systems by combining a plurality of functional blocks 1. This control drawing is the smallest set of functional blocks that can be considered as a set of control units.
uipment Module). Reference numerals 3a, 3b,... Are control areas in which a plurality of control drawings 2 are assembled to realize one independent control system. This control area is composed of a system (T
The scale is assumed to realize a control system in the range of about “rain) or“ Area ”. 4 is a control area 3a, 3b
A drawing execution control table, which is prepared for each execution and defines the execution order of the control drawing 2, is linked to the drawing execution control table 4, and a function block execution control table that defines the execution order of the function blocks 1 in the drawing 2. It is. The control drawing 2 and the function block 1 in each control area 3 are configured to be sequentially executed according to the definitions of the execution control tables 4 and 5.

FIG. 2 is a conceptual diagram showing the relationship between the control drawing 2 and the functional blocks. Here, an example of a control system for controlling the temperature of the polymerization vessel as shown in (a) by adjusting the flow rate of the heating fluid supplied to the outer vessel is shown.
In order to construct such a group of control systems, one control drawing 2 is configured by combining a plurality of functional blocks 1 as shown in FIG. In the control drawing 2, reference numeral 11 (tag name TIC102) is a functional block functioning as a temperature controller to which a temperature signal (T1IN) in the kettle is input, and 12 (tag name X10).
3) is a functional block that functions as a computing unit that inputs a signal from the functional block 11 as a temperature controller and a flow rate signal (F1IN) of raw materials introduced into the kettle.
3 is a flow signal (F2IN) of the heating fluid and a pressure signal (PI
N), which is a functional block functioning as an arithmetic unit for inputting a temperature signal (T2IN). In addition, 14 (tag name FIC
101) is a functional block functioning as a flow controller in which a signal from a functional block 12 functioning as a computing unit is applied as a set value SV and a signal from a functional block 13 functioning as a computing unit is applied as a process signal PV. The output MV (VOUT) from here is output to an operation terminal 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 the raw material put into the kettle.

In FIG. 1, each control drawing included in the control area 3a executes such a group of controls, for example, the control drawing 2a.
Performs heating control, the control drawing 2b performs, for example, stirring control of the material in the kettle, and the control drawing 2c performs, for example, control for discharging the stirred material from the kettle. By executing each control drawing in these control areas, one system of process control is realized. FIG. 3 shows each area 3a, 3b.
And a diagram showing a relationship between each area and a process control system in charge of each area. The area 3a is in charge of a first system process control, and the area 3b is in charge of a second system process control independent of the first system.
Each is executed asynchronously.

FIG. 4 is a conceptual diagram showing the structure of each table for managing the order of execution of control drawings and functional blocks in each control area. The control drawing execution control table 4 specifies the processing order of the control drawing, and the processing order is determined by the head drawing number (head D).
RW #) The processing is started from the control drawing indicated by the pointer, and when the processing in one drawing is completed, the drawing specified in the primary link direction is specified next. The function block execution control table 5 specifies the execution order of the function blocks. The order of the processing is such that the processing starts from the function block indicated by the first block number pointer, and when the processing in the function block ends, the secondary According to the link (block link), the next functional block is processed. Here, 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 described separately for the operation at the time of executing the control and the operation at the time of changing the execution order of the functional blocks. (Operation at the Time of Executing Control) The programs that execute the function block processing of each control area operate as independent tasks. Further, the program for executing the functional block process starts the process from the control drawing indicated by the head drawing number (head DRW #) pointer indicated in the drawing execution control table 4 at a fixed period. In the processing in each control drawing, the processing is started from the functional block indicated by the head block number pointer of the primary link node. When the processing of the functional block is completed, the secondary link (block link) of the functional block execution table 5
, The next function block is sequentially processed. When the processing of all the function 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 the control drawings connected to the primary link is completed, the control area processing in that cycle ends.

(Operation at the Time of Changing Functional Block Execution Order) When the execution order of the functional blocks is changed, the contents of the function block execution control table 5 are changed. Such changes can be made in the builder that builds the control system.
A control area number and a control drawing number indicating a control area are specified from the builder, and the correction data of the functional block execution control table 5 (list data in which the block numbers are listed along the execution order in the control drawing) in the control device are transmitted to the control device. Transfer to CS. The control device CS receiving such list data corrects the secondary link (block link) of the control drawing of the corresponding control area according to the correction data. When adding or deleting functional blocks (when changing the configuration of control drawing),
Function block execution control table 5 in the same way from the builder
The correction data can be transmitted to the control device.

In this embodiment, the program for performing the control area processing is assumed to be a separate task for each control area. However, the same task can be made to function equally by, for example, time division scheduling. It is possible. Further, regarding the control drawing execution control table 4 and the function block execution control table 5,
In each case, the link is bidirectionally linked. However, the bidirectional link has an advantage that the addition, deletion, and search of an element in the link can be performed at high speed. However, if such a merit is not desired, a secondary link (block link) may be a one-way link, for example.

[0013]

As described above in detail, according to the present invention, a control drawing for realizing a group of control systems by combining a plurality of functional blocks and a control system for realizing a plurality of control drawings are realized. A drawing execution control table that introduces the concept of a plurality of control areas and specifies the execution order of control drawings, and a function block execution that is linked to the drawing execution control table and specifies the execution order of the functional blocks in the drawing A control table is provided for each control area, and control drawing and each function block in each control area are sequentially executed according to the definition of each execution control table. With such a configuration, the present invention has the following effects. (A) The user can efficiently organize and manage the control system. Local maintenance such as addition and deletion of function blocks in the control drawing and change of the execution order can be performed by other control drawing configurations and It can be done without affecting execution at all. (B) Engineering work (control system construction / generation / test / execution / maintenance, etc.) can be easily performed in a distributed manner for each control area.

[Brief description of the drawings]

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

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

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

FIG. 4 is a conceptual diagram of the configuration of each table for managing the order of execution 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 technique for controlling the execution order of functional blocks.

[Explanation of symbols]

 CS process control device 1 function block 2 control drawing 3 control area 4 drawing execution control table 5 function block execution control table

Claims (1)

(57) [Claims] A predetermined control operation is performed based on read data.
It has a function to execute by software and output the calculation result.
A control system by combining multiple function blocks
In a process control device, a plurality of the functional blocks are combined to form a unit.
Control system as a control drawing and
Identification to identify the control drawing in the drawing
Allocate information and collect multiple control drawings to create one control system
Are used as control areas, and
Allocating identification information for specifying the control area, and corresponding to each control area,
Drawing execution system that specifies the execution order by identification information
And your table, if you are linked to this drawing execution control table,
Identifies the execution order of the function blocks in the control drawing
Function block execution control table specified by the
Only, drawing control of in each control area, each function floppy
Is a drawing execution control table and function block execution
Configured to be executed sequentially according to the control table definition
Process control device, characterized in that the.