JPH07261809A - Control arithmetic unit - Google Patents

Abstract

PURPOSE:To cascade two function blocks which are present in different areas. CONSTITUTION:An inter-area coupling block KO for cascading the two function blocks C1 and C2 which are present in the different areas is provided on the side of the area where the primary-side function block C1 is present, and the block KO consists of an inter-area coupling block data base 1 constituted with setting data set from the primary-side function block C1, output destination discrimination data specifying the secondary-side function block C2, and reference data stored from the secondary-side function block C2, a setting communication means 2 which reads an output value to be sent from the primary-side function block C1 to the secondary-side function block C2 out of a setting data area and sends it to the secondary-side function block C2, and a reference communication means 3 which accesses the secondary-side function block C2 specified with the output destination discrimination data to reads its cascade state out, and stores the cascade state as reference data in the reference data area of the data base 1.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a control arithmetic unit for performing process control using a computer, and more specifically, software for performing a predetermined arithmetic operation on an input signal and outputting the arithmetic operation result. It is a control arithmetic unit that constitutes a desired control system by appropriately combining a plurality of functional blocks made up of elements (this is also generally called an internal instrument). Two control arithmetic units exist in different logical or physical areas. The present invention relates to realization of an inter-area coupling function for cascading functional blocks.

[0002]

2. Description of the Related Art As a process control device, a distributed control system utilizing a computer has been widely put into practical use. Such a distributed control system is composed of an operation monitoring device (operator station) that has a man-machine interface function and a distributed control arithmetic device (control station) that is in charge of control arithmetic. On the arithmetic unit side, a plurality of functional blocks consisting of software elements that perform a predetermined arithmetic operation on the input signal and output the arithmetic result are appropriately constructed in a building block system so as to suit the process to be controlled. The control system constructed in combination is downloaded.

Here, in the conventional device of this type, it is assumed that a plurality of functional blocks connected to each other are connected in one control arithmetic unit, and they are provided in different control arithmetic units ( It was not possible to construct a control system (loop) by connecting functional blocks that exist).

[0004]

FIG. 4 is a diagram for explaining a problem in the case of constructing a cascade control system by combining functional blocks provided in different control arithmetic units. Here, ST1 is a first control arithmetic unit, in which a primary side PID controller C1 is provided, and an output signal MV of the primary PID controller C1 is transmitted to the second control arithmetic unit ST2 side. A transmitting means SD1 for performing the operation is provided. In the second control arithmetic unit ST2,
There are provided a receiving means SD2 for receiving the output signal MV sent via the communication bus BS, and a secondary side PID controller C2 having the output signal received here as a setting signal.

In the case of such a configuration, the control arithmetic unit ST
A control system of cascade connection is constructed by the one functional block and the functional block in the control arithmetic unit ST2, but the following problems occur. (A) Since the output coupling of the primary-side PID controller C1 is undefined, even if the secondary-side PID controller C2 is in the cascade open state, its state is not fed back to the primary-side PID controller C1. (B) Since the cascade open state of the secondary PID controller C2 is not fed back to the primary PID controller C1, the primary PID controller C1 does not initialize the PID calculation. For this purpose, the primary side PID controller C1
Widening of the integral term occurs at. (C) The transmitting means SD1 and the receiving means SD2 are the secondary side PI
Since the cascade open of the D controller is not detected, the output signal MV of the primary side PID controller C1 continues to be output as the set value even in such a state. For this reason, even if the setting value of the secondary PID controller C2 is changed manually, for example, the value is overwritten by the output signal MV of the primary PID controller C1, resulting in 2 Secondary PID
The set value of the controller C2 cannot be changed manually.

The present invention has been made in view of the above circumstances, and provides a control arithmetic unit capable of constructing a control system by cascade-connecting functional blocks provided in different control arithmetic units. The purpose is to provide.
Here, different control arithmetic devices are provided with a plurality of areas in the device even if the device is physically one in addition to the physically separated control arithmetic device, and each database is independent. Therefore, the case where a plurality of control arithmetic units are logically configured is also included. In addition, the cascade coupling includes all coupling methods in which a signal handled by each functional block is transmitted from upstream to downstream when a control system is constructed by combining a plurality of functional blocks.

[0007]

SUMMARY OF THE INVENTION The present invention to achieve such an object is a control arithmetic unit having a plurality of functional blocks each of which is composed of a software element which performs a predetermined arithmetic operation on an input signal and outputs an arithmetic result. Therefore, an inter-area coupling block for cascading two functional blocks existing in different logical or physical areas is provided on the area side where the primary-side functional block exists, and the inter-area coupling block is An inter-area combined block database constructed by setting data set from the primary side functional block, output destination identification data specifying the secondary side functional block, reference data stored from the secondary side functional block, and the primary Read the output value from the side function block to the secondary function block from the setting data area of the inter-area combined block database And setting a communication means for transmitting to the secondary functional blocks, it accesses the secondary functional blocks designated by the destination identification data read the cascade state,
The control arithmetic unit is configured by a reference communication unit that stores the cascaded state as reference data in a reference data area of the inter-area coupled block database.

[0008]

In the control arithmetic unit on the side where the primary-side controller exists, an inter-area coupling block is provided for cascade-coupling the functional blocks that are present separately in different control arithmetic units (areas). This inter-area combined block setting communication means accesses the database of its own combined block, reads the output value to be transmitted to the secondary functional block stored in the setting data area, and outputs it to 2
Transmit to the next functional block.

The reference communication means stores the cascade state of the secondary functional block designated by the output destination identification data in the database as reference data so that the primary functional block can read back the reference data. . As a result, it becomes possible to construct a control system by cascade-connecting functional blocks existing in different areas.

[0010]

Embodiments of the present invention will now be described in detail with reference to the drawings. FIG. 1 is a configuration block diagram showing an embodiment of the present invention. In this figure, the case where two PID controllers existing in different areas are combined to form a cascade control system is illustrated.

In the figure, ST1 and ST2 are first and second
In the control arithmetic unit of the above, these are areas which are physically or logically separated. C1 is a functional block existing in the first control arithmetic unit ST1 and serves as a primary side PID controller, and C2 is a second control arithmetic unit ST2.
In the function block existing in, it functions as a secondary side PID controller. The process signal PV1 from the sensor installed in the process is applied to the input terminal of the primary-side PID controller C1, and the operation result MV2 of the secondary-side PID controller C2 is the valve etc. installed in the process. Is output to the operation end of.

K0 is an inter-area coupling block which is a feature of the present invention, and is a primary side functional block between two functional blocks C1 and C2 existing in different logical or physical areas. It is provided on the side of the first control arithmetic unit ST1 in the area where C1 exists. In this inter-area combined block K0, 1 is an inter-area combined block database, which specifies the setting data area set from the PID controller C1 which is the primary side functional block and the PID controller C2 which is the secondary side functional block. Output destination identification data area and a reference data area stored from the secondary functional block, and a database is constructed by the data stored in each of these areas.

Reference numeral 2 denotes a setting communication means, which is an output value to be transmitted from the primary side functional block C1 to the secondary side functional block C2.
It has a function of reading from the setting data area of the database 1 and transmitting it to the secondary functional block C2. Reference numeral 3 is a reference communication means for transmitting the cascaded state of the secondary functional block C2 to the primary functional block C1. It has the function of storing in the area.

FIG. 2 is a conceptual diagram showing how data is exchanged between the database of the primary PID controller C1 and the database of the secondary PID controller C2. The setting communication means 2 in the inter-area coupling block K0 includes a function of accessing the database 20 of the function blocks (secondary side PID controller in this example) existing in another area, and the primary side PID controller C1. The setting data read from the database 10 is transmitted through the setting communication to the database 20 as a set value and written.

The reference communication means 3 also includes a function of accessing the database 20 of the functional blocks existing in other areas, and the output destination identification data stored in the database 10 of the primary side PID controller C1 is included in the reference communication means 3. The reference communication is executed to the secondary PID controller C2 designated based on the above, the cascade state and the set value stored in the database 20 are read, and the read data is written in the database 10 as reference data. I am doing it.

The operation of the apparatus thus constructed will be described below. FIG. 3 is a time chart showing a communication operation of cascade connection performed via the inter-area connection block K0. Here, the time axis is from the top to the bottom.
In this example, from the state of cascade close to the secondary PI
D controller C2 is set to the cascade open state, and the secondary side P
It is assumed that the set value SV2 of the ID controller C2 is manually operated and then the cascade close state is set again.

(Cascade closed state) Primary PID
The controller C1 sets the setting data MV1 desired to be output to the secondary-side PID controller C2 in the database 1 of the inter-area combined block K0 at a constant cycle and is stored in the reference data area of the database 1 The cascade state of the secondary PID controller C2 (in this state, the cascade closed state and the set value SV2 = MV1 set in the secondary PID controller C2) is read back.

The setting communication means 2 in the inter-area coupling block K0 is activated at a fixed cycle every time inter-area coupling communication is performed, and the setting data MV stored in its own database 1 is set.
1 is taken out and data is set in the database 20 of the secondary side PID controller C1 by the other area database access function. Similarly, the reference communication means 3 is also activated in a fixed cycle every time when the predetermined inter-area coupled communication is performed, the output destination identification data of the database 1 is taken out, and the output destination identification data is obtained by using the other area database access function. The setting value SV2 and the cascade closed state of the functional block C2 (database 20) designated by are read out and stored in the database 1 as reference data. As a result, the contents of database 1
It is constantly updated by the output set value MV1 (set value SV2) to the secondary PID controller C2 read back from the secondary PID controller C2 and the sequence state.

Therefore, the primary-side PID controller C1 accesses the database 1 of the inter-area coupling block K0, so that the secondary-side PID controller C2 existing in another area ST2 exists in the same area. Secondary PID
It can be treated as if it were cascade-connected to the controller. (Cascade open state) In this state, the reference communication means 3 is activated in a fixed cycle to perform reference communication, and the secondary side PI
The cascade open state of the D controller C2 and the set value SV2 set by manual operation are stored in the database 1 as reference data. The setting communication means 2 is a secondary side PI.
In response to the D controller C2 indicating the cascade open state, its operation is stopped.

In this state, when the value of the set value SV2 is changed by manual operation or the like, the value of the reference data stored in the database 1 is constantly updated accordingly. The primary-side PID controller C1 accesses the database 1 at regular intervals, recognizes from the reference data that the secondary-side PID controller C2 is in the cascade open state, and outputs its own output value MV1 as the reference data. It operates so as to track the set value SV2 (set value of the secondary side controller) included in the above.

With this operation, the PID control calculation can be initialized in the primary side PID controller C1,
Widening of the integral term can be prevented, and
When the cascade open state is switched to the cascade close state, bumps can be prevented from occurring. In the above embodiment, the PID controller is exemplified as each of the functional blocks on the primary side and the secondary side, but the functional blocks having, for example, a sequence control calculation function and a switch function, and are newly developed. It can also be applied to the case where functional blocks having various functions are cascade-connected.

[0022]

As described in detail above, the present invention is
Through the inter-area coupling block, two functional blocks existing in different areas can be cascade-coupled. Also, by enabling cascade connection between functional blocks in different areas, the degree of freedom in constructing a control system according to the plant to be controlled divided into control arithmetic units or areas is improved, and efficiency is improved. You can perform various engineering.

[Brief description of drawings]

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

FIG. 2 is a conceptual diagram showing how data is exchanged between a database of a primary PID controller C1 and a database of a secondary PID controller C2.

FIG. 3 is a time chart showing a communication operation of cascade connection performed via an inter-area connection block K0.

FIG. 4 is a diagram showing a case where functional blocks provided in different control arithmetic units are combined to construct a cascade control system,
It is a figure for demonstrating the problem.

[Explanation of symbols]

 ST1, ST2 Control computing device C1 Primary side functional block (Primary side PID controller) C2 Secondary side functional block (Secondary side PID controller) K0 Inter-area coupling block 1 Database of inter-area coupling block 2 Setting communication means 3 Reference communication means

Continuation of front page (51) Int.Cl. ⁶ Identification number Office reference number FI technical display location G05B 19/048

Claims (1)

[Claims] 1. A control arithmetic unit comprising a plurality of functional blocks each comprising a software element for performing a predetermined arithmetic operation on an input signal and outputting an arithmetic result, the control arithmetic apparatus being present in different logical or physical areas. The inter-area coupling block for cascading the two functional blocks is provided on the side of the area where the primary-side functional block exists, and the inter-area coupling block is the setting data set from the primary-side functional block, the secondary Output destination identification data that identifies the side functional block, inter-area combined block database constructed with reference data stored from the secondary side functional block, and the output value to be transmitted from the primary side functional block to the secondary side functional block Setting communication means for reading from the setting data area of the inter-area combined block database and transmitting it to the secondary side functional block; It is configured by a reference communication means for accessing the secondary functional block designated by the destination identification data, reading the cascaded state, and storing the cascaded state as reference data in the reference data area of the inter-area coupled block database. A control arithmetic unit characterized by the above.