JPS63268003A - programmable controller - Google Patents

Abstract

PURPOSE:To realize the optional control of the start timing for each loop via an optional loop by providing a work data area to store the arithmetic result of each loop. CONSTITUTION:A user program 14 is divided into plural loops and each of these loops has the address of a loop information area for the head address, etc., and the start condition address of its own. These addresses are stored in a loop control table 13. An arithmetic unit 11 refers periodically to a work data area 15 via the address of the table 13 and decides satisfaction of the relevant loop start conditions when the contents of the area 15 are equal to '1' and then carries out the control processing of the loop prescribed in the program 14 based on the contents of the loop information area. Thus the loop start conditions are stored in the area 15 storing the arithmetic result of each loop. As a result, the start conditions of a certain loop can be controlled with the arithmetic result of another loop.

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention relates to a control device that performs process control using a microcomputer, and in particular, a programmable control device suitable for a control system in which the amount of control processing changes depending on the process state. Regarding the controller.

[Conventional technology]

The conventional programmable controller is disclosed in Japanese Patent Application Laid-Open No. 59-1
As described in No. 14602, management information that defines the execution of control processing is registered in advance, and predetermined control calculations are sequentially performed based on this information.

[Problem that the invention seeks to solve]

The above-mentioned conventional technology does not take into consideration the dynamic development of control processing in response to changes in the process state, and because it is a method that repeatedly executes all set control processing at all times, it is possible to execute all control processing at all times. It is necessary to construct a control device with processing performance, which poses problems such as an increase in the scale of the control device.

An object of the present invention is to realize a rational and flexible control system by enabling dynamic switching of control processing contents depending on the control state of a process.

[Means for solving problems]

The above purpose is to divide the control processing contents into small groups (hereinafter referred to as loops) for each function, make this loop the execution unit of the control processing, set startup conditions for each loop, and set the startup timing from other loops. This is achieved by making it possible to control it arbitrarily.

[Effect]

Control processing is executed in functional units called loops, and control processing corresponding to a certain process state is performed as a set of multiple loops. This combination of loops can be arbitrarily configured by controlling the activation conditions of each loop in another loop.

Furthermore, by setting and resetting the loop starting conditions, it is possible to define the loop starting time, that is, the execution time of the control processing realized by the loop.

〔Example〕 Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 shows a system configuration diagram illustrating an embodiment of the present invention.

This figure shows the overall configuration of a programmable controller (hereinafter referred to as a controller) that performs process control, and the controller 1 includes two central processing units (hereinafter referred to as CPUs).
3 and 4, and sends and receives data via the transmission bus 2.

The CPUs 3 and 4 further have transmission control circuits 16 and 2, respectively.
6. Arithmetic devices 11 and 21. Loop management table 13.2
3. It has user programs 14 and 24° and work data areas 15 and 25, and the arithmetic units 11 and 21 are connected to the process input/output device (hereinafter abbreviated as PI 10) via the system bus 5.
Connect to 6.

The arithmetic unit 11 includes a user program 14 that defines process inputs and control processing contents to be imported via the PI 106, a loop management table 13 that stores management information regarding the user program, and a work data area 15 that stores control constants and calculation results. Perform control calculations using PI
A control signal is output to the process via 106. CPU
The arithmetic unit 21 of No. 4 also performs similar processing.

FIG. 2 shows a control calculation processing method that is a feature of the present invention. The user program 14 is divided into a plurality of loops, and each loop has a loop information area such as a start address and an activation condition address for the loop, and these are stored in the loop management table 13, respectively. Here, the activation condition address of each loop indicates an arbitrary data position on the work data area 15.

The arithmetic unit 11 periodically refers to the loop management table 13 and determines that the contents of the startup condition address of each loop are 111 IT
At this time, it is determined that the starting condition for the loop is satisfied (this is referred to as loop starting condition determination), and the control process for the loop specified in the user program 14 is executed according to the contents of the information area of the loop. Further, when the content of the loop starting condition address is 'O''', the next loop starting condition is determined.

That is, in the - cycle, the control processing of only those loops for which the activation condition is satisfied is executed.

The above content also applies to the arithmetic unit 21. Here, since the loop activation conditions are set on the work data area that stores the calculation results of each loop, the activation conditions of a certain loop can be controlled by the calculation results of other loops.

Next, we will discuss the degradation backup system in which the control calculation method shown in Fig. 2 is applied to the control system shown in Fig. 1.
As shown in the figure.

In this figure, the bold line portion indicates the control processing content executed by each CPU when both CPUs 3 and 4 are normal.
PU3 is loop 1, 2, 3, 6, CPU4 is loop 4,
5. Execute 6. Here, the contents of loops 1 to 6 are CPU
This is common to loops 3 and 4, especially loop 6, which monitors whether the other CPU is operating normally, and if either CPU is abnormal, switches the control processing executed by its own CPU to loops 3, 4, and 5゜6. . That is, when the CPUs 3 and 4 are normal, they operate as a load sharing system, and when one system is abnormal, for example, when CPU 3 is abnormal, CPU 4 backs up a part of the control processing (loop 3) of CPU 3, as shown by the broken line in FIG. Some functions as controller 1 (loop 1, 2)
Control processing continues to be executed in a reduced form. This is called a degenerate backup.

Here, by putting logic in loop 6 to determine which loop should be executed according to the process state,
The control processing content of the degenerate back amplifier is dynamically controlled depending on the process status when one system is abnormal.

In this embodiment, the back amplifier function is further improved by using a timer function in the loop 6 and configuring the loop to be activated at multiple times the frequency when one system is abnormal.

〔Effect of the invention〕

According to the present invention, it is possible to dynamically change the control processing contents of the programmable controller according to changes in the process state, so it is possible to execute the minimum necessary control processing according to the process state, and the controller hardware The software can be removed or greatly simplified.

[Brief explanation of drawings]

Fig. 1 is a control system configuration diagram of an embodiment of the present invention;
The figure shows a control arithmetic processing method, and FIG. 3 is a configuration diagram of a degenerate backup system. 1... Controller, 3, 4... CPU, 11.2
1... Arithmetic device, 13.23... Loop management table, 14.24... User program, 15.25.
- Work data area.

Claims (1)

[Claims] 1. In a process control system that includes an arithmetic unit that executes control processing, a user program memory that defines the contents of control processing, and a management table that stores information for executing the user program, the user program is divided into a plurality of functions in units of functions. By dividing the group into groups and arbitrarily combining these groups, control processing corresponding to the process state can be realized, and a starting condition that defines whether or not to execute the control processing of the group can be set arbitrarily from other groups. A programmable controller characterized in that it has a function that allows dynamic switching of control processing contents according to changes in process conditions.