JP2004102386A - Programmable controller - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a programmable logic controller PLC (programable logic controller) confirming microcomputer operating situation from the outside by a device indicating which degree the processing to apply a load to the microcomputer is executed, and keeping the ability to perform the processing designated by a user even when the processing to apply the load to the microcomputer of the PLC is frequently performed. <P>SOLUTION: This programmable controller 1 the microcomputer 13 having a software to control the programmable controller and performing the system processing to execute a user program. The programmable controller 1 has a display part 14 for performing the display in proportion to the number of times of processing for a specific time with respect to the specific processing. <P>COPYRIGHT: (C)2004,JPO

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
INDUSTRIAL APPLICABILITY The present invention is applied to a programmable controller (hereinafter, referred to as a "PLC"). In particular, a function for externally checking the operation state of a microcomputer mounted on the PLC and a processing time for a specific processing automatically change. Regarding functions.
[0002]
[Prior art]
The PLC is a device that operates in accordance with a program created by a user (hereinafter, referred to as a “user program”), and also performs an operation as a system of the PLC itself (hereinafter, referred to as “system processing”) while executing the user program. Typical examples of system processing include monitoring of a time schedule for performing the operation of the PLC, communication processing, and abnormality monitoring.
[0003]
Inexpensive PLCs often control the above processing with one microcomputer. Since a single microcomputer cannot execute a plurality of processes at the same time, in most cases, a method is used in which the execution time and the priority are determined for each process, and the priority of the process is switched according to the elapsed time.
[0004]
In the case of processing where the execution time is always constant, there is no problem if the processing is switched according to time, but if there is processing that is rarely executed or processing with variable processing time, the maximum time for performing the irregular processing Need to be provided. If the time prepared for the execution of the irregular processing is not performed or the processing is completed in a short time, the surplus time becomes a useless time in which no processing is performed. Therefore, a method of assigning priorities to the processes and switching the processes to be executed by managing the time and the priority is used. However, when a process having a high priority and being executed irregularly occurs, only the time for executing the irregular process is used. The time for performing a process with a lower priority is shorter.
[0005]
[Problems to be solved by the invention]
The PLC software is designed so that the operation continues even if the amount of work of the microcomputer increases and the processing is interrupted in the middle or interrupted by a higher priority processing during the processing. However, if the processing is aborted too frequently, the user performs an operation that is not desirable for the user, such as slowing down the execution speed of the user program and slowing down the response to communication.
[0006]
From the user's point of view, the slower execution speed of the user program and the slower response of the communication appear to degrade the performance of the PLC itself, and if the operation becomes too significant, it is felt that the PLC is defective. It cannot be inferred that the cause of such an operation is that specific processing is concentrated on the microcomputer of the PLC.
[0007]
The present invention solves the conventional problem, and it is possible to externally check the microcomputer operation status by using a device that displays the degree of execution of the process of applying a load to the microcomputer, and also allows the user to prioritize the operation. By setting the order, the time for performing the process specified by the user is automatically increased. Therefore, a PLC that can maintain the processing capability of the process specified by the user even when the process of applying a load to the microcomputer of the PLC frequently occurs. The purpose is to do.
[0008]
[Means for Solving the Problems]
The present invention provides a programmable controller that has software for controlling a programmable controller, includes a microcomputer that performs system processing, and a display unit that performs a display in proportion to the number of times of a predetermined process for a specific process in a programmable controller that executes a user program. Is a programmable controller.
[0009]
Further, according to the present invention, the display unit is a programmable controller that performs digital display.
[0010]
In the present invention, the display unit is a programmable controller that performs analog display.
[0011]
Furthermore, the present invention provides a programmable controller which classifies the processing to be executed into an important processing group and a normal processing group, and shortens the time for processing the normal processing group when the number of times of processing of the important processing group increases. is there.
[0012]
Further, the present invention is a programmable controller having a counter that operates at the end or start of each processing group.
[0013]
BEST MODE FOR CARRYING OUT THE INVENTION
An embodiment of the present invention will be described.
A programmable controller (PLC) according to the present invention includes a microcomputer for performing system processing, including software for PLC control, and a display unit for performing a display in proportion to the number of times of a specific process in a predetermined time. And execute the user program. Also, in the PLC software of the present invention, the system processing for controlling the PLC is classified into several processing groups that are always executed in a series of flow, and a counter for each processing group classified in the internal RAM. Prepare. The process of turning off the display device at the beginning of the process group that is being executed irregularly among the grouped process groups has a relatively low priority in the process group that is periodically executed, and must be performed at a certain period. A process for turning on the display unit is included in a process group to be executed. Further, a process of updating a counter for each process is added to each of the classified process groups. It is possible to reverse the process of turning on and off.
[0014]
When the PLC starts up, the PLC software turns off the microcomputer operation status display at the beginning of the processing group to be executed at irregular timing, and turns on the microcomputer operation status display in the processing of the processing group to be executed periodically. When the processing group is frequently executed, the time during which the microcomputer operation status display is turned off becomes longer. Frequent execution of irregular processing means, in other words, that the time for performing regular processing that should be normally performed is shortened, and it can be said that the operation state of the microcomputer is decreasing. . In other words, the user can visually determine the operation status of the microcomputer by looking at the display of the operation status of the microcomputer.
[0015]
The PLC software manages the processing performed in the next unit time in the processing group having the highest priority activated every unit time. In addition, several unit times are collectively set as a reference time, and one unit time is managed so that one processing group (excluding irregular processing groups) is always executed within the reference time. In the processing of the processing group having the highest priority, a counter elapsed value of each processing group is calculated, and a processing of changing a time distribution within a reference time allocated to each processing group is added based on a result of analyzing the update tendency of each counter. . Since the processing time allocated to each processing group can be automatically adjusted by the added processing, if the user specifies in advance the setting for automatically adjusting the time to the PLC and the processing group to be prioritized, the specified processing group Can be preferentially increased. Thereby, even if an event in which the irregular processing group is executed frequently occurs, the processing capacity of the processing group designated by the user as the priority processing can be made constant to some extent.
[0016]
Hereinafter, embodiments of the programmable controller according to the present invention will be described with reference to FIGS. FIG. 1 is a block diagram illustrating a PLC according to an embodiment. FIG. 2 is an explanatory diagram of a time chart of a system process in the PLC according to the embodiment. FIG. 3 is a schematic diagram illustrating a process when the system process is executed in the PLC according to the embodiment. FIG. 4 is an external view of the PLC according to the embodiment. FIG. 5 is an explanatory diagram of display contents of the microcomputer operation status display LED in the PLC of the embodiment.
[0017]
An embodiment will be described. As shown in FIG. 1, the PLC 1 of this embodiment includes a RAM 11, a ROM 12, an MPU 13, a display unit 14, an I / F 15, and the like. The ROM 12 stores PLC control software. The MPU 13 includes a microcomputer, and operates according to PLC control software stored in the ROM 12 to perform PLC system processing. The display unit 14 displays the microcomputer operation status. The I / F 15 performs an input / output interface with the peripheral device 2.
[0018]
The display of the microcomputer operation status and the automatic assignment of the processing time in the PLC according to the present embodiment will be described with reference to FIGS. As shown in FIGS. 2 and 3 (a) and 3 (b), the PLC control software 12 is divided into four groups of system processing groups A3a to D3d and executed according to the priority and the processing content.
[0019]
The system processing group A3a is the processing with the highest priority that is always executed every unit time. In the system processing group A3a, a processing 52 for switching the priority of other processing groups and the like are executed.
[0020]
The system processing group B3b is an interrupt processing 51 that is executed irregularly when an event occurs. The priority is next to the system processing group A3a. In the system processing group B3b, a part of processing for communicating with the peripheral device 2, an interrupt input processing which is a part of a user program, and the like are executed.
[0021]
The system processing groups C3c and D3d are processes in which priorities are switched according to time. The system processing group C3c executes processing of the PLC system having a lower priority than the system processing groups A3a and B3b, and the system processing group D3d executes user programs. If the processing time of the system processing group C3c is long, the processing capability other than the execution of the user program such as communication with the peripheral device 2 is improved, and if the processing time of the system processing group D3d is long, the processing capability of the user program is improved.
[0022]
The basic operation of the PLC 1 is as follows. The system processing group A3a is activated at every unit time 42, and when a predetermined time comes, the system processing group A3a switches the processing 6c and 6d of the system processing groups C3c and D3d. The time during which both of the system processing groups C3c and D3d execute once each time is set as the reference time 41, and thereafter the processing of the reference time 41 is repeated indefinitely. The processing 6b of the system processing group B3b is executed when an event for executing it occurs, but is interrupted or waited while the processing 6a of the system processing group A3a having the highest priority is being executed. Further, the system processing groups C3c and D3d are executed many times during the time reserved for the system processing groups C3c and D3d. The processing is continued in the processing.
[0023]
In the present embodiment, a process 64 for turning off the microcomputer operation status display LED 14 is added at the beginning of the process 6b of the system process group B3b. For the system processing groups C3c and D3d, a processing 65 for updating the system processing execution counter is added at the head of the series of processing 6c and 6d, and a processing 63 for turning on the microcomputer operation status display LED 14 is added last. When the PLC 1 is operated in this state, the microcomputer operation status display LED 14 is turned off each time the system processing group B3b is executed, and is not turned on until a series of processing of the system processing groups C3c and D3d is completed. If the system processing group B3b is frequently executed, the processing time of the system processing groups C3c and D3d becomes short, so that it takes time to complete a series of operations, and the time until the microcomputer operation status display LED 14 is turned on is long. Become. When the user looks at the microcomputer operation status display LED 14, as shown in FIG. 5, (1) if the execution frequency of the system processing group B3b is small (the load on the microcomputer is small), the number of processing times of the system processing groups C3c and D3 is large. (2) When the execution frequency of the system processing group B3b is slightly higher (the load on the microcomputer is slightly higher), the number of processings of the system processing groups C3c and D3 is slightly reduced, and the display 142 becomes slightly darker. {Circle around (3)} When the system processing group B3b is frequently executed (the load on the microcomputer is heavy), the operation status of the microcomputer 13 can be identified, such as the number of times of processing of the system processing groups C3c and D3 is reduced and the display 143 becomes dark. .
[0024]
By reading the counters of the system processing groups C3c and D3d, it is possible to determine how many times the system processing groups C3c and D3d have been executed. Specifically, the counter values of the system processing groups C3c and D3d are read by the system processing group A3a performed at the beginning of the reference time, and the values read during the previous reference time 41 are subtracted and assigned to the processing of the system processing groups C3c and D3d. Is divided by the unit time 42. The value calculated within the previous reference time 41 is compared with the value calculated this time. If the value is larger, the amount of execution of the system processing group is improved as compared with the previous reference time 41 (for the system processing group B3b). The effect is small), and when the value is small, it indicates that the value is lower than that in the previous reference time 41 (the effect of the system processing group B3b is large). The tendency of the counter value is analyzed by the system processing group A3a, and by changing the time for switching between the system processing groups C3c and D3d, the processing time of the system processing group C3c or D3d is automatically changed to change the work time at the reference time 41. It is possible to increase the amount. If the user sets in advance which system processing group is to be prioritized, it is also possible to increase only the system processing time of the prioritized one.
[0025]
In the above-described embodiment, the display on the display unit 14 is digitally displayed in proportion to the number of times of processing (the number of times of blinking). It is possible. Further, a counter operating in the middle of the processing group may be used instead of the counter operating at the end or start of each processing group.
[0026]
【The invention's effect】
ADVANTAGE OF THE INVENTION According to this invention, it is possible to confirm the microcomputer operation status from the outside by a device for displaying how much processing for applying a load to the microcomputer of the PLC is performed. Since the time for performing the process specified by the user is automatically increased, it is possible to obtain a PLC capable of maintaining the processing capability of the process specified by the user even when the process of applying a load to the microcomputer of the PLC occurs frequently.
[Brief description of the drawings]
FIG. 1 is a block diagram of a PLC according to an embodiment.
FIG. 2 is an explanatory diagram of a time chart of a system process in the PLC according to the embodiment.
FIG. 3 is a schematic diagram for explaining processing when the system processing is executed in the PLC according to the embodiment.
FIG. 4 is an explanatory view of the appearance of a PLC according to an embodiment.
FIG. 5 is an explanatory diagram of display contents of a microcomputer operation status display LED in the PLC according to the embodiment.
[Explanation of symbols]
1 Programmable controller (PLC)
11 RAM
12 ROM
13 Microprocessor 14 Microcomputer operation status display LED
141 LED display when processing is not concentrated 142 LED display when processing is slightly concentrated 143 LED display 15 when processing is concentrated 15 I / F
2 Peripheral device 3a System processing group A (processing group with highest priority)
3b System processing group B (processing group that is executed irregularly)
3c system processing group C (system processing group not included in system processing groups A and B)
3d system processing group D (processing group for executing user program)
41 Reference time (time to execute each processing group for at least one unit time)
42 Unit time (minimum time allocated to PLC processing group)
51 Irregular interrupt 52 Priority switching 6a to 6d Processing of system processing groups A to D 61 Irregular interrupt occurrence 62 Irregular interrupt processing 63 Display ON 64 Display OFF 65 Counter update processing

Claims (5)

A programmable controller that has software for controlling a programmable controller and includes a microcomputer that performs system processing, and executes a user program.
A programmable controller having a display unit for performing display in proportion to the number of times of a specific process in a predetermined time. The programmable controller according to claim 1,
A programmable controller, wherein the display unit performs digital display. The programmable controller according to claim 1,
A programmable controller, wherein the display unit performs analog display. The programmable controller according to any one of claims 1 to 3,
A programmable controller characterized in that the microcomputer classifies the processing to be executed into an important processing group and a normal processing group, and shortens the time for processing the normal processing group as the number of times of processing of the important processing group increases. The programmable controller according to any one of claims 1 to 4,
A programmable controller having a counter that operates at the end or start of each processing group.

Images