CN114375426A

CN114375426A - Error state control method of PLC system

Info

Publication number: CN114375426A
Application number: CN202080063500.3A
Authority: CN
Inventors: 朴昶佑
Original assignee: LS Electric Co Ltd
Current assignee: LS Electric Co Ltd
Priority date: 2019-09-11
Filing date: 2020-03-12
Publication date: 2022-04-19
Also published as: JP2022548014A; JP7394276B2; KR102219387B1; WO2021049727A1

Abstract

The invention relates to an error state control method of a PLC system, which comprises the following steps: a) a step of creating an error event task that can be executed by a central processing unit of the PLC system and causes a signal of an external module to be turned on, off, or blocked, by using a control program executed in a computer for setting the PLC system, and storing the error event task in a memory of the PLC system; b) a step of executing a program stored in a memory in stages by a central processing unit of the PLC system; c) a step of confirming, by the central processing apparatus, whether a signal notifying occurrence of an error is received from the external module; and d) preventing the central processing unit from operating in an error mode by executing an error event task when the signal notifying the occurrence of the error is received in the c).

Description

Error state control method of PLC system

Technical Field

The present invention relates to an error state control method for a PLC system, and more particularly, to an error state control method for a PLC system capable of minimizing a debugging process.

Background

Generally, a plc (programmable Logic controller) is mainly used in a non-contact sequential control circuit system for factory automation, and is used in a non-contact timing control system in which elements such as a relay, a timer, and a counter are connected to each other through hardware, or a changeable program is used.

The PLC has advantages of high speed, environmental resistance, easy operation, economy, and includes a plurality of control elements, enabling programmable real-time combination control, rather than a simple sequence controller.

Generally, a PLC includes: an input circuit connected to the plurality of sensors; an output circuit connected to a control target such as a motor; an internal memory and an external memory storing a program for executing processing according to an input; and a central processing unit that performs processing so that a signal input through the input circuit can be processed according to a program and output through the output circuit.

In order to improve the reliability of the PLC, the stability of the system itself is an important factor, but it is also important whether or not an abnormality can be effectively handled when the abnormality is caused by an undefined error occurring during the operation of the system.

The existing PLC system is designed to enter an Error Mode (Error Mode) by itself when an unexpected Error occurs to cause an abnormal control operation.

For this reason, the central processing device of the PLC has a self-diagnosis function, but there is a problem in that an additional safety circuit needs to be implemented for an input/output control section that the central processing device cannot detect.

In general, the output is completely turned off and an alarm is issued when the operation is performed in the error mode, and a mode in which all the outputs are kept in the current state or turned off depending on the parameter setting may be employed depending on the case.

Next, an error state control method of the conventional PLC system as described above will be described with reference to the drawings.

Fig. 1 is a scanning flowchart of a conventional PLC system.

Referring to fig. 1, the conventional PLC system includes an initialization processing step (S11), an input image region refreshing step (S12), a program operation processing step (S13), an output image region refreshing step (S14), an end processing step (S15), an error occurrence determination step (S16), and an error mode entering step (S17) of entering an error mode from an operating state in the case where an error occurs.

In the PLC system, SCAN (SCAN) refers to a process of repeatedly executing operations on a program which is a basic program operation system of the PLC from the beginning to the end.

First, the step S11 is a step in which the PLC is first driven by a power-on operation or a power-reset operation, and performs initialization of data and initialization of each module.

Next, in step S12, the state of the input module is read and stored in the memory. The input module at this time indicates various sensors, and reads the state values of the sensors and stores the state values as initial data in an internal memory of the PLC.

Next, as in step S13, the central processing unit of the PLC executes the program stored in the internal memory or the external memory, and at this time, the data stored in the memory is used for the execution of the program.

The execution of the program is continued from the start to the end of the created program.

Fig. 2 is a diagram showing an example of a program for arithmetic processing in the central processing unit of the PLC.

As shown in fig. 2, the program may include a scanning program 100 having a plurality of processing programs and an event task 200 added to a user program.

The event task may be added to be capable of performing various operations according to a cycle, a device condition, and the like.

Next, in a state where the program operation is completed, in step S14, an output value as a result of the operation is stored in the output image area, and the stored data is output to the output module. The output module in this case is various external devices, and may be a motor as a representative.

To return to the start again after performing an operation according to a given user program as described above, the end processing is executed as by step S15. The end processing at this time is a process of self-diagnosing and confirming whether or not there is a user event based on a self-diagnosis module included in the central processing apparatus.

User events can occur in a wide variety of ways and can include changes to the scanning program or changes in the physical environment such as the separation of particular input modules or output modules, new connections, etc.

Next, as in step S16, it is confirmed whether or not a failure error has occurred in the external device including the input module and the output module.

The failure error at this time is determined based on whether or not there is a failure diagnosis signal transmitted to the central processing unit of the PLC when the external device itself including the input module such as the sensor and the output module such as the motor has failed.

In the step S16, if it is determined that the failure diagnosis signal is not input from the external device, the step S11 is performed again.

In contrast, if it is determined that the failure diagnosis signal is input from the external apparatus, the operation proceeds to the error mode in step S17.

Here, the error mode is a state in which the central processing unit of the PLC is stopped, not in an operating state (Run), and the central processing unit of the PLC can operate in the operating state only when a user needs to solve or forcibly cancel the error state by using a PADT (Programmable debug Tool) and reset the error state.

At this time, the number of input modules and output modules connected by the PLC differs according to the system, but is connected to a very large number of external devices when applied to factory automation.

Conventionally, a central processing unit of a PLC responds to failure diagnosis signals of all external devices, and enters an error mode if the failure diagnosis signals are input, so that the operation state of the PLC is frequently stopped, and a user is required to manually cancel the error mode for reset, which causes problems that much time is required for maintenance and costs are increased.

Disclosure of Invention

Problems to be solved by the invention

In view of the above problems, an object of the present invention is to provide an error state control method for a PLC system that can reduce the frequency of entering an error mode.

Another object of the present invention is to provide a PLC system error state control method that can improve the flexibility of a PLC system and reduce user involvement.

Means for solving the problems

The error state control method of the PLC system according to the present invention for achieving the above object includes: a) a step of creating an error event task that can be executed by a central processing unit of the PLC system and causes a signal of an external module to be turned on, off, or blocked, by using a control program executed in a computer for setting the PLC system, and storing the error event task in a memory of the PLC system; b) a step of executing a program stored in a memory in stages by a central processing unit of the PLC system; c) a step of confirming, by the central processing apparatus, whether a signal notifying occurrence of an error is received from the external module; and d) preventing the central processing unit from operating in an error mode by executing an error event task when the signal notifying the occurrence of the error is received in the c).

In an embodiment of the present invention, the step d) includes a step of confirming whether there is an error event task for the external module in case of receiving the signal notifying the error occurrence, and the central processing apparatus may operate in an error mode in case of no error event task.

In an embodiment of the present invention, in the step d), when there is an error event task for the external module in which the error occurs, the error event task may be executed if the number of execution times of the error event task is less than the set number of times, and the central processing unit may operate in the error mode if the number of execution times of the error event task is equal to or greater than the set number of times.

In an embodiment of the present invention, the set number of times may be differently set according to the external module.

In an embodiment of the present invention, if the confirmation result of the step c) does not receive a signal notifying the occurrence of the error, the step b) may be performed again.

In an embodiment of the present invention, the confirmation of the number of times of execution of the error event task may be performed before or after the execution of the error event task.

In an embodiment of the present invention, in the a), the computer may display on a display so that a user can select a task on an event task registration screen and set an error event task by selecting an attribute of the task as an error occurrence.

In an embodiment of the present invention, if the user selects the attribute of the task as the error occurrence, the computer may display an error list on a display for the user to be able to select the error.

ADVANTAGEOUS EFFECTS OF INVENTION

According to the present invention, it is controlled to selectively perform the normal operation or the error mode operation when an error occurs according to the influence of the external device in which the error occurs on the entire PLC system, thereby reducing the frequency of entering the error mode, and thus reducing the time required for maintenance and repair, and reducing the cost.

Further, according to the present invention, the user can arbitrarily change the design of the system, for example, by checking whether or not the error occurrence of a specific external device is periodic or repetitive, and by performing normal operation without entering the error mode for the error occurrence up to the set number of times, and entering the error mode for the error occurrence exceeding the set number of times, it is possible to improve the control flexibility of the PLC system and to make management easy by reducing the user's involvement.

Drawings

Fig. 1 is a flowchart of a scanning operation of a conventional PLC system.

Fig. 2 is an exemplary diagram of a program processed in the PLC system.

Fig. 3 is a flowchart of an error state control method of a PLC system according to a preferred embodiment of the present invention.

Fig. 4 is an exemplary diagram of a screen of a task of registering an error event.

FIG. 5 is an exemplary diagram of a registered events task.

Detailed Description

In order that the structure and effects of the present invention can be fully understood, preferred embodiments of the present invention will be described with reference to the accompanying drawings. However, the present invention is not limited to the embodiments described below, but may be implemented in various forms and may be variously changed. However, the description of the present embodiments is intended to provide a complete disclosure of the present invention and to fully disclose the scope of the present invention to those of ordinary skill in the art to which the present invention pertains. In the drawings, the sizes of the constituent elements are exaggerated for convenience of explanation, and the proportions of the respective constituent elements may be exaggerated or reduced.

The terms "first", "second", and the like may be used to describe various constituent elements, but these constituent elements should not be limited to the above terms. The above terms may be used only to distinguish one constituent element from another constituent element. For example, a "first constituent element" may be named a "second constituent element", and similarly, a "second constituent element" may also be named a "first constituent element", without departing from the scope of the present invention. Furthermore, unless the context clearly dictates otherwise, expressions in the singular include expressions in the plural. Terms used in the embodiments of the present invention may be construed as meanings well known to those skilled in the art, unless otherwise defined.

The present invention relates to a "control method", and an operation subject of a control method composed of specific steps is specific hardware constituting a PLC system, and particularly, even if not described in particular, arithmetic processing of a program and processing of a task are performed by a central processing unit of the PLC system.

Next, a method for controlling an error state of a PLC system according to an embodiment of the present invention will be described in detail with reference to the drawings.

Referring to fig. 3, the error state control method of the PLC system according to the preferred embodiment of the present invention includes: an initialization processing step (S301); an input image area refreshing step (S302); a program arithmetic processing step (S303); an output image area refreshing step (S304); an end processing step (S305); an error occurrence determination step (S306); a step (S307) of confirming whether an error event task exists for the external device in which the error has occurred; a step (S308) of executing the error event task if there is an error event task; an error mode entry confirming step (S309) of confirming whether an error mode of the PLC is entered or not after the error event task is executed; and an error mode entering step (S310) of converting the operation state of the PLC into an error mode if the determination result of the step S307 is that there is no error event task or the determination result of the step S309 is that an error mode operation is required.

Next, the configuration and operation of the error state control method of the PLC system according to the preferred embodiment of the present invention configured as described above will be described in more detail.

The PLC system includes: a central processing device; an input circuit for inputting signals of input modules such as sensors to the central processing unit; an output circuit for outputting the calculation result to an external module such as a motor; and an internal memory or an external memory for storage of data.

As is well known, the central processing apparatus may be self-diagnostic.

In the present invention, an Error Event Task (Error Event Task) is registered by the user prior to scanning of the PLC.

At this time, as in the aforementioned program configuration of fig. 2, the error event task is registered in the event task area.

Fig. 4 is an exemplary diagram of a screen in which an error event task is registered, and fig. 5 is an exemplary diagram of a registered event task.

Referring to fig. 4 and 5, respectively, the user can register an event task by making a setting on the error event task registration screen 40 displayed on the display, and in particular, can embody the type of event by selecting the error occurrence time menu 41.

To facilitate the user, the error list may be pre-registered in the control program, and the user may select the error list through the error list selection window 42.

At this time, the error list may be reception of an external device diagnostic signal (ACK), an operation error, an I/O module error, a floating point error, or the like.

The user may register the error event task for the external module using such a control program.

The setting of the error event task can be very diverse, and the setting can be changed according to the influence of the external module on the whole system.

For example, a fault event task may not be registered for an external module that has a significant impact on the system, causing it to run in a fault mode.

In addition, the number of times the error event task is executed may be set in consideration of the influence of the error of a specific external module on the entire system. Even if an error occurring in an external module having a very small influence on the entire system continues to repeat, the operation in the error mode may be prevented, and the operation in the error mode may be continued until the number of error repetition occurrences reaches 10, 5, or 3 depending on the importance, and the operation in the error mode may be executed if the number of repetition occurrences reaches more than this.

The number of times of error repetition may be set differently for each external module. In this case, the external module having a smaller influence on the entire system may be set to have a larger value of the number of repetitions.

After the setting as described above, as shown in fig. 3, in step S301, a step of driving the PLC for the first time by the power-on operation or the power-reset operation or a state in which the program operation is completed as one cycle is executed, and initialization of data and initialization of the external device are executed.

Next, in step S302, the state of the input module is read and stored in the memory. The input module at this time represents various sensors, and reads the state values of the sensors and stores the state values as initial data in an internal memory of the PLC.

Next, as in step S303, the central processing unit of the PLC executes the program stored in the internal memory or the external memory, and at this time, the data stored in the memory is used for the execution of the program.

Next, in step S304, in a state where the program operation is completed, an output value as a result of the operation is stored in the output image area, and the stored data is output to the output module. The output module in this case is various external devices, and may be a motor as a representative.

As described above, in order to return to the start again after performing an operation according to a given user program, the end processing is performed as in step S305. The end processing at this time is a process of self-diagnosing based on the self-diagnosis module included in the central processing apparatus and confirming whether or not there is a user event.

Next, as in step S306, it is confirmed whether a failure error has occurred in the external module including the input module and the output module.

The failure error at this time is determined based on the presence or absence of a failure diagnosis signal (ACK) transmitted to the central processing unit of the PLC when the external module itself including the input module such as a sensor and the output module such as a motor has failed.

In the step S306, if it is determined that the fault diagnosis signal is not input from the external module, the step S301 is performed again.

If there is a failure diagnosis signal (ACK) input from the external module in the step S306, the central processing unit of the PLC confirms whether or not an error event task of the external module is registered in the program as in the step S307.

As a result of the confirmation in the step S307, if there is no error event task registered, the error mode entry in the step S310 is performed. At this time, the error mode enters the above-described state, in which the central processing unit of the PLC is in a stopped state, not in an operating state (Run), and the central processing unit of the PLC can be brought into an operating state only if the user solves or forcibly cancels and resets the error state using the padt (programmable debug tool).

If it is determined that there is a registered error event task as a result of the confirmation in the step S307, the central processing unit of the PLC executes the error event task.

As previously described, the error event task may ignore and prevent entry into the error mode when an error occurs, while maintaining the performance of the scanning process.

More specifically, it may be set such that if an error signal is input from the external module, the external module signal is set to ON (ON), OFF (OFF), or blocked according to the setting of the error event task.

That is, in the case where the external module malfunctions, the signal of the external module in the actually connected state may be turned OFF (OFF) by the MOVE command to be processed as not being mounted to the system, thereby being able to prevent entry into the error mode.

Thereafter, as in step S309, it is confirmed again whether or not the error mode is entered.

In step S309, it may be determined whether the number of times of the error occurred in the same external module reaches a set number, and if the number of times of the error does not reach the set number of times, the error mode is prevented from entering, and the step S301 is executed.

When the set number of times is reached, the entry to the error mode of step S310 is executed.

The order of the S309 step and the S308 step may also be changed.

This can be freely changed by various setting manners of determining whether to enter the error mode according to whether the set number of iterations is exceeded or not.

In this way, the present invention can prevent an error from occurring in an external module having a small influence from entering an error mode by preventing an error mode from being entered excessively frequently, thereby improving the degree of freedom of a user and improving the flexibility of a PLC system, without stopping the execution of the entire program and entering the error mode when an error occurs during the operation of the PLC and considering the influence of the external module having the error on the entire system.

The embodiments in accordance with the present invention have been described above, but this is by way of example only, and it will be understood by those skilled in the art that various modifications and equivalent ranges of the embodiments may be made thereto. Therefore, the true technical scope of the present invention should be determined by the appended claims.

Industrial applicability

The present invention relates to a PLC system used for factory automation and the like, and has industrial applicability by confirming an error state of an external device of the PLC through communication and determining an operation mode.

Claims

1. An error state control method of a PLC system, comprising:

a) a step of creating an error event task that can be executed by a central processing unit of the PLC system and causes a signal of an external module to be turned on, off, or blocked, by using a control program executed in a computer for setting the PLC system, and storing the error event task in a memory of the PLC system;

b) a step of executing a program stored in the memory in stages by a central processing unit of the PLC system;

c) a step of confirming, by the central processing apparatus, whether a signal notifying occurrence of an error is received from the external module; and

d) a step of preventing the central processing apparatus from operating in an error mode by executing an error event task when the signal notifying the occurrence of the error is received in the step c).

2. The error state control method of the PLC system according to claim 1,

in the step of d) of the above-mentioned step,

when there is an error event task for the external module where the error occurred,

executing the error event task under the condition that the execution times of the error event task is less than the set times,

when the number of times of execution of the error event task is equal to or more than a set number of times, the central processing unit operates in an error mode.

3. The error state control method of the PLC system according to claim 1,

the d) step includes a step of confirming whether there is an error event task for the external module in case that the signal informing the error occurrence is received, and the central processing apparatus operates in an error mode in case that there is no error event task.

4. The error state control method of the PLC system according to claim 3,

in the step of d) of the above-mentioned step,

when there is an error event task for an external module where an error has occurred,

5. The error state control method of the PLC system according to claim 2,

the number of times of setting may be set differently depending on the external module.

6. The error state control method of the PLC system according to claim 2,

if the confirmation result of the step c) does not receive the signal for notifying the error occurrence, the step b) is executed again.

7. The error state control method of the PLC system according to claim 2,

confirming the number of executions of the error event task is executed before or after executing the error event task.

8. The error state control method of the PLC system according to claim 2,

in the step a), the computer displays on a display so that a user can select a task in an event task registration screen and sets an error event task by selecting an attribute of the task as an error occurrence.

9. The error state control method of the PLC system according to claim 8,

if the user selects the attribute of the task as the error occurrence, the computer displays an error list on a display for the user to be able to select the error.