CN114375426B

CN114375426B - Error state control method of PLC system

Info

Publication number: CN114375426B
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: 2024-09-03
Anticipated expiration: 2040-03-12
Also published as: CN114375426A; JP2022548014A; KR102219387B1; WO2021049727A1; JP7394276B2

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 in a central processing unit of the PLC system and that causes signals of an external module to be turned on, off, or blocked, using a control program executed in a computer for PLC system setting, and storing the error event task in a memory of the PLC system; b) Step, the CPU of the PLC system executes the program stored in the memory in stages; 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 performing an error event task in the case that a signal notifying the occurrence of an error is received in the c) step.

Description

Error state control method of PLC system

Technical Field

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

Background

Generally, 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 sequential control in which elements such as a relay, a timer, and a counter are connected in hardware to constitute a control system, or in which a program is changeable.

The PLC has the advantages of high speed, environment resistance, easy operation and economy, and comprises a plurality of control elements, and can carry out programmable real-time combined control instead of a simple sequence controller.

In general, a PLC includes: an input circuit connected to the plurality of sensors; an output circuit connected to a control object such as a motor; an internal memory and an external memory storing a program for executing a process according to an input; and a central processing unit that performs processing such 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 if an abnormality occurs due to an undefined error in the operation of the system, it is also an important factor to be able to effectively cope with the abnormality.

The existing PLC system is designed to enter an Error Mode (Error Mode) by itself in case of unexpected errors resulting in abnormal control actions.

For this reason, the central processing unit 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 which cannot be detected by the central processing unit.

In general, the output is turned off and an alarm is given when the operation is performed in the error mode, and all the outputs may be kept in the on state or turned off according to parameter settings depending on the situation.

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

Fig. 1 is a scanning flow chart of a conventional PLC system.

Referring to fig. 1, the conventional PLC system includes an initialization processing step (S11), an input image area refreshing step (S12), a program operation processing step (S13), an output image area refreshing step (S14), an ending processing step (S15), an error occurrence judging step (S16), and an error mode entering step (S17) of entering an error mode from an operation state in the event of an error.

In the PLC system, SCAN (SCAN) is a process of repeatedly performing arithmetic operations on a program that is a basic program operation mode of the PLC.

First, step S11 is a step in which the PLC is driven for the first time by a power-on operation or a power-reset operation, and data initialization and initialization operations of the respective modules are performed.

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

Next, as 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 executing the program.

Execution of the program continues from the start to the end of the created program.

Fig. 2 is an example diagram of a program of arithmetic processing in a central processing unit of a 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 various execution according to a cycle, a device condition, and the like.

Next, as in step S14, 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 at this time is various external devices, and may be a motor as a representative.

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

User events can occur very variously and can include changes in the physical environment such as changes in the scanning program or the separation of specific input or output modules, new connections, etc.

Next, as step S16, it is confirmed whether a malfunction 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 fault 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 device, the error mode of step S17 is entered.

Here, the error mode means that the central processing unit of the PLC is in a stopped state rather than an operating state (Run), and a user is required to solve or forcibly cancel the error state and reset the error state by using a PADT (Programmable Debugging Tool, programmable debug tool), so that the central processing unit of the PLC can operate in the operating state.

At this time, the number of input modules and output modules connected through the PLC varies depending on 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 if a failure diagnosis signal is input, the operation state of the PLC is stopped very frequently, and a user is required to manually cancel the failure mode in order to reset, so that there is a problem in that maintenance requires much time and the cost increases.

Disclosure of Invention

Problems to be solved by the invention

In view of the above, an object of the present invention is to provide an error state control method of a PLC system capable of reducing the frequency of entering an error mode.

In addition, the invention also aims to provide an error state control method of the PLC system, which can improve the flexibility of the PLC system and reduce the intervention of a user.

Means for solving the problems

The error state control method of the PLC system of the present invention for achieving the object as described above includes: a) A step of creating an error event task that can be executed in a central processing unit of the PLC system and that causes signals of an external module to be turned on, off, or blocked, using a control program executed in a computer for PLC system setting, and storing the error event task in a memory of the PLC system; b) Step, the CPU of the PLC system executes the program stored in the memory in stages; 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 performing an error event task in the case that a signal notifying the occurrence of an error is received in the c) step.

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 that the signal informing the occurrence of the error is received, and the central processing unit may operate in an error mode in case that there is no error event task.

In an embodiment of the present invention, in the step d), when there is an error event task for an external module in which an error occurs, the error event task may be executed if the number of execution times of the error event task is less than a 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 greater than the set number of times.

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

In an embodiment of the present invention, if the confirmation result of the step c) is not received a signal informing that an error occurs, the step b) may be performed again.

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

In an embodiment of the present invention, if the user selects the attribute of the task as 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, the control is performed to selectively perform the normal operation or the error mode operation when an error occurs according to the influence of the external device having the error on the whole PLC system, thereby reducing the frequency of entering the error mode, thereby having the effect of being able to reduce the time required for maintenance and repair and being able to reduce the cost.

Further, according to the present invention, the user can arbitrarily change the design of the system, for example, check whether or not the occurrence of an error in a specific external device is periodic or repetitive, and perform normal operation without entering an error mode for the occurrence of an error until the number of times set, and enter an error mode for the occurrence of an error exceeding the number of times set, etc., thereby having the effect of improving the control flexibility of the PLC system and facilitating management by reducing the intervention of the user.

Drawings

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

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

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

Fig. 4 is an exemplary diagram of a screen on which an error event task is registered.

Fig. 5 is an example diagram of a registered event task.

Detailed Description

In order that the structure and effect of the present invention may 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 embodied in various forms and may be variously modified. However, the description of the present embodiment is intended to provide a complete disclosure of the present invention, and to fully disclose the scope of the present invention to those skilled in the art to which the present invention pertains. In the drawings, the size of the constituent elements is exaggerated and the proportion of each constituent element may be exaggerated or reduced for convenience of explanation.

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

The present invention relates to a "control method", in which the main operation of the control method comprising specific steps is specific hardware constituting a PLC system, and in particular, the arithmetic processing of a program and the processing of tasks are performed by a central processing unit of the PLC system, even if not specifically described.

Next, an error state control method of a PLC system according to an embodiment of the present invention will be described in detail with reference to the accompanying 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 operation processing step (S303); an output image area refreshing step (S304); ending the processing step (S305); an error occurrence determination step (S306); a step (S307) of confirming whether an error event task for the external device in which the error has occurred exists; a step (S308) of executing the error event task if there is the error event task; after executing the error event task, an error mode entry confirmation step (S309) of confirming whether an error mode of the PLC is entered or not; and an error mode entry step (S310) of converting the operation state of the PLC into an error mode if the judgment result of the step S307 is that there is no error event task or the judgment result of the step S309 is that the 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 comprises: a central processing unit; an input circuit for inputting signals of an input module such as a sensor to the central processing unit; an output circuit that outputs the operation 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, central processing units may be self-diagnostic.

In the present invention, an Error event task (Error EVENT TASK) is registered by the user before the scan of the PLC.

At this time, as in the program structure of fig. 2 described above, the error event task is registered in the event task area.

Fig. 4 is an example diagram of a screen on which error event tasks are registered, and fig. 5 is an example diagram of a registered event task.

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

For the convenience of the user, an error list may be registered in advance 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 use such a control program to register an error event task for the external module.

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

For example, an error event task may not be registered for an external module that has an important impact on the system, thereby causing it to operate in an error mode.

In addition, the number of execution times of the error event task may be set in consideration of the influence of an error of a specific external module on the entire system. The operation in the error mode may be prevented even if the error occurring in the external module having a very small influence on the entire system continues to be repeated, and the operation may be continued without being performed in the error mode until the number of times of repeated error occurrence reaches 10, 5, or 3 times according to the importance, and if the number of times of repetition reaches or exceeds the number, the operation in the error mode may be performed.

The setting of the number of times of error repetition may be set differently according to each external module. In this case, the number of repetitions of the external module may be set to be larger as the influence on the entire system is smaller.

After the setting as described above, as shown in fig. 3, in step S301, a step of causing the PLC to be driven for the first time by an operation of turning on the power or an operation of resetting the power, or a state in which the program operation as one cycle is completed, is performed, and the initialization of data and the initialization operation of the external device are performed.

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 them as initial data in the internal memory of the PLC.

Next, as 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 executing the program.

Next, as 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 at this time is various external devices, and may be a motor as a representative.

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

Next, as step S306, it is confirmed whether or not a fault error has occurred in the external module including the input module and the output module.

The fault error at this time is determined based on the presence or absence of a fault 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.

In the step S306, if there is a fault diagnosis signal (ACK) input from the external module, the central processing unit of the PLC confirms whether an error event task of the external module is registered in the program as in the step S307.

As a result of the confirmation of step S307, if there is no error event task registered, an error mode entry of step S310 is performed. At this time, the error mode is entered as described above, and the central processing unit of the PLC is in a stopped state instead of 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 releases the error state and resets with PADT (Programmable Debugging Tool).

And S307, if the registered error event task is judged, the central processing unit of the PLC executes the error event task.

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

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

That is, in the case where the external module fails, the signal of the external module in the actually connected state can be turned OFF (OFF) by the MOVE instruction, thereby processing to be not mounted to the system, whereby entry into the error mode can be prevented.

After that, as by step S309, whether to enter the error mode is again confirmed.

In step S309, it may be determined whether or not the error occurred in the same external module reaches the set number of times, and if the set number of times is not reached, the entry into the error mode is prevented, and the step S301 is executed.

In the case where the set number of times is reached, the entering error mode of step S310 is performed.

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

This can be freely changed by various setting modes for determining whether to enter an error mode according to whether the number of repetitions exceeds the setting number or not.

Thus, when an error occurs in the operation of the PLC, the invention considers the influence of the external module with the error on the whole system without adopting a mode of stopping the execution of the whole program and entering the error mode, and prevents the error from entering the error mode when the error of the external module with small influence occurs, thereby improving the degree of freedom of the user by preventing the error mode from being excessively frequently entered and improving the flexibility of the PLC system.

The embodiments according to the present invention have been described above by way of example only, and it will be understood by those skilled in the art that various modifications and embodiments within the equivalent scope may be implemented thereby. Accordingly, 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 for factory automation and the like, which has industrial application potential by confirming an error state of an external device of a PLC and determining an operation mode by communication.

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

b) Step, the CPU of the PLC system executes the program stored in the memory in stages;

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 unit from operating in an error mode by executing an error event task in the case that a signal notifying an error occurrence is received in the step c);

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

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

In the step d) of the process, a step of the method,

When there is an error event task for the external module in which the error occurs,

In the case where the number of times of execution of the error event task is smaller than the set number of times, the error event task is executed,

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

3. The error state control method of a PLC system according to claim 2, wherein,

The number of times of setting can be set differently according to the external module.

4. The error state control method of a PLC system according to claim 2, wherein,

And c) if the confirmation result of the step c) does not receive a signal for notifying the occurrence of errors, executing the step b) again.

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

The number of times of execution of the error event task is confirmed to be executed before or after the execution of the error event task.

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

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 set an error event task by selecting an attribute of the task as when an error occurs.

7. The error state control method of a PLC system according to claim 6, wherein,

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