WO2021049727A1

WO2021049727A1 - Method for controlling error state of plc system

Info

Publication number: WO2021049727A1
Application number: PCT/KR2020/003442
Authority: WO
Inventors: 박창우
Original assignee: 엘에스일렉트릭 주식회사
Priority date: 2019-09-11
Filing date: 2020-03-12
Publication date: 2021-03-18
Also published as: KR102219387B1; CN114375426A; JP7394276B2; JP2022548014A

Abstract

The present invention relates to a method for controlling an error state of a PLC system, and includes: a) a step of using a control program, executed in a computer for setting a PLC system, to create an error event task, which can be performed in a central processing unit of the PLC system and blocks or turns on or off a signal of an external module, and store the error event task in a memory of the PLC system; b) a step in which the central processing unit of the PLC system executes, in stages, the program stored in the memory; c) a step in which the central processing unit checks whether a signal for informing of the occurrence of an error is being received from the external module; and d) a step of performing the error event task to block the central processing unit from operating in an error mode, when the signal informing of the occurrence of the error is received in step c).

Description

How to control the error state of the PLC system

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

In general, PLC (Programmable Logic Controller) is mainly used in a non-contact sequential control circuit system for factory automation, and it is possible to configure a control system or change a program by connecting elements such as relays, timers, and counters in hardware. It is used to control the contact sequence.

The advantage of PLC is that it has the advantages of high speed, environmental resistance, ease of handling, and economy, and is capable of real-time complex control that can be programmed with numerous control elements rather than a simple sequential controller.

In general, PLC is an input circuit connected to a plurality of sensors, an output circuit connected to a control object such as a motor, internal and external memories that store programs for processing according to the input, and signals input through the input circuit according to the program. It includes a central processing unit that processes so that it can be processed and output through an output circuit.

In order to increase the reliability of PLC, the stability of the system itself is an important factor, but it is also an important factor to be able to effectively deal with abnormalities caused by undefined errors that occur during system operation.

The conventional PLC system is designed to enter an error mode by itself when an unexpected error occurs and an abnormality occurs in a control operation.

To this end, the central processing unit of the PLC includes a self-diagnosis function, but there is a problem in that a separate safe circuit must be implemented for the input/output control part that the central processing unit cannot detect.

In general, when operating in error mode, all outputs are turned off and a warning is generated. In some cases, all outputs are maintained or turned off by parameter setting.

A method of controlling the error state of such a conventional PLC system will be described with reference to the accompanying drawings.

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

Referring to FIG. 1, in a conventional PLC system, 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), and an end processing step (S15). , An error occurrence determination step (S16), and when an error occurs, an error mode entry step (S17) of entering an error mode in an operating state.

In the PLC system, SCAN refers to a process in which a program written in the basic program execution method of PLC is repeatedly operated from the beginning to the end.

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

Then, in step S12, the states of the input modules are read and stored in the memory. The input modules at this time mean various sensors, and they read the status values of the sensors and store them in the internal memory of the PLC as initial data.

Then, as in step S13, the central processing unit of the PLC executes a program stored in an internal memory or an external memory, and at this time, the data stored in the memory is used to execute the program.

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

Fig. 2 is an exemplary diagram of a program that is operated and processed by a central processing unit of a PLC.

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

Event tasks may be added to enable various executions according to periods, device conditions, and the like.

Then, in a state in which the program operation is finished as in step S14, the output value, which is the 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 a variety of external devices and may be representatively an electric motor.

In order to return to the beginning after performing the operation according to the given user program as described above, the end process is performed as in step S15. The end processing at this time is a process of checking whether there is a self-diagnosis and a user event through the self-diagnosis module included in the central processing unit.

User events can occur in a wide variety of ways, and may include changes in the physical environment such as a change in a scan program, separation of a specific input module or output module, or a new connection.

Then, as in step S16, it is checked whether a fault error has occurred from an external device including an input module and an output module.

The fault error at this time is determined based on the presence or absence of a fault diagnosis signal sent to the central processing unit of the PLC when a fault occurs in an external device including an input module such as a sensor and an output module such as a motor.

If it is determined that the fault diagnosis signal has not been input from the external device in step S16, the step S11 is performed again.

On the other hand, if it is determined that a fault diagnosis signal has been input from an external device, the error mode of step S17 is entered.

Here, the error mode is that the central processing unit of the PLC is in the stopped state, not in the running state, and the central processing of the PLC must be reset after the user resolves or forcibly releases the error state by using a programmable debugging tool (PADT). The device operates in an operating state.

At this time, the number of input modules and output modules connected by PLC varies depending on the system, but when applied to factory automation, a large number of external devices are connected.

Conventionally, the PLC's central processing unit reacts according to the fault diagnosis signals of all external devices, and when the fault diagnosis signal is input, it enters the error mode, so the operation status of the PLC is stopped with frequent probability. Since the mode must be released, maintenance takes a lot of time, and there is a problem in that the cost increases.

In view of the above problems, an object to be solved by the present invention is to provide a method for controlling an error state of a PLC system capable of reducing the frequency of entering an error mode.

In addition, another problem to be solved by the present invention is to provide a method for controlling an error state of a PLC system that can improve the flexibility of a PLC system and reduce user intervention.

The method for controlling an error state of the PLC system according to the present invention for solving the above technical problems may be performed in the central processing unit of the PLC system by using a control program executed in a computer for setting the PLC system, and , Creating an error event task for turning on, off, or blocking the signal of the external module and storing it in the memory of the PLC system; b) Stepwise executing the program stored in the memory in the central processing unit of the PLC system. Steps and, c) checking whether a signal notifying the occurrence of an error is received from the external module in the central processing unit; and d) performing an error event task when a signal notifying the occurrence of an error is received in step c). And blocking the central processing unit from operating in an error mode.

In an embodiment of the present invention, the step d) comprises the step of checking whether there is an error event task for an external module when a signal notifying the occurrence of the error is received, and when there is no error event task, the central processing unit is It can operate in error mode.

In an embodiment of the present invention, step d) is, when there is an error event task for an external module in which an error has occurred, and when the number of times the error event task is performed is less than a set number, the error event task is performed, and the error event task is performed. If the number is greater than or equal to the set number, the central processing unit may operate in an error mode.

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

In an embodiment of the present invention, if a signal indicating an error occurrence is not received as a result of the confirmation in step c), step b) may be performed again.

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

In an embodiment of the present invention, in step a), the computer may display on a monitor so that the user selects a task on the event task registration screen, and selects the task attribute as when an error occurs, so that an error event task can be set. .

In an embodiment of the present invention, when the user selects a task attribute as when an error occurs, the computer may display an error list on a monitor and provide the user to select an error.

The present invention controls to selectively perform normal operation or error mode operation when an error occurs according to the influence of an error-occurring external device on the entire PLC system, thereby reducing the frequency of entering the error mode and reducing the time required for maintenance and repair. It can be, and there is an effect that can reduce the cost.

In addition, the present invention checks whether the occurrence of an error of a specific external device is periodic or repetitive, and performs normal operation without entering the error mode for occurrences of errors up to a set number, and to the error mode for occurrences of errors exceeding the set number. By allowing the user to arbitrarily change the design of the system, such as entering, there is an effect of improving the control flexibility of the PLC system and reducing user intervention to facilitate management.

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

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

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

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

5 is an exemplary diagram of a registered event task.

In order to fully understand the configuration and effects of the present invention, 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 disclosed below, but may be implemented in various forms and various modifications may be made. However, the description of the present embodiment is provided to complete the disclosure of the present invention, and to fully inform the scope of the invention to those of ordinary skill in the art to which the present invention pertains. In the accompanying drawings, for convenience of explanation, the size of the components is enlarged compared to the actual one, and the ratio of each component may be exaggerated or reduced.

Terms such as'first' and'second' may be used to describe various elements, but the elements should not be limited by the above terms. The above terms can be used only for the purpose of distinguishing one component from another component. For example, without departing from the scope of the present invention, the'first element' may be named as the'second element', and similarly, the'second element' may also be named as the'first element'. I can. In addition, expressions in the singular include plural expressions unless clearly expressed otherwise in the context. Terms used in the embodiments of the present invention may be interpreted as meanings commonly known to those of ordinary skill in the art, unless otherwise defined.

The present invention relates to a'control method', and the operation subject of the control method consisting of specific steps is specific hardware constituting the PLC system, and in particular, the operation processing of the program and the processing of the task are the central processing unit of the PLC system even if there is no special description. It shall be made from.

Hereinafter, a method of 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.

3, a method for controlling an error state of a PLC system according to a preferred embodiment of the present invention includes an initialization processing step (S301), an input image area refresh step (S302), a program operation processing step (S303), and an output image area. The refresh step (S304), the end processing step (S305), the error occurrence determination step (S306), the step of checking whether there is an error event task for the external device in which the error occurred (S307), and the error event task if there is an error event task A step of performing (S308) and, after performing the error event task, an error mode entry confirmation step (S309) of checking whether or not the PLC enters the error mode, and as a result of the determination of step S307, there is no error event task, or the As a result of the determination in step S309, if the error mode operation is required, an error mode entry step (S310) of converting the operation state of the PLC to the error mode is included.

Hereinafter, the configuration and operation of a method for controlling an error state of a PLC system according to a preferred embodiment of the present invention configured as described above will be described in more detail.

The PLC system includes a central processing unit, an input circuit that inputs signals from input modules such as sensors to the central processing unit, an output circuit that outputs calculation results to an external module such as an electric motor, and an internal or external memory for storing data. Includes.

As is known, the central processing unit may be capable of self-diagnosis.

In the present invention, a user registers an Error Event Task before scanning the PLC.

In this case, it is assumed that the error event task is registered in the event task area as in the program structure of FIG. 2 described above.

4 is an exemplary diagram of a screen for registering an error event task, and FIG. 5 is an exemplary diagram of a registered event task.

Referring to FIGS. 4 and 5, respectively, a user can register an event task by performing settings on the error event task registration screen 40 displayed on the monitor, and in particular, specify the type of event by selecting the menu 41 when an error occurs. can do.

For the user's convenience, an error list may be previously registered in the control program, and the user may select an error list through the error list selection window 42.

At this time, the error list may include reception of external device diagnostic signals (ACK), operation errors, I/O module errors, and floating point errors.

Using such a control program, a user can register an error event task for an external module.

The setting of the error event task can be set in a wide variety, and the setting can be changed according to the effect of the external module on the entire system.

For example, by not registering an error event task for an external module that has an important influence on the system, it is possible to operate in the error mode.

In addition, it is possible to set the number of times the error event task is performed in consideration of the effect of an error of a specific external module on the entire system. Even if an error that occurs in an external module with a very small effect on the system is repeated continuously, operation in the error mode can be blocked. Depending on the importance, the number of error repetitions is up to 10, 5, and 3 without error mode operation. If there is more error repetition, it can be set to perform the error mode operation.

The number of times of error repetition can be set differently for each external module. In this case, the number of repetitions can be set to a larger value as the external module has a smaller effect on the entire system.

After such a setting, as shown in FIG. 3, in step S301, a step in which the PLC is driven for the first time by a power-on operation or a power reset operation or a program operation of one cycle has been completed. Initialization of

Then, in step S302, the states of the input modules are read and stored in the memory. The input modules at this time mean various sensors, and they read the status values of the sensors and store them in the internal memory of the PLC as initial data.

Then, as in step S303, the CPU 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 to execute the program.

Then, in the state in which the program operation is finished as in step S304, the output value, which is the 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 a variety of external devices and may be representatively an electric motor.

In order to return to the beginning after performing the operation according to the given user program as described above, the end process is performed as in step S305. The end processing at this time is a process of checking whether there is a self-diagnosis and a user event through the self-diagnosis module included in the central processing unit.

Then, as in step S306, it is checked whether a fault error has occurred from an external module including an input module and an output module.

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

If it is determined that the fault diagnosis signal has not been input from the external module in step S306, the step S301 is performed again.

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

If there is no registered error event task as a result of checking in step S307, the error mode is entered in step S310. At this time, entering the error mode is as described above, in the error mode, the central processing unit of the PLC is in a stopped state, not in a running state, and the user resolves or forcibly releases the error state using PADT (Programmable Debugging Tool). Then, the PLC's central processing unit can be put into operation only when it is reset again.

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

As mentioned above, when an error occurs, the error event task can block the entry of the error mode by ignoring it and allow the scanning process to proceed as it is.

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

In other words, if the external module is malfunctioning, the signal of the external module that is actually connected is turned off through the MOVE command and processed as not installed in the system, thereby preventing entry into the error mode.

Then, as in step S309, it is checked whether to enter the error mode again.

In step S309, it may be determined whether the occurrence of errors in the same external module has reached a set number. If the set number has not been reached, entry into the error mode is blocked and step S301 is performed.

When the set number is reached, the error mode is entered in step S310.

The order of steps S309 and S308 may be changed.

This can be freely changed by various setting methods that determine whether to enter the error mode according to whether or not the set number of repetitions is exceeded.

As such, the present invention does not use a method of stopping the execution of the entire program and entering the error mode when an error occurs during PLC operation, and has a small effect in consideration of the effect of the external module in which the error occurs on the entire system. When an error occurs in an external module, the error mode entry is blocked, thereby preventing excessively frequent error mode entry, increasing user freedom, and increasing the flexibility of the PLC system.

Although the embodiments according to the present invention have been described above, these are merely exemplary, and those of ordinary skill in the art will understand that various modifications and equivalent ranges of embodiments are possible therefrom. Therefore, the true technical protection scope of the present invention should be determined by the following claims.

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

Claims

a) By using a control program executed in a computer for setting up a PLC system, it can be executed in the central processing unit of the PLC system, and by creating an error event task that turns on, off, or blocks the signal of an external module, Storing in the system's memory;

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

c) checking whether a signal indicating an error occurrence is received from the external module in the central processing unit; And

d) blocking the operation of the central processing unit in an error mode by performing an error event task when a signal indicating the occurrence of an error is received in step c).
The method of claim 1,

Step d),

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

If the number of times the error event task is executed is less than the set number, the error event task is executed,

Error state control method of the PLC system in which the central processing unit operates in error mode when the number of times the task is executed is more than the set number.
The method of claim 1,

Step d),

Including the step of checking whether there is an error event task for an external module when a signal indicating the occurrence of the error is received,

A method of controlling the error status of the PLC system in which the central processing unit operates in error mode when there is no error event task.
The method of claim 3,

Step d),

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

If the number of times the error event task is executed is less than the set number, the error event task is executed,

Error status control method of the PLC system in which the central processing unit operates in error mode when the number of times of execution of the error event task is more than the set number.
The method of claim 2,

The set number of times,

An error state control method of a PLC system, characterized in that it can be set differently according to the external module.
The method of claim 2,

If a signal indicating the occurrence of an error is not received as a result of the confirmation in step c), the error state control method of the PLC system performs step b) again.
The method of claim 2,

Checking the number of times the error event task is performed,

A method of controlling an error state of a PLC system performed before or after the error event task is performed.
The method of claim 2,

The step a),

The method of controlling the error state of the PLC system, wherein the computer displays on a monitor so that a user selects a task on the event task registration screen, selects a task attribute as when an error occurs, and sets an error event task.
The method of claim 8,

When the user selects the attribute of the task as when an error occurs, the computer

Error status control method of a PLC system, characterized in that by displaying an error list on a monitor, and providing a user to select an error.