KR102262090B1 - Apparatus and method for duplexing input of plc - Google Patents

Abstract

The present invention relates to an input duplication processing apparatus and method of PLC. According to an embodiment of the present invention, a detection unit that converts an input signal received through a plurality of input contacts into an internal logic signal, compares the states of contact pairs to be duplicated for the plurality of input contacts, and the states do not match If not, a determination unit that replaces the detection input with a previously declared safety input and determines it as the final input, generates an alarm flag for the final input, and a bus connection unit that transmits the final input and the warning flag to the outside through a system bus It provides an input duplication processing device of PLC comprising a.

Description

APPARATUS AND METHOD FOR DUPLEXING INPUT OF PLC

The present invention relates to an apparatus and method for processing an input duplication of a PLC, and more particularly, the present invention enables a duplication of a digital signal input to a PLC with a minimum configuration, thereby determining whether a signal is abnormal and as accurately as possible. , relates to an input duplication processing apparatus and method of PLC configured so that control can be performed in a direction that can secure the safety of the system in the event of an abnormality.

PLC is an industrial computer widely used in automation systems. In particular, the core function is to receive signals from various sensors, perform logic operations, and output control signals according to the results. These PLCs are being applied and operated in automatic control systems in various fields. Some of these automatic control systems require specially safe system configuration and operation. This is the case when it is necessary to ensure the safety of workers while the controlled facility is operating. Also, a case in which a control operation performed due to a failure of an input sensor causes a large property loss is also applicable.

There are various methods to respond to this request, but in the prior art, an input duplication method of module unit was used. A typical digital input module processes several signals from 8 to 64 in one module. Therefore, conventionally, even when only a few key input contacts are to be double-processed, the entire module must be used in a redundant configuration, resulting in wastage of contacts.

Korean Patent Publication No. 10-0786668 (2007.12.11)

An object of the present invention is to provide an input duplication processing apparatus and method of a PLC.

According to an embodiment of the present invention, a detection unit that converts an input signal received through a plurality of input contacts into an internal logic signal, compares the states of contact pairs to be duplicated for the plurality of input contacts, and the states do not match If not, a determination unit that replaces the detection input with a previously declared safety input to determine the final input, generates an alarm flag for the final input, and a bus that transmits the final input and the warning flag to the outside through a system bus It provides a PLC input duplication processing device including a connection unit.

In addition, in the plurality of input contacts, at least one pair of contacts may be set as a duplicated contact pair, and at least one of the duplicated contact pairs may be set to a safety input state.

In addition, the safety input state may be a signal state used for correction when the state of the redundant contact pair is determined to be abnormal.

In addition, the remaining contacts among the plurality of input contacts may be set as general contacts.

In addition, when the state of the redundant contact pair does not match, the determination unit may generate the alarm flag and insert it into the final input, and transmit the final input into which the alarm flag is inserted to the bus connection unit.

In addition, the alarm flag may be separately provided for each pair of redundant contact points, and may be configured to easily identify the corresponding redundant contact pair when an abnormality occurs.

According to another embodiment of the present invention, (a) converting an input signal received through a plurality of input contacts into an internal logic signal, (b) the input signal to perform dual input processing on the plurality of input contacts , generating an alarm flag for when the final input and the final input do not match by calculating , and (c) transmitting the final input and the warning flag to the outside through a system bus. of the input duplication processing method.

In addition, in step (b), at least one pair of contacts among the plurality of input contacts is set as a duplicated contact pair, and the other contacts among the plurality of input contacts are set as general contacts, and at least one of the duplicated contact pairs is set as a general contact. can be set as the safety input state.

In addition, the safety input state may be a signal state used for correction when the state of the redundant contact pair is determined to be abnormal.

In addition, in step (b), when the state of the redundant contact pair does not match, the alarm flag may be generated and inserted into the final input.

In addition, the setting and processing results for the redundant input processing can be applied through a function block.

The present invention does not require any other external hardware or software, so that the system configuration can be simply designed, and the dual input signal configuration is possible at a minimum cost.

In addition, the present invention proposes a method capable of rationally responding to a logical limit in which perfect abnormal detection is impossible, and when an abnormality occurs, an alarm flag is used to notify the operator of the abnormal occurrence and at the same time apply a preset safety input to the control operation to ensure the safety of the system can be secured, and it is possible to continue operation without stopping the system.

In addition, the present invention adopts the duplication method in units of input modules, and unlike the prior art in which there is a waste factor of input contacts, it is possible to configure a more efficient duplication system by presenting a duplication method in units of contacts.

In addition, according to the present invention, by easily applying the setting and processing results for input duplication through a function block, it is possible to freely designate input duplication by setting as needed within a single input module.

In addition, the present invention can at least automatically perform the input redundancy setting available in the PLC programming tool, thereby greatly reducing the programming time and reducing the possibility of errors.

The effects of the present invention are not limited to the above-mentioned effects, and other effects not mentioned will be clearly understood by those skilled in the art from the following description.

1 is a diagram showing the configuration of an input duplication processing apparatus of a PLC according to an embodiment of the present invention.
2 is a diagram illustrating an example of an external program for setting a safety input of a duplicated contact pair in the input duplication processing apparatus of a PLC according to an embodiment of the present invention.
3 is a logic table explaining the state of the final input and the alarm flag determined according to the input state of the redundant contact pair.
FIG. 4 is a diagram illustrating an algorithm performed by the determination unit of FIG. 1 .
5 is a diagram showing an example of a format in which the input redundant processing unit transmits the current state of the normal contact and the redundant contact pair to the central processing unit module.
6 is a diagram illustrating an example of data transmitted by the input duplication processing unit to the central processing unit module in a normal duplex contact pair input state.
7 is a diagram illustrating an example of data transmitted by the input duplication processing unit to the central processing unit module when the duplex input state is abnormal.
8 is a diagram illustrating an example of a format for transmitting a set value from a central processing unit module to an input duplication processing unit.
9 is a view showing an example of a function block for an input duplication processing apparatus of a PLC according to an embodiment of the present invention and a ladder program written using the function block.
FIG. 10 is a diagram illustrating a processing flow inside the function block of FIG. 9 .

Hereinafter, the present invention will be described in more detail based on preferred embodiments of the present invention. However, the following examples are merely examples to help the understanding of the present invention, thereby not reducing or limiting the scope of the present invention.

The present invention may be configured in a configuration in which all redundant contact pairs are connected to one digital input module, not in a redundant configuration using two modules. In particular, among the input contacts provided in the input duplication processing apparatus of PLC according to an embodiment of the present invention, the remaining contacts that are not used as duplicate contact pairs may be configured to be used as general contacts.

Hereinafter, an input duplication processing apparatus of a PLC according to an embodiment of the present invention will be described in more detail with reference to the drawings.

1 is a diagram showing the configuration of an input duplication processing apparatus of a PLC according to an embodiment of the present invention.

Referring to FIG. 1 , the input duplication processing unit 102 of PLC according to an embodiment of the present invention includes a detection unit 104 that converts an input signal received through a plurality of input contacts into an internal logic signal, a plurality of inputs A determination unit that compares the states of contact pairs to be duplicated for a contact, and if the states do not match, replaces the detection input with a pre-declared safety input to determine the final input, and generates an alarm flag for the final input 105 and a bus connection unit 106 that transmits the final input and the alarm flag to the outside through the system bus.

The detection unit 104 is connected to an external input circuit 103 and can convert an input signal received through the input circuit 103 into a signal that can be recognized by the input duplication processing device of PLC. Here, the detector 104 may convert a signal using an insulating element such as a photocoupler. The detection unit 104 may prevent external noise from being transmitted into the system.

The determination unit 105 may perform dual input processing by using a microprocessor unit or a similar logic operation device. In addition, when the calculated final input is transmitted to the central processing unit module 101 , the determination unit 105 may generate an alert flag and insert it into the final input.

The bus connection unit 106 may transmit the final input calculated by the determination unit 105 and the alarm flag to the central processing unit module 101 through the system bus 100 .

The input duplication processing device of PLC according to an embodiment of the present invention is connected to the system bus 100 like other general modules and is configured to exchange data with the central processing unit (PLC CPU) module 101. have. The exchanged data is a digital form of '1' and '0' in which the state of an externally input switch is converted in real time.

On the other hand, in the present invention, there is no need to connect or use a separate device to the external input circuit 103 for the redundant configuration of the input contact. Therefore, in the present invention, it is possible to configure the input circuit 103 including a conventional switch and connect it to the input duplication processing apparatus of the PLC.

In addition, according to the present invention, a pair of general contacts and redundant contacts can be mixed and connected to one module. In order to take advantage of this advantage, in the present invention, the configuration method (normal contact or redundant contact pair) of each input contact can be specified in the system installation step. The designation of these input contacts can be set in various ways. It can be solved simply by installing a function selection switch inside the module. Alternatively, it may be set using the instruction of the sequence program of the determination unit 105 . This method is described in detail using examples at the end of this description.

Here, a method of setting the purpose of each contact point using an external computer (PC) will be described with reference to FIG.

Referring to FIG. , it is assumed that the input duplication processing apparatus of PLC according to an embodiment of the present invention provides a total of 8 input points from X0 to X7 as shown in the setting window. Since a total of 8 input contacts are provided, the user can configure up to 4 redundant contact pairs.

Here, the X2 contact 201 and the X3 contact 202 can be set as a redundant contact pair by using the redundant input checkbox. The redundant input checkbox may be implemented using software or hardware such as a switch. For example, it is possible to create a PLC program in which the redundant input checkbox is set using a PLC programming tool, and check the redundant input checkboxes of the X2 contact 201 and X3 contact 202 to set as a redundant contact pair. Alternatively, for the redundant input checkbox, 8 switch contacts are connected in a circuit, and the switch contacts corresponding to the X2 contact 201 and X3 contact 202 can be operated to set as a redundant contact pair.

At this time, the remaining 6 contacts can be set to be used as general contacts. However, the redundant contact pair must additionally input the state of the safety input (Safe Input) 205 .

2, in the present invention, the safety input 205 may be designated as '1'. The designated safety input 205 may be represented by the symbol Isafe as follows. In other words, Isafe can be said to be a signal state used for correction when the state of the redundant contact pair is judged to be abnormal. Also, it may mean a state in which safe operation of the system is guaranteed among two states of 1 or 0. Using this, it is possible to overcome the logical limitations inherent in the normal signal determination method during the multiplexing input signal processing process.

Here, the logical limit may mean that it is logically impossible to determine which of the two differently input signals is normal when an error occurs in one of the duplicated inputs. This logical limit is a limit encountered even if the signal is multiplexed into a triple or a larger number of signals.

For example, a person in charge of designing a PLC system may well know which of the two states can ensure safety, so the state in which safety can be secured can be designated as an Isafe signal in advance. And, when an actual abnormal state is detected, the input duplication processing device of PLC according to an embodiment of the present invention processes Isafe as shown in the logic table shown in FIG. It is possible to prevent personal injury or property damage as much as possible.

In addition, the input duplication processing apparatus of PLC according to an embodiment of the present invention may notify an automated facility operator of an abnormal state of the duplicated contact pair signal for safe follow-up measures. At this time, since the input duplication processing apparatus of PLC can recognize in advance that a problem has occurred in the duplex contact pair, it sets an alarm flag indicating an abnormal state, and sends an input signal to which the alarm flag is set via the system bus 100 . may be transmitted to the central processing unit module 101 . Here, the above-described Isafe derivation process and the process of determining the state of the alert flag may be performed by the determination unit 105 .

Hereinafter, a process calculated by the determination unit will be described with reference to FIG.

4 is a detailed description of a process performed by the determination unit.

First, the determination unit detects external input signals (In, n=0 to 7) (S110), and may determine whether the input signals are redundant inputs (S120).

Here, if the converted external input signals (In, n = 0 to 7) are normal contacts other than the redundant contact pair, the determination unit 105 does not need to operate the alarm flag. Therefore, the determination unit 105 resets the warning flag An (n=0-7) to '0' (S122), and then copies the external input data In to Xn (n=0-7) (S124) It may be ready to be delivered to the central processing unit module 101 .

Among the converted external input signals (In, n = 0 to 7), in the case of a duplicated contact pair, the determination unit 105 may perform a process of comparing the duplexed-connected two signals Ia and Ib (S130). If the two signals are the same, the determination unit 105 may determine that it is in a normal state, reset the alarm flags Aa and Ab to '0' (S142), and copy the input signals Ia and Ib to Xa and Xb, respectively (S144) . If the two signals do not coincide, the determination unit 105 sets the alarm flags Aa and Ab (S152), and then records the preset safety input Isafe in both Xa and Xb (S154) to the central processing unit module 101 ) to prepare for transmission.

When the input data Xn (n=0-7) and the alarm data An (n=1-7) to be transmitted to the central processing unit module 101 are prepared through the above-described process, the bus connection unit 106 is connected to the system bus 100 ) to the central processing unit module 101 via the input data Xn (n = 0 ~ 7) and the alarm data An (n = 1 ~ 7) can be transmitted.

Specifically, as for the data transmission method of the bus connection unit 106, various methods may be used according to the design content of the PLC system. Here, the simplest and smallest data size method is described as an example.

A typical PLC system can design the size of data to be as small as possible in order to transmit the input data to the central processing unit module 101 as quickly as possible. 5 shows an example of the data format designed in this way.

Here, it can be configured to use one byte to transmit eight input states. That is, it is a structure in which 8 bits constituting 1 byte data are 1:1 with 8 inputs. If the redundant contact pair is not included, the relationship between the input contact and the bit position can be intuitively understood.

For example, if it is assumed that one redundant contact is connected through terminals I2 and I3 as in the example of FIG. 2 , the inputs of terminals I2 and I3 using the logic table of FIG. 3 and the algorithm of FIG. 4 are respectively It is converted into X2 and X3, and X2 and X3 can always have the same state value regardless of whether there is an abnormality in the redundant contact pair. Using this characteristic, in the example of FIG. 5 , the current state values of X2 and X3 may be recorded where the value of X2 is located. Alarm flags A2 and A3 may also have the same value as the redundant contact pair.

In the example of FIG. 5 , this warning flag may be recorded and transmitted where the X3 value is located. This is mutually agreed between the central processing unit module 101 and the input duplication processing unit of PLC. Data actually transmitted in this way are exemplified in FIGS. 6 and 7 .

6 shows transmission data when the state value of the redundant contact pair is normally input as '0'.

Referring to FIG. 6 , the alarm flag value recorded at position X3 may be set to '0'.

7 shows transmission data in the case where the value of the redundant contact pair is input differently and the abnormal state is confirmed. Here, the alarm flag value recorded in X3 can be set to '1'. In addition, the Isafe value set in FIG. 2 may be set to '1' at the X2 position.

Hereinafter, a method of setting a redundant contact pair and a safety input Isafe value according to another embodiment of the present invention will be described with reference to FIG. 8 .

In particular, the process of setting the redundant contact pair and the safety input Isafe value by using a command in the central processing unit module 101 will be described here. The set value may be transmitted from the central processing unit module 101 toward the input duplication processing unit of the PLC. Here too, it is advantageous to configure the transmission data to a minimum size. Assuming a module that accommodates a total of 8 inputs, a maximum of 4 redundant contact pairs can be configured, so 4 bits for setting the contact pair and 4 bits for setting the safety input Isafe status of each redundant contact pair are combined to 1 It can be composed of byte transfer data. When configured in this way, FIG. 8 exemplarily shows a case in which the same set value as that of FIG. 2 is transmitted. At this time, X2 and X3 inputs are designated as redundant contact pairs, and the safety input Isafe state value of this contact pair can be set to '1'.

On the other hand, the input duplication processing apparatus of PLC according to an embodiment of the present invention may perform duplex contact pair setting and operation setting using a function block. Here, the function block can be understood as a ladder program component that acts like a kind of library function, and helps to easily utilize the duplicated input connected to the PLC's duplicated input processing device. These function blocks receive the program activation signal and input parameters specifying the mounting position of the PLC input redundant processing device, access the PLC system bus, and then acquire data from the PLC input redundant processing device and finalize the obtained data. Input and alarm flags can be extracted and output to be used in an external logic circuit.

9 shows an example of a ladder program using a function block. In FIG. 9 , reference number 301 is an example of a circuit for executing the function block 300 , reference number 302 is an example of a circuit processed after the function block 300 is executed, and reference number 303 is a function block 300 . is an example of an input parameter used for execution of , and reference number 304 is an example of transferring or storing the execution result of the function block 300 in the internal memory.

The function block 300 for the input duplication processing apparatus of PLC according to an embodiment of the present invention may be composed of four inputs and three outputs. A signal for activating a function of the function block 300 may be connected to an enable input among the four inputs. This signal can be defined as a general logic circuit.

A simple logic circuit 301 activating the function block 300 is illustrated in FIG. 9 . When the operation result of this circuit is True, the logic inside the function block 300 is activated to execute the program.

10 shows a program operation process inside the function block 300 for the input duplication processing apparatus of the PLC.

First, it is determined whether an enable signal is input (S210), and when the enable signal is not input, the output can be reset (S215).

Next, the position of the redundant input signal may be analyzed (S220). At this time, the information input together with the enable signal in FIG. 10 is the input parameter 303 of FIG. 9 , the location information ('Base#' and 'Slot#') where the input duplication processing device of PLC is mounted and The contact number ('Point#') in the corresponding module may be included. After analyzing the above-mentioned input parameters in the function block 300, it is possible to access the system bus 100 based on this and acquire the data of the input duplication processing device of the PLC (S230). The data acquired through such a data acquisition process is exemplarily shown in FIG. 5 .

The redundancy input and the redundancy alarm flag recorded in the acquired data can be extracted through the following process (S240). Referring to the example presented in FIG. 5 as a reference, the signals may be X2(X3) and A2(A3) signals, respectively.

Finally, the extracted data is output to the circuits marked with State and Alarm, respectively, and the circuit marked with Enable Out (En_Out) is converted to a logic true state and the function block 300 is executed. to inform the external circuit that the result value is ready (S250). These output signals may be processed or utilized by the external circuits 302 and 304 configured by being connected to the output of the function block 300 .

To this end, in the present invention, a PLC program can be easily set using a box-shaped function block. That is, in the present invention, it is possible to easily configure the input and output of the input duplication processing apparatus of the PLC by using a separate and independent means made of hardware or software.

The present invention proposes an input duplication processing apparatus of PLC capable of duplicating input processing within a single module. In addition, the present invention can be easily applied through a function block that can provide setting and processing results for input duplication in the form of a system library.

In the present invention, it is assumed that an input duplication processing device of PLC supporting 8 inputs is assumed, and technical features and examples have been described. However, it should be noted that this is set to help the understanding of the description, and common input modules are manufactured to accommodate inputs of various combinations, such as 8 points, 16 points, 32 points, and 64 points, in one module. The digital input duplication process of the above-described method can be easily applied to these modules as well.

Conventionally, it did not support the duplication processing of input modules ranging from 8 to 64 points within a single module, but used the module itself in a way that overlapped, resulting in excessive cost for numerous input contacts and complicated configuration of the system. , additional cost is incurred because the data control unit must exist separately for redundant processing, and the data control unit cannot detect the problem of the input signal itself because it is separated into the run state and the standby state.

As described above, while there are clear cost aspects and technical limitations in the prior art, the present invention can reduce costs by freely designating input redundancy by setting within a single input module, if necessary, and is called redundancy designation. It is easy to configure and set by using a box-shaped function block (PLC standard language) rather than composing all sequences with a complicated ladder (PLC standard language).

In particular, the present invention does not require any external hardware or software, and thus the system configuration can be designed simply, and the dual input signal configuration is possible at a minimum cost.

In addition, the present invention proposes a method capable of rationally responding to a logical limit in which perfect abnormal detection is impossible, and when an abnormality occurs, an alarm flag is used to notify the operator of the abnormal occurrence and at the same time apply a preset safety input to the control operation to ensure the safety of the system can be secured, and it is possible to continue operation without stopping the system.

In addition, the present invention adopts the duplication method in units of input modules, and unlike the prior art in which there is a waste factor of input contacts, it is possible to configure a more efficient duplication system by presenting a duplication method in units of contacts.

In addition, according to the present invention, by easily applying the setting and processing results for input duplication through a function block, it is possible to freely designate input duplication by setting as needed within a single input module.

In addition, the present invention can at least automatically perform the input redundancy setting available in the PLC programming tool, thereby greatly reducing the programming time and reducing the possibility of errors.

Although the technical idea of the present invention has been described in conjunction with the accompanying drawings in the above, the preferred embodiment of the present invention is exemplarily described and does not limit the present invention. In addition, it is clear that any person with ordinary skill in the art can make various modifications and imitations without departing from the scope of the technical idea of the present invention.

104: detection unit
105: judgment unit
106: bus connection

Claims (11)

a detection unit that converts an input signal received through a plurality of input contacts into an internal logic signal;
By comparing the states of contact pairs to be duplicated for a plurality of input contacts, if the states do not match, the detection input is replaced with a pre-declared safety input to determine the final input, and an alarm flag for the final input is generated judging unit; and
a bus connection unit for transmitting the final input and the warning flag to the outside through a system bus; including,
In the plurality of input contacts, at least one pair of contacts is set as a redundant contact pair, and at least one of the redundant contact pairs is set to a safety input state,
When the state of the redundant contact pair does not match, the determination unit generates the alarm flag and inserts it into the final input, and transfers the final input into which the alarm flag is inserted to the bus connection unit,
The alarm flag is separately provided for each duplicated contact pair, and is configured to easily identify the duplicated contact pair when an abnormality occurs.
delete According to claim 1,
The safety input state is a signal state used for correction when the state of the duplicated contact pair is determined to be abnormal.
According to claim 1,
Among the plurality of input contacts, the remaining contacts are set as general contacts, an input duplication processing device of PLC.
delete delete (a) converting an input signal received through a plurality of input contacts into an internal logic signal;
(b) setting at least one pair of contacts among a plurality of input contacts as a duplicated contact pair, calculating the input signal to perform duplicated input processing for the plurality of input contacts, a final input, and a final input for the final input generating an alert flag; and
(c) transmitting the final input and the warning flag to the outside through a system bus,
In step (b), when the state of the duplicated contact pair does not match, the alarm flag is generated and inserted into the final input, the PLC input duplication processing method.
8. The method of claim 7,
In step (b), the remaining contacts among the plurality of input contacts are set as normal contacts, and at least one of the duplicated contact pairs is set to a safety input state.
9. The method of claim 8,
The safety input state is a signal state used for correction when the state of the redundant contact pair is determined to be abnormal.
delete 8. The method of claim 7,
PLC's input duplication processing method for applying the setting and processing results for the duplex input processing through a function block.

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