KR102188746B1 - Distributed control device including a real-time compensation means - Google Patents

Abstract

The distributed control apparatus of the present invention includes a plurality of slave devices connected to a network master through a serial or redundant network; When each slave device is initialized, a first operation to ensure real-time performance and a second operation to guarantee real-time of each slave device are performed in consideration of changed time information in the case of a redundant connection due to disconnection of any one network Real-time compensation means; Includes.

Description

Distributed control device equipped with real-time compensation means {DISTRIBUTED CONTROL DEVICE INCLUDING A REAL-TIME COMPENSATION MEANS}

The present invention relates to a network-based distributed control device.

As the control target system becomes large and complex with the development of factory automation, technology is gradually developing from a single control system to a distributed control system based on a network.

An industrial network can be used for the Distributed Control System. Industrial networks refer to field buses that control distributed control devices at the field level.

If any one connection is disconnected from the serial (line topology) connection of an industrial network, a ring connection can be used to ensure stability.

There is a need for a technology that guarantees real-time in the redundant connection of industrial networks for control and control stability of distributed control devices.

The present invention is provided with a real-time compensation means, and enables real-time control and control of each distributed control device upon redundant connection.

The distributed control apparatus of the present invention includes a plurality of slave devices connected to a network master through a serial or redundant network; When each slave device is initialized, a first operation to ensure real-time performance and a second operation to guarantee real-time of each slave device are performed in consideration of changed time information in the case of a redundant connection due to disconnection of any one network Real-time compensation means; Includes.

Slave device refers to each control device connected to the network master in the distributed control system.

The present invention performs a first operation that guarantees real-time performance when initializing each slave device and a second operation that guarantees real-time performance of a slave device in consideration of changed time information when a network connection is disconnected and redundantly connected at any one place. And a real-time compensation means.

There is a need for a means of ensuring real-time in serial or redundant connections in industrial networks. The present invention can guarantee real-time performance of each slave device when the slave device is initially set as well as when the slave device is connected in redundancy. A real-time compensation means is provided that can guarantee real-time when any one connection is disconnected in a redundant connection.

The real-time compensation means of the present invention requires stability and reliability and maintains real-time within fault tolerance in industrial fields such as production automation and nuclear power plants that adopt a redundant connection, and provides a distributed control device with high precision as well as stability and reliability. Make it possible to implement.

1 is a flowchart for correcting master time, time delay, and jitter by the real-time compensation means of the present invention.
2 shows the structure of raw data corrected by the real-time compensation means of the present invention.
3 is a block diagram showing a network master and a real-time compensation means during a redundant connection according to the present invention.
4 is a block diagram showing transmission data, conveyance data, time compensation data, and processed data according to the present invention.
5 is a block diagram showing a detailed configuration of a real-time compensation means of the present invention.
6 is a block diagram showing a data transfer time, a data copy time, and a transmission delay time in a redundant connection according to the present invention.

Referring to FIGS. 1 to 3, the real-time compensation unit 150 may correct a timer generating a synchronization signal of each slave device during a first operation. That is, the timer of each slave device may be corrected to match the timer of the network master 100 in order to guarantee real-time performance.

In order to guarantee real-time in an industrial network, for each connected slave device, the difference in master time (MASTER TIME, absolute time), which is the reference time for synchronization, the time delay for each slave device to receive data, and each slave device. It is necessary to remove or correct the jitter that has been introduced.

The real-time compensation unit 150 performs a first operation for removing or correcting a master time difference of each slave device, a time delay of each slave device, and jitter of each slave device. For the first operation, the real-time compensation unit 150 may periodically transmit the master time.

During the first calculation of the real-time compensation means 150, the correction of the master time difference and the time delay may be performed when each slave device is initialized. Jitter correction can be performed by periodically transmitting the master time a predetermined number of times immediately before sending data.

Referring to FIG. 1, the correction value of the master time difference and the time delay may be calculated based on time information obtained from each slave device when initializing each slave device. A correction value of a master time difference and a time delay of each slave device may be set according to time information acquired during initialization of each slave device.

Jitter correction can be corrected by repeatedly transmitting the master time a predetermined number of times within a short period immediately before sending data periodically. For example, jitter can be eliminated by repeatedly transmitting the master time three times and averaging the deviation for each master time.

The real-time compensation unit 150 checks whether the operation start flag of the distributed control device is on (step S10). When the operation start flag is turned on, the real-time compensation means 150 checks each connected slave device (step S11). Check the time information of the connected slave device (step S12). The difference between the master time of the connected slave devices and the master time of the network master 100 is calculated (step S13). The real-time compensation means 150 transmits the master time difference to the connected slave devices (step S14). The difference in master time of each slave device may be removed or corrected according to steps S10 to S14. Next, it is necessary to remove or correct the delay in the time it takes for each slave device to receive data.

The real-time compensation means 150 calculates a time delay before the connected slave device receives data (step S15). A time delay is transmitted to the connected slave devices (step S16). The time delay required for each slave device to receive data may be removed or corrected by steps S15 and S16. Next, you need to correct the jitter.

The real-time compensation means 150 transmits the master time to each slave device (step S17).

The master time is repeatedly transmitted a predetermined number of times in steps S17, S18, and S18, and jitter may be corrected accordingly. The real-time compensation unit 150 periodically transmits the master time repeatedly a predetermined number of times within a short time period immediately before sending data. Accordingly, jitter of each slave device can be corrected.

If the operation start flag is not turned off and continues to be turned on (step S21), data can be periodically sent and thereby the synchronization state can be maintained. Since there is still time until periodically sending data, the remaining time from the cycle time is waited (step S22), and when the next cycle time returns, the master time and data are periodically transmitted (step S20).

Since the timer of each slave device that generates the synchronization signal of each slave device is corrected, the real-time compensation unit 150 may synchronize real-time transmission data. If the real-time compensation means 150 shown in FIG. 1 and ƒˆ removes or corrects the master time difference of each slave device, the time delay of each slave device, and jitter of each slave device, data can be synchronized.

In an industrial network, each slave device must operate as if it were one device with the network master 100. To this end, the network master 100 and the timers of each slave device were synchronized. In accordance with this synchronization signal, data is sent periodically to maintain synchronization.

Since the network master 100 and each of the slave devices generate a synchronization signal at the same time, the received data can be processed at the same time. A master time for continuously correcting jitter is repeatedly transmitted to the periodically transmitted data, and slave devices receive the master time and can continuously correct a synchronization occurrence timer. As a result, data can be synchronized through periodic data transmission after timer synchronization.

However, the first operation as described above may be limited to a case in which time information checked at the time of initializing each slave device is not changed. For example, the first operation may be necessary when the connection to one location is not disconnected and the initial state is the same, or when the connection of point a was disconnected at the time of the previous synchronization, but the connection of point a remains disconnected. .

The real-time compensation means 150 is not limited to the first operation, and a second operation that quickly calculates the changed time delay and synchronizes the timer and data even when the connection of any part of the distributed control device is disconnected in the middle. Can be done. For example, the second operation can be performed when the connection at one place is disconnected and the network state is different from the initial state, or when the connection at point a was disconnected at the time of the previous synchronization and the connection at point b was newly disconnected. have.

Next, the second operation of the real-time compensation means 150 will be described.

As shown in FIG. 3, when a part is disconnected from the ring connection (Cable Failure), a time delay may be newly induced before each slave device receives data. In contrast to the initialization time of each slave device, a difference in synchronization signal may occur as much as a new time delay in the redundant connection. In severe cases, the real-time performance of the entire system may be distorted.

In a networked distributed control device, real-time or synchronization between devices must be guaranteed based on the master time. Synchronization between slave devices must always be guaranteed even during system operation, such as interlock and simultaneous operation.

The real-time compensation means 150 of the present invention performs a second operation on the newly made redundant connection when a redundant connection is made due to disconnection of any one place, and it is impossible to guarantee the real-time performance of the first operation. It calculates the delay quickly and keeps the synchronization between each slave device even during the operation of the distributed control device.

3 and 4, the real-time compensation means 150 may be located under the network stacks 110, 120, 130 and 140. The network master 100 may include a network stack 110, 120, 130, 140, a packet forwarding unit 190, and a real-time compensation unit 150. The Rx terminal / Tx terminal of the real-time compensation means 150 may be the same as the Rx terminal / Tx terminal of the network master 100.

The real-time compensation means 150 may process and process the raw data in the form of a packet of FIG. 2 received from the network stacks 110, 120, 130, and 140 through the packet transfer unit 190.

The industrial network stacks 110, 120, 130, and 140 mean a general field bus and may be representatively EtherCAT. The packet transfer unit 190 may be a data transfer module such as a memory block or a message queue that transfers raw data generated by the industrial network stacks 110, 120, 130, and 140.

Referring to FIG. 4, data between the real-time compensation means 150 and each slave device may include transmission data, conveyance data, time compensation data, and processing completion data. These can all be of the raw data format of FIG. 2.

Referring to FIGS. 3 and 6, when several slave devices are connected in series, a slave device arrangement 200 is formed. For the sake of explanation, the slave device connected to the network master 100 for the first time is the first slave device 210a, the second slave device 210b, the slave device at the final location to which data is normally transmitted, and the connection is disconnected to establish a redundant connection. The slave device at the position where data is to be retransmitted in the reverse direction is defined as the N-1th slave device. Here, N is a natural number of 4 or more.

Referring to FIG. 4, in the second operation, the real-time compensation unit 150 may transmit transmission data, conveyance data, time compensation data, and processing completion data. The real-time compensation means 150 may transmit time information for guaranteeing real-time quality of the transmitted data and information for confirming whether or not the transmission data is processed by each slave device.

The transmission data is data for controlling and controlling the slave device, and may include time information for guaranteeing real-time performance of the slave device.

The return data is data that has not yet been processed by the N-1th slave device due to a network disconnection or an error. The conveyance data may include location information or ID information of the second slave device 210b that has been normally processed.

The time compensation data is information for compensating the real-time property of the N-1th slave device to receive the return data, which is the unprocessed data. The time compensation data may be retransmitted to the N-1th slave device together with the carrier data.

The processed data is data that has been processed by each slave device connected to the network master 100.

4 to 6, when the network master 100 or the real-time compensation means 150 obtains the conveyance data during the second calculation, the raw data of FIG. 2 is processed to ensure the real-time performance of the slave device to compensate for time. Data may be transmitted back to the N-1th slave device.

Referring to FIG. 6, the real-time compensation means 150 during the second operation ensures the stability of data even when a connection is disconnected from a redundant connection and guarantees real-time between each slave device to enable synchronization.

5, the real-time compensation means 150 obtains the conveyance data and passes through the device connection diagnosis unit 151, the device data transmission unit 153, and the time compensation processing unit 157, and the real-time performance of the distributed control device It is possible to generate time compensation data that guarantees.

The device connection diagnosis unit 151 may obtain the conveyance data, and check the location information or ID information of the second slave device 210b, which is the final slave device normally processed based on the conveyance data.

The device data transmission unit 153 may transmit data so that data of the N-1th slave device, which is an unprocessed slave device, is not damaged. That is, the device data transfer unit 153 may change the transmission direction of the transport data transmitted in the direction of the first slave device 210a and then conveyed from the second slave device 210b to the direction of the N-1th slave device. .

The time compensation processing unit 157 calculates the delayed time based on the master time and generates new data that guarantees the real-time properties of the N-1th slave device in order to guarantee the real-time properties of the N-1th slave device that did not process the data Can be generated.

The time compensation processing unit 157 may include a data transfer time calculation unit 154, a data copy time calculation unit 155, and a transmission delay time calculation unit 156.

The data transfer time calculation unit 154 may calculate a delay time generated when data is transferred from the second slave device 210b, which is the last slave device that has been normally processed.

The data copy time calculation unit 155 may calculate a delay time generated when data is copied from the device data transfer unit 153 that transmits data to be transmitted to the N-1th slave device without damage.

The transmission delay time calculation unit 156 may estimate a transmission delay time that may physically occur when data is conveyed and when time-compensated data is transmitted, using a statistical method.

Referring to FIG. 6, time information to be received in order for the time compensation processing unit 157 to calculate a compensation time value is shown.

Time information corresponding to the data transfer time is T1 and T2.

For example, T1 is the time when the transmission data is transmitted from the network master 100 to the second slave device 210b, or the transmission data is transmitted from the Tx terminal of the network master 100 to the second slave device 210b. It's time.

For example, T2 is the time at which the transfer data is transferred from the second slave device 210b to the network master 100, or the transfer data is transferred from the second slave device 210b to the Rx terminal of the network master 100. It's time.

Time information corresponding to the data copy time is T3 and T4.

Transmission data and carrier data may be obtained by the real-time compensation means 150 through the first port 160 of FIG. 4. In the case of a duplex connection, time compensation data and processing completion data may be output from the real-time compensation unit 150 through the second port 170 of FIG. 4 for reverse transmission. The first port 160 and the second port 170 may each include an Rx terminal for receiving data and a Tx terminal for outputting data.

For example, T3 is a time for converting data in the reverse direction inside the network master 100, the real-time compensation unit 150, or the device data transmission unit 153. Alternatively, T3 is the time at which data is transferred from the Rx terminal or Tx terminal of the first port 160 of the real-time compensation unit 150 to the Rx terminal or the Tx terminal of the second port 170 of the real-time compensation unit 150 Can be.

For example, T4 is a time during which carrier data or time compensation data is transferred from the network master 100 to the N-1th slave device in the reverse direction through a redundant connection. Alternatively, T4 is a time during which the carrier data or time compensation data is transferred from the Tx terminal of the network master 100 to the N-1th slave device in the reverse direction during the redundancy connection.

Time information corresponding to the transmission delay time is T5 to T8.

For example, the transmission delay time may include a time required by hardware or physically inside the Tx terminal / Rx terminal, or a time required for data processing in a processing unit installed inside each slave device. The transmission delay time can be estimated through repetitive performance results or statistical methods.

T1 to T4 can be known as a time counter installed inside the network master 100 or slave device, or when raw data is transmitted or received from the Rx terminal and Tx terminal installed inside the network master 100 or slave device. It can be known by the time capture information of.

T5 to T8 may be time consumed by hardware in the Tx terminal / Rx terminal of the network master 100 or a processing unit installed inside each slave device.

For example, T5 to T8 may differ from each other when data flows in the first direction when the serial network is normal and when data flows in the second direction, which is the reverse direction of the first direction due to the redundancy connection. For T5 to T8, predicted values may be calculated based on time information of each slave device checked at the time of initialization and time information captured at T1 to T4, and a final value may be estimated through a statistical technique.

When a value obtained by adding T1 to T8 is defined as a compensation time value Tcomp, a new master time may be calculated by Equation 1 below. The new master time updated by the compensation time value may be newly recorded (overriding) in the'MASTER TIME' field of the raw data of FIG. 2.

(Equation 1)

New Master Time = Previous Master Time + Compensation Time Value (Tcomp)

Compensation time value (Tcomp) = the sum of T1 to T8

100...network master 110,120,130,140...network stack
150...Real-time compensation means 151...Device connection diagnostics
153...device data transmission unit 157...time compensation processing unit
154...Data transfer time calculation unit 155...Data copy time calculation unit
156...transmission delay time calculation unit 160...first port
170...second port 190...packet delivery
200...Slave device arrangement 210a...First slave device
210b...2nd slave device 210n...Nth slave device

Claims (11)

A plurality of slave devices connected to the network master through a serial or redundant network;
When each slave device is initialized, a first operation that guarantees real-time performance and a second operation that guarantees real-time performance of each slave device are performed in consideration of changed time information in the case of redundant connection due to disconnection of a network connection at any one place. Real-time compensation means; Including,
During the first calculation, the real-time compensation means,
Correcting a timer for generating a synchronization signal of each of the slave devices to match the timer of the network master,
The real-time compensation means,
The first operation for removing or correcting the master time difference between the slave devices, the time delay of the slave devices, and the jitter of the slave devices is performed. For the first calculation, the real-time compensation means periodically Transfer the master time to each of the slave devices,
During the first calculation of the real-time compensation means,
The correction of the master time difference of each of the slave devices and the time delay of each of the slave devices is calculated based on time information obtained from each of the slave devices when initializing each of the slave devices,
The jitter correction of each of the slave devices is performed by repeatedly transmitting the master time a predetermined number of times immediately before sending data periodically.
delete delete delete The method of claim 1,
The network master includes a network stack, a packet forwarding unit, and the real-time compensation means,
The real-time compensation means is connected by the network stack and the packet forwarding unit,
The Rx terminal / Tx terminal of the real-time compensation means is the same as the Rx terminal / Tx terminal of the network master,
The real-time compensation means is a distributed control device for correcting raw data in the form of a packet transmitted from the network stack through the packet transfer unit.
The method of claim 1,
The slave device connected to the network master for the first time is a first slave device, and the slave device at the final position to which the data is normally transmitted is a second slave device, and the redundant connection is made and the data is retransmitted in the reverse direction. When the slave device is defined as the N-1th slave device (here, N is a natural number of 4 or more),
The data transmitted between the real-time compensation means and each of the slave devices includes transmission data, conveyance data, time compensation data, and processing completion data,
The transmission data is data for control and control of the slave device, and includes time information for guaranteeing real-time performance of the slave device,
The conveyance data is data that has not been processed by the N-1th slave device due to a network disconnection or an error,
The time compensation data is information for compensating the real-time property of the N-1th slave device to receive the conveyance data again,
The processed data is data that has been processed by each of the slave devices connected to the network master.
The method of claim 1,
The slave device connected to the network master for the first time is a first slave device, and the slave device at the final position to which the data is normally transmitted is a second slave device, and the redundant connection is made and the data is retransmitted in the reverse direction. When the slave device is defined as the N-1th slave device (here, N is a natural number of 4 or more),
In the second calculation, the network master or the real-time compensation means,
A distributed control device configured to transmit time compensation data obtained by processing the raw data to the N-1th slave device when raw data conveyed from the second slave device is received.
The method of claim 1,
The slave device connected to the network master for the first time is a first slave device, and the slave device at the final position to which the data is normally transmitted is a second slave device, and the redundant connection is made and the data is retransmitted in the reverse direction. When the slave device is defined as the N-1th slave device (here, N is a natural number of 4 or more),
The real-time compensation means obtains the conveyed data conveyed from the second slave device, and passes through a device connection diagnosis unit, a device data transfer unit, and a time compensation processing unit, to ensure real-time performance of the N-1th slave device. Distributed control device that generates data.
The method of claim 8,
The device connection diagnostic unit obtains the conveyance data, checks the location information or ID information of the second slave device based on the conveyance data,
The device data transfer unit switches the transmission direction of the transport data to the N-1th slave device direction,
The time compensation processor calculates the delayed time based on the synchronized master time and generates new data that guarantees real-time performance of the N-1th slave device.
The method of claim 1,
The slave device connected to the network master for the first time is a first slave device, and the slave device at the final position to which the data is normally transmitted is a second slave device, and the redundant connection is made and the data is retransmitted in the reverse direction. When the slave device is defined as the N-1th slave device (here, N is a natural number of 4 or more),
The network master and each of the slave devices are synchronized with a new master time obtained by adding a compensation time value to the previous master time,
The compensation time value is a sum of T1 to T4,
The T1 is a time when transmission data is transferred from the network master to the second slave device,
The T2 is a time at which carrier data is transferred from the second slave device to the network master,
The T3 is a time to reverse data in the network master during the redundant connection,
The T4 is a distributed control device that is a time when the carrier data or time compensation data is transferred from the network master to the N-1th slave device during the redundancy connection.
The method of claim 10,
The compensation time value is,
The sum of the T1 to T4 and the time required inside the Tx terminal and Rx terminal installed in the network master or each slave device, or
A distributed control device that is a value obtained by adding a sum of the T1 to T4 to a time required for data processing by a processing unit installed inside each of the slave devices.

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