WO2020138704A1

WO2020138704A1 - Distributed control apparatus having real-time compensation means

Info

Publication number: WO2020138704A1
Application number: PCT/KR2019/015143
Authority: WO
Inventors: 최성훈
Original assignee: 알에스오토메이션주식회사
Priority date: 2018-12-27
Filing date: 2019-11-08
Publication date: 2020-07-02
Also published as: KR20200080866A; KR102188746B1

Abstract

A distributed control apparatus of the present invention comprises: a plurality of slave devices connected to a network master by means of a serial or ring network; and a real-time compensation means for performing a first operation for guaranteeing real-timeness when initializing each of the slave devices, and a second operation for guaranteeing the real-timeness of each of the slave devices in consideration of changed time information when a ring connection is made as the network connection at a certain location is lost.

Description

Distributed control device with real-time compensation means

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

With the development of factory automation, the system to be controlled becomes large and complex, and the technology is gradually developing from a single control system to a network-based distributed control system.

An industrial network can be used for a distributed control system. Industrial networks are field buses that control field level distributed control devices.

In order to ensure stability when a connection is lost in a serial (line topology) connection of an industrial network, a ring connection may be used.

For the control and control stability of distributed control devices, there is a need for a technology that ensures real-time performance in a redundant connection of an industrial network.

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

The distributed control apparatus of the present invention includes: a plurality of slave devices connected to a network master in a serial or redundant network; Performs a first operation to guarantee real-time performance during initialization of each slave device and a second operation to ensure real-time performance of each slave device in consideration of variable time information when one network connection is disconnected and redundantly connected. Real-time compensation means; It includes.

A slave device refers to each control device connected to a network master in a distributed control system.

The present invention performs a first operation to guarantee real-time performance at the time of initialization of each slave device and a second operation to ensure real-time performance of the slave device in consideration of fluctuating time information when one network connection is disconnected and redundantly connected. It provides a real-time compensation means.

There is a need for a means to ensure real-time performance over serial or redundant connections in industrial networks. The present invention can guarantee the real-time performance of each slave device during the initial setup of the slave device as well as the redundant connection. A real-time compensation means is provided to ensure real-time performance when a connection is lost in a redundant connection.

The real-time compensation means of the present invention requires stability and reliability to maintain real-time in fault tolerance in industrial fields such as production automation, nuclear power plants, etc. that adopt redundant connections, and provide a distributed control device with stability and reliability as well as high precision. To be implemented.

1 is a flow chart for real-time compensation means of the present invention to correct the master time, time delay, jitter.

Figure 2 shows the structure of the raw data to be corrected by the real-time compensation means of the present invention.

3 is a block diagram showing a network master and real-time compensation means in the redundant connection of the present invention.

4 is a block diagram showing transmission data, conveyance data, time compensation data, and processing completion data of the present invention.

5 is a block diagram showing a detailed configuration of the 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 the redundant connection of the present invention.

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

In order to guarantee real-time performance in an industrial network, for each connected slave device, the difference between the master time (MASTER TIME, absolute time), which is the reference time for synchronization, and the time delay before each slave device receives data, each slave device It is necessary to remove or correct the jitter they have.

The real-time compensation means 150 performs a first operation to remove or correct the master time difference of each slave device, time delay of each slave device, and jitter of each slave device. For the first operation, the real-time compensation means 150 may periodically transmit the master time.

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

Referring to FIG. 1, a correction value of a master time difference and a time delay may be calculated based on time information obtained from each slave device when initializing each slave device. The correction value of the master time difference and the time delay of each slave device may be set according to the time information obtained 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 three master times and averaging the deviation for each master time.

The real-time compensation means 150 checks whether the operation start flag of the distributed control device is turned 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). According to steps S10 to S14, the master time difference of each slave device may be removed or corrected. Next, it is necessary to eliminate or correct the time delay for each slave device to receive data.

The real-time compensation means 150 calculates a time delay for the connected slave device to receive data (step S15). The time delay is transmitted to the connected slave devices (step S16). The time delay 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 thus jitter may be corrected. The real-time compensation means 150 periodically transmits the master time a predetermined number of times within a short time interval immediately before sending data. Accordingly, jitter of each slave device can be corrected.

If the operation start flag is not turned off and remains on (step S21), data can be periodically transmitted and thereby synchronized. Since there is still time to send data periodically, the time remaining in 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 means 150 can synchronize real-time transmission data. When the real-time compensation means 150 of FIG. 1 removes or corrects a master time difference of each slave device, a time delay of each slave device, and jitter of each slave device, data may be synchronized.

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

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

However, the first operation as described above may be limited to a case in which the time information checked at the initialization of each slave device is not changed. For example, the first operation may be necessary in the case where the connection of one point is not disconnected and the initial state is the same, or the connection of point a is disconnected during the previous synchronization and the connection of point a is still maintained. .

The real-time compensation means 150 is not limited to the first operation, and the second operation for quickly calculating the changed time delay and synchronizing the timer and data even when the connection of any one part is disconnected in the redundant connection of the distributed control device You can do For example, the second operation may be performed when one of the connections is disconnected to become a network state different from the initial state, or when the point a is disconnected while the previous synchronization is disconnected and the point b is newly disconnected. have.

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

As shown in FIG. 3, when a part of a connection is lost in a redundancy connection (Cable Failure), a time delay may be newly generated until each slave device receives data. When preparing for the initialization timing of each slave device, a difference in synchronization signals may occur as much as a new time delay in a redundant connection. In severe cases, the real-time performance of the entire system may be compromised.

In a network-type distributed control device, real time or synchronization between devices should be guaranteed based on the master time. Synchronization between slave devices should 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 formed redundancy connection when the connection of one of the places is disconnected and the redundancy connection is made and the real-time performance of the first operation cannot be guaranteed. The delay can be calculated quickly and the synchronization between each slave device can be maintained even during the operation of the distributed control device.

3 and 4, the real-time compensation means 150 may be located under the network stack (110,120,130,140). The network master 100 may include a

network stack

110, 120, 130, 140, a packet transfer unit 190, and real-time compensation means 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 (RAW) data in the form of packets of FIG. 2 received from the network stacks 110, 120, 130, and 140 through the packet delivery unit 190.

Industrial network stack (110,120,130,140) means 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 message queue that transmits 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, carrier data, time compensation data, and processing completion data. These can all be in the raw data format of FIG. 2.

3 and 6, when several slave devices are connected in series, the slave device array 200 is formed. For explanation, the first slave device connected to the network master 100 is the first slave device 210a, the slave device at the final location where data is normally transmitted, the second slave device 210b, the connection is broken, and a redundant connection is made. A slave device at a position where data should be retransmitted in the reverse direction is defined as an N-1 slave device. Here, N is a natural number of 4 or more.

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

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 been processed in the N-1 slave device due to a network connection disconnection or an error. The carrier 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-1 slave device that will receive back data, which is unprocessed data. The time compensation data may be retransmitted to the N-1 slave device together with the carrier data.

The processed data is data that has been processed in 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 carrier data during the second operation, time compensation is performed by processing the raw data of FIG. 2 to guarantee real-time performance of the slave device. Data can be transmitted back to the N-1 slave device.

Referring to FIG. 6, in the second operation, the real-time compensation means 150 ensures stability of data and ensures real-time synchronization between each slave device even when one connection is lost in a redundant connection, so that synchronization is possible.

Referring to FIG. 5, the real-time compensation means 150 obtains the conveyed data and passes the device connection diagnosis unit 151, the device data transmission unit 153, and the time compensation processing unit 157, and real-time property of the distributed control device. It can generate time compensation data to ensure.

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

The device data transfer unit 153 may transfer data so that data of the N-1 slave device, which is a slave device that is not processed, is not damaged. That is, the device data transfer unit 153 may be transferred in the direction of the first slave device 210a and then switch the transmission direction of the transport data conveyed by the second slave device 210b to the N-1 slave device direction. .

The time compensation processing unit 157 calculates the delayed time based on the master time and provides new data that guarantees the real-time performance of the N-1 slave device to ensure real-time performance of the N-1 slave device that has failed to process the data. Can be created.

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 that occurs when data is transferred from the second slave device 210b, which is the last slave device that is normally processed.

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

The transmission delay time calculator 156 may predict a transmission delay time that may occur physically when data is returned and when time compensation data is transmitted using a statistical method.

Referring to FIG. 6, time information to be received by the time compensation processing unit 157 to calculate the compensation time value is illustrated.

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

For example, T1 is a time when transmission data is transmitted from the network master 100 to the second slave device 210b, or a 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 when the carrier data is transferred from the second slave device 210b to the network master 100, or the carrier 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.

The transmission data and the carrier data may be obtained by the real-time compensation means 150 through the first port 160 of FIG. 4. In the case of duplex connection, time compensation data and processing completion data may be output from the real-time compensation means 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 within the network master 100, real-time compensation means 150, or device data transfer unit 153. Alternatively, T3 is the time during which data is transferred from the Rx terminal or Tx terminal of the first port 160 of the real-time compensation means 150 to the Rx terminal or Tx terminal of the second port 170 of the real-time compensation means 150. Can be.

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

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

For example, the transmission delay time may include time spent in hardware or physically inside the Tx terminal / Rx terminal or time spent in processing data in a processing unit installed inside each slave device. The transmission delay time may be estimated through the iterative performance result or a statistical method.

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

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

For example, T5 to T8 may be different 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 redundant connection. T5 to T8 may calculate an expected value through time information of each slave device checked at initialization and time information captured in T1 to T4, and estimate a final value through a statistical technique.

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

(Equation 1)

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

Compensation time value (Tcomp) = T1 to T8 plus

(Explanation of codes)

100...network master 110,120,130,140...network stack

150...real-time compensation means 151...device connection diagnosis

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...1st port

170...second port 190...packet delivery

200...slave device arrangement 210a...1st slave device

210b...2nd slave device 210n...Nth slave device

Claims

A plurality of slave devices connected to the network master in a serial or redundant network;

Performs a first operation to guarantee real-time performance during initialization of each slave device and a second operation to ensure real-time performance of each slave device in consideration of variable time information when one network connection is disconnected and redundantly connected. Real-time compensation means; Distributed control device comprising a.
According to claim 1,

The real-time compensation means during the first calculation,

A distributed control device that corrects a timer generating a synchronization signal of each slave device to match the timer of the network master.
According to claim 1,

The real-time compensation means,

Perform the first operation to remove or correct the master time difference of each slave device, time delay of each slave device, and jitter of each slave device,

For the first operation, the real-time compensation means periodically distributes the master time to each of the slave devices.
According to claim 1,

In the first calculation of the real-time compensation means,

The correction of the master time difference of each slave device and the time delay of each slave device is calculated based on time information obtained from each slave device when initializing each slave device,

The jitter correction of each slave device is performed by repeatedly transmitting the master time a predetermined number of times just before sending data periodically.
According to claim 1,

The network master includes a network stack, a packet delivery unit and the real-time compensation means,

The real-time compensation means is connected to the network stack and the packet transmission 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 the raw (RAW) data in the form of packets received from the network stack through the packet delivery unit.
According to claim 1,

The first slave device connected to the network master is the first slave device, the slave device at the last position where the data is normally transmitted is the second slave device, the redundant connection is made and the data is to be retransmitted in the reverse direction. When defining the slave device as the N-1 slave device (where N is a natural number greater than or equal to 4),

Data transmitted between the real-time compensation means and each of the slave devices includes transmission data, carrier data, time compensation data, and processing completion data,

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

The transport data is data that has not been processed in the N-1 slave device due to a network connection disconnection or an error,

The time compensation data is information for compensating the real-time property of the N-1 slave device to receive the carrier data again,

The processed data is distributed control device that is data that has been processed in each of the slave devices connected to the network master.
According to claim 1,

The first slave device connected to the network master is the first slave device, the slave device at the final position where the data is normally transmitted is the second slave device, the redundant connection is made and the data is to be retransmitted in the reverse direction. When defining the slave device as the N-1 slave device (where N is a natural number greater than or equal to 4),

When the second calculation, the network master or the real-time compensation means,

When the raw data returned from the second slave device is obtained, the distributed control device transmits time compensation data processed from the raw data to the N-1 slave device.
According to claim 1,

The first slave device connected to the network master is the first slave device, the slave device at the final position where the data is normally transmitted is the second slave device, the redundant connection is made and the data is to be retransmitted in the reverse direction. When defining the slave device as the N-1 slave device (where N is a natural number of 4 or more),

The real-time compensation means, time compensation to obtain the carrier data returned from the second slave device and pass through the device connection diagnosis unit, the device data transmission unit, and the time compensation processing unit to ensure real-time performance of the N-1 slave device Distributed control device that generates data.
The method of claim 8,

The device connection diagnosis unit obtains the transport data, and checks location information or ID information of the second slave device based on the transport data,

The device data transfer unit converts the transmission data transmission direction to the N-1 slave device direction,

The time compensation processing unit calculates the delayed time based on the synchronized master time and generates a new data that guarantees the real-time performance of the N-1 slave device.
According to claim 1,

The first slave device connected to the network master is the first slave device, the slave device at the final position where the data is normally transmitted is the second slave device, the redundant connection is made and the data is to be retransmitted in the reverse direction. When defining the slave device as the N-1 slave device (where N is a natural number greater than or equal to 4),

The network master and each slave device are synchronized to a new master time by adding a compensation time value to the previous master time,

The compensation time value is the sum of T1 to T4,

The T1 is a time when transmission data is transmitted from the network master to the second slave device,

The T2 is a time when carrier data is transferred from the second slave device to the network master,

The T3 is a time to convert data in the network master in the reverse direction during the redundant connection,

The T4 is a distributed control device in which the carrier data or time compensation data is transmitted from the network master to the N-1 slave device during the redundant connection.
The method of claim 10,

The compensation time value,

Or the sum of T1 to T4 plus the time taken 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 the time taken for data processing by a processing unit installed inside each slave device to the sum of the T1 to T4 values.