WO2011131081A1

WO2011131081A1 - Method and apparatus for implementing redundancy serial bus

Info

Publication number: WO2011131081A1
Application number: PCT/CN2011/072355
Authority: WO
Inventors: 王常力; 史洪源; 温宜明; 虞日跃
Original assignee: 杭州和利时自动化有限公司
Priority date: 2010-04-20
Filing date: 2011-03-31
Publication date: 2011-10-27
Also published as: CN101807986A

Abstract

A method and apparatus for implementing a redundancy serial bus are disclosed in the present invention. The method includes: receiving data on one of a main link and a stand-by link, buffering data transmitted on the main link and the stand-by link in real time, monitoring the transmission state of the current link receiving the data in real time while buffering the data (301); judging whether the current link fails, if yes, switching to the stand-by link without failure for receiving the data (302). The implementation scheme of the present invention can realize a non-interference switch, namely when one link fails and the link is switched to the other link, it is ensured that normal data on the other link are not lost.

Description

The present invention claims to be submitted to the Chinese Patent Office on April 20, 2010, and the application number is 201010153090.X, the invention name is "a redundant serial bus implementation method and device" The priority of the Chinese Patent Application, the entire contents of which is incorporated herein by reference. TECHNICAL FIELD The present invention relates to the field of industrial automation technology, and more particularly to a method and apparatus for implementing a redundant serial bus. BACKGROUND In a distributed control system (DCS), a controller exchanges data with each slave station through a certain communication link. If the current communication link fails, such as data interference, disconnected wiring, etc., communication will be directly affected. Short-term interference can cause packet loss, affecting the reliability of the entire system. Long-term faults (such as broken wires) may cause the entire system to malfunction and may cause huge economic losses.

Currently, in order to improve the reliability of communication between controllers and slave modules in a distributed controller system, two separate communication links are usually used, as shown in Figure 1. Two independent communication links are hot backups. When one of the links fails, you can switch to another normal link as soon as possible to maintain communication continuity.

The existing implementation of the serial communication redundancy can be referred to FIG. 2, wherein FIG. 2(a) is a schematic diagram of the slave station transmitting data to the system controller, and FIG. 2(b) is the slave station receiving system control. Schematic diagram of the data sent by the device. As shown in Figure 2, the slaves mainly include: a drive unit, a data selection unit, a switching switch, and a processing unit. The data selection unit and the switch are at the same logic level, and the two operate in parallel.

When the slave module transmits data, the data is allocated to two independent drive units, and the drive unit respectively transmits the same data to the independent link A and link B; When the slave module receives data, the data on the two independent communication links A and B is sent to the data selection logic through the drive unit, and one of the two channels of data is selected and sent to the processing unit, and the data selection logic is based on two Whether the link is faulty, select a normal link to input data into the processing unit.

According to the research of the inventors, at least the following defects exist in the prior art:

When the processing unit receives the data, the data of which link is selected is determined by the data selection logic, and the data selection logic determines whether to switch to another link according to whether there is a fault on the link. The data selection logic and the data switch are at the same level, which brings a problem: when the data selection logic determines that there is a problem with the current link, and needs to control the switch to another link, the other link Normal data has been missed, which will inevitably result in data loss when the link is switched. Lost data interrupts the periodic data exchange between the slave module and the controller, introducing instability.

Summary of the invention

In view of this, an embodiment of the present invention provides a method and an apparatus for implementing a redundant serial bus, so as to implement a bumpless handover, that is, when one link fails, when another link is switched, another one is guaranteed. Normal data on the link is not lost.

An embodiment of the present invention provides a method for implementing a redundant serial bus. The method includes: collecting data through a link in a primary link and a backup link, and real-time buffering data transmitted by the primary link and the backup link. Simultaneously monitoring the transmission status of the current link receiving data while performing data buffering;

It is judged whether the current link is faulty, and if so, it is switched to the backup link that has not failed to receive data.

Preferably, the method further includes:

If it is judged that the current link has not failed, the current link reception data is maintained, and the failure notification information is output to the outside world.

Preferably, the method further includes:

If it is determined that all links have failed, the current link is kept receiving data.

Preferably, the determining whether the current link is faulty includes:

Determining whether the current link is faulty according to the check bit indication information carried in the transmitted data. If the check bit indication information is preset information, determining that the current link has not failed; if not, Then determining that the current link is faulty. Preferably, the method further includes:

Determining whether the recipient of the data is a local slave, and if so, caching the data; if not, discarding the data.

A device for implementing a redundant serial bus, the device comprising:

a receiving buffer module, configured to receive data through one link in the primary link and the backup link, and cache data transmitted by the primary link and the backup link in real time;

a monitoring module, configured to monitor, in real time, the transmission status of the current link of the received data while the data is buffered by the receiving buffer module;

a fault judging module, configured to determine whether the current link is faulty;

And a switching module, configured to: if the fault judging module determines that the current link is faulty, switch to the non-failed backup link to receive data.

Preferably, the fault judging module is further configured to:

If the fault judging module determines that the current link has not failed, the current link is maintained.

Preferably, the fault judging module is further configured to: if all the links fail, keep the current link receiving data, and output the fault notification information to the outside world.

Preferably, the check bit indication information carried in the data, the fault determination module determines, according to the check bit indication information, whether the current link is faulty, if the check bit indication information is preset When the information is determined, it is determined that the current link has not failed; if not, it is determined that the current link is faulty.

Preferably, the device further includes:

The receiving determining module is configured to determine whether the recipient of the data is a local slave, and if so, cache the data; if not, discard the data.

Compared with the prior art, the technical solution provided by the present invention collects data transmitted on the primary link and the backup link in real time through a link in the primary link and the backup link, and monitors the data in real time. The transmission status of the current link receiving the data; once the current link fails, it automatically switches to other unfailed links to continue receiving data. In this way, since the data being transmitted is stored in real time in the link after the handover, the defect that the packet loss does not occur after the link switching can be ensured, so that the number According to the transmission, it is more reliable and stable. BRIEF DESCRIPTION OF THE DRAWINGS In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings used in the embodiments or the description of the prior art will be briefly described below. Obviously, the drawings in the following description are merely Some embodiments of the present invention may also be used to obtain other drawings based on these drawings without departing from the prior art.

1 is a schematic diagram of a communication link of a distributed controller system in the prior art;

2 (a), (b) are schematic diagrams showing the implementation of serial communication redundancy in the prior art;

FIG. 3 is a schematic diagram of a method for implementing a redundant serial bus according to an embodiment of the present invention; FIG. 4 is a schematic diagram of a slave module in a distributed control system according to an embodiment of the present invention; FIG. Schematic diagram of data transmitted by a slave module in a distributed control system;

Figure 6 is a schematic diagram showing the time difference between two links in data output;

7 is a schematic diagram of redundancy switching of two links in FIG. 6;

FIG. 8 is a schematic structural diagram of an apparatus for implementing a redundant serial bus according to an embodiment of the present invention. detailed description

BRIEF DESCRIPTION OF THE DRAWINGS The technical solutions in the embodiments of the present invention will be described in detail below with reference to the accompanying drawings. All other embodiments obtained by a person of ordinary skill in the art based on the embodiments of the present invention without the creative work are all within the scope of the present invention.

After analyzing the implementation of serial communication redundancy in the prior art, it can be concluded that: the data selection logic and the data switching switch are at the same logic level, which determines that the method is not timely enough for link switching, when the link fault is diagnosed. When it comes out, the distance processing unit has received the erroneous data for some time. Although the fault information indicates which link is faulty, even if the link is switched, the packet loss data cannot be avoided. It can be seen that if the fault information can be obtained immediately when the fault occurs, and the bumpless handover is performed at the same time, those skilled in the art need to solve the problem. In order to avoid data packet loss caused by link switching, the present invention provides a method for implementing a non-disturbing redundant serial bus. The following describes the implementation of the redundant serial bus provided by the present invention. Referring to FIG. 3, the specific implementation process of the method may include the following steps:

Step 301: Receive data through one link in the primary link and the backup link, and cache data transmitted by the primary link and the backup link in real time, and simultaneously monitor the transmission status of the current link of the received data while performing data buffering. ;

Step 302: Determine whether the current link is faulty. If yes, switch to the backup link that does not fail to receive data.

Compared with the prior art, the technical solution provided by the present invention collects data transmitted on the primary link and the backup link in real time through a link in the primary link and the backup link, and monitors the data in real time. The transmission status of the current link receiving the data; once the current link fails, it automatically switches to other unfailed links to continue receiving data. In this way, since the data being transmitted is stored in real time in the link after the handover, the defect of packet loss does not occur after the link is switched, and the data transmission is more reliable and stable.

In the specific implementation of the technical solution of the present invention, when data is started to be received, data is received from a link by default. At this time, if it is determined that the current link has not failed, the current link reception data is maintained.

In addition, if it is judged that all links have failed, the current link reception data is maintained, and the failure notification information is output to the outside, waiting for the link failure recovery.

The embodiment of the present invention provides a preferred implementation manner for quickly verifying whether a link is faulty, and the specific implementation is: determining whether the current link is faulty according to the check digit indication information carried in the transmitted data, if the school When the location indication information is preset information, it is determined that the current link has not failed; if not, it is determined that the current link is faulty.

The check bit is judged to be closely related to the check type. For example, even parity in parity is used, the byte to be transmitted is 11000001, and in the normal transmission state, the check bit should be 0. If the data is interfered by the link failure during transmission, the actual transmitted data becomes 11100001, and the parity bit is 1. The receiver calculates that the check digit should be 0 according to the received data, and the actually received check digit is 1, so that the data error can be judged. In order to facilitate a further understanding of the present invention, the invention will be described in detail below with reference to the specific embodiments of the invention.

The distributed control system is taken as an example to describe the implementation method of the redundant serial bus provided by the present invention.

It should be noted that, for convenience of description, two transmission links are taken as an example for description in this embodiment. As shown in Figure 4, the slave modules in the distributed control system mainly include: a drive unit, a redundant switching logic, and a processing unit. The driving unit is used to realize the conversion of the signal standard and increase the driving capability. For example, the redundant switching logic outputs the CMOS level signal and the link transmits the RS485 signal, then the driving unit functions to adjust the CMOS level on one hand. Converting to a differential 485 signal, on the other hand, increases the load capacity of the link to enable as many slave modules as possible to be attached to the bus. The implementation of the redundant serial bus of the present invention primarily involves redundant switching logic.

It should be noted that, in the embodiment of the present invention, when the slave module sends data, as shown in FIG. 5, the processing unit writes data into the redundancy switching logic through the bus interface, and the redundancy switching logic first caches the current sending data. Then, the mode conversion of parallel data into serial data is performed, and the serial data after the switching is simultaneously sent to two independent driving units, and each driving unit corresponds to one communication link, for example, link A in FIG. 5 and Link B.

With the implementation method of the redundant serial bus provided by the present invention, when the slave module receives data, the redundancy switching logic first synchronizes the data packets on the two links and B respectively output by the driving unit. This is because the transmission start time of data on the two links may be different. The output transmission time of the two communication links may not be exactly the same. The time difference between the two links in data output is as shown in Figure 6 for t _delay. Said. For example, when the minimum unit of data transmission is byte, since the minimum unit of data transmission is byte, the maximum value allowed by t _delay is 1 byte of data transmission time, if another time during this time If no data arrives on one link, it is considered that the synchronization of the two links fails. Otherwise, it is considered that there is data available for selection on both links, and the synchronization is successful. It can be seen that when the time difference between the two links in the data output is smaller than the transmission time of the minimum unit in the data transmission, the two links are successfully synchronized.

It should be noted that if the link that the data stream first arrives is the currently selected link, it is determined whether the check bit of each byte received in the current link is correct, and if it is correct, the link data is kept received. Invariant; if not correct, determine if the check digit on the other link is correct, if another link If the check bit is normal, switch to another link to receive data. If the check bit on the other link is also incorrect, the current two links are faulty, keep the current receiving link unchanged, and go to the outside world. The output fault informs the information to wait for the fault recovery.

If the link that the data stream arrives first is not the currently selected link, the data of the two links needs to be synchronized. If the synchronization succeeds within the time interval of receiving 1 byte, the current selected link is received. When the synchronization fails within the time interval of receiving 1 byte, it switches to another link to receive data. At the same time, the logical judgment of the switching link is performed according to the parity bit of each byte. It should be noted that the so-called synchronization in the embodiment of the present invention refers to: detecting whether the time interval in which the two links receive the same byte is within a predetermined time interval, and if so, the two links are considered to be successfully synchronized. Depending on the time application scenario, those skilled in the art will be able to calculate specific values for the synchronization time.

After the data transmitted on the two links is synchronized, the mode conversion of the serial data to the parallel data is continuously performed on the transmission data on each link.

After mode switching, the redundancy switching logic caches the data on each link in real time. While performing data buffering, each byte is received for comparison of corresponding check digits, and according to the comparison between the indication information of the current check digit and the indication information of the preset check digit, it is judged whether the corresponding link is faulty: If the check bit indication information of both links is correct, the currently selected link is kept unchanged; if the check bit indication information of one link of the two links is correct, and the check bit of the other link is correct If the indication information is incorrect or there is no data, the correct link reception data is selected; if the check digit indication information of both links is wrong, the current selected link is also kept unchanged, and the recovery of the failure is waited for. The "Processing Unit" reads the data received in the "Redundant Switching Logic" via the bus interface. Compared with the prior art solution, the redundant switching logic internally buffers data of two links, and when detecting the current receiving data link failure, can immediately switch to another link and enable real-time buffering on another link. The data so that the process data is switched is not affected at all.

The above redundant switching logic can be further illustrated by FIG. As shown in Figure 7, the serial data of link A and link B is converted into parallel data and then temporarily stored in the buffer according to the byte. At the same time of buffering, the two links are determined according to the check bit indication information. Is this byte data correct? If the data of the link A is found to be erroneous, the control switches to the buffer read data of the link B, and the data of the real-time transmission remains in the link B buffer area, so the data is not lost after the link switching. Lost. In this process, the case where the minimum unit of data transmission is byte is taken as an example. In this process, the transmission time of t _delay not exceeding 1 byte needs to be met. If t _{delay is} too long, more than 1 byte is exceeded. The transmission time, the next byte of data on the faster link has arrived, will overwrite the previous data, resulting in the data stored in the slower link and the faster link cache are not the same byte, therefore, can not Ensure data synchronization between the two links.

Of course, the link switching scheme in the embodiment of the present invention is also applicable to the following link failure scenarios: Taking the transmission link as two as an example, for the convenience of description, the two links are the first link and the second link. Make a distinction. The data is transmitted along the two links of the first link and the second link. When the first link receives the data first, and the second link does not receive the data within the synchronization time, then the synchronization time is also considered. The second link that did not receive the data failed. If the default is to use the second link for data reception, link switching is required, and data reception is performed by the first link.

In another preferred embodiment of the present invention, whether the recipient of the current data is the current slave can be obtained by the destination address byte carried in the received normal data. Data that does not belong to the current slave can be discarded directly to save cache space; data belonging to the current slave can be temporarily stored in the buffer area, waiting for reading and subsequent processing of the data.

It can be seen that the implementation method of the redundant serial bus provided by the present invention can detect the transmission state of the two links in real time, and therefore, the real-time performance of the link fault diagnosis is stronger. The present invention is highly versatile and has a weak correlation with communication protocols, regardless of the protocol, as long as the byte transmission contains a parity bit. The present invention also provides a device for implementing a redundant serial bus. As shown in FIG. 8, the device may include:

The receiving buffer module 801 is configured to receive data through one link in the primary link and the backup link, and cache data transmitted by the primary link and the backup link in real time;

The monitoring module 802 is configured to monitor the transmission status of the current link of the received data in real time while the receiving buffer module 801 performs data caching;

The fault judging module 803 is configured to determine whether the current link is faulty.

The switching module 804 is configured to: if the fault determining module 803 determines that the current link is faulty, switch to the backup link that does not fail to receive data. The implementation device of the redundant serial bus provided by the present invention receives data in a main link and a backup link, and simultaneously caches data transmitted on the primary link and the backup link through the receiving buffer module. And the real-time monitoring of the transmission status of the current link receiving data; once the current link fails, it automatically switches to other non-faulty links to continue receiving data. In this way, since the data being transmitted is stored in real time in the link after the handover, the defect of packet loss does not occur after the link is switched, and the data transmission is more reliable and stable.

Preferably, the fault judging module is further configured to:

If the fault judging module determines that the current link has not failed, the current link is received and the fault notification information is output to the outside world.

Preferably, the fault judging module is further configured to: if all links fail, keep the current link receiving data.

In another preferred embodiment of the present invention, the device further includes:

The receiving determining module is configured to determine whether the recipient of the data is a local slave, and if so, cache the data; if not, discard the data. For the device embodiment, since it basically corresponds to the method embodiment, the description is relatively simple, and the relevant parts can be referred to the description of the method embodiment. The device embodiments described above are merely illustrative, wherein the units described as separate components may or may not be physically separated, and the components displayed as units may or may not be physical units, ie may be located One place, or it can be distributed to multiple network elements. Some or all of the modules may be selected according to actual needs to achieve the purpose of the solution of the embodiment. Those of ordinary skill in the art can understand and implement without any creative effort.

A person skilled in the art can understand that all or part of the process of implementing the above embodiment method can be completed by a computer program to instruct related hardware, and the program can be stored in a computer readable storage medium. When executed, the flow of an embodiment of the methods as described above may be included. The storage medium may be a magnetic disk, an optical disk, a read-only memory (ROM), or a random access memory (RAM).

The above description of the disclosed embodiments enables those skilled in the art to make or use the invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the embodiments of the invention. . Therefore, the present embodiments of the invention are not to be limited to the embodiments shown herein, but are to be accorded to the broadest scope of the principles and novel features disclosed herein.

Claims

Rights request

A method for implementing a redundant serial bus, the method comprising: collecting data through a link in a primary link and a backup link, and real-time buffering transmission of the primary link and the backup link Data, while performing data buffering, monitoring the transmission status of the current link of the received data in real time;

2. The method of implementing a redundant serial bus according to claim 1, wherein the method further comprises:

If it is determined that the current link has not failed, the current link reception data is maintained.

The method for implementing a redundant serial bus according to claim 1, wherein the method further comprises:

If it is determined that all links have failed, the current link is kept and the fault notification information is output to the outside world.

The method for implementing the redundant serial bus according to claim 1, wherein the determining whether the current link is faulty comprises:

Determining whether the current link is faulty according to the check bit indication information carried in the transmitted data. If the check bit indication information is preset information, determining that the current link has not failed; if not, Then determining that the current link is faulty.

The method for implementing a redundant serial bus according to any one of claims 1 to 4, wherein the method further comprises:

A device for implementing a redundant serial bus, the device comprising: a receiving buffer module, configured to receive data through a link in a primary link and a backup link, and cache the main chain in real time. Data transmitted by the road and backup link;

a monitoring module, configured to monitor, in real time, the transmission state of the current link of the received data while the data is buffered by the receiving buffer module; a fault judging module, configured to determine whether the current link is faulty;

The apparatus for implementing a redundant serial bus according to claim 6, wherein the fault judging module is further configured to:

The apparatus for implementing a redundant serial bus according to claim 6, wherein the fault judging module is further configured to: if all links fail, keep the current link receiving data, and send the data to the outside world. Output fault notification information.

The apparatus for implementing a redundant serial bus according to claim 6, wherein the check bit indication information carried in the data, the fault determination module determines the location according to the check bit indication information Whether the current link is faulty, if the check digit indication information is preset information, determining that the current link has not failed; if not, determining that the current link is faulty.

The apparatus for implementing a redundant serial bus according to any one of claims 6-9, wherein the apparatus further comprises: