WO2015172398A1 - Method and apparatus for acquiring packet transmission delay - Google Patents

Abstract

Disclosed are a method and apparatus for acquiring a packet transmission delay. The method comprises: acquiring first clock information for receiving a communication packet by a receiving port and second clock information for sending the communication packet by a sending port; and determining a transmission delay of the communication packet in a switch according to the first clock information and the second clock information. By using the technical scheme, corresponding timestamp information is added by a switch to a designated position in the communication packet, and a transmission delay of the corresponding communication packet in the switch is determined during the local transmission process of the communication packet in the switch according to the timestamp information, so that the transmission delay of the communication packet in the switch can still be conveniently and rapidly determined in a case in which an industrial measurement and control system is out of synchronization with a synchronous source, thereby ensuring device fault protection in the industrial measurement and control system and the accuracy of a fault detection result.

Description

 Method and device for acquiring message transmission delays The present application claims to be filed on May 16, 2014 by the Chinese Patent Office, the application number is 201410207297.9, and the invention name is a message transmission delay acquisition method and device. Priority is hereby incorporated by reference in its entirety. Technical field

 The present invention relates to the field of communications technologies, and in particular, to a packet transmission delay acquisition method and apparatus. Background technique

 At present, in the industrial measurement and control system, taking the intelligent substation system as an example, when any one of the intelligent substation systems fails, the sampling device in the intelligent substation system generates SV according to the data related to the fault (Sample Sampled) Value; sampled value), and the SV message is transmitted to the protection device through the switch network.

 Based on the performance limitation of the existing switching network, there is a transmission delay in the transmission of the SV packet in the switching network. That is, the protection device receives the SV packet later than the substation device sends the SV packet. Therefore, in the smart substation system or outside the intelligent substation system, a synchronization source corresponding to the intelligent substation system is provided, which is used for ensuring the synchronization of the data acquired by the substation equipment. Specifically, the protection device calibrates the local clock information of the protection device according to the clock information of the synchronization source according to the preset period. After receiving the SV message, the protection device acquires the sample data carried in the SV message, and according to the The collection time corresponding to the sample data carried in the SV packet determines the fault occurrence time of the faulty device, thereby performing corresponding operations on the faulty device. In particular, when the synchronization source corresponding to the intelligent substation system is faulty, since the transmission delay corresponding to the transmission network transmission SV is not determined, the protection device cannot determine the data when receiving the SV message. Synchronization, based on the settings of the existing intelligent substation, the above protection device will be out of operation, which is not conducive to the protection of equipment and fault detection in the intelligent substation system.

Similarly, in the industrial measurement and control system using the intelligent industrial measurement and control system as an example, the above method is also used for GOOSE (Generic Object Oriented Substation Event) Station event) The message is transmitted. Therefore, the protection device cannot determine the transmission delay of the GOOSE message in the switch.

 In addition, for some industrial communication protocols as communication messages, for example: profinet (real-time deterministic industrial Ethernet protocol) transmission delays in the transmission of the switch can not be determined.

 To sum up, at present, in the industrial measurement and control system, the transmission delay of the communication message of the switching network in the switch cannot be obtained, which causes the problem of failure detection and fault protection of the equipment in the industrial measurement and control system. Summary of the invention

 The embodiment of the invention provides a method and a device for acquiring a message transmission delay, which are used to solve the problem that the device in the industrial measurement and control system cannot detect faults and protect faults in the industrial measurement and control system.

 The specific technical solutions provided by the embodiments of the present invention are as follows:

 A packet transmission delay acquisition method is applied to an industrial measurement and control system, where the industrial measurement and control system includes at least one switch, and the method includes:

 After the receiving port of the switch receives the communication packet, the first clock information corresponding to the clock source of the switch is added to the specified location in the communication packet; wherein the first clock information is a link. The absolute value of the difference between the delay and the time at which the receiving port receives the communication message;

 Determining the second clock information corresponding to the clock source after determining that the sending port of the switch obtains the communication message that adds the first clock information, where the second clock information includes the sending port acquiring the Adding a time of the communication message of the first clock information; or, the second clock information includes a time at which the sending port acquires the communication message to which the first clock information is added, and a number of times of inversion of the clock source;

 Obtaining a transmission delay of the communication packet in the switch according to the first clock information carried in the communication packet and the second clock information.

Optionally, the communication packet further carries the first current time and the link delay The size relationship of the clock source time corresponding to the first current time and the half of the maximum time recordable by the clock source, and the link delay and half of the maximum time recordable by the clock source Corresponding clock source time relationship; when the second clock information only includes the second current time, when the first current time is less than the link delay, the link delay is greater than the clock source And when the second current time is less than the clock source time, calculating a sum of the second current time and the first clock information as an initial communication message transmission delay, if the initial communication is The transmission delay is less than the maximum time recordable by the clock source, and the initial communication delay is used as the transmission delay of the communication message in the switch; when the first current time is less than the Calculating the second current time and the first clock information when the link delay is less than the clock source time, and the second current time is less than the clock source time And a transmission delay of the communication message in the switch; when the first current time is less than the link delay, the link delay is greater than the clock source time, and the second current time When the time of the clock source is greater than the clock source, the sum of the second current time and the first clock information is calculated as a transmission delay of the communication message in the switch; when the first current time is smaller than the link a delay, when the link delay is less than the clock source time, and the second current time is greater than the clock source time, calculating a sum of the second current time and the first clock information as a communication report a transmission delay in the switch; when the first current time is greater than the link delay, the first current time is greater than the clock source time, and the second current time is less than the clock Calculating, by the source time, a difference between the maximum time recordable by the clock source and the first clock information, and obtaining a sum of the difference and the second current time as a transmission of the communication message in the switch Delay When the first current time is greater than the link delay, the first current time is greater than the clock source time, and the second current time is greater than the clock source time, the second current time is calculated. The difference between the first clock and the first clock is the transmission delay of the communication packet in the switch; when the first current time is greater than the link delay, the first current time is smaller than the clock source And when the second current time is less than the clock source time, calculating a difference between the second current time and the first clock information as a transmission delay of the communication message in the switch; The current time is greater than the link delay, the first current time is less than the clock source time, and the second time is When the previous time is greater than the clock source time, the difference between the second current time and the first clock information is calculated as the transmission delay of the communication message in the switch.

 Optionally, the communication packet further carries a size relationship between the first current time and the link delay; when the second clock information includes a second current time and a reverse of the clock source The number of times, when the first current time is less than the link delay, according to the first clock information, the second current time, the maximum time that the clock source can record, and the clock source The number of times of inversion, the transmission delay of the communication message in the switch; the delay when the first current time is greater than the link, according to the first clock information, the second current The time at which the clock source can record, and the number of times the clock source is inverted, obtains a transmission delay of the communication message in the switch.

 With the above technical solution, the first clock information and the second clock information acquired by the switch are clock information provided according to the local clock source, and need not be synchronized with the synchronization source, thereby reducing the letter between the industrial measurement and control system and the synchronization source. Make interactions and save system resources.

 Optionally, the communication is sent to the local device by the sampling device in the industrial measurement and control system, or the communication is sent to the local device by other switches in the industrial measurement and control system.

 After the transmission delay of the communication packet is obtained, the binary delay information corresponding to the transmission delay of the communication packet is generated, and the binary delay information is added to the specified location in the communication message; Sending the communication message to the protection device in the industrial measurement and control system, and causing the protection device to perform a corresponding protection operation on the faulty device according to the data carried in the communication message.

 A message transmission delay acquisition device is applied to an industrial measurement and control system, the industrial measurement and control system comprising at least one switch, the device comprising:

 a writing unit, configured to add a first clock information corresponding to a clock source of the switch, at a specified position in the communication packet, after determining that the receiving port of the switch receives the communication packet; A clock information is an absolute value of a difference between a link delay and a time at which the receiving port receives the communication message;

a clock information obtaining unit, configured to: when determining that the sending port of the switch is acquired, adding the first After the communication message of the clock information, the second clock information corresponding to the clock source is determined; wherein the second clock information includes a time when the sending port obtains the communication message that adds the first clock information; or The second clock information includes a time at which the sending port obtains the communication message that adds the first clock information, and a number of times the clock source is inverted.

 And a transmission delay obtaining unit, configured to obtain, according to the first clock information carried in the communication packet, and the second clock information, a transmission delay of the communication packet in the switch.

Optionally, the transmission delay obtaining unit is specifically configured to: if the communication packet further carries a size relationship between the first current time and the link delay, the first current moment a magnitude relationship between a clock source time corresponding to a half of a maximum time recordable by the clock source, and a magnitude relationship between the link delay and a clock source time corresponding to a half of a maximum time recordable by the clock source, When the second clock information includes only the second current time, if the first current time is less than the link delay, the link delay is greater than the clock source time, and the second current time If the time of the clock source is less than the clock source, the sum of the second current time and the first clock information is calculated as the initial communication message transmission delay, if the initial communication message transmission delay is smaller than the clock source a transmission delay; if the first current time is less than the link delay, the link delay is less than the clock source time, and the second current time is less than the clock source time, then calculating Said The sum of the current time and the first clock information is used as the transmission delay of the communication message in the switch; if the first current time is less than the link delay, the link delay is greater than the a clock source time, and the second current time is greater than the clock source time, the sum of the second current time and the first clock information is calculated as a transmission delay of the communication message in the switch; The first current time is less than the link delay, the link delay is less than the clock source time, and the second current time is greater than the clock source time, and the second current time is calculated. The sum of the first clock information is used as a transmission delay of the communication packet in the switch; if the first current time is greater than the link delay, the first current time is greater than the clock source time, And the second current time is less than the clock source time, and the maximum time and the recordable time of the clock source are calculated. a difference between the first clock information, and a sum of the difference and the second current time as a transmission delay of the communication message in the switch; if the first current time is greater than the link delay If the first current time is greater than the clock source time, and the second current time is greater than the clock source time, calculate a difference between the second current time and the first clock information as a communication message. a transmission delay in the switch; if the first current time is greater than the link delay, the first current time is less than the clock source time, and the second current time is less than the clock source time And calculating a difference between the second current time and the first clock information as a transmission delay of the communication packet in the switch; if the first current time is greater than the link delay, the Calculating a difference between the second current time and the first clock information as a communication message in the switch, if a current time is less than the clock source time, and the second current time is greater than the clock source time Transmission delay.

 Optionally, the transmission delay acquiring unit is specifically configured to: when the communication packet further carries a size relationship between the first current time and the link delay, when the second When the clock information includes the second current time and the number of times of inversion of the clock source, if the first current time is less than the link delay, the second current time, according to the first clock information, The maximum time that can be recorded by the clock source, and the number of times the clock source is reversed, obtains a transmission delay of the communication packet in the switch; if the first current time is greater than the link delay, Obtaining, according to the first clock information, the second current time, the maximum time recordable by the clock source, and the number of times of inversion of the clock source, acquiring the communication message in the switch Transmission delay.

 With the above technical solution, the first clock information and the second clock information acquired by the switch are clock information provided according to the local clock source, and need not be synchronized with the synchronization source, thereby reducing the letter between the industrial measurement and control system and the synchronization source. Make interactions and save system resources.

 Optionally, the writing unit is configured to: receive the communication message sent by the sampling device in the industrial measurement and control system, or receive the message sent by another switch in the industrial measurement and control system Communication text.

Further, the foregoing apparatus further includes: a sending unit, configured to: after acquiring the transmission packet transmission delay, generate binary delay information corresponding to the transmission delay of the communication packet, and perform the binary And the delay information is added to the specified location in the communication message; the communication message is sent to the protection device in the industrial measurement and control system, and the protection device is caused to be carried according to the communication message. The data performs the corresponding protection operations on the failed device.

 In the embodiment of the present invention, the first clock information of the communication packet received by the receiving port is obtained, and the second clock information of the communication packet is sent by the sending port, and the second clock information is determined in the switch according to the first clock information. The transmission delay of the communication message in the switch. Using the above technical solution, the switch adds corresponding timestamp information to the specified location in the communication message, and according to the timestamp information, determines the communication message corresponding to the communication message in the switch during the local transmission process of the switch. Delay, in the case of industrial measurement and control system and synchronization source out of step, it is still convenient and quick to determine the transmission delay of communication messages in the switch, thus ensuring the fault protection of equipment in the industrial measurement and control system and the accuracy of fault detection results. . DRAWINGS

 1 is a schematic structural diagram of an industrial measurement and control system according to an embodiment of the present invention;

 2 is a flow chart of obtaining a transmission delay of a communication packet in a switch according to an embodiment of the present invention; FIG. 3 is a schematic structural diagram of a switch according to an embodiment of the present invention;

 4a and 4b are schematic diagrams of SV 4艮 in the embodiment of the present invention;

 FIG. 5 is a schematic diagram of an SV packet after a transmission delay of an SV packet is added to a switch according to an embodiment of the present disclosure;

 FIG. 6 is a schematic structural diagram of a device for acquiring a packet transmission delay according to an embodiment of the present invention. detailed description

In order to solve the current problem in the intelligent industrial measurement and control system, there is a problem that the fault detection and fault protection of the equipment in the intelligent industrial measurement and control system cannot be performed. In the embodiment of the present invention, the first clock information of the communication port is received by the receiving port, and the second clock information of the communication message is sent by the sending port, and the second clock information is determined according to the first clock information and the second clock information. The transmission delay of the communication message in the switch. Using the above technical solution, the switch adds the specified location in the communication message. Adding corresponding timestamp information, and determining the transmission delay of the corresponding communication message in the switch during the local transmission process of the communication message according to the timestamp information, in the case that the industrial measurement and control system and the synchronization source are out of step, It is still convenient and quick to determine the transmission delay of the communication message in the switch, thereby ensuring the fault protection of the equipment in the industrial measurement and control system and the accuracy of the fault detection result.

 In the following specific embodiments, the communication message is an SV message as an example. Similarly, the GOOSE message has the same message format as the SV message, and the reserved location is also specified in the GOOSE message. The location is used to carry packet transmission delay information. In addition, the industrial communication protocol is used as a communication message. For example, the data area in the Profinet format is not specifically defined. Therefore, the data area can be used as a designated location for carrying packet transmission delay information. Similarly, in other industrial communication protocols, the relevant location can be delineated as a designated location, and the requirements of the present invention can also be met.

 The preferred embodiment of the present invention will now be described in detail with reference to the accompanying drawings.

 Referring to FIG. 1 , which is a structural diagram of an industrial measurement and control system according to an embodiment of the present invention, the industrial measurement and control system includes a faulty device, a sampling device, a switching network, and a protection device, wherein the switching network includes at least one switch, which can be exchanged. Each switch in the network obtains the transmission delay of the SV packet in the switch. The transmission delay of the SV packet of the switching network in the switch can also be obtained by the special transmission delay acquisition device. In the embodiment of the present invention, the transmission delay of the SV packet in the switch is obtained by using each switch in the switching network as an example.

 Referring to FIG. 2, in the embodiment of the present invention, the process of obtaining the transmission delay of the SV packet in the switch is:

 Step 200: After the switch determines that the local receiving port receives the SV packet, the switch obtains the first clock information corresponding to the local clock source at the specified location in the SV packet.

 Referring to FIG. 3, in the embodiment of the present invention, the switch includes a receiving port, a sending port, a switching array, and a clock source. The receiving port is configured to receive the SV packet; the sending port is used to send the SV packet to the protection device; the clock source is used to mark the clock information, and the clock source has a recordable maximum time (ie, td), when the clock source When it reaches its own recordable maximum time, the clock source is inverted (ie, restarting from 0).

In the embodiment of the present invention, at least one exchange is included in the switching network in the industrial measurement and control system Therefore, the SV message is sent to the local switch by the sampling device in the industrial measurement and control system; or, when the switching system includes at least two switches, the SV message can also be sent by other switches in the industrial measurement and control system. Local to the switch. When the SV packet received by the switch is sent by the sampling device, the link delay (indicated as Δ to ) of the switching network carried in the SV packet is 0; when the SV packet received by the switch is sent by another switch The link delay A tO of the switching network carried in the SV packet is not 0. For example, when the switch 1 receives the SV packet sent by the switch 0, the switch 1 can obtain the link delay carried in the SV packet. The link delay is the transmission delay of the SV packet corresponding to the switch 1 in the switch 1.

 The first current time corresponding to the first bit information in the SV packet is received from the clock source receiving port when the receiving port receives the SV packet, and the SV packet is calculated in the SV packet. The absolute value of the difference between the carried link delay and the first current time, and the absolute value of the difference between the link delay and the first current time is written as the first clock information to the designated position in the SV message.

 Referring to FIG. 4a, it is a schematic diagram of the SV "^" in the embodiment of the present invention. Optionally, the reserved field of the Reservedl and the Reserved2 in the SV is added as the first clock information as a specified location. Specifically, refer to FIG. 4b. As shown in the figure, a part of the SV packet includes 32 bits, and the position corresponding to the bit number 0 to 23 is the designated position of the SV packet, that is, the first clock information is saved to the SV packet. The position corresponding to the first bit to the 24th bit; the position corresponding to the bit number 24~29 is the extended bit of the SV text; the position corresponding to the bit number 30 is the quality bit of the SV text, and when the position is 0, it means valid, when If the position is 1, it means invalid; the position corresponding to bit number 31 is the test bit of SV "3⁄4".

Optionally, after the switch obtains the first clock information, converting the first clock information into a binary format, and storing the first clock information in the binary format to the specified location; and storing the time in the SV packet The information is in nanoseconds. Since the SV message contains 24 bits to store the time information, the maximum time value represented by the time information stored in the SV message is 16.777215 milliseconds (ie, 2 ²⁴ nanoseconds).

Further, the maximum time td recordable by the clock source is preset according to a specific application scenario. In order to facilitate the process of obtaining the transmission delay of the SV packet in the switch, it is preferred. The maximum time td recordable by the clock source is equal to the maximum time value represented by the time information storable in the SV message.

Optionally, the SV packet carries the first current time (denoted as t1), the link delay AtO, and the maximum time td that can be recorded by the clock source. When the SV message reaches the sending port, the foregoing a current time t1 and a link delay AtO, a link time delay AtO corresponding to a clock source time (recorded as td/2) corresponding to a half of a maximum time recordable by the clock source, and a first current time and a clock source recordable The clock source time td/2 corresponding to half of the maximum time is compared separately. Or, when the receiving port receives the SV packet, the switch compares the obtained first current time t1 with the link delay Δt0, the link delay AtO, and the clock time corresponding to half of the maximum time that the clock source can record. Td/2, and a clock source time td/2 corresponding to a half of the maximum time recordable by the clock source, and generating a corresponding binary identifier according to the foregoing three comparison results, the sequence number added to the SV message is 0. Bits of ~2. For example, if tl<td/2, record f _t corpse 1, if tl>td/2, record f _t corpse 0; if At0<td/2, record f _M0 =l, if At0>td/2 Then, f _M0 =0 is recorded; if tl < AtO, f _tMl ddi _e = l is recorded, and if tl > Δ t0 , f _tMlddle =0 is recorded, where tMiddle= |ΔίΟ - tl. It can be seen that when the above technical solution is used, if the binary identifier corresponding to the bit number 0~2 in the SV message is f _tMl ddi _e = l, ft corpse 1, it means tl> AtO, tl < Td/2. Compared with the manner in which the above tl, AtO, t2, and td/2 are directly added to the SV message in the former solution, when the latter technical solution is used, tl, At0, and t2 are represented by three binary identifiers. And the relationship between the td/2 and the specified position in the SV message, in addition to the above three bits, the first clock information may be carried, thereby improving the accuracy of the clock information carried in the SV message.

 Step 210: After the switch determines that the local sending port obtains the SV packet that adds the first clock information, the switch determines the second clock information corresponding to the clock source.

In the embodiment of the present invention, when the switch determines that the SV packet reaches the local sending port, the switch determines that the sending port obtains the second current time of the clock source corresponding to the first bit information in the SV packet, and the clock source is obtained. The second current time is recorded as the second clock information; or, when the switch determines that the SV message reaches the local sending port, it is determined that the sending port obtains the SV report. The second current time of the clock source corresponding to the first bit information in the text, and the number of times of inversion of the clock source, and the second current time of the clock source and the number of times of inversion of the clock source are recorded as the second clock information. It can be seen that the foregoing second clock information is obtained by representing the sending port of the switch.

The information of the first bit time of the SV packet; or the second clock information is information indicating the first bit time of the SV message and the number of times of inversion of the clock source.

 With the above technical solution, the first clock information and the second clock information acquired by the switch are clock information provided according to the local clock source, and need not be synchronized with the synchronization source, thereby reducing the letter between the industrial measurement and control system and the synchronization source. Make interactions and save system resources.

 Step 220: Acquire a transmission delay of the SV packet in the switch according to the first clock information carried in the SV packet and the second clock information.

 In the embodiment of the present invention, according to whether the second clock information includes the number of inversions, the manner in which the switch obtains the transmission delay of the SV packet in the switch is divided into two types:

 The first mode: when the second clock information includes only the first clock information, the switch according to the first current time t1, the second current time included in the second clock information (denoted as t2), and the clock source recordable The maximum time td, and the clock source time td/2 corresponding to half of the maximum time recordable by the clock source; and the first current time t1 and the link delay A tO , the link delay A tO and the clock source respectively One half of the recorded maximum time corresponds to the clock source time td/2, the first current time t1 corresponds to the clock source time td/2 corresponding to half of the maximum time recordable by the clock source, and the second current time t2 and the clock source are recordable The comparison of the clock source time td/2 of the half of the maximum time can be used to obtain the following eight comparison results. The process of obtaining the transmission delay A t of the SV message in the switch according to the eight comparison results is:

The first case: when the first current time is less than the link delay, the link delay is greater than the clock source time, and the second current time is less than the clock source time, the switch calculates the sum of the second current time and the first clock information as The initial SV packet transmission delay is used as the transmission delay of the SV packet in the switch if the initial SV packet transmission delay is less than the maximum time that can be recorded by the clock source. If you use a formula, you can express it as: When tl < AtO, At0>td/2, t2 < td/2, Δ t=t2+ |AtO- tl.

 In the first case, since At0>td/2, tl < AtO, and t2<td/2, when tl < td/2, it indicates that the clock source has not reversed. At this time, At=t2+| AtO- tl| ; When tl >td/2, it indicates that the clock source is inverted. At this time, M0 obtained according to M=t2+|AtO- tl| will be greater than td. If td is equal to 16.777215 milliseconds, since td exceeds SV The maximum time value that can be indicated by the specified location in the packet. Therefore, the switch needs to send an error report. The specified location in the SV packet cannot indicate the transmission delay of the SV packet in the switch.

 The second case is: when the first current time is less than the link delay, the link delay is less than the clock source time, and the second current time is less than the clock source time, the sum of the second current time and the first clock information is calculated as The transmission delay of the SV packet in the switch. If you use a formula, you can express it as:

 When tl < AtO, Δ t0 < td/2, t2 < td/2, Δ t = t2+ | AtO - tl.

 The third case is: when the first current time is less than the link delay, the link delay is greater than the clock source time, and the second current time is greater than the clock source time, the sum of the second current time and the first clock information is calculated as The transmission delay of the SV packet in the switch. If you use a formula, you can express it as:

 When tl < AtO, Δ t0 > td/2, t2 > td/2, Δ t = t2+ | AtO - tl.

 The fourth case: when the first current time is less than the link delay, the link delay is less than the clock source time, and the second current time is greater than the clock source time, the second current time and the first clock information are calculated as the SV report. The transmission delay of the text in the switch. If you use a formula, you can express it as:

 When tl < AtO, Δ t0 < td/2, t2 > td/2, Δ t = t2+ | AtO - tl.

 The fifth case: when the first current time is greater than the link delay, the first current time is greater than the clock source time, and the second current time is less than the clock source time, the maximum time recordable by the clock source is obtained and the first clock is The difference between the information, and the sum of the difference and the second current time is taken as the transmission delay of the SV message in the switch. In the fifth case, since tl>AtO, tl>td/2, and t2<td/2, it indicates that the clock source has been inverted, which can be expressed as:

When tl > Δ t0 , t2 > td/2 , t2 < td / 2, Δ t = td - | Δί Ο - til + t2. The sixth case is: when the first current time is greater than the link delay, the first current time is greater than the clock source time, and the second current time is greater than the clock source time, the difference between the second current time and the first clock information is calculated as The transmission delay of the SV packet in the switch. If you use the formula, you can express it as: When tl > AtO, tl>td/2, t2>td/2, Δ t=t2- |AtO- tl.

 The seventh case is: when the first current time is greater than the link delay, the first current time is less than the clock source time, and the second current time is less than the clock source time, the difference between the second current time and the first clock information is calculated as The transmission delay of the SV packet in the switch. If you use the formula, you can express it as: When tl> AtO, tl<td/2, t2<td/2, At=t2-|AtO- tl.

 The eighth case is: when the first current time is greater than the link delay, the first current time is less than the clock source time, and the second current time is greater than the clock source time, the difference between the second current time and the first clock information is calculated as The transmission delay of the SV packet in the switch. If you use the formula, you can express it as: When tl> AtO, tl<td/2, t2>td/2, At=t2-|AtO- tl.

 In the first implementation manner, the switch determines whether the clock source is reversed according to the relationship between tl, AtO, t2, and td/2. Therefore, the transmission delay of the obtained SV packet in the switch is not greater than td. /2.

The second mode: when the second clock information includes the second current time and the number of times of inversion of the clock source, the switch according to the first current time t1 included in the first clock information, and the second current information included in the second clock information At time t2, and the number of times of inversion of the clock source, comparing the first current time t1 and the link delay AtO, the following two comparison results can be obtained, and according to the two comparison results and the number of times of inversion of the clock source, N can be supported here. The number of inversions N correctly determined depends on the number of bits n reserved in the SV message. The relationship is Ν=2 ^η -1 . The process of obtaining the transmission delay Δ t of the SV message in the switch is:

The first case: when the first current time is less than the link delay, according to the link delay, the first current time, the second current time, the maximum time that the clock source can record, and the number of times the clock source is inverted, The transmission delay of the SV packet in the switch. In the first case, since tl < AtO, N > 1, it indicates that the clock source is inverted. If you use a formula, you can express it as: When tl < A tO , A t = td * N + t2 + | AtO - tl .

 In the above process, if td is equal to 16.777215 milliseconds, since td exceeds the maximum time value that can be represented by the specified position in the SV "3⁄4 text", therefore, the specified position of the SV message is optionally divided into two parts, and part of The other part is used to carry the transmission delay of the SV packet that is not greater than td in the switch in the case of ensuring the transmission delay of the SV packet in the switch.

 The second case: when the first current time is greater than the link delay, according to the link delay, the first current time, the second current time, the maximum time that the clock source can record, and the number of times the clock source is inverted, The transmission delay of the SV packet in the switch. If you use a formula, you can express it as:

 When tl > Δ t0 , Δ t = td * N + t2 - | Δί Ο - tl .

 Further, in the SV packet, the number of the sequence number 3 to 6 is added with an identifier indicating the number of times the clock source is inverted. For example, when the number of times of inversion of the clock source is three, the number of times of inversion of the clock source is The identifier is 11, and the binary identifier is added to the bit numbered 3-6 in the SV message.

 In the second implementation manner, the SV packet is in the specified location of the SV packet, and the transmission delay of the SV packet in the switch is no longer affected by the td. /2 limit.

 After the switch obtains the transmission delay of the SV packet in the switch, the switch generates the binary delay information corresponding to the transmission delay of the SV packet in the switch, and adds the binary delay information to the specified in the SV packet. The SV message is sent to the protection device in the industrial measurement and control system, so that the protection device performs a corresponding protection operation on the faulty device according to the data carried in the SV message. For example, when the first bit of the SV packet enters the receiving port, the recording arrival time is tl=193.457101130 seconds. When the first bit of the SV packet is sent out from the sending port, the switch records the sending time t2=193.457204970 seconds; In the current switch's dwell time At=t2-tl=103840 ns, the At value is converted to binary: 11001010110100000, and the above binary delay information is sequenced from the low to the high in the SV message shown in FIG.

釆 Using the above technical solution, accurately calculate the SV message by adding a timestamp in the SV message. The transmission delay in the changeover, and the transmission delay of the SV packet in the switch is sent to the protection device; after receiving the transmission delay of the SV packet in the switch, the protection device relies on the local time reference and utilizes

The MU inherently delays the occurrence of the received data of the plurality of intervals, and completes the synchronization processing of the sample values.

 After the technical solution of the present invention is used, the transmission delay of the SV packet obtained by the switch in the switch is ±100 nanoseconds (determined according to the test result, not less than 1 microsecond); when there are multiple switches in the switching network The multi-switch cascading delay per hop is ±100 nanoseconds (determined according to the test result, not less than 1 microsecond); the technical solution of the present invention supports a message with a line rate greater than or equal to 64 bytes (hundred megabits per thousand) Mega).

 Based on the foregoing technical solution, as shown in FIG. 6, the present invention further provides a packet transmission delay obtaining apparatus, including a writing unit 60, a clock information acquiring unit 61, and a transmission delay obtaining unit 62, wherein:

 The writing unit 60 is configured to: after determining that the receiving port of the switch receives the communication packet, add the first clock information corresponding to the clock source of the switch in the specified location in the communication packet; The first clock information is an absolute value of a difference between a link delay and a time at which the receiving port receives the communication message;

 The clock information acquiring unit 61 is configured to: after determining that the sending port of the switch acquires the communication packet that adds the first clock information, determine the second clock information corresponding to the clock source; where the second clock information includes And the time at which the sending port obtains the communication message that adds the first clock information; or the second clock information includes the time and the time at which the sending port obtains the communication message that adds the first clock information The number of inversions of the clock source;

 The transmission delay obtaining unit 62 is configured to obtain, according to the first clock information carried in the communication packet, and the second clock information, a transmission delay of the communication packet in the switch.

Further, the foregoing apparatus further includes: a sending unit 63, configured to: after acquiring a transmission delay of the communication packet in the switch, generate a binary time corresponding to a transmission delay of the communication packet in the switch Extending the information, and adding the binary delay information to the communication Specifying a location; sending the communication message to the protection device in the industrial measurement and control system, and causing the protection device to perform a corresponding protection operation on the faulty device according to the data carried in the communication message.

 In summary, in the embodiment of the present invention, when the switch determines that the local receiving port receives the sampled value communication message, the first clock information corresponding to the local clock source is added to the designated position in the communication message; After the local sending port receives the communication message that adds the first clock information, the second clock information corresponding to the clock source is obtained, and the communication is obtained according to the first clock information and the second clock information carried in the communication packet. The transmission delay of the message in the switch. According to the technical solution of the present invention, the switch adds corresponding timestamp information to the specified location in the communication packet, and according to the timestamp information, determines that the corresponding communication packet of the communication packet in the local transmission process of the switch is in the switch. The transmission delay, in the case of the industrial measurement and control system and the synchronization source out of step, can still conveniently and quickly determine the transmission delay of the communication message in the switch, thereby ensuring the fault protection of the equipment in the industrial measurement and control system and Accuracy of fault detection results.

 Those skilled in the art will appreciate that embodiments of the present invention can be provided as a method, system, or computer program product. Accordingly, the present invention may take the form of an entirely hardware embodiment, an entirely software embodiment, or a combination of software and hardware. Moreover, the invention can be embodied in the form of one or more computer program products embodied on a computer-usable storage medium (including but not limited to disk storage, CD-ROM, optical storage, etc.) in which computer usable program code is embodied.

 The present invention has been described with reference to flowchart illustrations and/or block diagrams of methods, apparatus (system), and computer program products according to embodiments of the invention. It will be understood that each flow and/or block of the flowcharts and/or block diagrams, and combinations of flow and/or blocks in the flowcharts and/or block diagrams can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general purpose computer, special purpose computer, embedded processor, or other programmable data processing device to produce a machine for the execution of instructions for execution by a processor of a computer or other programmable data processing device. Means for implementing the functions specified in one or more of the flow or in a block or blocks of the flow chart.

These computer program instructions can also be stored in a bootable computer or other programmable data processing device. In a computer readable memory that operates in a particular manner, causing instructions stored in the computer readable memory to produce an article of manufacture comprising instruction means implemented in one or more flows and/or block diagrams of the flowchart The function specified in the box or in multiple boxes.

 These computer program instructions can also be loaded onto a computer or other programmable data processing device such that a series of operational steps are performed on a computer or other programmable device to produce computer-implemented processing for execution on a computer or other programmable device. The instructions provide steps for implementing the functions specified in one or more of the flow or in a block or blocks of a flow diagram.

 Although the preferred embodiment of the invention has been described, it will be apparent to those skilled in the < Therefore, the appended claims are intended to be interpreted as including the preferred embodiments and the modifications and modifications The spirit and scope of the embodiments of the present invention are departed. Thus, it is intended that the present invention cover the modifications and modifications of the embodiments of the invention.

Claims

Rights request

A method for acquiring a transmission delay delay, which is applied to an industrial measurement and control system, wherein the industrial measurement and control system includes at least one switch, and the method includes:

 After the receiving port of the switch receives the communication packet, the first clock information corresponding to the clock source of the switch is added to the specified location in the communication packet; wherein the first clock information is a link. The absolute value of the difference between the delay and the time at which the receiving port receives the communication message;

 Determining the second clock information corresponding to the clock source after determining that the sending port of the switch obtains the communication message that adds the first clock information, where the second clock information includes the sending port acquiring the Adding a time of the communication message of the first clock information; or, the second clock information includes a time at which the sending port acquires the communication message to which the first clock information is added, and a number of times of inversion of the clock source;

 Obtaining a transmission delay of the communication packet in the switch according to the first clock information carried in the communication packet and the second clock information.

 The method according to claim 1, wherein the communication message further carries a size relationship between the first current time and the link delay, and the first current time and location a relationship between a clock source time corresponding to a half of a maximum time recordable by the clock source, and a clock source time corresponding to a half of a maximum time recordable by the clock source; When the second clock information includes only the second current time, according to the first clock information carried in the communication message, and the second clock information, when the communication message is transmitted in the switch, Delay, specifically including:

When the first current time is less than the link delay, the link delay is greater than the clock source time, and the second current time is less than the clock source time, the second current time is calculated. And the sum of the first clock information as the initial communication message transmission delay, if the initial communication message transmission delay is less than the maximum time recordable by the clock source, the initial communication message transmission delay As a transmission delay of the communication message in the switch; Calculating the second current moment when the first current time is less than the link delay, the link delay is less than the clock source time, and the second current time is less than the clock source time And a sum of the first clock information as a transmission delay of the communication message in the switch;

 Calculating the second current moment when the first current time is less than the link delay, the link delay is greater than the clock source time, and the second current time is greater than the clock source time And a sum of the first clock information as a transmission delay of the communication message in the switch;

 When the first current time is less than the link delay, the link delay is less than the clock source time, and the second current time is greater than the clock source time, the second current time is calculated. And a sum of the first clock information as a transmission delay of the communication message in the switch;

 When the first current time is greater than the link delay, the first current time is greater than the clock source time, and the second current time is less than the clock source time, the clock source is recordable a difference between the maximum time and the first clock information, and obtaining a sum of the difference and the second current time as a transmission delay of the communication message in the switch;

 When the first current time is greater than the link delay, the first current time is greater than the clock source time, and the second current time is greater than the clock source time, the second current time is calculated. The difference between the first clock and the first clock is the transmission delay of the communication packet in the switch; when the first current time is greater than the link delay, the first current time is smaller than the clock source And when the second current time is less than the clock source time, calculating a difference between the second current time and the first clock information as a transmission delay of the communication message in the switch; Calculating the second current time and the first time when a current time is greater than the link delay, the first current time is less than the clock source time, and the second current time is greater than the clock source time The difference between the clock information is used as the transmission delay of the communication message in the switch.

 The method according to claim 1, wherein the communication message further carries a size relationship between the first current time and the link delay;

Obtaining, according to the first clock information carried in the communication packet, and the second clock information, when the second clock information includes a second current time and a number of times of inversion of the clock source The transmission delay of the communication packet in the switch includes: When the first current time is less than the link delay, according to the first clock information, the second current time, the maximum time that the clock source can record, and the number of times the clock source is inverted Obtaining a transmission delay of the communication packet in the switch;

 When the first current time is greater than the link delay, according to the first clock information, the second current time, the maximum time that the clock source can record, and the number of times the clock source is inverted And acquiring a transmission delay of the communication packet in the switch.

 The method according to any one of claims 1-3, wherein the communication message is sent to the local device by the sampling device in the industrial measurement and control system, or the communication message is controlled by the industrial device. Other switches in the system are sent locally.

 The method of claim 1, wherein after obtaining the transmission delay of the communication message, the method further comprises:

 Generating a binary delay information corresponding to the transmission delay of the communication message, and adding the binary delay information to a specified location in the communication >3⁄4 text;

 Sending the communication message to the protection device in the industrial measurement and control system, and causing the protection device to perform a corresponding protection operation on the faulty device according to the data carried in the communication message.

 6. A message transmission delay acquisition device, which is applied to an industrial measurement and control system, wherein the industrial measurement and control system comprises at least one switch, and the device comprises:

 a writing unit, configured to add a first clock information corresponding to a clock source of the switch, at a specified position in the communication packet, after determining that the receiving port of the switch receives the communication packet; A clock information is an absolute value of a difference between a link delay and a time at which the receiving port receives the communication message;

 a clock information acquiring unit, configured to: after determining that the sending port of the switch acquires the communication packet that adds the first clock information, determine the second clock information corresponding to the clock source; where the second clock information includes The time at which the sending port obtains the communication message to which the first clock information is added; or the second clock information includes the time at which the sending port obtains the communication message to which the first clock information is added, and the The number of times the clock source is inverted;

a transmission delay obtaining unit, configured to: according to the first clock signal carried in the communication packet And the second clock information, obtaining a transmission delay of the communication message in the switch.

 7. The apparatus according to claim 6, wherein the transmission delay acquisition unit is specifically configured to:

And if the communication packet further carries a size relationship between the first current time and the link delay, the clock source corresponding to the first current time and a half of the maximum time recordable by the clock source The relationship between the size of the time and the size of the clock source corresponding to the half of the maximum time recordable by the clock source, and when the second clock information only includes the second current time, The first current time is less than the link delay, the link delay is greater than the clock source time, and the second current time is less than the clock source time, and the second current time is calculated. The sum of the first clock information is used as an initial communication message transmission delay. If the initial communication message transmission delay is less than the maximum time recordable by the clock source, the initial communication message transmission delay is used as the communication. The transmission delay of the packet in the switch; if the first current time is less than the link delay, the link delay is less than the clock source time, and the second current time is less than the And calculating, by the clock source, a sum of the second current time and the first clock information as a transmission delay of the communication message in the switch; if the first current time is less than the link delay, If the link delay is greater than the clock source time, and the second current time is greater than the clock source time, calculate a sum of the second current time and the first clock information as a communication message. a transmission delay in the switch; if the first current time is less than the link delay, the link delay is smaller than the clock source time, and the second current time is greater than the clock source time, Calculating a sum of the second current time and the first clock information as a transmission delay of the communication message in the switch; if the first current time is greater than the link delay, the first Calculating a difference between a maximum time recordable by the clock source and the first clock information, and acquiring the difference, when the current time is greater than the clock source time, and the second current time is less than the clock source time Value and number The sum of the current time is the transmission delay of the communication message in the switch; if the first current time is greater than the link delay, the first current time is greater than the clock source time, and the Calculating the second current time and the first time when the second current time is greater than the clock source time The difference between the clock information is the transmission delay of the communication message in the switch; if the first current time is greater than the link delay, the first current time is smaller than the clock source time, and the If the current time is less than the clock source time, calculate a difference between the second current time and the first clock information as a transmission delay of the communication message in the switch; if the first current time is greater than the current time Calculating a link delay, where the first current time is less than the clock source time, and the second current time is greater than the clock source time, calculating a difference between the second current time and the first clock information As the transmission delay of the communication message in the switch.

 8. The apparatus according to claim 6, wherein the transmission delay acquisition unit is specifically configured to:

 If the communication message further carries a size relationship between the first current time and the link delay, when the second clock information includes the second current time and the number of times the clock source is inverted And, if the first current time is less than the link delay, according to the first clock information, the second current time, the maximum time recordable by the clock source, and the inverse of the clock source The number of rotations, the transmission delay of the communication message in the switch; if the first current time is greater than the link delay, according to the first clock information, the second current time, The maximum time that the clock source can record, and the number of times the clock source is inverted, obtains the transmission delay of the communication message in the switch.

 9. The apparatus according to any one of claims 6-8, wherein the writing unit is used to:

 Receiving the communication message sent by the sampling device in the industrial measurement and control system, or receiving the communication message sent by other switches in the industrial measurement and control system.

 The device according to claim 6, further comprising: a sending unit, configured to: after acquiring the transmission delay of the communication message, generate binary delay information corresponding to a transmission delay of the communication message, And adding the binary delay information to a specified location in the communication message; sending the communication message to a protection device in the industrial measurement and control system, so that the protection device is configured according to the communication message The carried data carries out corresponding protection operations on the faulty device.