Transmission state analysis device, data transmission system, transmission state analysis method, and control program

Abstract

To allow investigation of a transmission abnormality to be facilitated even when a system has already recovered from the transmission abnormality, and thereby to allow appropriate measures to be taken against the transmission abnormality.SOLUTION: A transmission state analysis device of an embodiment includes a logging unit that logs transmission data transmitted over transmission paths that constitute a communication network to which a plurality of communication nodes are connected, and an estimation unit that, when a transmission abnormality is detected by the communication nodes, estimates the location of the transmission abnormality based on the pattern of missing transmission data within a predetermined time before and after the detection of the transmission abnormality.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The embodiments of the present invention relate to a transmission state analyzing device, a data transmission system, a transmission state analyzing method, and a control program. [Background technology]

[0002] Conventionally, in monitoring and control systems for power receiving and transforming equipment, PLCs have been known as devices that transmit digital signals such as open / close status signals for circuit breakers and analog data such as current values ​​to a control center, receive on / off commands for circuit breakers and other devices transmitted from the control center, and output command signals to the circuit breakers and other devices.

[0003] The substation equipment contains multiple PLCs, each with its own role, and these multiple PLCs transmit and receive signals to each other via transmission. Therefore, it is necessary to monitor whether transmission is occurring normally, and the PLC application program constantly monitors the transmission status. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Publication No. 2023-93104 Summary of the Invention [Problem to be solved by the invention]

[0005] If an abnormality occurs in the transmission between PLCs, a transmission abnormality is sent to the control center. Even if a transmission abnormality is detected, it is often the case that the system immediately returns to normal. If the abnormality has been corrected by the time an investigation to determine the cause of the transmission abnormality begins, it can be very difficult to determine whether the problem was with the PLC or the transmission path. As a result, there is a high possibility that appropriate measures cannot be taken to deal with transmission abnormalities. The present invention has been made in consideration of the above, and aims to provide a transmission status analysis device, a data transmission system, a transmission status analysis method, and a control program that can easily investigate a transmission abnormality even if the transmission abnormality has already been resolved, and that can ultimately take appropriate measures against the transmission abnormality. [Means for solving the problem]

[0006] The transmission state analysis device of the embodiment includes a logging unit that logs transmission data transmitted over a transmission path that constitutes a communication network to which multiple communication nodes are connected, and an estimation unit that, when a transmission abnormality is detected by the communication node, estimates the location of the transmission abnormality based on the pattern of missing transmission data within a predetermined time before and after the detection of the transmission abnormality. [Brief explanation of the drawings]

[0007] [Figure 1] FIG. 1 is a block diagram showing the general configuration of a data transmission system according to an embodiment. [Figure 2] FIG. 2 is an explanatory diagram of a specific example of a data transmission system according to an embodiment. [Figure 3] FIG. 3 is a diagram illustrating a typical transmission data format in PLC. [Figure 4] FIG. 4 is an explanatory diagram of logging data of transmission data. [Figure 5] FIG. 5 is an explanatory diagram of logging timing and storage triggers. [Figure 6] FIG. 6 is a diagram (part 1) explaining the operation when an abnormality occurs in the transmission path. [Figure 7] FIG. 7 is a diagram (part 2) for explaining the operation when an abnormality occurs in the transmission path. [Figure 8] FIG. 8 is a diagram (part 3) for explaining the operation when an abnormality occurs in the transmission path. [Figure 9] FIG. 9 is a diagram (part 4) for explaining the operation when an abnormality occurs in the transmission line. [Figure 10]FIG. 10 is an explanatory diagram of data loss patterns of transmission abnormalities and transmission abnormality detection results. [Figure 11] FIG. 11 is an explanatory diagram (part 1) of the analysis procedure for a transmission abnormality. [Figure 12] FIG. 12 is a diagram (part 2) illustrating the analysis procedure for a transmission abnormality. DETAILED DESCRIPTION OF THE INVENTION

[0008] Next, a preferred embodiment will be described with reference to the drawings. FIG. 1 is a block diagram showing the general configuration of a data transmission system according to an embodiment. In the data transmission system of the embodiment, a log of transmission data is recorded and analyzed to function as a transmission status monitoring system, which is useful for analyzing the cause of a transmission abnormality. In this case, the logs are recorded at three locations: a pair of PLCs that communicate with each other, and an analysis tool. If a transmission abnormality occurs, it is possible to narrow down the cause of the transmission abnormality by comparing and analyzing the log data from the three locations.

[0009] As shown in FIGS. 1 and 2, the data transmission system 10 includes PLCs 11-1, 11-2, 11-3, . . . , 11-n, an analysis tool 12, and a hub device (HUB) 13. In the above configuration, the PLC 11-1, PLC 11-2, PLC 11-3, . . . are connected to the normal communication port CP of the hub device 13 via LAN cables.

[0010] Furthermore, one of the communication ports of the hub device 13 is set as a mirror port MP, and the analysis tool 12 is connected to the mirror port MP of the hub device 13 via a LAN cable. Here, the mirror port MP is a port for realizing a port mirroring function, and is a port that outputs the same packets as those relayed by the hub device 13 functioning as a switching hub.

[0011] As a result, the analysis tool 12 can collect all packets relayed by the hub device 13 . In the following description, the transmission path between PLC 11-1 and hub device 13 will be identified as transmission path RTA, the transmission path between PLC 11-2 and hub device 13 will be identified as transmission path RTB, and the transmission path between analysis tool 12 and hub device 13 will be identified as transmission path RTC.

[0012] FIG. 2 is an explanatory diagram of a specific example of a data transmission system according to an embodiment. For ease of understanding, the following description will be given taking as an example a case where the data transmission system 10 is configured by two PLCs, PLC 11-1 and PLC 11-2, as shown in FIG.

[0013] The PLC 11-1 constantly logs the transmitted and received data and stores it in a buffer area 111BF in the CPU memory area 111MA.

[0014] Furthermore, the PLC 11-1 has a storage 111ST installed therein, and when a save trigger such as the occurrence of a transmission abnormality is detected, the logged data in the buffer area 111BF is saved in the storage 111ST. In the above configuration, the PLC 11-1 functions as a communication node, and the buffer area 111BF functions as a buffer unit.

[0015] Similarly, the PLC 11-2 constantly logs the transmitted and received data and stores it in a buffer area 112BF in the CPU memory area 112MA.

[0016] Furthermore, the PLC 11-2 has a storage 112ST installed therein, and when a save trigger such as the occurrence of a transmission abnormality is detected, the logged data in the buffer area 112BF is saved in the storage 112ST. In the above configuration, the PLC 11-2 functions as a communication node, and the buffer area 112BF functions as a buffer unit.

[0017] Furthermore, the analysis tool 12 constantly logs the transmission data flowing through the transmission path and stores it in a buffer area 12BF in the CPU memory area 12MA.

[0018] Furthermore, the analysis tool 12 has a storage 12ST installed therein, and when a storage trigger such as the occurrence of a transmission abnormality is detected, the logged data in the buffer area 12BF is stored in the storage 12ST. In the above configuration, the analysis tool 12 functions as a transmission state analysis device, the CPU as a control device of the analysis tool functions as an estimation unit, the buffer area 12BF functions as a buffer unit, and the buffer area 12BF and the storage 12ST function as a logging unit.

[0019] First, a method for logging the data sent and received in each of the PLCs 11-1 and 11-2 and a method for logging the transmission data in the analysis tool 12 will be described. After that, a method for saving the logged data when a saving trigger is detected will be described.

[0020] First, a method for logging transmitted and received data in a PLC will be described. The PLC 11-1 stores the transmitted data and the received data in the buffer area 111BF in the CPU memory area 111MA. The PLC 11-2 stores the transmitted data and the received data in a buffer area 112BF in the CPU memory area 112MA.

[0021] The capacity of these buffer areas 111BF and 112BF is such that several tens of minutes of data can be logged. Furthermore, the buffer areas 111BF and 112BF form a so-called ring buffer, and when the upper limit of the buffer area capacity is reached, the oldest data is overwritten.

[0022] In this case, the timing at which the PLCs 11-1 and 11-2 store data in the buffer areas 111BF and 112BF differs between when receiving and when transmitting.

[0023] (1) Logging timing of received data in PLC In the PLCs 11-1 and 11-2, the timing for logging received data is when the received data is updated, which is determined by the healthy counter in the received data format.

[0024] FIG. 3 is a diagram illustrating a typical transmission data format in PLC. The transmission data 20 includes a header section 21 and a data section 31 . The header section 21 includes a date data section 22, a healthy counter data section 23, a save command data section 24, and a system information storage section 25. The date data section 22 stores the transmission date (year, month, day, hour, minute, second) of the transmission data.

[0025] The healthy counter data section 23 stores the value of the healthy counter at the time of transmission.

[0026] Here, the healthy counter is a counter that counts up every time the CPU that controls the PLC scans. As a result, if the healthy counter value stored in the healthy counter data unit 23 is different from the previously received healthy counter value, it can be determined that the received data has been updated.

[0027] The save command data unit 24 stores a save command when data in the buffer area is to be saved in storage. The system information storage unit 25 stores various types of system information such as the type of data stored in the data unit. The data section 31 stores the actual data to be transmitted.

[0028] (2) Logging timing of transmitted data in PLC Next, the logging timing when storing transmission data in the PLCs 11-1 and 11-2 in the buffer areas 111BF and 112BF will be described. In the PLC 11-1, the timing for logging transmitted data is not constant but differs depending on the transmission protocol.

[0029] In the PLCs 11-1 and 11-2, depending on the transmission protocol, the application may or may not be able to recognize whether transmission has succeeded or failed. Therefore, if the application can recognize whether transmission has succeeded or failed, it will use this as a trigger to store the transmission data in buffer areas 111BF and 112BF.

[0030] FIG. 4 is an explanatory diagram of logging data of transmission data. As shown in Figure 4, when PLCs 11-1 and 11-2 log transmission data, they add transmission success / failure data 41, which indicates whether the transmission was successful or unsuccessful, to the transmission data and save it as transmission data 40A, as shown in Figure 4(A).

[0031] On the other hand, if the success or failure of transmission cannot be recognized, all transmission data is saved in the transmission buffer area of ​​its own buffer area as transmission data 40B in the format shown in FIG. 4(B) for each scan of the CPU.

[0032] (3) Logging timing of transmission data in the analysis tool Like PLC11-1 and 11-2, the analysis tool's ring buffer has a buffer area capacity that can log several tens of minutes of data, and when the buffer area capacity limit is reached, the oldest data is overwritten. The analysis tool 12 saves the transmission data when the data flows through the transmission path. The transmission data 40C logged by the analysis tool 12 includes an Ethernet header 51, an IP header 52, a TCP header 53, etc., as shown in Figure 4(C), in order to store the packets flowing on the transmission path, i.e., the transmission data input from the mirror port, as is.

[0033] (4) Triggers for saving logging data for each component The save trigger differs depending on the component (PLC or analysis tool). In the case of PLC 11-1 and 11-2, it is when a transmission error is detected or when a recording command is sent from the PLC of the other end of the transmission.

[0034] More specifically, when the PLC 11-1 or the PLC 11-2 itself detects a transmission abnormality, logging data is saved. In addition, PLC11-1 stores logging data when a recording command is sent from PLC11-2, the other PLC of the transmission, and PLC11-2 stores logging data when a recording command is sent from PLC11-1, the other PLC of the transmission.

[0035] In the case of the analysis tool 12, this occurs when a recording command sent from either of the PLCs 11-1 and 11-2 is detected, or when a bit indicating a forced termination of communication is detected in the captured TCP header. The data recorded in the buffer area by each component (PLC or analysis tool) is saved in the storage implemented in each component for a predetermined time (for example, N seconds) before and after the detection of a save trigger. When saving, the "save trigger detection time" and "save trigger type" are recorded along with the transmitted and received data.

[0036] FIG. 5 is an explanatory diagram of logging timing and storage triggers. In FIG. 5, the same parts as those in FIG. 3 are denoted by the same reference numerals. In this case, the storage trigger type is information indicating whether the storage trigger is (1) or (2) in FIG.

[0037] As shown in FIG. 5, the data transmitted by the PLC is logged every time the PLC is scanned. In this case, the save trigger is either (1) when a transmission error is detected, or (2) when a recording command REC, which will be described later, is received from the other PLC, which is the PLC to which the data is being transmitted.

[0038] As shown in Figure 5, the data received by the PLC is logged when the healthy counter is updated. In this case, the save trigger is the same as for the PLC transmission data: (1) when a transmission error is detected, or (2) when a record command REC is received from the other PLC, which is the transmission target PLC.

[0039] As shown in FIG. 5, the analysis tool 12 logs the transmission data when it is transmitted. The save trigger in this case is either (1) when a recording command REC is received from the PLC, or when a communication forced termination flag in the TCP header 53 is detected.

[0040] (5) Transmission error detection method and recording command transmission Transmission anomalies can be detected by the PLC application. Each PLC 11-1, 11-2 detects a transmission abnormality when a certain period of time has passed without updating the healthy counter of the previously received data, or when the difference between the previously received healthy counter value and the currently received healthy counter value exceeds a certain period of time.

[0041] As a result, the PLC that detected the transmission abnormality transmits a recording command REC to the other PLC and the analysis tool 12 .

[0042] Next, an example of operation when a transmission abnormality is detected will be described. FIG. 6 is a diagram (part 1) explaining the operation when an abnormality occurs in the transmission path. FIG. 7 is a diagram (part 2) for explaining the operation when an abnormality occurs in the transmission path. Here, as an example, an operation will be described in which an abnormality occurs in the transmission path RTA between the PLC 11-1 and the hub device 13, and a transmission abnormality is detected, but the transmission abnormality is subsequently restored to a normal state.

[0043] The PLC 11-1, PLC 11-2 and analysis tool 12 constantly store transmitted and received data in their own buffer areas 111BF, 112BF and 112BF, respectively. However, since the transmission line RTA between the PLC 11-1 and the hub device 13 is abnormal, the data cannot be transmitted via the transmission line RTA.

[0044] Therefore, neither PLC 11-1 nor PLC 11-2 has a normal transmission path for transmitting data, and while the abnormality is occurring, the data received by PLC 11-1 and PLC 11-2 is lost. That is, the transmission data DT13 that PLC 11-1 sent to PLC 11-2 while the transmission line RTA was abnormal cannot be received by PLC 11-2 and is lost.

[0045] Similarly, the transmission data DT23 that PLC 11-2 sent to PLC 11-1 while the transmission line RTA was abnormal cannot be received by PLC 11-1 and is lost.

[0046] In contrast, even if a transmission abnormality occurs in the transmission path RTA, the transmission path RTB between PLC 11-2 and the hub device 13 and the transmission path RTC between the hub device 13 and the analysis tool 12 are normal, data transmission is possible, and the transmission data DT23 from PLC 11-2 can be received, with only the transmission data DT13 from PLC 11-1 being missing.

[0047] Due to an abnormality in the transmission path RTA, PLC11-1 is unable to receive the transmission data DT23 from PLC11-2, and PLC11-2 is able to receive the transmission data DT13 from PLC11-1 but is unable to receive the reception data D13, so the healthy counters of PLC11-1 and PLC11-2 are not updated for a predetermined period of time or more.

[0048] As a result, the PLC 11-1 and PLC 11-2 detect that a transmission abnormality has occurred, and upon detecting the transmission abnormality, the PLC 11-1 and PLC 11-2 store part of the logging data in the storages 111ST and 112ST.

[0049] After that, the abnormality in the transmission line RTA is recovered and communication is resumed, so that PLC 11-1 can receive the transmission data DT24 to DT26 from PLC 11-2, and PLC 11-2 can receive the transmission data DT14 to DT16 from PLC 11-1.

[0050] As a result, the PLC 11-1 and PLC 11-2 store in storage the transmitted and received data for a predetermined time (for example, M seconds) before and after the transmission abnormality is detected. When saving, the "save trigger detection time" and "save trigger type" are also saved. In the save trigger type, both PLC 11-1 and PLC 11-2 store data indicating the detection of a transmission abnormality.

[0051] 7, PLC 11-1 stores in storage 111ST the received data DR22 and the received data DR24 to DR25 from PLC 11-2 within a predetermined time before and after the detection of the transmission abnormality. Also, PLC 11-1 stores in storage 111ST the transmitted data DT12 to DT15 to PLC 11-2 within a predetermined time before and after the detection of the transmission abnormality.

[0052] Similarly, PLC 11-2 stores in storage 112ST the received data DR12 and the received data DR14 to DR15 from PLC 11-1 within a predetermined time before and after the detection of the transmission abnormality. Also, PLC 11-2 stores in storage 112ST the transmitted data DT22 to DT25 to PLC 11-1 within a predetermined time before and after the detection of the transmission abnormality.

[0053] Next, the transmission of recording commands from the PLC 11-1 and PLC 11-2 and the storage of logging data in the analysis tool 12 will be described. The PLC 11-1 and PLC 11-2 transmit a recording command REC to the other PLC and the analysis tool 12.

[0054] In this case, since the transmission path RTA is in an abnormal state, the recording command REC sent from the PLC 11-1 does not reach the analysis tool 12. However, the recording command REC sent from the PLC 11-2 reaches the analysis tool 12 via the transmission path RTB, the hub device 13, and the transmission path RTC.

[0055] FIG. 8 is a diagram (part 3) for explaining the operation when an abnormality occurs in the transmission path. FIG. 9 is a diagram (part 4) for explaining the operation when an abnormality occurs in the transmission line. As a result, the analysis tool 12 saves in storage 12ST, as shown in FIG. 9, the logging data stored in buffer area 12BF as shown in FIG. 8, for a predetermined time (e.g., M seconds) before and after the time when the recording command REC from PLC 11-2 is detected.

[0056] Furthermore, when saving the logging data in the storage, the analysis tool 12 also saves the "save trigger detection time" and the "save trigger type." In this case, the type of save trigger to be saved stores data indicating the recording command REC from the PLC 11-2.

[0057] Specifically, the analysis tool 12 stores in storage 12ST the transmission data DT12, transmission data DT14 to DT15 of PLC 11-1, transmission data DT22 to DT25 of PLC 11-2, storage trigger detection time data TT, and storage trigger type data TK within a predetermined time before and after the detection of a transmission abnormality.

[0058] Next, a data loss pattern of a transmission abnormality and a result of the transmission abnormality detection will be described. FIG. 10 is an explanatory diagram of data loss patterns of transmission abnormalities and transmission abnormality detection results. The data loss patterns are classified based on the storage status of transmitted and received data and the PLC that detected the transmission abnormality in each of PLC 11-1, PLC 11-2 and analysis tool 12. Furthermore, when the abnormality is in PLC 11-1 or PLC 11-2, the data loss patterns are classified according to whether each of PLC 11-1 and PLC 11-2 is unable to transmit, unable to receive, or unable to transmit or receive.

[0059] In this embodiment in which there are two PLCs, PLC 11-1 and PLC 11-2, data loss patterns are classified into transmission abnormality patterns A to I.

[0060] Each transmission abnormality pattern will be explained below. [1] Transmission abnormality pattern A In the case of transmission abnormality pattern A, PLC 11-1 is unable to transmit data, so the healthy counter in PLC 11-2 is not updated for a predetermined time or longer. This causes PLC 11-2 to detect a transmission abnormality and save the logged data in storage.

[0061] In this case, the PLC 11-2 is normal, so the PLC 11-2 transmits a recording command to the PLC 11-1 and the analysis tool 12. As a result, PLC 11-1 is ready to receive data, and when it receives a recording command from PLC 11-2, it stores the logged data in storage. When the analysis tool receives a recording command from PLC11-2, it saves the logged data in storage.

[0062] [2] Transmission abnormality pattern B In the case of transmission abnormality pattern B, PLC 11-1 is unable to receive data, so the healthy counter in PLC 11-1 is not updated based on the data received from PLC 11-2, and PLC 11-1 detects the transmission abnormality and saves the logged data in storage.

[0063] In this case, PLC11-1 is in a state where it can transmit, so A recording command is sent to the PLC 11-2 and the analysis tool 12. As a result, the PLC 11-2 and the analysis tool 12, which have received the recording command from the PLC 11-1, store the logged data in their respective storages.

[0064] [3] Transmission abnormality pattern C In the case of transmission abnormality pattern C, PLC 11-1 is in a state where it cannot send or receive data, so reception is not possible in PLC 11-1 and the healthy counter based on the received data from PLC 11-2 is not updated, so PLC 11-1 detects the transmission abnormality and saves the logged data in storage 111ST.

[0065] Here, since PLC 11-1 is in a state where it cannot even transmit, it cannot send a recording command to PLC 11-2 even if it tries to do so.

[0066] On the other hand, in PLC 11-2, the data that should have been sent from PLC 11-1 does not arrive, so the healthy counter based on the data received from PLC 11-1 is not updated, and PLC 11-2 detects a transmission abnormality and saves the logged data in storage 112ST.

[0067] In this case, since the PLC 11-2 is normal, a recording command is sent from the PLC 11-2 to the PLC 11-1 and the analysis tool 12. As a result, the analysis tool that receives the recording command from PLC 11-2 saves the logged data in storage.

[0068] [4] Transmission abnormality pattern D In the case of transmission abnormality pattern D, since the transmission line RTA is in an abnormal state, transmission data cannot be transmitted (sent and received) via the transmission line RTA. Therefore, the healthy counters of PLC 11-1 and PLC 11-2 are not updated in each other's cases.

[0069] Therefore, it is possible to detect a transmission abnormality in each of the PLC 11-1 and the PLC 11-2, and the PLC 11-1 and the PLC 11-2 store the logged transmission data in their own storage.

[0070] Then, the PLC 11-1 and the PLC 11-2 transmit recording commands to the destination PLC (the other PLC) and the analysis tool 12, respectively. In this case, the transmission line RTA is in an abnormal state, so the recording command sent from the PLC 11-1 does not reach the PLC 11-2 and the analysis tool 12.

[0071] On the other hand, since the transmission paths RTB and RTC are in a normal state, the recording command sent from the PLC 11-2 reaches the analysis tool 12. As a result, when the analysis tool 12 receives a recording command from the PLC 11-2, it stores the logged data in its own storage.

[0072] [5] Transmission abnormality pattern E In the case of transmission abnormality pattern E, the hub device 13 is in an abnormal state, so the transmission data cannot be transmitted through the hub device 13 .

[0073] Therefore, in PLC11-1 and PLC11-2, the healthy counter is not updated in association with the sending and receiving of transmission data, and after a predetermined time has elapsed, PLC11-1 and PLC11-2 detect a transmission abnormality and save the logged data in their respective storages.

[0074] In parallel with this, the PLC 11-1 and PLC 11-2 transmit recording commands to the destination PLC (the other PLC) and the analysis tool 12, respectively. However, in this case, the recording commands sent from the PLC 11-1 and PLC 11-2 do not reach the analysis tool 12 because the hub device 13 is in an abnormal state (transmission disabled state).

[0075] Therefore, the analysis tool 12 does not store the logged data in its own storage.

[0076] [6] Transmission abnormality pattern F The case of transmission abnormality pattern F is the same as the case of transmission abnormality pattern D. More specifically, in the case of transmission abnormality pattern F, the transmission path RTB is in an abnormal state, and therefore transmission data cannot be transmitted (sent or received) via the transmission path RTB. Therefore, the healthy counters of PLC 11-1 and PLC 11-2 are not updated in each other's cases.

[0077] Therefore, it is possible to detect a transmission abnormality in each of the PLC 11-1 and PLC 11-2, and the PLC 11-1 and PLC 11-2 store the logged transmission data in their own storages 111ST and 112ST.

[0078] Then, the PLC 11-1 and the PLC 11-2 transmit recording commands to the destination PLC (the other PLC) and the analysis tool 12, respectively. In this case, the transmission path RTB is in an abnormal state, so the recording command sent from the PLC 11-2 does not reach the PLC 11-1 or the analysis tool 12.

[0079] On the other hand, since the transmission paths RTA and RTC are in a normal state, the recording command sent from the PLC 11-1 reaches the analysis tool 12. As a result, when the analysis tool 12 receives a recording command from the PLC 11-1, it stores the logged data in its own storage 12ST.

[0080] [7] Transmission abnormality pattern G The case of transmission abnormality pattern G is the same as the case of transmission abnormality pattern A. More specifically, in the case of transmission abnormality pattern G, PLC 11-2 is unable to transmit data, and therefore the healthy counter in PLC 11-1 is not updated for a predetermined time or longer, which causes PLC 11-1 to detect a transmission abnormality and store the logged data in storage 111ST.

[0081] In this case, the PLC 11-1 is normal, so the PLC 11-1 transmits a recording command to the PLC 11-2 and the analysis tool 12. As a result, PLC 11-2 is ready to receive data, and upon receiving a recording command from PLC 11-1, it stores the logged data in storage 112ST. When the analysis tool 12 receives a recording command from the PLC 11-1, it stores the logged data in the storage 12ST.

[0082] [8] Transmission abnormality pattern H The case of transmission abnormality pattern H is the same as the case of transmission abnormality pattern B. More specifically, in the case of transmission abnormality pattern H, PLC 11-2 is in a state where it cannot receive data, so in PLC 11-2, the healthy counter based on the received data from PLC 11-1 is not updated, and PLC 11-2 detects the transmission abnormality and saves the logged data in storage.

[0083] In this case, the PLC 11-2 is in a state where it can transmit, and therefore transmits a recording command REC to the PLC 11-1 and the analysis tool 12. As a result, the PLC 11-1 and the analysis tool 12 that have received the recording command from the PLC 11-2 each store the logged data in their respective storages.

[0084] [9] Transmission abnormality pattern I The case of transmission abnormality pattern I is the same as the case of transmission abnormality pattern C. More specifically, in the case of transmission abnormality pattern I, PLC 11-2 is in a state where it cannot send or receive data, so PLC 11-2 is unable to receive data and the healthy counter based on the received data from PLC 11-1 is not updated, so PLC 11-2 detects the transmission abnormality and saves the logged data in storage.

[0085] Here, since PLC 11-2 is in a state where it cannot even transmit, it cannot send a recording command to PLC 11-1 even if it tries to do so.

[0086] On the other hand, in PLC 11-1, the data that should be sent from PLC 11-2 does not arrive, so the healthy counter based on the data received from PLC 11-2 is not updated, and PLC 11-1 detects a transmission abnormality and saves the logged data in storage.

[0087] In this case, since the PLC 11-1 is normal, a recording command is sent from the PLC 11-1 to the PLC 11-2 and the analysis tool 12. As a result, the analysis tool 12 receives the recording command from the PLC 11-1 and stores the logged data in storage.

[0088] Next, an analysis procedure (method) performed by the analysis tool 12 based on the above-mentioned transmission abnormality pattern will be described. FIG. 11 is an explanatory diagram (part 1) of the analysis procedure for a transmission abnormality. The analysis tool 12 can analyze the transmission abnormality pattern and estimate the transmission abnormality location in the following procedure.

[0089] Here, the analysis procedure for a transmission abnormality will be specifically explained using an example in which the transmission line RTA goes into a transmission abnormal state and then recovers. First, the analysis tool 12 acquires transmission data of the PLCs (PLC 11-1 and PLC 11-2 in this embodiment) connected to the communication port CP of the hub device 13 corresponding to the mirror port MP to which the analysis tool 12 is connected.

[0090] More specifically, after the analysis tool 12 saves its own logging data in its own storage, it executes the GET command FGC of FTP communication after a predetermined time has elapsed, and acquires the saved data stored in storages 111ST and 112ST of PLC11-1 and PLC11-2.

[0091] If the transmission abnormality has not yet returned to a normal state, the execution of the GET command FGC will fail. In such a case, the on-site investigator can manually obtain the saved data stored in the storage of PLC 11-1 and PLC 11-2 and transfer the data to the analysis tool 12.

[0092] FIG. 12 is a diagram (part 2) illustrating the analysis procedure for a transmission abnormality. Next, as shown in FIG. 12, the analysis tool 12 sorts the transmission data from among the acquired saved data stored in the storages of the PLC 11-1 and PLC 11-2 by transmission source.

[0093] Next, the analysis tool 12 refers to the healthy count value stored in the healthy counter data section 23 in the transmission data, and determines whether or not there is a loss in the transmission data based on whether or not there is an inconsistency in the count value.

[0094] For example, the healthy counter value of the transmission data DT23 acquired from the PLC 11-2 and the transmission data DT23 of the PLC 11-2 stored by the analysis tool 12 are determined to be the same data because the healthy counter values ​​match. On the other hand, if the received data obtained from PLC11-1 does not contain data having the same healthy count value as the transmitted data DT23 obtained from PLC11-2, it is determined that there was a missing received data (transmission abnormality) in PLC11-1.

[0095] Next, estimation of an abnormality location will be described. Around the time when the transmission abnormality occurred, some kind of transmission data loss must have occurred, and the loss of transmission data must have occurred in a manner that fits one of the transmission abnormality patterns shown in FIG.

[0096] Therefore, the analysis tool refers to the organized transmission data, and if it matches a transmission abnormality pattern, it presents (displays) it to the operator of the analysis tool as the estimated abnormality location.

[0097] In this example, there is a gap in the received data in PLC 11-1, and the analysis tool shows that only the transmitted data from PLC 11-1 is missing. Furthermore, looking at the save trigger types for the data in the storage of PLC11-1, we see that both types of data were saved when a transmission abnormality was detected, so we determine that either transmission abnormality pattern C or transmission abnormality pattern D in Figure ## applies. As a result, the analysis tool 12 presents (displays) to the operator "transmission path RTA" and "PLC 11-1 (transmission and reception disabled)" as the estimated abnormal locations.

[0098] In this case, the location of the abnormality cannot be precisely identified, but by presenting the above information to an administrator (for example, an operator of an analysis tool), the administrator can investigate the logging data and, if the logging data (error log) of PLC 11-1 contains a transmission abnormality, determine that PLC 11-1 is likely to be the location of the abnormality.

[0099] Furthermore, if the logging data (error log) of PLC 11-1 does not include any abnormalities related to transmission, the administrator can determine that there is a high possibility that the transmission line RTA is the abnormal location.

[0100] That is, according to the embodiment, even if a transmission abnormality is detected and then recovered, it is possible to use the information to narrow down the cause after recovery. More specifically, in the past, it was extremely difficult to investigate the cause of a transmission abnormality that had already been resolved by the time of investigation, and in the end the cause often remained unknown. However, according to this embodiment, it is possible to more easily estimate or assist in estimating the location of the transmission abnormality, and therefore appropriate measures can be taken to deal with the transmission abnormality.

[0101] The PLC or analysis tool of this embodiment is equipped with a control device such as a CPU, a storage device such as a ROM or RAM, an external storage device (storage) such as an HDD or SSD, a display device such as a display device, and an operation panel or input device such as a keyboard or mouse, and has a hardware configuration that utilizes a normal computer.

[0102] The program executed by the PLC or analysis tool of this embodiment is provided as an installable or executable file recorded on a computer-readable recording medium such as a USB memory, a semiconductor storage device such as an SSD, or a DVD (Digital Versatile Disk).

[0103] The program executed by the PLC or analysis tool of this embodiment may be stored on a computer connected to a network such as the Internet and provided by being downloaded via the network.The program executed by the PLC or analysis tool of this embodiment may be provided or distributed via a network such as the Internet.

[0104] The PLC or analysis tool program of this embodiment may be provided in a state where it is pre-installed in a ROM or the like.

[0105] Although several embodiments of the present invention have been described, these embodiments are presented as examples and are not intended to limit the scope of the invention. These novel embodiments can be embodied in various other forms, and various omissions, substitutions, and modifications can be made without departing from the spirit of the invention. These embodiments and their modifications are included within the scope and spirit of the invention, and are also included in the scope of the invention and its equivalents as defined in the claims.

[0106] For example, in the above explanation, we have described the case of a PLC and an analysis tool that are communicatively connected via a hub device as communication nodes, but the present invention is not limited to PLCs and can be similarly applied to information processing devices such as computers that perform various controls. [Explanation of symbols]

[0107] 10 Data Transmission System 11 PLC 12 Analysis Tools 12BF Buffer Area 12MA CPU memory area 12ST Storage 13 Hub Device 20 Transmission Data 21 Header section 22 Date data section 23 Healthy Counter Data Section 24 Save command data section 25 System information storage section 31 Data section 40A~40C Transmission data 41 Success / Failure Data 51 Ethernet Header 52 IP Header 53 TCP Header D13 Received data 11-1~11-n PLC 111BF Buffer Area 111MA CPU memory area 111ST Storage 112BF Buffer Area 112MA CPU memory area 112ST Storage FGC GET command MP Mirror Port REC Record command RTA~RTC transmission line

Claims

1. a logging unit that logs transmission data transmitted through a transmission path that constitutes a communication network to which a plurality of communication nodes are connected; an estimation unit that, when a transmission abnormality is detected by the communication node, estimates a location of the transmission abnormality based on a pattern of loss of the transmission data within a predetermined time before and after the detection of the transmission abnormality; A transmission state analyzer comprising:

2. The logging unit is configured as a ring buffer, and includes a buffer unit for storing the transmission data; a storage that stores, when the transmission abnormality is detected, the transmission data transferred from the buffer unit within a predetermined time before and after the detection of the transmission abnormality, the estimation unit determines a loss pattern of the transmission data based on a storage state of the transmission data stored in the logging unit and on which communication node detected the transmission abnormality. The transmission state analyzer according to claim 1 .

3. a plurality of communication nodes; a transmission state analyzer; a hub device to which the communication node is connected via a communication port and to which the transmission state analyzer is connected via a mirror port; the transmission state analysis device logs transmission data transmitted through a transmission path constituting a communication network to which a plurality of communication nodes are connected, and when a transmission abnormality is detected by the communication node, estimates the location of the transmission abnormality based on a pattern of loss of the transmission data within a predetermined time before and after the detection of the transmission abnormality; Data transmission system.

4. The transmission state analyzer includes a logging unit that logs transmission data transmitted through a transmission path that constitutes a communication network to which a plurality of communication nodes are connected, and an estimation unit that, when a transmission abnormality is detected by the communication node, estimates a location of the transmission abnormality based on a pattern of loss of the transmission data within a predetermined time before and after the detection of the transmission abnormality. The communication nodes are configured as ring buffers and each includes a buffer unit for storing transmission data corresponding to itself, and a storage unit for storing the transmission data transferred from the buffer unit within a predetermined time before and after the detection of the transmission abnormality when the transmission abnormality is detected, and capable of transferring the stored transmission data to the transmission state analyzer when the transmission abnormality is detected.

4. The data transmission system according to claim 3.

5. The communication node is configured as either a PLC or a hub device.

5. The data transmission system according to claim 3 or 4.

6. A transmission state analysis method executed by a transmission state analysis device, comprising: A step of logging transmission data transmitted through a transmission path constituting a communication network to which a plurality of communication nodes are connected; when a transmission abnormality is detected by the communication node, estimating a location of the transmission abnormality based on a pattern of loss of the transmission data within a predetermined time before and after the detection of the transmission abnormality; A transmission state analysis method comprising:

7. A control program for controlling, by a computer, a transmission state analyzer connected to a mirror port of a hub device in a data transmission system including a plurality of communication nodes, a transmission path constituting a communication network to which the plurality of communication nodes are connected, and a hub device to which the communication nodes are connected via a communication port, the control program comprising: The computer a logging unit that logs transmission data transmitted through the transmission path; an estimation unit that, when a transmission abnormality is detected by the communication node, estimates a location of the transmission abnormality based on a pattern of loss of the transmission data within a predetermined time before and after the detection of the transmission abnormality; A control program that makes the device function.

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