JP2011134061A - Programmable controller - Google Patents

Abstract

An object of the present invention is to provide a programmable controller capable of reducing the work load, shortening the work time, and improving the accuracy of abnormality detection.
A programmable controller includes a first storage unit that stores all of a header portion and a data portion of a communication packet transmitted and received via a communication unit, and analyzes data in the storage unit when an abnormality occurs. Thus, an analysis unit 4 is provided to investigate the cause. Since the information of the predetermined number of communication packets most recently at the time of occurrence of the abnormality is stored, the analysis unit 4 investigates the cause of the abnormality based on the stored information.
[Selection] Figure 1

Description

  The present invention relates to a PLC that automatically investigates the cause of an abnormal stop that occurs between a programmable controller (hereinafter referred to as “PLC”) and a peripheral device connected to the Ethernet (registered trademark) LAN.

  FIG. 6A is a schematic diagram showing a configuration of a communication packet exchanged by the application protocol, and is composed of a header portion 11 constituted by control information and a data portion 12 subsequent thereto. In the data transmission / reception between the PLC and the PLC peripheral devices, the information required by the user is only the data portion 12, and therefore the information in the header portion 11 is discarded upon completion of transmission.

  FIG. 6B is a diagram illustrating an example of the configuration of the header portion 11 of the communication packet. The header 11 includes a packet length 13, a source address 14, a destination address 15, a source port number 16, a destination port number 17, a sequence number 18 that is a communication serial number, and the received data. Confirmation number 19 indicating how far the packet has been received, header length 20 indicating the start position of data portion 12 in the packet, code bit 21 indicating the type of packet, and check for checking packet consistency Information with the thumb 22 is included. If an abnormal stop of communication occurs, analyzing the information in the header part 11 of the communication packet exchanged immediately before the abnormal stop contributes to investigation of the cause of the communication abnormality.

  FIG. 7 is a schematic view showing a conventional method for investigating the cause of abnormal communication stop. Conventionally, when an abnormal stop of communication occurs, in order to investigate the cause, a communication packet capturing device 10 transmits a communication packet exchanged between the PLC 8 and the peripheral device 9 of the PLC connected by the Ethernet LAN 7. The user has analyzed the information in the header portion 11 of the packet that was received immediately before the abnormal stop. Since the communication packet capturing device 10 is often not included in the system configured by the user, it is added to the system after the abnormal stop occurs to investigate the cause, waits for the abnormal stop to be reproduced, The connection will continue until the causal factor is removed.

  There has been proposed a PLC system that includes a network including a plurality of PLCs and one development support apparatus, and the development support apparatus investigates the cause of communication abnormality when a communication failure occurs (Patent Documents 1 and 2). The development support device narrows down the factors by section division or narrows down the factors by routing table analysis, clarifies the normal range and abnormal range of communication and notifies the user, and the user is narrowed down By checking the status of the communication path in the range, the time required for investigating the cause is shortened. There has also been proposed a communication facility management system comprising a PLC that collects various types of data indicating the operating state of communication equipment, and a diagnostic device that analyzes the collected data and diagnoses the state of equipment in the base station (patent). Reference 3).

JP 2008-181572 A JP 2006-277728 A JP 2002-132955 A

W. Richard Stevens “Detailed TCP / IP Vol. 1 Protocol ”, Pearson Education, Yasuo Tachibana, Naoji Inoue, 2000

  Such a conventional method has the following problems. That is, there is no immediacy because a communication packet capturing device is newly added in the system configuration after the occurrence of an abnormality and the cause is investigated at the time of reproducing the abnormality. Since the cause investigation work is carried out after the abnormal phenomenon is reproduced, there is a time lag from when the first abnormal phenomenon occurs until the cause investigation work starts. In the case of a phenomenon with low reproducibility, this time lag may extend over one month. Further, until the cause of the abnormality is investigated and the cause is removed, it is necessary to continue to connect a communication monitoring device such as a communication packet capturing device that is not originally required for the system.

  Since the user analyzes the communication packet by himself / herself, the user cannot make a determination unless he / she understands the configuration of the communication packet exchanged by the application protocol. Even if you understand the structure of the communication packet, it takes a lot of time and effort to elucidate the cause of the abnormality. In addition, since there are various forms of communication abnormality, it is difficult to investigate the cause of the abnormality unless the user has know-how.

  The present invention has been made to solve such problems, and automatically detects abnormalities in the communication sequence due to reduction of the work load for investigation of the cause, reduction of the work time, and loss of communication packets. The purpose is to improve the accuracy of abnormality detection.

  A programmable controller according to the present invention is a programmable controller that controls the peripheral device while transmitting and receiving a communication packet including a signal for controlling the peripheral device, the storage unit storing the communication packet, and abnormal communication stop And an analysis unit that analyzes the communication packet stored in the storage unit and investigates the cause of the abnormal stop based on the analysis result.

  According to this programmable controller, when the communication is abnormally stopped, the analysis unit analyzes the communication packet stored in the storage unit, so there is no need to wait for reproduction of the abnormal stop, and the cause of the abnormal stop can be determined based on the analysis result. Can be investigated.

  In the programmable controller, the storage unit stores information on a header part of a predetermined number of the communication packets immediately before an abnormal stop, or information on a header part and a data part, as log data upon log analysis of the communication packet. Can do. Since the cause of the abnormal stop is expected to be hidden in the information of the communication packet immediately before the abnormal stop, the information of the header part of the predetermined number of the communication packets immediately before the abnormal stop or the information of the header part and the data part is stored. Therefore, it is estimated that the cause of the abnormal stop can be investigated with sufficient accuracy.

  The programmable controller includes a communication unit that transmits and receives the communication packet, and the communication unit stops storing the communication packet in the storage unit 3 and stops the analysis unit when the communication is abnormally stopped. It is possible to automatically request the start of analysis processing. By providing the function of the communication unit in this way, it is possible to automatically investigate the cause of the abnormal stop when the communication is abnormally stopped.

  In this programmable controller, the level can be changed for the items and depth of analysis performed by the analysis unit. The level of the analysis is to determine whether or not the communication packet is missing by determining whether or not the sequence number and the acknowledgment number are in a normal relationship in order from the oldest of the communication packets. One level can be included. In addition, the level of the analysis may include a second level that is higher than the first level and set to whether or not communication is forcibly disconnected.

  The programmable controller may include another storage unit that stores the analysis result obtained by the analysis unit. Moreover, the display part which displays the analysis result which the said analysis part performed can be provided. By providing such a separate storage unit and display unit, it is possible to help the user to easily determine the cause of an abnormal stop, such as a communication packet error or a communication sequence error, using an error code or the like. it can.

  According to the present invention, the communication packet is stored in the storage unit, and when the communication is abnormally stopped, the communication packet stored in the storage unit is analyzed by the analysis unit, and the cause of the abnormal stop is automatically determined based on the analysis result. Therefore, it is possible to reduce the workload for investigating the cause of the abnormality and to improve the accuracy of detecting the abnormality of the communication sequence due to the loss of the communication packet.

FIG. 1 is an internal configuration diagram of a programmable controller in Embodiment 1 of the present invention. FIG. 2 is a flowchart showing processing executed by the analysis unit according to the first embodiment of the present invention. FIG. 3 is a configuration diagram of packet data referred to by the analysis unit in level 1 of the first embodiment of the present invention. FIG. 4 is a flowchart showing processing executed by the analysis unit according to the first embodiment of the present invention. FIG. 5 is a configuration diagram of packet data referred to by the analysis unit in level 2 of the first embodiment of the present invention. FIG. 6 is a configuration diagram of communication packets exchanged by the application protocol. FIG. 7 is a schematic diagram showing a conventional method for investigating the cause of abnormal communication stop.

  Hereinafter, embodiments for carrying out the present invention will be described with reference to the drawings of FIGS. These drawings and examples are drawings and examples for explaining one embodiment of the present invention, and the present invention is not limited by these drawings and examples.

  FIG. 1 is an internal configuration diagram of a programmable controller (PLC) in Embodiment 1 of the present invention. In FIG. 1, the PLC 1 according to the present invention is a first storage that stores all of the communication unit 2 that communicates with another device (not shown) via the Ethernet LAN 7 and the header unit 11 and the data unit 12 of the communication packet. 3 and an analysis unit 4 that analyzes the cause of communication stoppage using packet data stored in the first storage unit 3. The PLC 1 also encodes and stores the analysis results obtained in the display unit 5 and the analysis unit 4 that display packet data stored in the first storage unit 3 and the analysis results obtained in the analysis unit 4. A second storage unit 6 is provided. In addition, although the 1st memory | storage part 3 and the 2nd memory | storage part 6 are arrange | positioned on a different memory in FIG. 1, you may arrange | position on the same memory.

  The user can set an analysis level for the analysis process executed by the analysis unit 4. As the analysis level, expressions such as levels 0 to 5 can be considered. As the level number increases, the number of analysis items increases, or finer analysis with a deeper analysis depth is executed.

  In the embodiment of the present invention having such a feature, the analysis level is level 2, and the analysis items are a communication packet loss (level 1) and presence / absence of forced disconnection (level 2). Will be described in detail with reference to the flowcharts of FIGS.

  First, while the PLC and the peripheral device are communicating, the header part 11 and the data part 12 of the communication packet are stored in the first storage part 3. At this time, the first predetermined number of the communication packets are stored in the first storage unit 3 (S1). When the communication is stopped, the storage of the communication packet from the communication unit 2 to the first storage unit 3 is stopped, and the communication unit 2 issues an analysis process start request to the analysis unit 4. Also, the user may directly input the analysis process start request. Upon receiving the start request, the analysis unit 4 executes analysis processing using the communication packet data stored in the first storage unit 3.

  When there is a request to start the analysis process (S2), the analysis unit 4 executes the process of S3 as level 1. S3 is a process of determining whether or not the sequence number 18 and the acknowledgment number 19 are in a normal relationship in order from the oldest communication packet stored in the first storage unit 3.

  This determination process will be described with reference to FIG. FIG. 3 is an example of a configuration diagram of packet data referred to by the analysis unit 4 at level 1. The example noted here is the sequence number determined in S3 in the communication packet data stored in the first storage unit 3. 18 and the acknowledgment number 19 required to express the relationship, the transmission source address 14, the transmission source port number 16, the transmission destination address 15, the transmission destination port number 17, and the code bit 21 (FIG. 6). The packet type 24 obtained from (b)), the sequence number 18, the acknowledgment number 19, and the data size 25 that can be calculated from the packet length 13 and the header length 20 (FIG. 6B).

  When attention is paid to a communication packet whose communication order 23 is No. 1 (hereinafter referred to as “No. 1”), the sequence number 18 is “5” and the confirmation response number 19 is “1”. The first packet type 24 is “transmission”, and its data size 25 is “10”. The response to No. 1 is a communication packet whose communication order 23 is No. 2 (hereinafter referred to as “No. 2”). In order to indicate that it is the first response, the second sequence number 18 is “1”, which is the same as the first confirmation response number 19. Further, in order to indicate that the first data has been normally received, the second confirmation response number 19 is “15” obtained by adding “10” which is the data size 25 to “5” which is the first sequence number 18. " In S2 described above, it is determined whether or not a packet has been lost by utilizing the unique relationship among the sequence number 18, the confirmation response number 19, and the data size 25 (S4).

  When packet loss is recognized in S4, a predetermined error code is stored in the second storage unit 6 (S5) and the error code is displayed on the display unit 5 (S6), and the analysis is terminated. If no missing packet is recognized in S4, the presence / absence of an unexecuted item is determined (S7). If there is no unexecuted item, the process ends. A determination process A (FIG. 4) for determining whether or not a forced disconnection of communication has occurred is executed.

  FIG. 5 is a configuration diagram of packet data referred to by the analysis unit 4 at level 2. The example noted here is the communication sequence 23 and the source address in the communication packet data stored in the first storage unit 3. 14, source port number 16, destination address 15, destination port number 17, packet type 24, sequence number 18, confirmation response number 19, and data size 25.

  When attention is paid to a communication packet whose communication order 23 is No. 25 (hereinafter referred to as “No. 25”), the packet type 24 is “forced disconnection”. In this case, it can be considered that the device whose destination address 15 of No. 25 is “192.168.0.1” has fallen into the communication disabled state, and thus it is possible to narrow down the abnormal stop points.

  In process A shown in FIG. 4, as shown in S <b> 10, it is determined whether or not forced disconnection has occurred in the communication packet stored in the first storage unit immediately before the communication is stopped. That is, in the determination of whether or not there is a forced disconnection in S11 (S11), if the forced disconnection of communication is recognized, a predetermined error code is stored in the second storage unit 6 (S12) and displayed on the display unit 5 The error code is displayed (S13), and the analysis is terminated. Even if the forced disconnection of communication is not recognized in S11, the process A ends, but it is conceivable that the check process is continued for items such as whether or not the value of the checksum 22 is normal.

  As described above, the analysis of the packet data is executed for each analysis item, and when it is determined that the abnormal stop has occurred, the error code corresponding to the corresponding item is stored in the second storage unit 6 and the error is displayed on the display unit 5. Since the code is displayed, the user can easily determine whether the communication packet is abnormal or the communication sequence is abnormal by looking at the error code displayed on the display unit 5.

  One end of the analysis method executed by the analysis unit 4 in the first embodiment is shown. However, it is also conceivable that the user has unique know-how in analyzing communication packets. Therefore, even when the user wants to perform an analysis that is not included in the items of the analysis program held in the analysis unit 4, the external device is connected by referring to the data stored in the first storage unit 3 directly from the display unit 5. It is possible to carry out analysis work utilizing the user's unique know-how.

DESCRIPTION OF SYMBOLS 1 Programmable controller (PLC) of this invention 2 Communication part 3 1st memory | storage part 4 Analysis part 5 Display part 6 2nd memory | storage part 7 Ethernet LAN 8 PLC
9 Peripheral device 10 Monitoring means 11 Header part 12 Data part 13 Packet length 14 Source address 15 Destination address 16 Source port number 17 Destination port number 18 Sequence number 19 Confirmation response number 20 Header length 21 Code bit 22 Checksum 23 Communication sequence 24 Packet type 25 Data size

Claims (8)

In a programmable controller that controls the peripheral device while transmitting and receiving a communication packet including a signal for controlling the peripheral device,
A storage unit that stores the communication packet; and an analysis unit that analyzes the communication packet stored in the storage unit when communication is abnormally stopped and investigates the cause of the abnormal stop based on the analysis result;
Programmable controller characterized by   The storage unit stores information on a header part of a predetermined number of the communication packets immediately before an abnormal stop or information on a header part and a data part as log data upon log analysis of the communication packet. Item 12. The programmable controller according to item 1. A communication unit for transmitting and receiving the communication packet;
The communication unit, when stopping the communication abnormally, stops storing the communication packet in the storage unit 3 and automatically requests the analysis unit to start an analysis process. The programmable controller according to 1 or 2.   The programmable controller according to any one of claims 1 to 3, wherein the level of the items and depth of analysis performed by the analysis unit can be changed.   The level of the analysis is to determine whether or not the communication packet is missing by determining whether or not the sequence number and the acknowledgment number are in a normal relationship in order from the oldest of the communication packets. 5. The programmable controller of claim 4, comprising one level.   The programmable controller according to claim 5, wherein the level of the analysis includes a second level that is higher than the first level and is set to whether or not communication is forcibly disconnected.   The programmable controller according to claim 1, further comprising another storage unit that stores an analysis result obtained by the analysis unit.   The programmable controller according to any one of claims 1 to 7, further comprising a display unit that displays an analysis result obtained by the analysis unit.

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