Distributed system and distributed device constituting the distributed system

Abstract

To estimate the cause of failure in a distributed system composed of a plurality of distributed devices.SOLUTION: A distributed system is composed of a plurality of distributed devices that can communicate via communication paths. Each of the distributed devices includes: a communication port that receives communication signals from other distributed devices; a storage unit that stores device information indicating characteristics of the distributed system; and an inspection unit that detects a communication error based on the communication signal, indicates the communication error, compares communication error information including the time of occurrence of the communication error, the type of the communication error, and the location where the communication error was detected with the device information, and estimates the cause of the communication error.SELECTED DRAWING: Figure 5

Description

[Technical Field]

[0001] The present invention relates to a distributed system in which the entire system is composed of multiple units (distributed devices) and to communication technology in the distributed system. Distributed systems include communication systems composed of multiple communication devices and distributed control systems that control objects such as the entire system. Distributed control systems can also be applied to industrial equipment such as semiconductor inspection equipment and medical inspection and analysis equipment. [Background technology]

[0002] In industrial equipment such as semiconductor testing equipment and medical testing and analysis equipment, it is common to use electronic control systems that have analog input / output paths to sensors and actuators mounted on the equipment from multiple centrally managed control boards.In this case, it is necessary to respond to the diversifying needs of equipment in recent years, but with current systems, expanding functionality requires an increase in the amount of wiring and the redesign of boards, so there is an urgent need to improve the design productivity of electronic systems.

[0003] Therefore, as described in Patent Document 1, applying a network-type distributed control system to the electronic system within the equipment can be expected to reduce analog wiring while improving functional expandability. On the other hand, due to the recent increase in the complexity of the system configuration within the equipment, the probability of electrical abnormalities occurring between the installed devices is increasing. However, there are currently few means to estimate the location and cause of the malfunction.

[0004] Furthermore, Patent Document 2 discloses a control system having a plurality of control objects provided on a robot and a distributed control system that performs distributed control of the plurality of control objects, and is equipped with an abnormality management unit that manages whether or not there is an abnormality in a plurality of functional units that constitute the control system, and a display control unit that displays each of the plurality of functional units on a display unit, wherein the display control unit displays on the display unit those of the plurality of functional units that are not experiencing an abnormality in a first manner, and displays on the display unit those functional units that are experiencing an abnormality in a second manner that is different from the first manner. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Publication No. 2018-22939 [Patent Document 2] Patent Publication No. 2021-120165 Summary of the Invention [Problem to be solved by the invention]

[0006] However, as mentioned above, the technology described in Patent Document 1 makes it difficult to estimate the location and cause of a malfunction. Furthermore, the technology described in Patent Document 2 requires that the causal relationship between an abnormal event and its cause be prepared in advance within the control system. In other words, if an unexpected abnormality occurs, it is not possible to identify the cause of the abnormality, and it takes time to return from the abnormal state to a normal state. Therefore, the present invention aims to estimate the cause of a malfunction in a distributed system composed of multiple distributed devices. [Means for solving the problem]

[0007] From the above, in the present invention, The system is designed for a distributed system that is composed of multiple distributed devices and has communication paths between the distributed devices. Each distributed device detects a communication error in the communication, and compares communication error information indicating the content of the detected communication error with device information indicating the characteristics of the distributed system or the distributed devices that make up the distributed system, thereby inferring the cause of the communication error.

[0008] More specifically, in a distributed system consisting of multiple distributed devices capable of communication via a communication path, each of the distributed devices has a communication port that accepts communication signals from other distributed devices, a memory unit that stores device information that indicates the characteristics of the distributed system, and an inspection unit that detects communication errors using the communication signals, indicates the communication error, and compares the device information with communication error information that includes the time the communication error occurred, the type of the communication error, and the location where the communication error was detected to estimate the cause of the communication error.

[0009] The present invention also includes a distributed device that constitutes a distributed system.Furthermore, one aspect of the present invention also includes a method for estimating the cause of an abnormality using a distributed system. [Effects of the Invention]

[0010] According to the present invention, it is possible to estimate the cause of a problem occurring in a distributed system. [Brief explanation of the drawings]

[0011] [Figure 1] FIG. 1 is a diagram showing an example of the configuration of a distributed control system according to an embodiment of the present invention. [Figure 2] FIG. 1 is a diagram illustrating details of a serial communication unit according to a first embodiment. [Figure 3] FIG. 1 shows packets used in a distributed control system 1 according to a first embodiment. [Figure 4] FIG. 1 is a diagram showing an example of the data structure of a communication signal (packet) used in the distributed control system 1 in the first embodiment. [Figure 5] FIG. 10 is a diagram illustrating how a communication error is detected in the first embodiment. [Figure 6] FIG. 1 is a diagram showing the correspondence between abnormal patterns occurring in a communication signal and the detection means thereof in the first embodiment. [Figure 7] FIG. 10 is a diagram showing the correspondence between the estimated content estimated from the communication error information and the device information to be referenced in the first embodiment. [Figure 8]1 is a flowchart showing a procedure for estimating the cause of an abnormality in the first embodiment. [Figure 9] FIG. 10 is a diagram showing an example of industrial equipment equipped with a distributed control system according to a second embodiment. [Figure 10] FIG. 10 is a diagram showing an example of a result of tallying communication error information for each communication port in the second embodiment. [Figure 11] FIG. 10 is a graph visualizing the intervals between communication errors and a graph showing the operation history of each control device in Example 2. [Figure 12] FIG. 10 is a diagram showing a communication error monitoring screen that displays an estimated cause of an abnormality in the distributed control system according to the third embodiment. [Figure 13] 1 is a diagram showing an application example of each embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0012] An embodiment of the present invention will be described below. In this embodiment, a distributed control system for controlling a control target including itself will be taken as an example of a distributed system. FIG. 1 is a diagram showing an example of the configuration of a distributed control system 1 in this embodiment. In FIG. 1, the distributed control system 1 includes a communication master station 10, a communication path 11, and a communication slave station 12. Here, the communication master station 10 and the communication slave station 12 correspond to distributed devices of the present invention. Each of the communication master station 10 and the communication slave station 12 includes a serial communication unit 101 and a communication port 102. Of these, the communication port 102 communicates with other devices (the communication master station 10 and the communication slave station 12). In other words, the communication master station 10 and the communication slave station 12 transmit and receive communication signals to and from each other. The serial communication unit 101 also includes a CRC calculation unit 20 that detects communication errors as malfunctions in the distributed control system 1 and estimates the cause of the errors.

[0013] Specific processing of each of these components will be described in each embodiment. The CRC calculation unit 20 is a type of inspection unit that detects malfunctions such as communication errors in the distributed control system 1 and estimates the causes of those malfunctions.

[0014] Furthermore, the communication master station 10 and the communication slave stations 12 have a storage unit that stores device information indicating the characteristics of the distributed control system 1. Here, the device information may be information indicating the characteristics of the industrial device in which the communication master station 10, the communication slave stations 12, or the distributed control system 1 is installed.

[0015] In this embodiment, it is also desirable to connect to a central processing unit 13 in order to execute operations and settings for managing the entire distributed control system 1 in an integrated manner.

[0016] The malfunctions in this embodiment include various malfunctions such as communication errors, failures, breakdowns, deterioration, and abnormalities. The malfunctions also include malfunctions in the distributed control system 1, the communication master station 10, the communication slave station 12, and the industrial equipment. This concludes the description of this embodiment, and below, we will explain each example showing more specific contents. [Example]

[0017] A first embodiment will be described below with reference to Fig. 1. In Fig. 1, the devices constituting the distributed control system 1 are as described above. The communication master station 10 includes a master station communication control unit 100 that manages all communications in the distributed control system 1, a serial communication unit 101 that transmits data by receiving or transmitting communication signals, and a communication port 102 that serves as the physical layer of the communication function. The master station communication control unit 100 is connected to the serial communication unit 101, and the serial communication unit 101 is connected to the communication port 102. The communication master station 10 may also be connected to a central processing unit 13 to operate and set the distributed control system 1.

[0018] The communication slave station 12 also includes a slave station communication control unit 120 that manages responses to the communication master station 10 or relays communications to other communication slave stations 12, and, like the communication master station 10, a serial communication unit 101 and a communication port 102.

[0019] Here, the communication master station 10 is connected to the communication slave station 12 via a communication port 102 and a communication path 11. Furthermore, the communication slave station 12 is connected to another communication slave station 12 or the communication master station 10 via the communication port 102 and a communication path 11. Furthermore, the communication master station 10 and the communication slave station 12 transmit any data to each other via serial communication.

[0020] The distributed control system 1 can be installed in industrial equipment that performs various operations such as production and transportation. If a failure or noise occurs in the industrial equipment, an abnormality is expected to occur in the communication signal transmitted through the communication path 11. In the present invention, the distributed control system 1 detects an abnormality occurring in the communication signal on the communication path 11 as a communication error in the communication master station 10 or the communication slave station 12. The distributed control system 1 also estimates the cause of the communication error based on information about the communication error. The operation of serial communication and communication error detection will be described below. An example of installation in industrial equipment will be described in detail in Example 2.

[0021] 2 is a diagram showing details of the serial communication unit 101 in this embodiment. The serial communication unit 101 includes a CRC calculation unit 20, which is a type of inspection unit, an encoding unit 21, a serializing unit 22, a decoding unit 23, a deserializing unit 24, and a sampling unit 25. The detailed operations of these units will be described later.

[0022] 3 is a diagram showing a packet 3 used in the distributed control system 1 in this embodiment. The packet 3 is one form of communication signal communicated in the distributed control system 1, and may include code data such as a data code or a control code. The packet 3 in this embodiment includes a CRC section 30, a data section 31, a time section 32, a command section 33, and an address section 34.

[0023] The CRC section 30 is a value used to check whether there are any errors in the binary sequence provided in the packet 3, and is generally called a cyclic redundancy check (CRC). It is calculated based on the binary sequence that constitutes the packet 3 according to an arbitrary polynomial. The data section 31 stores arbitrary data that the communication master station 10 or the communication slave station 12 wants to transmit via communication. The time section 32 stores the time when the packet 3 is issued. The command section 33 stores attributes of the value in the data section 31, such as system settings and error information. The address section 34 stores the destination to which the packet 3 should be transmitted.

[0024] Next, communication errors that occur in communications in the distributed control system 1 will be described using noise occurring in the communication signal as an example. Figure 4 shows an example of the data structure of a communication signal (packet) in this embodiment. In the serial communications targeted in this embodiment, when a binary sequence representing arbitrary data is transmitted as a communication signal, the binary sequence may be converted into another binary sequence to improve the reliability of the communication signal or add additional information. For example, a technique called 8B10B encoding converts an 8-bit binary sequence into a 10-bit binary sequence. This distributes the sequence of 1s and 0s in the communication signal, minimizing the DC component contained in the signal and improving the quality of the communication signal. In such encoding techniques, the binary sequence after conversion is predefined, and the converted binary sequence is often further classified into data codes representing normal numerical values ​​and control codes of special binary sequences that can be used to control communications.

[0025] The serial communication of the distributed control system 1 in this embodiment applies this encoding technology. Again, as shown in Figure 4, the communication signal of the distributed control system 1 is synchronized with a clock 40 and transmitted at a fixed width as a predefined binary sequence, such as serial data 41. In this case, the control code 42 is a special binary sequence used to control communication, and the data code 43 is a binary sequence representing normal numerical values, both of which are predefined. Therefore, when a packet 3 is transferred, it is composed of at least one data code.

[0026] Here, the basic operation of the serial communication unit 101 will be described again with reference to FIG. 2. First, the operation on the transmitting side of the serial communication unit 101 will be described. The master station communication control unit 100 or slave station communication control unit 120 inputs a packet 3 to be transmitted to the CRC calculation unit 20. The CRC calculation unit 20 calculates a CRC value (cyclic redundancy check value) for the packet 3 and stores it in the CRC section 30 of the packet 3. The encoding unit 21 converts the packet 3 into a predefined data code 43. In this process, the CRC calculation unit 20 divides the packet 3 into data units that the encoding unit 21 can convert, and sequentially inputs these to the encoding unit 21. The data code 43 converted by the encoding unit 21 is input to the serialization unit 22 and transmitted bit by bit. This communication signal is then transmitted to the communication master station 10 or the communication slave station 12 via the communication port 102 and the communication path 11. In this process, if there is no data code 43 to transmit, the serialization unit 22 transmits a control code 42 instead. Furthermore, the control code 42 is assumed to transfer at least one type of predefined control code in sequence. Therefore, the control code 42 or the data code 43 is continuously transmitted over all communication paths 11 provided in the distributed control system 1. Here, continuous transmission includes transmission of a communication signal at a predetermined cycle, transmission of a transmission signal sporadically, transmission of a communication signal without gaps, and transmission of a transmission signal including a dummy signal. Note that sporadic transmission also includes temporary suspension of transmission.

[0027] Next, the operation of the receiving side of the serial communication unit 101 will be described. A communication signal received at the communication port 102 via the communication path 11 is first input to the sampling unit 25. The sampling unit 25 samples the input communication signal at appropriate timing for each bit of data. The sampled communication signal is then restored as a data code 43 by the deserialization unit 24 and transferred to the decoding unit 23. The deserialization unit 24 also transfers a control code 42 to the decoding unit 23 when it receives it. At this time, the deserialization unit 24 continuously performs a disconnection test, which determines that communication has been interrupted if the value of the received communication signal remains at 1 or 0 and does not change for a certain period of time.

[0028] When the decoding unit 23 receives the data code 43, it decodes it into normal data and transfers it to the CRC calculation unit 20. Note that this transfer may be performed only when the data code 43 is received. At this time, the decoding unit 23 continuously performs a code error check to check whether the received control code 42 or data code 43 is a correct predefined binary sequence. Furthermore, when the decoding unit 23 continues to receive the control code 42, it performs a control code reception check to check whether the control code 42 is in the predefined order.

[0029] Furthermore, the CRC calculation unit 20 sequentially converts the data transferred from the decoding unit 23 into packets 3, and again calculates the CRC value of the packets 3. At this time, a cyclic redundancy check is performed to check whether the CRC value stored in the packets 3 matches the newly calculated CRC value. Furthermore, the CRC calculation unit 20 receives the first data code 43 and then performs a packet timeout check to check whether reception of the packets 3 is completed within a certain time.

[0030] As described above, in the receiving side operation of the serial communication unit 101, code error check, control code reception check, cyclic redundancy check, packet timeout check, and disconnection check are continuously performed, and if an abnormality occurs in any of the checks, the results are notified to the communication control unit as a communication error.

[0031] Here, communication operations when noise 50 occurs in the distributed control system 1 will be described with reference to FIG. 5. FIG. 5 is a diagram illustrating how a communication error is detected in this embodiment. FIG. 5 illustrates a case where an abnormality due to noise 50 occurs in the communication path 11 connecting two communication slave stations 12. In this case, the communication error is detected in the serial communication unit 101 connected to the two communication ports 51. When the serial communication unit 101 of the communication slave station 12 detects a communication error, it notifies the slave station communication control unit 120. The slave station communication control unit 120 stores information about the time when the communication error notification was received, the type of communication error, and the communication port 51 that detected the communication error in packet 3. At this time, packet 3 is transmitted to the communication master station 10 via serial communication from the communication port 102 as communication error information 52.

[0032] The same operation occurs when noise occurs in the communication path 11 between the communication master station 10 and the communication slave station 12, but information about the communication error detected by the communication master station 10 may be stored in a log in the communication master station 10 or may be directly transferred to the central processing unit 13. In any case, the time of occurrence, the type of error, and the communication port 102 where the error was detected are recorded for each piece of detected communication error information in all communication master stations 10 and communication slave stations 12.

[0033] So far, we have explained the basic functions of the distributed control system 1, including the operation of serial communication. Next, we will explain a method for estimating the cause of an abnormality in the distributed control system 1. Figure 6 is a diagram showing the correspondence between abnormality patterns that occur in communication signals transmitted over the communication path 11 and their detection means. In Figure 6, we will explain a case where the communication signal has become garbled as an abnormality. When noise is mixed into the communication signal, an error occurs in the binary sequence of the control code 42 or data code 43 being transmitted, which can result in garbled data. There are also four possible patterns in which garbled data can occur.

[0034] If the control code 42 or the data code 43 becomes an undefined binary sequence, this can be detected by the code error check as described above.

[0035] If a different data code 43 is unintentionally received while receiving the data code 43, this can be detected by a cyclic redundancy check, since the data code 43 is transmitted substantially only when the packet 3 is transferred.

[0036] Here, the data code 43 is transmitted only when transferring packet 3, and furthermore, the data code 43 is supposed to be received continuously, so reception of the data code 43 that makes up packet 3 is completed within a certain time. Therefore, if the control code 42 unintentionally becomes a different data code 43, this can be detected by packet timeout inspection. If the control code 42 unintentionally becomes a different control code 42, this can be detected by the control code reception check, as described above.

[0037] Next, a case where the communication signal is interrupted due to a failure or the like within the distributed control system 1 will be described. When a communication signal is interrupted, the voltage of the communication signal often stops changing for a certain period of time. This means that the 1s and 0s of the communication signal received by the serial communication unit 101 no longer change, and this can be detected by a disconnection test. This makes it possible to detect each abnormal pattern of the communication signal that may occur on the communication path 11. Furthermore, the distributed control system 1 estimates the location where the cause of the communication error (cause of abnormality) is likely to occur based on the communication error information and various information about the industrial equipment in which the distributed control system 1 is installed.

[0038] FIG. 7 shows the correspondence between the estimated content 70 estimated from a communication error in this embodiment and the device information 71 to be referenced. The communication error information includes the type of communication error, the time the communication error occurred, and information about the communication port 102 where the communication error was detected. Furthermore, by aggregating the communication error information issued by the communication master station 10 or the communication slave station 12, the number of occurrences of various communication errors can be obtained. As described above, the device information 71 is information indicating the characteristics of the distributed control system 1, which is an example of a distributed system. Examples of this device information 71 include operational information about the distributed control system 1, such as the control procedures of industrial equipment and the locations and functions of devices within the industrial equipment. It is desirable for the device information 71 to be stored in a memory unit (not shown) of the serial communication unit of each communication slave station or the communication master station 10.

[0039] As a result, there are four types of judgment factors for communication errors: communication port information 700, occurrence count information 701 (number of communications), occurrence time information 702, and error type information 703. Furthermore, by combining these judgment factors, an inferred content 70 inferred from the communication error is determined.

[0040] First, the CRC calculation unit 20 can estimate an abnormal communication path 704 by combining communication port information 700 and occurrence count information 701. This is because, when an abnormality occurs in a communication path 11 among the communication ports 102 provided in the distributed control system 1, as shown in Fig. 5, a communication error is detected in at least one of the communication ports 102 connected to the communication path 11 in which the abnormality occurred. Therefore, in the distributed control system 1, the communication paths 11 connected to the two pairs of communication ports 102 that detected the most communication errors within a certain period of time can be estimated as the abnormal communication path 704.

[0041] In this case, the cause of the communication error is likely to be a device installed near the abnormal communication path 704. Therefore, by referring to the device layout information 710 of the industrial equipment included in the equipment information 71 using the CRC calculation unit 20, it is possible to list the devices installed near the communication path 704 where the abnormality has occurred.

[0042] Next, the CRC calculation unit 20 can obtain information 705 about the intervals at which communication errors occur by using information 702 about multiple occurrence times. This information is particularly useful for abnormalities that occur periodically. In this case, the cause of the communication error is likely to be a device having a drive frequency that is similar to the information 705 about the intervals. Therefore, by referring to information 711 about the drive frequencies of the industrial equipment devices included in the equipment information 71, the CRC calculation unit 20 can list devices that are likely to be the cause of the abnormality.

[0043] Furthermore, in the information 702 on the time of the communication error, it is highly likely that a device in the industrial equipment that was operating at the same time was the cause of the abnormality. Therefore, by referring to the information 712 on the operation plan and operation history of the equipment, it is possible to list the devices that were operating when the communication error occurred.

[0044] Here, in the distributed control system 1, it is difficult to predict how noise voltage or noise current will affect the communication signal being transmitted through the communication path 11. In the distributed control system 1, the CRC calculation unit 20 can detect data corruption that occurs when affected by noise over a certain period (relatively short time) by the code error check, cyclic redundancy check, packet timeout check, and control code reception check described above.

[0045] On the other hand, in the disconnection test, a condition for detecting a disconnection is that there is no change in the communication signal for a certain period of time. In this case, it can be determined that the communication signal has been affected by noise for a relatively long period of time, in addition to cases where the communication signal is constantly interrupted. Therefore, by combining the information 703 on the type of communication error and the information 701 on the number of occurrences, the CRC calculation unit 20 determines that the failure in the distributed control system 1 is serious if the following condition is met. Here, the condition refers to the relatively high number of occurrences of communication errors, and also to cases where a disconnection is detected among the communication errors.

[0046] Here, the procedure for estimating the cause of an abnormality based on the communication error information and the device information 71 will be described with reference to Fig. 8. Fig. 8 is a flowchart showing the procedure for estimating the cause of an abnormality in this embodiment. For the sake of convenience, it is assumed from here on that a control device required for the operation of the industrial device is connected to the communication slave station 12.

[0047] When a malfunction occurs in device control, that is, in the distributed control system 1, first, in step S80, the CRC calculation unit 20 checks whether or not a communication error has occurred. As a result, if a communication error has not occurred (NO), the process proceeds to step S81. On the other hand, if a communication error has occurred (YES), the process proceeds to step S84.

[0048] Also, in step S81, the CRC calculation unit 20 checks whether the control values ​​have been updated. As a result, if there is no update for each control value (for example, the control value), communication has not been established in the distributed control system 1, and input / output via communication to / from the control device is not possible. In this case, it is determined that there has been no update (YES), and the process proceeds to step S83. Then, in step S83, the CRC calculation unit 20 determines that the system has not been established due to a failure of the communication master station 10 or a fault in the device power supply.

[0049] On the other hand, if some of the control values ​​have been updated normally in step S81 (NO), the process proceeds to step S82. At this time, possible patterns for the control values ​​corresponding to the occurrence of an abnormality include no update, deviation of the control values, or an abnormal update frequency of the control values. For this reason, in step S82, the CRC calculation unit 20 determines that the most likely cause is a failure in the communication slave station 12 corresponding to the input / output of the control values ​​or in the control device connected to the communication slave station 12.

[0050] In step S84, the CRC calculation unit 20 counts the number of occurrences of each type of communication error. Then, in step S89, the CRC calculation unit 20 determines the severity of the current internal equipment failure based on the counted number of occurrences. Note that it is desirable that a specific severity be defined for each piece of industrial equipment into which the distributed control system 1 is installed.

[0051] Furthermore, in step S85, the CRC calculation unit 20 compiles the number of times communication errors have occurred and information on the communication port where the communication error was detected, and uses this information to estimate the communication path 11 where an abnormality has occurred. Furthermore, in step S810, the CRC calculation unit 20 identifies control devices in the vicinity of the communication path 11 estimated in step S85 as candidates for the control device where an abnormality has occurred. Here, "in the vicinity" includes a control device connected to the estimated communication path 11 and a control device located in a predetermined position, such as the control device located closest.

[0052] Next, in step S86, the CRC calculation unit 20 analyzes the intervals at which communication errors occur, i.e., identifies the utterance intervals. Furthermore, in step S811, the CRC calculation unit 20 identifies control devices with drive frequencies that approximate the analyzed intervals at which communication errors occur as candidates for the control device in which an abnormality has occurred. Here, "approximate" indicates a predetermined relationship, such as a difference of less than a threshold.

[0053] Next, in step S87, the CRC calculation unit 20 identifies the time history of when the communication error occurred. Then, in S812, the CRC calculation unit 20 compares the time history with the operation history or operation plan of the distributed control system 1 or the industrial device in which it is installed. Using this result, the CRC calculation unit 20 identifies the control device that was operating at the time the communication error occurred as a candidate for the control device in which the abnormality occurred.

[0054] Then, in step S88, the CRC calculation unit 20 estimates the control device that is thought to be the cause of the abnormality and the severity of the failure that will occur. Then, by step S812, the CRC calculation unit 20 extracts the control device that is the cause of the abnormality from the candidates identified in steps S810, S811, and S812. To do this, for example, the CRC calculation unit 20 extracts the control device that is the cause of the abnormality in descending order of the number of conditions used for identification in each step. Here, the extracted control device may be a control device that is a predetermined number higher than the other, or may be a device with a predetermined number of conditions or more. This concludes the description of the first embodiment. [Example]

[0055] Next, a second embodiment will be described. In this embodiment, the distributed control system 1 is mounted on an industrial device. FIG. 9 is a diagram showing a configuration example when the distributed control system 1 of this embodiment is mounted on an industrial device. In FIG. 9, the industrial device 90 includes a communication master station 10, a communication path 11, a communication slave station 12, an input / output board 93, and a control device 94. The input / output board 93 inputs and outputs control commands or feedback values ​​to the control device 94 via communication, and the control device 94 is a control target such as an actuator or a sensor that constitutes the industrial device.

[0056] The communication slave stations 91 and 92 have the same functions as the communication slave station 12, and the control device 95 has the same functions as the control device 94. Furthermore, the communication path 96 has the same functions as the communication path 11.

[0057] In this embodiment, an example of estimation will be described in which the control device 95 is the cause of an abnormality in the distributed control system 1. It is assumed here that a communication error occurs and the estimation procedure shown in FIG.

[0058] In this embodiment, as explained in the explanation of FIG. 8 in the first embodiment, the type of communication error is detected as the communication error. Here, FIG. 10 is a diagram showing an example of the aggregation result of communication error information for each communication port in this embodiment. Here, the aggregation result of the communication error information is used as the aggregation result of the number of times communication errors have occurred. The aggregation result 1000 in FIG. 10 shows the communication ports 102 provided for each communication master station 10 or communication slave station 12, and further shows the number of times communication errors have occurred detected for each communication port 102. This aggregation result 1000 is aggregated by the CRC calculation unit 20.

[0059] Here, by using the count result 1000, it can be seen that a communication error has occurred. That is, the count result 1000 uses the communication error count 1001 corresponding to the communication port 102 of the communication master station 10, the communication error count 1002 corresponding to the communication port 102 of the communication slave station 91, and the communication error count 1003 corresponding to port 1 of the communication slave station 92. In this case, the communication error counts 1002 and 1003 stand out, indicating a high number of communication errors. Furthermore, since no communication error involving disconnection has occurred, the CRC calculation unit 20 can infer that an abnormality due to noise has occurred in the communication path 96 connecting the communication slave station 91 and the communication slave station 92.

[0060] 11 is a diagram showing graph 1100 visualizing the intervals between communication errors and graph 1102 showing the operation history of each control device. Here, the vertical axis of graph 1100 indicates the number of communication errors, and the horizontal axis of graphs 1100 and 1102 indicates the passage of time. In addition, the example of graph 1100 shows that noise is mixed into communication path 96 with a frequency of communication error interval 1101. Also shown is control device 94 or control device 95 that was operating at each time.

[0061] Through the above steps, the CRC calculation unit 20 can finally estimate the cause of the abnormality. For example, it is estimated that the control device 95 (equipment) shown below is most likely to be the cause of the abnormality within the device. Devices located near the communication path 96 determined by the aggregation result 1000 Devices with a drive frequency close to the communication error occurrence interval 1101 determined by graph 1100 -Devices whose operation time coincides with the time when a communication error occurred In the second embodiment described above, even if an abnormality occurs in an industrial device to which the control system is introduced due to an unknown fault or noise inside the device, it is possible to estimate the cause of the abnormality. This concludes the description of the second embodiment. [Example]

[0062] Next, in a third embodiment, the output of the estimated cause of occurrence will be described. Fig. 12 is a diagram showing a communication error monitoring screen 1200 that displays the estimated cause of occurrence of an abnormality in the distributed control system 1 in this embodiment. This communication error monitoring screen 1200 is preferably displayed on a display device connected to the central processing unit 13 in Fig. 1. Alternatively, it may be displayed on a terminal device 902, which will be described later.

[0063] Also, in FIG. 12, the communication error monitoring screen 1200 includes a network display screen 1201 that displays the configuration of the distributed control system 1 introduced into the industrial equipment, and an error information screen 1202 that displays communication error information.

[0064] The error information screen 1202 includes an error history screen 1203, an error message screen 1204, and an error cause list screen 1205. Here, the error history screen 1203 displays the type of communication error, the time of occurrence, etc. The error message screen 1204 displays an error message when a communication error occurs in the distributed control system 1. The error cause list screen 1205 displays devices in the distributed control system 1 as candidate abnormality causes. Here, as with the communication error monitoring screen 1200, visually displaying the status of a communication error that has occurred in the distributed control system 1 and the location of the estimated abnormality cause, as has been described up to the second embodiment, can contribute to the early recovery of industrial equipment to normal. This concludes the description of the third embodiment.

[0065] Next, application examples of each embodiment will be described. FIG. 13 is a diagram showing an application example of each embodiment. In this application example, a central processing unit 13 can manage multiple distributed control systems 1. For this purpose, a server device 130 having a central processing unit 13 is provided in FIG. 13. The server device 130 is connected to a network 901 and a terminal device 902. The terminal device 902 inputs various instructions to the server device 130 and outputs the processing results of the server device 130. This output includes a communication error monitoring screen 1200. The server device 130 can be realized by a so-called computer, and can be called a cloud system.

[0066] Furthermore, the server device 130 is connected to a plurality of distributed control systems 1 via a network 901 such as the Internet. As a result, the server device 130 can receive the cause of the abnormality from each distributed control system 1. Note that at least a part of the estimation of the cause of the abnormality in the first embodiment may be executed by the server device 130. Furthermore, in the configuration of the first embodiment, at least a part of the estimation of the cause of the abnormality may be executed by the central processing unit 13.

[0067] This concludes the description of the embodiments and examples of the present invention, but the present invention is not limited to these. For example, the distributed system also includes systems other than the distributed control system 1, such as a communication system. The present invention also includes the following aspects. Note that the distributed control system described below can be interpreted as a distributed system including a communication system.

[0068] (1) At least one communication master station and at least one communication slave station; a distributed control system in which the communication master station and the communication slave station, or the communication slave station and another communication slave station, are connected by a communication path, The communication master station or the communication slave station continuously transmits either the data code or the control code, The communication master station or the communication slave station performs error detection every time it receives the data code or the control code, and issues a communication error when an error occurs, the distributed control system defines a characteristic of the signal abnormality occurring on the communication path based on the communication error; Furthermore, the time when the communication error occurred, the type of the communication error, and the location where the communication error was detected are recorded; The distributed control system estimates the electrical cause of a communication error by comparing multiple pieces of communication error information with operating information such as the control procedures of the industrial equipment in which the distributed control system is installed and the locations of devices within the equipment.

[0069] (2) In the distributed control system of (1), The data code and the control code are both binary sequences predefined in the distributed control system; In a distributed control system, the communication master station or the communication slave station detects a communication error due to a code error if the binary sequence is undefined when receiving the data code or the control code.

[0070] (3) In the dispersion control system of (1), the distributed control system comprises a packet combining at least one of the data codes; When receiving the packet, the communication master station and the communication slave station perform a redundancy cyclic check; If the redundancy cyclic check is invalid, a communication error due to a redundancy cyclic check error is detected in the distributed control system.

[0071] (4) In the distributed control system of (1), the distributed control system comprises a packet combining at least one of the data codes; The communication master station and the communication slave station receive the data codes, and if they do not receive a certain number of the data codes after a certain time, A distributed control system that detects a communication error of timeout in receiving said packets.

[0072] (5) In the distributed control system of (1), While the communication master station and the communication slave station continue to receive the control code, If the control code is not received according to the predefined order of the control codes, A distributed control system that detects a communication error due to an error in receiving the control code.

[0073] (6) In the distributed control system of (1), In a distributed control system, the communication master station or the communication slave station detects a communication error such as a disconnection when the value of the communication signal does not change for a certain period of time.

[0074] (7) In any of the distributed control systems (1) to (6), A distributed control system that determines, based on the communication port from which the communication error was issued and the number of times the communication error occurred, that the communication path connected to the communication port with the highest number of detected communication errors is the communication path located near the cause of the abnormality.

[0075] (8) In any of the distributed control systems (1) to (6), A distributed control system that determines the interval between occurrences of the communication errors based on the time from when at least one of the communication errors occurs until the next occurrence of at least one of the communication errors.

[0076] (9) In the distributed control system of (7) or (8), The industrial device is and a control device including at least one actuator or at least one sensor, the control device being connected to the communication slave station, The distributed control system includes: A cause of the communication error is estimated, If there is no communication error, checking whether at least one control value collected by the distributed control system during control of the industrial device has been updated; If all the control values ​​are not updated, it is determined that the communication master station has failed. A distributed control system that determines that a failure has occurred in the control device or the communication slave station in question when at least one of the control values ​​is not updated.

[0077] (10) In the distributed control system of (9), A distributed control system that determines the severity of a failure that has occurred in the industrial equipment based on the distribution of types of communication errors and the number of occurrences of at least one of the communication errors.

[0078] In the distributed control system of (11)(9), When the communication error occurs, the distributed control system is compared with the device information of the industrial device in which the distributed control system is installed, In the communication path where the communication error occurred, the control devices arranged in the vicinity of the communication path are sequentially selected as candidates for the cause of the communication error; A distributed control system that lists the control devices in the order of the candidates as causes of the communication error.

[0079] (12) In the distributed control system of (9), When the communication error occurs, the distributed control system is compared with the device information of the industrial device in which the distributed control system is installed, comparing the interval between occurrences of the communication errors with the drive frequency of the control device; Control devices whose occurrence interval and drive frequency are similar to each other are selected in order as candidates for the cause of the communication error; A distributed control system that lists the control devices in the order of the candidates as causes of the communication error.

[0080] (13) In the dispersion control system of (9), When the communication error occurs, the distributed control system is compared with the device information of the industrial device in which the distributed control system is installed, Based on the time when the communication error occurred and the control plan or operation history of the industrial device, the control devices that were operating during the time when the communication error occurred are sequentially selected as candidates for the cause of the communication error; A distributed control system that lists the control devices in the order of the candidates as causes of the communication error.

[0081] (14) In any one of the distributed control systems (10) to (13), A distributed control system that lists the control devices as causes of the communication error in order of the number of conditions that are candidates for the cause of the communication error.

[0082] (15) In the distributed control system of (1), The distributed control system uses a packet combining at least one of the data codes, the communication port includes a serial communication unit; the serial communication unit continues to transmit the control code when there is no packet transfer; A distributed control system in which, as soon as preparation for transmission of the packet is complete and transmission of the control code being transmitted is completed, the data codes contained in the packet are transmitted sequentially, and the communication master station or the slave station resumes transmission of the control code as soon as transmission of the packet is completed.

[0083] (16) In the distributed control system of (1), the communication master station is connected to a central processing unit; the communication master station or the communication slave station includes a communication control unit, The communication control unit is connected to the serial communication unit, The communication error is detected by the serial communication unit, the communication slave station stores the time when the communication error was detected and information about the communication error in the packet; The communication signal is transferred to the communication master station via the communication path, the communication master station notifies the central processing unit of the time when the communication error was detected and the communication error information, The communication master station notifies the central processing unit of the information on the communication error transferred from the communication slave station and the time of occurrence of the communication error.

[0084] (17) In the distributed control system of (14), A distributed control system comprising: an output device that visually displays information comprising the configuration of the distributed control system, information about the communication error, and candidate causes of the communication error.

[0085] (18) A method for estimating the cause of an abnormality using any one of the distributed control systems (1) to (17). [Explanation of symbols]

[0086] 1. Distributed Control System 10 Communication master station 100 Master station communication control unit 101 Serial communication unit 102 communication port 11 Communication Channels 12 Communication substation 120 Slave station communication control unit 20 CRC calculation section 21 Encoding section 22 Serialization section 23 Decoding section 24 Deserialization part 25 Sampling section 3 packets 30 CRC Department 31 Data Section 32 Time section 33 Command Section 34 Address section 40 Clock 41 Serial Data 42 Control Codes 43 Data Code 50 Noise 51 communication port 52 Communication error information 90 Industrial Equipment 91 Communication Substation 92 Communication Substation 93 Input / Output Board 94 Control Devices 95 Control Devices 96 Communication Channel 1000 Counting results 1100 graphs 1101 Communication Error Occurrence Interval 1102 graph 1200 Communication error monitoring screen 1201 Network Display Screen 1202 Error Information Screen 1203 Error history screen 1204 Error message screen 1205 Error Cause List Screen

Claims

1. In a distributed system that is composed of a plurality of distributed devices that can communicate via a communication path, Each of the dispersion devices comprises: a communication port for receiving communication signals from other distributed devices; a storage unit that stores device information indicating characteristics of the distributed system; A distributed system having an inspection unit that detects a communication error from the communication signal, indicates the communication error, and compares communication error information including the time the communication error occurred, the type of the communication error, and the location where the communication error was detected with the device information to estimate the cause of the communication error.

2. 10. The distributed system of claim 1, The communication port of the other distribution device continuously outputs the communication signal to the distribution device; A distribution system in which the communication port continuously outputs the communication signal to the other distribution device.

3. 3. The distributed system of claim 2, A distributed system in which the inspection unit of the distributed device performs error detection when it receives the accepted communication signal and detects the communication error based on the result of the error detection.

4. 4. The distributed system of claim 3, In the distributed system, the inspection unit of the distributed device detects a communication error due to a code error if the received communication signal is an undefined binary sequence.

5. 4. The distributed system of claim 3, the communication signal is a packet containing one or more data codes; The inspection unit of the distributed device performs a redundancy cyclic check on the packet, and if the redundancy cyclic check is invalid, detects a communication error due to a redundancy cyclic check error.

6. 4. The distributed system of claim 3, the communication signal is a data code; In the distributed system, the inspection unit of the distributed device detects a communication error due to a timeout in receiving a packet combining the data codes when a certain number of the data codes cannot be received within a certain time.

7. 4. The distributed system of claim 3, the communication signal is a control code, A distributed system that detects a communication error due to incorrect reception of the control code if the inspection unit of the distributed device does not receive the control code in a predefined order while the communication port is continuously outputting the communication signal.

8. 4. The distributed system of claim 3, A distributed system in which the inspection unit detects a communication error such as a disconnection of the communication when the value of the communication signal does not change for a certain period of time.

9. 4. The distributed system of claim 3, A distributed system in which an inspection unit of the distributed device identifies the communication path connected to the communication port with the highest number of detected communication errors as the communication path closest to the occurrence of the communication error.

10. 10. A distributed system according to claim 1, the distributed system is a distributed control system further having a control device, and the communication signal is a control code including a control value for controlling the control device; the plurality of distributed devices are a communication master station and a plurality of communication slave stations in the communication, A distributed system in which the inspection unit checks whether the multiple control values ​​have been updated, and if the multiple control values ​​have not been updated, determines that the communication parent station has failed, and if some of the multiple control values ​​have not been updated, determines that the control device or the communication child station has failed.

11. The distributed system of claim 10, The distributed control system is a distributed system mounted on an industrial device that includes actuators and sensors.

12. 12. The distributed system of claim 11, The inspection unit is a distributed system that determines the severity of a failure that has occurred in the industrial equipment based on the distribution of types of communication errors and the number of times they have occurred.

13. In a distributed device that is capable of communicating with other distributed devices via a communication path and that constitutes a distributed system, a communication port that receives a communication signal from the other distributed device; a storage unit that stores device information indicating characteristics of the distributed system; A distributed device having an inspection unit that detects a communication error using the communication signal, indicates the communication error, and compares communication error information including the time the communication error occurred, the type of the communication error, and the location where the communication error was detected with the device information to estimate the cause of the communication error.

14. 14. The dispersion device according to claim 13, The communication port of the other distribution device continuously outputs the communication signal to the distribution device; A distribution device in which the communication port continuously outputs the communication signal to the other distribution device.

15. 15. The dispersion device according to claim 14, The inspection unit is a distributed device that, upon receiving the received communication signal, performs error detection and detects the communication error based on the result of the error detection.

16. 16. The dispersion device according to claim 15, The inspection unit is a distributed device that detects a communication error due to a code error if the received communication signal is an undefined binary sequence.

17. 16. The dispersion device according to claim 15, the communication signal is a packet containing one or more data codes; The inspection unit performs a redundancy cyclic check on the packet, and if the redundancy cyclic check is invalid, detects a communication error due to a redundancy cyclic check error.

18. 16. The dispersion device according to claim 15, the communication signal is a data code; The inspection unit is a distributed device that detects a communication error due to a timeout in receiving a packet combining the data codes when a certain number of the data codes cannot be received within a certain time.

19. 16. The dispersion device according to claim 15, the communication signal is a control code, A distributed device that detects a communication error due to incorrect reception of the control code if the inspection unit does not receive the control code in a predefined order while the communication port is continuously outputting the communication signal.

20. 16. The dispersion device according to claim 15, A distributed device in which the inspection unit detects a communication error such as a disconnection of the communication when the value of the communication signal does not change for a certain period of time.

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