JP2014052671A - Programmable logic controller - Google Patents

Abstract

PROBLEM TO BE SOLVED: To easily recognize communication content between PLCs without interrupting a protocol analyzer in a network for making a connection between the PLCs.SOLUTION: A program creation support device 100 is connected to a PLC 1a instead of connecting a protocol analyzer to a network for connecting the PLC 1a and a PLC 1b, and the program creation support device 100 is operated as the protocol analyzer or a debug device. The program creation support device 100 analyzes, by pattern matching, a frame structure of communication data transmitted and received between the PLC 1a and the PLC 1b, or between the PLC 1a and a device to be controlled, and displays the frame structure. As a result, communication content between the PLC and the PLC and between the PLC and the device to be controlled can easily be recognized without interrupting the protocol analyzer in the network for making a connection between the PLCs.

Description

  The present invention relates to a technique for displaying a frame structure of communication data transmitted or received by a programmable logic controller.

Programmable logic controller (hereinafter referred to as PLC) is FA (Factory
Automation) is a sequence controller widely used in control systems, and operates according to a dedicated program called a ladder program. The operator (operator) connects input devices such as limit switches, sensors, and thermometers, and output devices such as electromagnetic switches, solenoids, motors, actuators, cylinders, relays, and positioning systems to the PLC. Control the controlled device.

  An operator creates a ladder program on a program creation support device such as a personal computer (hereinafter referred to as a PC), connects the PC and the PLC, and stores the ladder program in the storage unit of the PLC. Various data such as device information is also stored in the storage unit of the PLC. The device information is information indicating an input state from the input device, an output state to the output device, and states of an internal relay (auxiliary relay), a timer, a counter, a data memory, and the like set on the ladder program. A device is a name indicating an area on a memory provided for storing device information. By connecting the program creation support apparatus to the PLC, the device information (device value) held by the PLC can be displayed on the program creation support apparatus for visual recognition.

  Incidentally, the PLC may communicate with one or more other PLCs or controlled devices via a communication line such as a Modbus network. Patent Document 1 describes an invention in which a plurality of PLCs are connected via a network, one of which is connected to a programming device, and system debugging is performed by monitoring the operation state of the PLC. Has been.

JP-A-5-241619

  In the invention of Patent Document 1, the operation state of each PLC can be confirmed from a programming device, but it is not known what information is transmitted / received between a plurality of PLCs via a network. For example, in a case where the PLC malfunctions because the data transmitted on the network is incorrect, it is difficult to identify the cause by the conventional method.

  Therefore, it is conceivable to insert a protocol analyzer into a communication line connecting a certain PLC and another PLC to capture raw information being transmitted and received. However, in order to insert the protocol analyzer into the communication line, it is necessary to wire the protocol as a repeater, and the network configuration must be changed. In addition, the protocol analyzer itself inserted into the communication line becomes a new noise source, and it may be difficult to specify the original noise source. Further, in the protocol such as Modbus that is most popular for PLC, even if the raw signal being communicated is displayed as it is, it is not easy for the operator to understand it. Furthermore, since Modbus is a classic protocol developed in the 1970s, there is no bit indicating the start position of a frame, and it is extremely difficult for an operator to understand from where to where the frame is.

  Therefore, an object of the present invention is to make it possible to easily grasp communication contents between PLCs without interrupting a protocol analyzer in a network connecting PLCs.

  The present invention is a program creation support apparatus, which is a program creation support apparatus connected to a first programmable logic controller among the plurality of programmable logic controllers in a network in which a plurality of programmable logic controllers are connected, Request signal for requesting the first programmable logic controller to transfer the communication data transmitted or received by the first programmable logic controller to or from the second programmable logic controller or controlled device to the program creation support device A communication data requesting unit for transmitting the communication data, a communication data receiving unit for receiving the communication data transmitted by the first programmable logic controller that has received the request signal, and storing the communication data A communication data storage unit, an analysis unit for analyzing the frame structure of the communication data stored in the communication data storage unit by pattern matching, and displaying the communication data according to the frame structure obtained by the analysis unit And a display unit.

  The present invention also provides a first communication unit that communicates with a program creation support device that creates a ladder program, a second communication unit that communicates with another programmable logic controller or a controlled device, and the other programmable logic controller. Alternatively, a buffer unit that temporarily stores communication data transmitted to or received from the controlled device, and the communication that is stored in the buffer unit from the program creation support device via the first communication unit A programmable logic controller comprising: a control unit that controls the first communication unit to copy and transmit the communication data to the program creation support device when receiving a request signal for requesting data To do.

  According to the present invention, instead of connecting a protocol analyzer to a network connecting PLCs, a program creation support device is connected to one programmable logic controller and operated as a protocol analyzer or a debugging device. The program creation support device analyzes and displays the frame structure of communication data transmitted / received between another programmable logic controller or controlled device and the monitored programmable logic controller by pattern matching. Therefore, the communication contents between the PLCs can be easily grasped without interrupting the protocol analyzer in the network connecting the PLCs.

It is a figure which shows the external appearance of a programmable logic controller (PLC) and a program creation assistance apparatus. It is a functional block diagram about PLC and a program creation assistance apparatus. It is the figure which showed an example of the frame structure used by the Modbus protocol. It is a figure explaining the method to detect the head of the frame structure in the communication protocol in which a clear head identifier is prescribed | regulated. It is a flowchart which shows each step about search mode which an analysis part performs. It is a flowchart which shows each step about the command mode which an analysis part performs. It is a figure which shows an example of the user interface which displays an analysis result. It is a figure which shows an example of the user interface which displays an analysis result. It is a figure which shows an example of the user interface which displays an analysis result. It is a figure which shows an example of the user interface which displays an analysis result.

  An embodiment of the present invention is shown below. The individual embodiments described below will help to understand various concepts, such as the superordinate concept, intermediate concept and subordinate concept of the present invention. Further, the technical scope of the present invention is determined by the scope of the claims, and is not limited by the following individual embodiments.

  FIG. 1 shows a first programmable logic controller (PLC1a), a second programmable logic controller (PLC1b), and a program creation support apparatus 100. The PLC 1 a and the PLC 1 b are connected via a communication line 2 such as a serial communication cable to construct a PLC network 3. Here, as an example, it is assumed that the PLC 1a and the PLC 1b are connected by a serial communication cable, but via a communication line such as a LAN cable or a USB cable, a wireless interface such as a wireless LAN, Bluetooth (registered trademark), or IrDA. These may be connected. The communication cable may be a metal wire or an optical fiber.

  The program creation support device 100 is an information processing device that connects to the PLC 1a to transfer a ladder program, monitors the operation of the PLC 1a, and executes debugging. The program creation support apparatus 100 may be a personal computer (PC) in which a program having a program creation support function is installed. The program creation support device 100 and the PLC 1a may also be connected by either wired or wireless as described above. However, since the program creation support apparatus 100 does not participate in the PLC network 3, it does not directly give noise to the PLC network 3. One PLC 1b is connected to the PLC 1a, but two or more other PLCs may be connected, or a controlled device may be connected. Examples of controlled devices include input devices such as limit switches and sensors, and output devices such as electromagnetic switches, solenoids, motors, actuators, cylinders, relays, and positioning systems.

  FIG. 2 is a functional block diagram of the PLC 1a and the program creation support apparatus 100. The program creation support apparatus 100 is provided with a display unit 10 such as a liquid crystal display device or a self-luminous display device, and an operation unit 11 for an operator to input various instructions. The operation unit 11 includes a keyboard and a pointing device for receiving operator operations.

  The control unit 5 is a controller realized by a CPU, an ASIC, a logic circuit, and a program. The control unit 5 has various control functions. The instruction creating unit 51 is a unit that creates an instruction for the PLC 1a. For example, the command creation unit 51 functions as a communication data request unit that requests the PLC 1a to transfer communication data transmitted or received by the PLC 1a to or from the PLC 1b to the program creation support apparatus 100. In this way, the instruction creation unit 51 can create a communication data acquisition request command (request) and transmit it to the PLC 1a. The PC communication unit 7 is connected to the PC communication unit 21 of the PLC 1a, and is used for transmitting and receiving data and commands between the program creation support apparatus 100 and the PLC 1a. For example, the PC communication unit 7 transmits an acquisition request signal for acquiring the transmission byte sequence 24 and the reception byte sequence 25, which are communication data transmitted and received between the PLC 1a and the PLC 1a1b, to the PLC 1a. Further, the PC communication unit 7 functions as a communication data receiving unit that receives communication data transmitted by the PLC 1 a that has received the acquisition request signal and stores the received communication data in the storage unit 6. The storage unit 6 is configured by a storage device such as a RAM, an SSD, and an HDD, for example.

  For example, the analysis unit 52 analyzes the frame structure of communication data stored in the storage unit 6 by pattern matching. The storage unit 6 includes matching data 61 to be used for pattern matching, commentary information 62 indicating what meaning the byte sequence included in the communication data has, and a history of analysis results. Some log data 63 and the like may be stored. The Modbus protocol established in the 1970s is a classic protocol, and therefore does not have a special head identifier indicating the head of the frame. Therefore, it is not possible to easily identify from where to where the frame is based only on the raw communication data. However, the information that can enter the head of the frame is information within a certain limited range. That is, only some of the logically possible values are mounted near the beginning of the frame. Therefore, a value that can be actually mounted as the head of the frame is stored in the storage unit 6 as matching data 61, and when the analysis unit 52 finds a portion that matches the matching data 61 in the communication data, It may be determined that there is a possibility. Thus, a part of the storage unit 6 functions as a matching data storage unit that stores the matching data 61 that may be arranged at the head of the frame structure. The analysis unit 52 functions as a head specifying unit that compares the matching data 61 stored in the storage unit 6 with the communication data and specifies the head of the frame structure. The commentary information 62 is a label (meaning information) such as a name or abbreviation for an information element constituting the frame structure, or a brief explanation sentence. The explanation information 62 is used by the display information creation unit 53 to make it easy for the operator to understand the analysis result. A part of the storage unit 6 functions as a comment information storage unit that stores comment information 62 indicating the meaning of each of a plurality of information elements constituting the frame structure.

  The display information creation unit 53 creates display information for displaying communication data on the display unit 10 according to the frame structure obtained by the analysis unit 52. For example, the display information creation unit 53 includes, in accordance with the frame structure acquired by the analysis unit 52, information elements included in the communication data and commentary information 62 indicating the meaning of the information elements read from the storage unit 6. Display information for displaying in association with each other may be created. The display unit 10 displays the analysis result according to the display information created by the display information creation unit 53. If the analysis unit 52 fails in pattern matching, the display unit 10 may display the communication data as raw data. When the analysis unit 52 detects an error of an information element included in the communication data, the display unit 10 may highlight the information element in which the error is detected. There are cases where the pattern matching fails, such as a case where the head of the frame structure is not found, a case where a portion that seems to be the head is found, but a subsequent byte sequence is different from that of the known frame structure. The number of information elements constituting the frame structure, the size of each information element, and the value (hexadecimal) that can be taken as the contents of each information element are known. Therefore, if there is no communication error and there is no malfunction in the PLC or the controlled device, the contents of the information elements constituting the frame structure are within a predetermined range. However, when a communication error or malfunction occurs, an error occurs at the bit level, so that the frame structure itself may not be a specified structure, or the contents of the information element may be distorted to non-standard information. Therefore, if information on a plurality of types of frame structures defined by the communication protocol is stored in the storage unit 6 as matching data 61, not only the frame structure can be specified but also which information element has an error can be analyzed. Part 52 becomes discoverable.

  The PLC 1a includes a PC communication unit 21 that functions as a first communication unit connected to the program creation support apparatus 100, and a PLC communication unit 22 that functions as a second communication unit connected to the PLC 1b and the controlled device. . The control unit 20 executes a ladder program to control the controlled device, and controls communication with the PLC 1b and the controlled device. The transmission byte sequence 24 and the reception byte sequence 25 that pass through the PLC communication unit 22 are stored in the buffer unit 23. When receiving an acquisition request signal for requesting communication data from the program creation support apparatus 100, the byte string acquisition unit 26 copies the transmission byte string 24 and the reception byte string 25 temporarily stored in the buffer unit 23, and the PC It transmits to the program creation support apparatus 100 via the communication unit 21. The buffer unit 23 is a small memory that can temporarily store communication data of about several bytes, and may be built in the PLC communication unit 22. Since the size of the buffer unit 23 is small, the program creation support apparatus 100 can acquire the transmission byte sequence 24 and the reception byte sequence 25 from the PLC 1a by transmitting the acquisition request signal relatively frequently. The transmission byte sequence 24 and the reception byte sequence 25 acquired from the PLC 1a are stored in the storage unit 6 that functions as a communication data storage unit, and analyzed by the analysis unit 52.

<Analysis of frame structure by pattern matching>
Some communication protocols, such as Modbus, do not define a head identifier that defines the head of the frame structure. If a communication protocol in which a head identifier is defined is used, it is possible to easily recognize that a frame starts from the head identifier by finding the head identifier. However, it is not easy to find the head of the frame structure with a communication protocol that does not specify a head identifier. In particular, even if raw communication data in hexadecimal notation is displayed on the display unit 10, not only where the frame starts but also what the communication data means for an operator who is at a normal technical level. You won't understand at all.

  3A to 3C show an example of a frame structure used in the Modbus protocol. FIG. 3A shows a frame structure on the request side and a frame structure on the response side used for reading the state of the coil. The station is identification information indicating a transmission source such as a server address. The function code is identification information for identifying a function (command type) given to the frame structure. The address indicates a starting address. The score indicates the number of coils. CRC is an error check code calculated on the transmission side. The size indicates the size of the data part. The data stores information indicating the state of the coil. FIG. 3B shows a frame structure used for reading out an error state. In the function code, a code indicating reading of an error state is set. Information indicating an error state is stored in the data. FIG. 3C shows an echo back frame structure for investigating the communication path. In order to inspect the communication path by echo back, the request and the response have the same frame structure.

  As can be seen from FIGS. 3A to 3C, the station data and the function code occupy the top of every frame structure. Of course, unlike the head identifier, although the station data and the function code are always changing byte strings, only the values within a certain range are mounted. For example, when the station data is 2-byte data, the station data can take a value from 0 to 65535 in decimal notation. However, the station data does not actually take all of these values, and often ranges from 0 to several tens. The function code is the same, and only a part of the logically possible range (for example, 0 to 65535 in decimal notation) can be taken. Therefore, the search target for the analysis unit 52 to find the head cannot be narrowed down to one like the head identifier, but can be narrowed down to several candidates that can be taken as the head of the frame structure. Therefore, in the present invention, some candidates that can be taken as the head of the frame structure are stored as matching data 61 in the storage unit 6, and the frame structure can be specified by comparison with the matching data 61.

  FIG. 4 is a diagram for explaining a method of detecting the head of the frame structure in the communication protocol in which a clear head identifier is defined. In this example, the station data 401 takes values from 0x01 to 0x2A, and the function code 402 takes values from 0x00 to 0x6E. Therefore, the range 403 that can be the head of the frame structure is a combination of 0x01 to 0x2A and 0x00 to 0x6E. Therefore, the matching data 61 only needs to include all of these combinations.

<Search mode>
In the present embodiment, the analysis unit 52 transitions between a search mode for searching for information on a command type that is to be arranged near the head of the frame structure, and a command mode for analyzing and displaying the contents of the command. While analyzing the frame structure of the communication data. In FIG. 4, the combination of the station data and the function code has been described as an example of the matching data. Here, in order to simplify the description, a function code is used as an example of the command type.

  FIG. 5 is a flowchart showing the steps for the search mode executed by the analysis unit 52. FIG. 6 is a flowchart showing each step regarding the command mode executed by the analysis unit 52. 7 to 10 are diagrams illustrating an example of a user interface. For example, when the start button 702 is depressed by the pointer 701 that moves in conjunction with the operation of the operation unit 11 in the user interface shown in FIG. 7, the analysis unit 52 starts the search mode. In FIG. 7, when the end button 703 is pressed by the pointer 701, the analysis unit 52 ends the analysis processing. When the save button 704 is pressed, the analysis result is saved in the storage unit 6 as log data. When the print button 705 is pressed, the analysis result is printed by the printer 12. Hereinafter, a case where the received byte string 25 is acquired will be described.

  In S501 of FIG. 5, the instruction creation unit 51 creates an acquisition request command for acquiring the received byte string 25 from the PLC 1a, and transmits the acquisition request command to the 1a from the PLC 1a via the PC communication unit 7. The byte string acquisition unit 26 of the PLC 1 a copies the received byte string 25 stored in the buffer unit 23 and transmits it to the program creation support apparatus 100 via the PC communication unit 21.

  In S <b> 502, the analysis unit 52 receives the received byte string 25 via the PC communication unit 7 and stores it in the storage unit 6. In the case where not only the reception byte string 25 but also the transmission byte string 24 is acquired, each is distinguished and stored in the storage unit 6.

  In S503, the analysis unit 52 determines whether the received byte sequence 25 includes a byte end. The byte end is information indicating the end of the frame structure. For example, the Modbus protocol stipulates that CRC is added to the end of the frame structure. Therefore, when the analysis unit 52 finds a byte string that seems to be a CRC, the analysis unit 52 may determine that the end of the frame structure has been found. For example, the end of the frame structure may be determined by calculating a CRC for the frame structure and determining whether it matches the CRC that was attached to the end of the frame structure. Alternatively, the end of the frame structure may be determined by determining that the portion is not already a valid portion when 0 continues for a predetermined number or more. If the received byte sequence 25 includes a byte end, the analysis unit 52 ends the search mode. On the other hand, if the received byte sequence 25 does not include a byte end, the process proceeds to S504.

  In step S504, the analysis unit 52 determines whether information indicating the command type is included in the byte string. Here, the command type indicates what the command is, and corresponds to the function code 402 as described with reference to FIG. Here, the head of the frame structure is detected by detecting the function code 402 as the command type. Of course, the head of the frame structure may be specified by combining the function data 402 with the station data 401. When the command type is detected, the mode transitions to the command mode, and when the command type cannot be detected, the process proceeds to S505.

  In step S505, the analysis unit 52 notifies the display information creation unit 53 that the command type could not be found (that is, the analysis failed), and the display information creation unit 53 uses the raw communication data as a byte string. Is displayed on the display unit 10. The display unit 10 displays the byte string as raw communication data according to the display information.

<Command mode>
The command mode is a mode in which communication data is analyzed in detail and a detailed frame structure is displayed in a visually easy-to-understand manner. When the search mode is changed to the command mode, the analysis unit 52 starts the command mode from step S604. Note that S601 to S603 are the same processing as S501 to S503 described above, and thus description thereof is omitted.

  In step S604, the analysis unit 52 analyzes the communication data from the beginning of the frame structure, and checks whether or not it matches the frame structure of the command specified by the function code. In the Modbus protocol, there are 40 types of commands, and their frame structures are known. Also, the information elements that make up the frame structure of each command have known values that can actually be taken in the same way as station data and function codes. Therefore, if the value that can be taken by the information element included in the frame structure of the command specified by the function code and the value obtained from the received byte sequence do not match, there is an error in the bit of the function code, or It can be said that there is an error in the information element itself. The analysis unit 52 may determine whether the received byte sequence matches a byte sequence having a length defined by the protocol. The analysis unit 52 may determine whether the received byte sequence has an error detection code such as CRC. Further, it may be determined whether or not the received byte sequence has a format (frame structure) defined by the protocol. However, the analysis unit 52 may determine that the analysis has been successful when a bit that does not hinder the frame structure identification, such as a data portion indicating the state of the coil, is incorrect. However, in order to explicitly indicate to the operator that an error has occurred, the display information creation unit 53 may create display information so that the erroneous byte is highlighted. As described above, the analysis unit 52 may function as an error detection unit that detects an error of an information element included in communication data.

  In step S605, the analysis unit 52 determines whether the communication data (received byte string 25) has been successfully analyzed. For example, the analysis unit 52 determines that the analysis is successful when the known frame structure can be restored from the received byte sequence 25, and determines that the analysis fails when the known frame structure cannot be restored. If the analysis fails, the process proceeds to S608, and the display unit 10 displays the received byte string 25 as raw data (in hexadecimal notation). The display information creation unit 53 also creates display information at this time. On the other hand, when the command analysis is successful, the process proceeds to S606.

  In step S <b> 606, the analysis unit 52 determines whether the end of the command is detected from the received byte sequence 25. When the end of the command is detected, it means that the analysis of the received byte string 25 has been completed up to the end of the frame structure, and thus the process proceeds to S607. On the other hand, when the end of the command has not been detected, it means that the analysis of the received byte string 25 has not been completed until the end of the frame structure, and thus the process proceeds to S601, where the instruction creation unit 51 again issues an acquisition request command. It transmits to PLC1a. As described above, the analysis of one frame structure is achieved by repeatedly executing S601 to S606.

  In step S <b> 607, the analysis unit 52 notifies the display information creation unit 53 that the analysis has been completed, and the display information creation unit 53 displays display information for displaying the frame structure and the information elements that are found after the analysis is completed. The frame structure is created and displayed on the display unit 10. Then return to search mode to find the next command.

  FIG. 7 shows an example in which the response to the FIFO queue read command found from the received byte string 25 is displayed. The user interface 700 includes analysis results in addition to the various operation buttons described above.

  The user interface 700 includes a byte scale 711 indicating the number of bytes, layer information 710 indicating what the layer of the frame structure restored from the received byte sequence means, and a command frame obtained by analysis. A structure 712 is displayed. In this way, by displaying the frame structure in a hierarchical manner such as command names, information elements (format), and raw data of byte strings (hexadecimal notation), the operator can determine the meaning contents of the communication data and the actual contents. It becomes easy to grasp the data. It should be noted that the command information and information elements (format) are read by the display information creation unit 53 from the explanation information 62 stored for each command in the storage unit 6 and included in the display information.

  FIG. 8 shows an error data emphasis display 801. The analysis unit 52 identifies the frame structure from the function code (FC), thereby determining whether or not a plurality of information elements constituting the frame structure have values within a known possible range. It should be noted that the value of the range that each of the plurality of information elements constituting the frame structure for each command can take is stored in the storage unit 6 for each command. For example, according to FIG. 8, an error occurs in the size information indicating the length of the data portion of the command, and a value outside the range that can be originally taken is stored as the size information. Therefore, the analysis unit 52 notifies the display information creation unit 53 that the size information is incorrect. The display information creation unit 53 creates display information so as to highlight the size information pointed out by the analysis unit 52 that an error has occurred. The highlighting method can be used to display an information element that has an error in a different character color from that of other information elements that do not generate an error, blink, or change the background color. Various methods are conceivable. Any highlighting method may be employed as long as the operator can visually recognize the occurrence of an error.

  FIG. 9 shows another display example of the analysis result. When the entire frame structure is displayed at a time, each information element may be simply displayed with an abbreviation or the like because of the display space. It is not easy to understand what it means by simple display alone. Therefore, when the coordinates of the pointer 701 match the display coordinates of each information element, the display information creation unit 53 reads the detailed description information 62 of the information element from the storage unit 6 and includes the detailed description information 62. Display information may be created. FIG. 9 shows that a detailed description 901 is displayed for the information element represented by the abbreviation “data”. This will enable the operator to easily grasp what each information element is specifically.

  FIG. 10 shows the transmission data 1001 and the reception data 1002 simultaneously on one screen so that the operator can easily compare the reception data and the transmission data. FIG. 10 shows a request and a response regarding the echo back command, and the operator can easily determine whether or not the communication state between the PLC 1a and the PLC 1b is good by comparing the two.

  Incidentally, the analysis unit 52 may store the analysis result in the storage unit 6 as the log data 63. When the execution of the search is instructed from the operation unit 11, the control unit 5 executes the search according to the search keyword input from the operation unit 11, and hits the command (frame structure restored from the received byte sequence or the transmitted byte sequence). May be displayed on the display unit 10. At this time, the display information creation unit 53 may create display information so as to display the user interface 700 shown in FIGS. As a search keyword, for example, only the name of an information element (eg, size, station, FC, etc.) may be used, or actual data (eg, 00, 06, 2A, etc.) may be added. FC is an abbreviation for function code.

  When the print button 705 is operated through the operation unit 11, the control unit 5 may cause the printer 12 to execute printing in the same print format as the frame structure shown in the user interface 700.

  As described above, according to the present embodiment, instead of connecting the protocol analyzer to the network connecting the PLC 1a and the PLC 1b, the program creation support device 100 is connected to the PLC 1a and operates as a protocol analyzer or a debugging device. The program creation support apparatus 100 analyzes and displays the frame structure of communication data transmitted / received between the PLC 1a and the PLC 1b or between the PLC 1a and the controlled device by pattern matching. Therefore, it becomes possible to easily grasp the communication contents between the PLC and the PLC and between the PLC and the controlled device without interrupting the protocol analyzer in the network connecting the PLCs. That is, if the program creation support apparatus 100 is connected between PLC networks, the program creation support apparatus 100 may function as a noise source for communication between PLCs. In the present embodiment, the program creation support device 100 is separated from the PLC network and connected only to the PLC 1a. Therefore, the program creation support device 100 is less likely to be a noise source for the PLC network.

  In the present embodiment, matching data 61 that may be placed at the beginning of the frame structure is stored in the storage unit 6, and the analysis unit 52 compares the matching data 61 with the communication data to determine the frame structure. Identify the beginning. Therefore, even if the communication protocol does not specify a head identifier that explicitly indicates the head of the frame structure, the analysis unit 52 can easily specify the head of the frame structure. In the communication protocol having the head identifier, the analysis unit 52 can identify the head of the frame structure from the communication data by searching for the head identifier.

  Since the display unit 10 displays the explanatory information indicating the meaning of each of the plurality of information elements constituting the frame structure together with the information element included in the communication data, which information element means what The operator can easily grasp whether or not.

  If the analysis unit 52 fails in pattern matching (that is, failure in analysis of the frame structure), the display unit 10 displays the communication data as raw data. As a result, the operator can grasp that an error has occurred. In addition, since a skilled operator may understand the cause of the error from the raw data, the raw data may be displayed as it is.

  Further, since the display unit 10 executes the highlight display 801 for the information element in which the error is detected in the communication data, the operator can easily grasp which information element has the error. For example, if an error does not occur in the information element indicating the operating status of the controlled device and an error occurs in another information element, the controlled device is not broken and some error occurs in the communication part. The operator will understand what he is doing.

  Furthermore, since the display unit 10 displays the analysis result as a hierarchical structure, the operator can easily grasp the command configuration and the frame structure visually. Further, when any one of the plurality of information elements constituting the frame structure is designated by the operation unit 11, the display unit 10 may display an explanation 901 indicating the meaning of the designated information element. When the frame structure is displayed according to the normal hierarchical structure, it may be difficult for the operator to grasp the contents of the information elements at a glance, such as displaying some information elements with abbreviations. Therefore, for the information element designated by the pointer 701, the display unit 10 may display a detailed description 901 of the information element. Further, the control unit 5 may function as a search unit that searches for an analysis result according to a keyword input by the operator through the operation unit 11. In this case, the display unit 10 may display an analysis result by hitting the search. For example, an operator may be able to grasp a tendency for an information element by executing a search for a specific information element. The printer 12 may print the analysis result. This makes it easy to share analysis results among a plurality of operators, so that the cause of the error can be discovered early.

Claims (10)

A program creation support device connected to a first programmable logic controller among the plurality of programmable logic controllers in a network to which a plurality of programmable logic controllers are connected,
Request for requesting the first programmable logic controller to transfer the communication data transmitted or received by the first programmable logic controller to or from the second programmable logic controller or controlled device to the program creation support device A communication data request unit for transmitting a signal;
A communication data receiving unit that receives the communication data transmitted by the first programmable logic controller that has received the request signal;
A communication data storage unit for storing the communication data;
An analysis unit for analyzing the frame structure of the communication data stored in the communication data storage unit by pattern matching;
A program creation support apparatus comprising: a display unit configured to display the communication data in accordance with the frame structure obtained by the analysis unit. A matching data storage unit that stores matching data that may be arranged at the top of the frame structure;
2. The program creation support apparatus according to claim 1, wherein the analysis unit compares the matching data stored in the matching data storage unit with the communication data to identify a head of the frame structure. 3. . Commentary information storage unit that stores commentary information indicating the meaning of each of a plurality of information elements constituting the frame structure;
In accordance with the frame structure acquired by the analysis unit, the information element included in the communication data and the comment information indicating the meaning of the information element read from the comment information storage unit are displayed in association with each other. The program creation support apparatus according to claim 1, further comprising a display information creation unit that creates display information.   4. The program creation support apparatus according to claim 1, wherein when the analysis unit fails in the pattern matching, the display unit displays the communication data as raw data. 5. The analysis unit includes an error detection unit that detects an error of an information element included in the communication data,
The program creation support apparatus according to claim 1, wherein the display unit highlights an information element in which the error is detected.   6. The program creation support apparatus according to claim 1, wherein the display unit displays the analysis result of the communication data as a hierarchical structure. It further includes an operation unit that receives the operation of the operator
The display unit, when any one of a plurality of information elements constituting the frame structure is designated by the operation unit, displays a description indicating the meaning of the designated information element. Item 7. The program creation support device according to any one of Items 1 to 6. A search unit for searching the analysis result according to the keyword input by the operator;
8. The program creation support apparatus according to claim 1, wherein the display unit is hit by the search unit and displays an analysis result.   9. The program creation support apparatus according to claim 1, further comprising a printer that prints the analysis result of the communication data. A first communication unit that communicates with a program creation support device that creates a ladder program;
A second communication unit that communicates with other programmable logic controllers or controlled devices;
A buffer unit for temporarily storing communication data transmitted or received between the other programmable logic controller or the controlled device;
When a request signal for requesting the communication data stored in the buffer unit is received from the program creation support device via the first communication unit, the communication data is copied and transmitted to the program creation support device. A programmable logic controller comprising: a control unit that controls the first communication unit.

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