Communication setting method of PLC system and the PLC system

Abstract

To reduce delay of a manufacturing step even in the case of using a radio communication for transmission and a reception of a signal for the control in an industrial facility.SOLUTION: A PLC system comprises: an objective PLC that can perform a LAN communication; an access point; and an information terminal device. The objective PLC includes: a memory that stores communication parameter information for setting a timeout time of a packet communication in a radio LAN; and a processor for performing a communication reset processing for resetting the radio LAN communication in the case where the packet communication is not in success within the timeout time. The communication parameter information contains timeout time information for setting the timeout time. A communication setting method of the PLC system contains: a first step of determining the timeout time; a second step of determining the communication parameter information so as to become the timeout time to be determined; and a third step of setting the communication parameter information to be determined.SELECTED DRAWING: Figure 4

Description

Technical Field

[0001] The present disclosure relates to a communication setting method for a PLC system and a PLC system.

Background Art

[0002] Conventionally, as industrial equipment, information exchange via a network has been performed between a PLC (Programmable Logic Controller) and another PLC, or between a PLC and an information processing device. Further, for wiring reduction, wireless communication has been attempted for these communications. For example, in the system described in Patent Document 1, wireless communication is performed between an information processing device connected to a PLC and a maintenance center.

[0003] In recent years, as an industrial network, a standard wireless LAN (Local Area Network) can be used. In wireless LAN communication, when packet communication fails within the timeout period, communication reset processing is executed.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] In industrial equipment, when wireless communication is used for sending and receiving control signals, if communication reset processing frequently occurs, wireless LAN communication is stopped during the period when the communication reset processing is being executed, which may cause a delay in the manufacturing process.

Means for Solving the Problems

[0006] The present disclosure can be realized in the following forms.

[0007] (1) According to the first aspect of the present disclosure, a communication setting method for a PLC system is provided. The PLC system includes a target PLC capable of LAN communication, an access point connected to the target PLC via a wireless LAN, and an information terminal device capable of LAN communication connected via the wireless LAN. The target PLC has a memory that stores communication parameter information for setting a timeout time for packet communication in the wireless LAN, and a processor that performs a communication reset process for resetting the wireless LAN communication when the packet communication fails within the timeout time. The communication parameter information includes timeout time information for setting the timeout time. The communication setting method for the PLC system includes a first step of determining the timeout time, a second step of determining the communication parameter information so as to be the determined timeout time, and a third step of setting the determined communication parameter information. According to this aspect, by appropriately setting the timeout time, it is possible to make it difficult for the communication reset process to occur. Therefore, it is possible to suppress the manufacturing process from being delayed. (2) In the communication setting method of the PLC system of the above form, the PLC system further includes another PLC different from the target PLC and capable of LAN communication. The timeout time includes first timeout time information associated with control information used in the manufacturing process using the target PLC, which is the first timeout time for setting the timeout time used for the communication of the control information, and second timeout time information associated with the operation information of the manufacturing process, which is the second timeout time for setting the timeout time used for the communication of the operation information. In the second step, the communication parameter information may be determined such that the second timeout time is longer than the first timeout time. According to this form, by setting the second timeout time corresponding to the operation information to be longer than the first timeout time corresponding to the control information, it is possible to make it difficult for communication reset processing to occur. And by setting the first timeout time corresponding to the control information to be shorter than the second timeout time corresponding to the operation information, when an abnormality occurs in the communication of the control information, the communication reset processing can be executed early. By making it difficult for communication reset processing to occur and promptly recovering from communication abnormalities that directly affect the process time of the manufacturing process, it is possible to suppress delays in the manufacturing process. (3) In the communication setting method of the PLC system of the above form, the access point is connected to the Internet, the control information is information communicated between the target PLC and the other PLCs, the operation information is information communicated between the target PLC and the information terminal device, and the communication parameter information is third timeout time information associated with server information communicated between the target PLC and a server connected to the Internet, and is the third timeout time which is the timeout time used for communication of the server information. The method further includes third timeout time information for setting the third timeout time. In the second step, the third timeout time is further determined to be longer than the second timeout time. In the third step, the communication parameter information may be further set so as to be the determined third timeout time. According to this form, in the PLC system, when communication of server information is performed, by setting the third timeout time corresponding to the server information to be longer than the second timeout time corresponding to the operation information, it is possible to make it difficult to cause communication reset processing. Therefore, even when communication of server information is performed in the PLC system, it is possible to suppress the manufacturing process from being delayed. (4) In the communication setting method of the PLC system of the above form, before the first step, there is further an acquisition step of acquiring measured data of the reception required time from the first packet transmission to packet communication success in each packet communication of all the packet communications in a predetermined measurement period, and in the first step, the first timeout time may be statistically determined using the measured data. According to this form, since the first timeout time is determined including the actual variation in the reception required time, it is possible to make it difficult to cause communication reset processing. (5) In the communication setting method of the PLC system of the above form, before the first step, it further has an acquisition step of acquiring the communication volume in the wireless LAN, and in the first step, the communication volume in the wireless LAN and the maximum reception required time which is the maximum value of the reception required time from the first packet transmission in the packet communication to the success of the packet communication are used. The first timeout time may be determined using the maximum reception required time corresponding to the acquired communication volume in the wireless LAN by using a previously obtained prediction formula. According to this form, the first timeout time can be easily determined using the acquired communication volume. (6) In the communication setting method of the PLC system of the above form, the access point is connected to the Internet, the control information is information communicated between the target PLC and the other PLCs, the operation information is information communicated between the target PLC and the information terminal device, and the communication parameter information is third timeout time information associated with server information communicated between the target PLC and a server connected to the Internet, and is third timeout time information for setting a third timeout time that is the timeout time used for communication of the server information. The acquisition step further includes acquiring each of the communication volume of the control information, the communication volume of the operation information, and the communication volume of the server information. The communication setting method of the PLC system includes a first determination step performed between the acquisition step and the first step, for determining whether the communication volume in the wireless LAN is smaller than a predetermined reference communication volume. When it is determined in the first determination step that the communication volume in the wireless LAN is equal to or greater than the reference communication volume, the method further includes a fourth step of determining to restrict the communication of the server information. When it is determined in the first determination step that the communication volume in the wireless LAN is smaller than the reference communication volume, the first step, the second step, and the third step may be performed. According to this form, when communication of server information is performed, by performing the first determination step, it is possible to determine whether the overall communication volume of the wireless LAN is small enough to enable smooth wireless LAN communication. By performing the fourth step, it is possible to restrict the communication of the server information when the overall communication volume of the wireless LAN is large to the extent that it is difficult to perform smooth wireless LAN communication. Thereby, the overall communication volume of the wireless LAN can be appropriately managed, and it is possible to suppress the manufacturing process from being delayed. (7) In the communication setting method of the PLC system of the above-described embodiment, a second determination step of determining whether or not the total communication amount of the control information and the operation information, which is performed after the fourth step, is smaller than the reference communication amount; in the second determination step, when it is determined that the total communication amount is equal to or greater than the reference communication amount, a third determination step of determining whether or not the communication amount of the control information is smaller than the communication amount of the operation information; in the third determination step, when it is determined that the communication amount of the control information is smaller than the communication amount of the operation information, a fourth determination step of determining whether or not the communication amount of the control information is smaller than the reference communication amount; in the fourth determination step, when it is determined that the communication amount of the control information is smaller than the reference communication amount, a fifth step of determining to use a wireless LAN for the communication of the control information and a wired LAN for the communication of the operation information; in the third determination step, when it is determined that the communication amount of the control information is equal to or greater than the communication amount of the operation information, a fifth determination step of determining whether or not the communication amount of the operation information is smaller than the reference communication amount; in the fifth determination step, when it is determined that the communication amount of the operation information is smaller than the reference communication amount, a sixth step of determining to use a wired LAN for the communication of the control information and a wireless LAN for the communication of the operation information may further be included. According to this embodiment, when the total communication amount of the wireless LAN in a state where the communication of the server information is restricted is so large that it is difficult to smoothly perform the wireless LAN communication, the wireless LAN communication of either the control information or the operation information can be restricted. Thereby, the total communication amount of the wireless LAN can be appropriately managed, and it is possible to suppress the manufacturing process from being delayed. (8)According to the second aspect of the present disclosure, a PLC system is provided. This PLC system includes a target PLC capable of LAN communication and an access point connected to the target PLC via a wireless LAN. The target PLC has a memory for storing communication parameter information for setting a timeout time for packet communication in the wireless LAN, and a processor for performing a communication reset process for resetting the wireless LAN communication when the packet communication fails within the timeout time. The communication parameter information includes timeout time information for setting the timeout time. According to this aspect, by appropriately setting the timeout time, it is possible to make the communication reset process less likely to occur. Therefore, it is possible to suppress the delay of the manufacturing process. The present disclosure can be realized in various forms, and in addition to the above forms, it can be realized in the form of, for example, a setting program.

Brief Description of the Drawings

[0008]

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Embodiments for Carrying Out the Invention

[0009] A. First Embodiment: FIG. 1 is a diagram showing the configuration of the PLC system 1. As shown in FIG. 1, the PLC system 1 includes an AP 10, a plurality of wireless slave units 20, a plurality of PLCs 30, a plurality of facilities 40, and an information terminal device 70. The AP 10 is connected to the Internet INT via a modem (not shown). The server 80 is connected to the Internet INT. Each PLC 30 is connected to another PLC 30 so as to be capable of LAN communication. Also, each PLC 30 is connected to the information terminal device 70 so as to be capable of LAN communication. Here, being connected so as to be capable of LAN communication means that either wired LAN or wireless LAN communication is possible. Also, each PLC 30 is communicably connected to the server 80 via the Internet INT.

[0010] The facility 40 has an NC device 42, peripheral devices 44, a control panel 46, and an operation panel 47. The NC device 42 is a numerically controlled (NC) device such as a servo motor, for example. The NC device 42 operates according to a control signal transmitted from the control panel 46. The peripheral devices 44 include, for example, sensors. The peripheral devices 44 operate according to a control signal from the PLC 30 and output an output signal output from the sensors included in the peripheral devices 44. The operation panel 47 has a display unit 48 and operation buttons (not shown). The operation panel 47 displays the operating status of the facility 40 on the display unit 48 and accepts operations to the facility 40 via the operation buttons. The control panel 46 receives an input from the operation buttons of the operation panel 47 and a signal from the sensor and controls the NC device.

[0011] The PLC 30 includes a processor 32, a memory 34, and a communication unit 36. The PLC 30 controls the facility 40 by the processor 32 executing a ladder program (not shown) stored in the memory 34. The communication unit 36 is provided with an interface for performing communication using a LAN. The communication unit 36 performs wired LAN communication with the facility 40 and transmits and receives wireless LAN data to and from the wireless slave unit 20. Communication parameter information 35 is stored in the memory 34. As will be described later, the communication parameter information 35 includes information on a plurality of parameters in wireless LAN communication.

[0012] The wireless slave unit 20 transmits and receives data to and from the access point AP10, which is the master unit, via wireless LAN communication. The wireless slave unit 20 is, for example, USB-connected to the communication unit 36 of the PLC 30. Thereby, wireless LAN communication is realized in the PLC 30. Note that the wireless slave unit 20 is not limited to a configuration provided separately from the PLC 30, and wireless LAN communication may be realized by a wireless LAN communication interface being built into the PLC 30. The AP10 is an access point connected via a wireless LAN. In the present embodiment, EtherNet / IP (trademark) is used as the LAN used by the PLC system 1. Since Ethernet (trademark) is applied to EtherNet / IP (trademark), a standard wireless LAN (Local Area Network) can be used.

[0013] The information terminal device 70 is a device capable of both wired LAN communication and wireless LAN communication, and is, for example, a tablet terminal. The information terminal device 70 includes a display unit 71. The information terminal device 70 displays the operating status of the facility 40 on the display unit 71. The server 80 accumulates information on the past operating status of the PLC system 1 and provides the accumulated data in response to a request.

[0014] Figure 2 is a diagram for explaining information that the target PLC 30 exchanges with other devices via a wireless LAN. As shown in Figure 2, the target PLC 30 exchanges control information used in the manufacturing process with other PLCs 30. Here, the target PLC 30 is also referred to as target PLC 30A. Another PLC 30 different from target PLC 30A is also referred to as other PLC 30B. When the distinction between target PLC 30A and other PLC 30B is unnecessary, it is also referred to as PLC 30.

[0015] Specifically, as control information, there is a signal for permitting or prohibiting the acceptance of a workpiece. The signals constituting the control information are transmitted, for example, by the processor 32. Target PLC 30A exchanges operation information of the manufacturing process with the information terminal device 70. Specifically, as the operation information, there are an emitted abnormal signal, the number of products produced, and the stop time when the facility 40 has stopped abnormally. The signals constituting the operation information are transmitted, for example, by the processor 32. The information terminal device 70 displays the operation information provided from target PLC 30A on the display unit 71. Thereby, an operator located at a place away from target PLC 30A can confirm the operation information displayed on the display unit 71. Target PLC 30A exchanges information with the server 80. Specifically, as the server information, there are performance data such as the past number of products produced and a production plan. Target PLC 30A causes the server information provided from the server 80 to be displayed on the display unit 48 of the facility 40. As another embodiment, a display device may be connected to the PLC 30 to display the server information on the display device.

[0016] Figure 3 is a diagram for explaining the transmission and reception of packets in a wireless LAN. Figure 4 is a diagram for explaining the communication parameter information 35. For example, when transmitting a packet from target PLC 30A to other PLC 30B, the "transmission side" shown in Figure 3 is the target PLC 30A. Also, in the exemplary case, the "reception side" shown in Figure 3 is other PLC 30B.

[0017] When a packet is sent from the transmitting side to the receiving side and so-called packet loss occurs where the packet reception at the receiving side fails, after a predetermined interval time has elapsed, the transmitting side sends the packet again. This predetermined interval time is also called RPI (Requested Packet Interval). When the number of times of packet transmission without successful packet reception at the receiving side reaches a predetermined number of times or more, the transmitting side resets the communication. In this embodiment, specifically, the processor 32 performs a communication reset process for resetting the wireless LAN communication. In the communication reset process, processes such as reconnecting the communication link between the transmitting side and the receiving side are performed. In FIG. 3, the case where the predetermined number of times is 5 times is illustrated. The predetermined number of times used for determining whether to reset this communication is called the retry count. The time from the first packet transmission until the communication is reset is called the timeout time. The timeout time is a value calculated by multiplying the interval time by the retry count. Note that the interval time is a fixed value and is set to the same value regardless of which communication of the packet communication it is.

[0018] When packet communication fails, a communication reset process is performed. While the communication reset process is being performed, communication cannot be carried out. In particular, when communication of control information is not performed, there is a possibility that the production line will stop. Therefore, it is conceivable to set a long timeout time so that communication resets do not occur frequently. However, if the timeout time is set long, there is a possibility of a delay in response when, for example, communication is abnormal due to radio wave interference or when an abnormal signal is being emitted on the production line. Therefore, in this embodiment, the timeout time is set according to the type of information to be communicated.

[0019] Specifically, as shown in FIG. 4, the communication parameter information 35 is information in which the type of information, the timeout time, and the number of retries are grouped together. In the order of server information, operation information, and control information, the timeout time is set shorter. Specifically, the timeout time for the control information is set to the reference timeout time ts. The timeout time for the operation information is set to a value obtained by multiplying the reference timeout time ts by the operation adjustment integer n. Note that the operation adjustment integer n is a number greater than "1". The timeout time for the server information is set to a value obtained by multiplying the reference timeout time ts by the server adjustment integer m. Note that the server adjustment integer m is a number greater than the operation adjustment integer n.

[0020] The timeout time for the control information is also referred to as the first timeout time. The timeout time for the operation information is also referred to as the second timeout time. The timeout time for the server information is also referred to as the third timeout time. The timeout time and the number of retries associated with the control information are also referred to as the first timeout information. The timeout time and the number of retries associated with the operation information are also referred to as the second timeout information. The timeout time and the number of retries associated with the server information are also referred to as the third timeout information.

[0021] By setting the timeout time in the case of the control information to be the shortest, it is possible to respond to abnormalities in the production line at an early stage. Also, by setting the timeout time corresponding to the operation information to be shorter than the timeout time corresponding to the server information, the operator can check the current operation information of the equipment 40.

[0022] FIG. 5 is a flowchart showing the procedure of communication parameter setting processing for realizing a communication setting method of a PLC system. FIG. 6 is a diagram showing a measurement system 101 when measuring the traffic of a LAN. The setting of the communication parameter information 35 is performed, for example, when a new PLC 30 is introduced into the PLC system 1. Note that the setting of the communication parameter information 35 is not limited to the introduction of the PLC 30, and may be performed, for example, during maintenance of the communication system of the PLC system 1. The communication parameter setting processing is performed by the administrator of the PLC system 1.

[0023] In step S10 as the acquisition step of FIG. 5, the measured data of the reception required time of each packet communication at a predetermined measurement time is acquired. The reception required time is the time from when the first packet is transmitted until the packet communication is successful. When performing step S10, the measurement system 101 shown in FIG. 6 is constructed. As shown in FIG. 6, the measurement system 101 includes, in addition to the AP 10, the PLC 30, and the facility 40, a HUB 50 which is a repeater hub, and a PC 60. The PC 60 is a personal computer used to measure the reception required time and to set the communication parameter information 35 of the PLC 30. When step S10 is performed, the timeout time is set to the maximum timeout time within a settable range.

[0024] In the measurement system 101, the AP 10 and the HUB 50 are connected by a wired LAN cable. The HUB 50 and the PLC 30 are connected by a wired LAN cable. And the PC 60 is connected to the HUB 50 by a wired LAN cable. In step S10, it is measured using a general-purpose application for measuring the reception required time, which is pre-introduced into the PC 60. Specifically, for all packets flowing through the LAN during the measurement period, the data of the reception required time is acquired. For example, when the packet transmission is successful at the second time, the reception required time is the value obtained by multiplying the interval time by "2". In this embodiment, the measurement period is 1 hour, but the measurement period is not limited to 1 hour.

[0025] In step S12 as the first step, statistically, the timeout time and the reference timeout time ts as the first timeout time are determined using the measured data obtained in step 10. Specifically, first, a histogram is created for the data obtained in step S10. FIG. 7 is an example of the histogram created in step S10. The horizontal axis of the histogram is the class that divides the reception required time, and the vertical axis is the frequency. In the present embodiment, the value of "3σ" obtained by multiplying the standard deviation σ of the measurement data of the reception required time by "3" is set as the reference timeout time ts. Thereby, the reference timeout time ts can be determined including the variation of the measurement data of the reception required time obtained in step S10.

[0026] In step S14 as the second step shown in FIG. 5, the communication parameter information 35 is determined. Specifically, in the present embodiment, the timeout time and the retry count included in the communication parameter information 35 are determined. FIG. 8 is a diagram showing the relationship between the retry count and the interval time when the timeout time is the same. The first characteristic line LIT1 is a characteristic line where the timeout time is "4×Ts". The second characteristic line LIT2 is a characteristic line where the timeout time is "4×Ts×n". The third characteristic line LIT3 is a characteristic line where the timeout time is "4×Ts×m". When the timeout time is set to "4×Ts", the value of the retry count and the value of the interval time are set so that the plot points indicated by the value of the retry count and the value of the interval time lie on the first characteristic line LIT1. In the present embodiment, the retry count is set to "4". In the present embodiment, since each timeout time is set according to the preset first characteristic line LIT1, second characteristic line LIT2, and third characteristic line LIT3, the second timeout time is determined to be longer than the first timeout time. Also, the third timeout time is determined to be longer than the second timeout time.

[0027] In step S16 as the third step shown in FIG. 5, the communication parameter information 35 of the PLC 30 is set. Specifically, it is set by operating a user interface (UI) for setting the communication parameter information 35 provided from the PLC 30 using the PC 60. Thereby, the communication parameter information 35 is set so as to be the first timeout time, the second timeout time, and the third timeout time determined in step S14. When step S16 ends, the setting of the communication parameter information 35 is completed.

[0028] The wireless slave unit 20 connected to the PLC 30 performs wireless LAN communication according to the communication parameter information 35 possessed by the PLC 30.

[0029] According to the first embodiment described above, in step S12, by determining the timeout time to an appropriate time, it is possible to make the communication reset process less likely to occur. Further, the PLC system 1 includes the target PLC 30A, another PLC 30B, and an AP 10 connected to the target PLC 30A and the other PLC 30B via a wireless LAN. The target PLC 30A has a memory 34 that stores the communication parameter information 35. The target PLC 30A has a processor 32 that performs a communication reset process for resetting the wireless LAN communication when packet communication fails. The communication parameter information 35 includes first timeout time information for setting a first timeout time associated with control information and second timeout time information for setting a second timeout time associated with operation information. The second timeout time is longer than the first timeout time. Thereby, it is possible to make the communication reset process less likely to occur. And by setting the first timeout time corresponding to the control information to be shorter than the second timeout time corresponding to the operation information, when an abnormality occurs in the communication of the control information, the communication reset process can be executed earlier. By making the communication reset process less likely to occur and promptly recovering from communication abnormalities that directly affect the process time of the manufacturing process, it is possible to suppress the manufacturing process from being delayed.

[0030] In addition, the communication parameter setting process for realizing the setting method of LAN communication used in the PLC system 1 includes a step S10 of acquiring measured data of the reception required time, a step S12 of determining a first timeout time, a step 14 of determining a second timeout time, and a step S16 of setting communication parameter information 35. Therefore, it is possible to make it difficult for communication reset processing to occur, and by quickly restoring communication abnormalities that directly affect the process time of the manufacturing process, it is possible to suppress the manufacturing process from being delayed. Also, since the first timeout time of the control information is determined including the actual variation in the reception required time, it is possible to make it difficult for communication reset processing to occur.

[0031] In addition, the communication parameter information 35 further includes third timeout time information for setting a third timeout time associated with the server information. In step S14 of the communication parameter setting process, the third timeout time is determined to be longer than the second timeout time. In step S16 of the communication parameter setting process, the communication parameter information 35 is set to be the determined third timeout time. Therefore, in the PLC system 1, when communication of server information is performed, it is possible to make it difficult for communication reset processing to occur. Therefore, also in the PLC system 1, when communication of server information is performed, it is possible to suppress the manufacturing process from being delayed.

[0032] B. Second Embodiment: The quality of wireless LAN communication is affected by factors such as the communication volume, radio wave environment, and radio wave interference amount. When the communication volume is large, when the radio wave environment is poor, or when the radio wave interference amount is large, communication failures are likely to occur. Therefore, in this embodiment, it is determined whether to apply a wireless LAN or a wired LAN to the PLC system 1. The same components and processing steps as those in the first embodiment are denoted by the same reference numerals, and detailed descriptions are omitted as appropriate.

[0033] FIG. 9 is a first-half flowchart showing the procedure of communication system setting processing according to the present embodiment. FIG. 10 is a second-half flowchart showing the procedure of communication system setting processing according to the present embodiment. The communication system setting processing is performed, for example, when a new PLC 30 is introduced into the PLC system 1, similar to the communication parameter setting processing of the first embodiment. Further, the communication parameter setting processing is performed by the administrator of the PLC system 1.

[0034] In step S30 as the acquisition step of FIG. 9, the radio wave intensity RS, the radio wave interference amount IA, and the communication amount DT at the installation location where the new PLC 30 is installed are measured. Specifically, the radio wave intensity RS is measured at the PC 60 using a commercially available spectrum analyzer and the attached application software. The measurement result of the radio wave intensity RS is represented by a graph with the frequency on the horizontal axis and the radio wave intensity on the vertical axis. Specifically, for the radio wave interference amount IA, the radio wave intensity from another AP 10 different from the AP 10 to which the target PLC 30 is connected is measured.

[0035] Specifically, the communication amount is measured using the PC 60 and commercially available application software for measuring the communication amount. The measurement result of the communication amount is displayed as a graph with the time on the horizontal axis and the data amount [Mbps]. The communication amount is aggregated for a predetermined aggregation period. Further, the communication amount is aggregated for each communication partner shown in FIG. 2. That is, the communication amount DT (IT1) of the control information exchanged between the PLC 30s, the communication amount DT (IT2) of the operation information exchanged between the PLC 30 and the information terminal device 70, and the communication amount DT (IT3) of the server information exchanged between the PLC 30 and the server 80 are respectively aggregated.

[0036] In step S32 of FIG. 9, it is determined whether or not the radio wave intensity RS measured in step S30 is greater than a predetermined reference radio wave intensity RSs. The reference radio wave intensity RSs is a radio wave intensity at which it is determined that it is difficult to perform wireless LAN communication when the radio wave intensity RS is smaller than the reference radio wave intensity RSs, and is an intensity obtained in advance by experiments or the like.

[0037] In step S32, when it is determined that the radio wave intensity RS is not greater than the reference radio wave intensity RSs, in step S34, measures for improving the radio wave intensity are implemented. Specifically, the distance between the wireless slave unit 20 and the AP10 is adjusted to be closer, and a wireless radio wave repeater is introduced. In step S32, when it is determined that the radio wave intensity RS is greater than the reference radio wave intensity RSs, the process proceeds to step S36.

[0038] In step S36, it is determined whether the radio wave interference amount IA measured in step S30 is less than a predetermined reference radio wave interference amount IAs. The reference radio wave interference amount IAs is a radio wave interference amount at which it is determined that it is difficult to perform wireless LAN communication when the radio wave interference amount IA is greater than the reference radio wave interference amount IAs, and is an intensity obtained in advance through experiments or the like.

[0039] In step S36, when it is determined that the radio wave interference amount IA is not less than the reference radio wave interference amount IAs, in step S38, measures for reducing the radio wave interference amount are implemented. Specifically, a shielding plate that shields the radio wave from the AP10 emitting the interfering radio wave is attached. In step S36, when it is determined that the radio wave interference amount IA is less than the reference radio wave interference amount IAs, the process proceeds to step S40.

[0040] In step S40 as the first determination step, it is determined whether the communication amount DT measured in step S30 is less than a predetermined reference communication amount DTs. Here, the communication amount DT is the communication amount in the wireless LAN, and is the total amount of the communication amount DT (IT1) of the control information, the communication amount DT (IT2) of the operation information, and the communication amount DT (IT3) of the server information. The reference communication amount DTs is a communication amount at which it is determined that it is difficult to perform wireless LAN communication for the communication of all information when the communication amount DT is greater than the reference communication amount DTs, and is a communication amount obtained in advance through experiments or the like.

[0041] In step S40, when it is determined that the communication volume DT of the wireless LAN is smaller than the reference communication volume DTs, in step S42 as the first step, communication parameter information 35 is determined. In this embodiment, different from the first embodiment, the timeout time is determined using a prediction formula obtained in advance.

[0042] FIG. 11 is a diagram for explaining a prediction formula for determining the timeout time. FIG. 11 is obtained by experiments. In this experiment, two levels are set for the radio wave intensity RS and two levels are set for the communication volume DT, and the maximum reception required time, which is the maximum value of the reception required time, is measured under a total of four conditions. Note that the radio wave interference amount is set to the reference radio wave interference amount IAs. The two levels of the radio wave intensity RS are specifically the reference radio wave intensity RSs and the first radio wave intensity RSa that is larger than the reference radio wave intensity RSs. The two levels of the communication volume DT are specifically the reference communication volume DTs and the first communication volume DTa that is smaller than the reference communication volume DTs. The horizontal axis of the graph in FIG. 11 is the communication volume. The vertical axis of the graph in FIG. 11 is the maximum reception required time. The conditions corresponding to each of the measurement points P1 to P4 plotted in the graph of FIG. 11 are as shown in the table of FIG. 11. The straight line connecting the measurement point P1 and the measurement point P2 is the first prediction formula corresponding to the reference radio wave intensity RSs. The straight line connecting the measurement point P3 and the measurement point P4 is the second prediction formula corresponding to the first radio wave intensity RSa. When not distinguishing between the first prediction line and the second prediction line, it is called a prediction line.

[0043] In step S42, the maximum reception required time corresponding to the measured traffic volume on the prediction line is obtained. Then, the obtained maximum reception required time is set as the reference timeout time ts. When the measured radio wave intensity RS is greater than the first radio wave intensity RSa, the second prediction line is used. When the measured radio wave intensity RS is less than or equal to the first radio wave intensity RSa, the first prediction line is used. For example, when the measured radio wave intensity RS is greater than the first radio wave intensity RSa and the measured traffic volume DT is the traffic volume DTm, the time Tm is set as the reference timeout time ts. In step S44 as the second step, other timeout times are determined. Since the other timeout times are set in the same manner as in the first embodiment, the description thereof is omitted. In step S46 as the third step, similar to the first embodiment, the communication parameter information 35 of the PLC 30 is set, and this communication system setting process ends.

[0044] In step S40 of FIG. 9, when it is determined that the traffic volume DT is not less than the reference traffic volume DTs, that is, the traffic volume DT is greater than or equal to the reference traffic volume DTs, it is determined in step S48 as the fourth step that the wireless communication of the server information is restricted. As specific restriction methods, there are a method of prohibiting the access itself from the PLC 30 to the server 80 and a method of restricting the traffic volume between the PLC 30 and the server 80 to a predetermined value.

[0045] In step S50 as the second determination step, it is determined whether the total amount of the traffic volume DT (IT1) of the control information and the traffic volume DT (IT2) of the operation information is less than the reference traffic volume DTs. When it is determined that the total amount of the traffic volume DT (IT1) of the control information and the traffic volume DT (IT2) of the operation information is less than the reference traffic volume DTs, the process proceeds to step S42.

[0046] When the total amount of the communication volume DT(IT1) of the control information and the communication volume DT(IT2) of the operation information is not less than the reference communication volume DTs, that is, when it is determined that the total amount of the communication volume DT(IT1) of the control information and the communication volume DT(IT2) of the operation information is equal to or greater than the reference communication volume DTs, in step S52 as the third judgment step in FIG. 10, it is judged whether the communication volume DT(IT1) of the control information is less than the communication volume DT(IT2) of the operation information. When it is judged in step S52 that the communication volume DT(IT1) of the control information is less than the communication volume DT(IT2) of the operation information, in step S54 as the fourth judgment step, it is judged whether the communication volume DT(IT1) of the control information is less than the reference communication volume DTs. When it is judged in step S54 that the communication volume DT(IT1) of the control information is not less than the reference communication volume DTs, that is, when it is determined that the communication volume DT(IT1) of the control information is equal to or greater than the reference communication volume DTs, in step S58, it is determined to set all the LANs in the PLC system 1 to wired LANs, and this communication system setting process is terminated. The case where step S58 is performed is a case where even if the server information is restricted in the PLC system 1, the communication volume is large and there is a risk of causing communication failures in wireless LAN communication.

[0047] When it is judged in step S54 that the communication volume DT(IT1) of the control information is less than the reference communication volume DTs, in step S56 as the fifth step, it is determined to set the control information to wireless LAN and set the operation information to wired LAN.

[0048] In step S52, when it is determined that the communication volume DT(IT1) of the control information is not less than the communication volume DT(IT2) of the operation information, that is, the communication volume DT(IT1) of the control information is greater than or equal to the communication volume DT(IT2) of the operation information, in step S60 as the fifth determination step, it is determined whether the communication volume DT(IT2) of the operation information is less than the reference communication volume DTs. In step S60, when it is determined that the communication volume DT(IT2) of the operation information is not less than the reference communication volume DTs, that is, the communication volume DT(IT2) of the operation information is greater than or equal to the reference communication volume DTs, the process proceeds to step S58. In step S60, when it is determined that the communication volume DT(IT2) of the operation information is less than the reference communication volume DTs, in step S62 as the sixth step, it is determined that the control information is set to the wired LAN and the operation information is set to the wireless LAN.

[0049] After the execution of step S56 and after the execution of step S62, step S64 is executed. In step S64, in the same manner as in step S42, the reference timeout time is determined. Here, when it is determined that the control information is to be set to the wireless LAN, the reference timeout time is determined using the communication volume DT(IT1) of the control information and each prediction line shown in FIG. 11. When it is determined that the operation information is to be set to the wireless LAN, the reference timeout time is determined using the communication volume DT(IT2) of the operation information and each prediction line shown in FIG. 11. In step S66, in the same manner as in step S44, the communication parameter information 35 is determined. Next, in step S68, in the same manner as in step S46, the communication parameter information 35 of the PLC 30 is set, and this communication system setting process ends.

[0050] According to the second embodiment described above, in step S42, using the prediction formula obtained in advance between the communication volume in the wireless LAN and the maximum reception required time, the first timeout time is determined using the maximum reception required time corresponding to the obtained communication volume DT in the wireless LAN. Therefore, the first timeout time can be easily determined using the obtained communication volume.

[0051] In addition, the communication parameter setting process for realizing the setting method further includes step S40 of determining whether the communication volume DT in the wireless LAN is greater than a reference communication volume DTs, and step S48 of determining to restrict the communication of server information when it is determined in step S40 that the communication volume is greater than the reference communication volume DTs. When it is determined in step S40 that the communication volume DT is not greater than the reference communication volume DTs, steps S42, S44, and S46 are performed. Therefore, when the communication of server information is performed, by performing step S40, it is possible to determine whether the overall communication volume DT of the wireless LAN is small enough to enable smooth wireless LAN communication. By performing step S48, it is possible to restrict the communication of server information when the overall communication volume DT of the wireless LAN is large to the extent that it is difficult to perform smooth wireless LAN communication. Thereby, the overall communication volume of the wireless LAN can be appropriately managed, and it is possible to suppress the manufacturing process from being delayed.

[0052] Also, the communication parameter setting process includes step S50 of determining whether the total communication volume of the control information communication volume DT(IT1) and the operation information communication volume DT(IT2) is smaller than the reference communication volume DTs, and in step S50, when it is determined that the total communication volume is equal to or greater than the reference communication volume DTs, step S52 of determining whether the communication volume DT(IT1) of the control information is smaller than the communication volume DT(IT2) of the operation information. Further, in step S52 of the communication parameter setting process, when it is determined that the communication volume DT(IT1) of the control information is smaller than the communication volume DT(IT2) of the operation information, step S54 of determining whether the communication volume DT(IT1) of the control information is greater than the reference communication volume DTs, and in step S54, when it is determined that the communication volume DT(IT1) of the control information is smaller than the reference communication volume DTs, step S56 of determining to use a wireless LAN for the communication of the control information and a wired LAN for the communication of the operation information. Further, in step S52 of the communication parameter setting process, when it is determined that the communication volume DT(IT1) of the control information is equal to or greater than the communication volume DT(IT2) of the operation information, step S60 of determining whether the communication volume DT(IT2) of the operation information is smaller than the reference communication volume DTs, and in step S60, when it is determined that the communication volume DT(IT2) of the operation information is smaller than the reference communication volume DTs, step S62 of determining to use a wired LAN for the communication of the control information and a wireless LAN for the communication of the operation information. Therefore, when the total communication volume of the wireless LAN in the state where the communication of the server information is restricted is large to the extent that it is difficult to smoothly perform the wireless LAN communication, the wireless LAN communication of either the control information or the operation information can be restricted. Thereby, the total communication volume of the wireless LAN can be appropriately managed, and it is possible to suppress the manufacturing process from being delayed.

[0053] C. Other Embodiments: (C1) In the above first embodiment, the PLC system 1 includes two PLCs 30, two facilities 40, and one information terminal device 70, but the numbers of the PLC 30, the facility 40, and the information terminal device 70 are not limited to this.

[0054] (C2) In the above first embodiment, the measurement system 101 is used to measure the reception required time. The system for measuring the reception required time is not limited to this. For example, the PC 60 may be directly connected to the AP 10 to measure the reception required time.

[0055] (C3) In each of the above embodiments, the communication parameter setting process is performed by an administrator. As another embodiment, the communication parameter setting process may be realized by a program for communication parameter setting process stored in advance in the memory of the PC 60 being executed by the processor of the PC 60.

[0056] (C4) In step S42 of the second embodiment above, the obtained maximum reception required time is set as the reference timeout time ts. As another embodiment, a time longer than the obtained maximum reception required time may be set as the reference timeout time ts.

[0057] (C5) The wireless communication in each of the above embodiments can be any one of wireless LANs conforming to the IEEE802.11 standard, such as Wi-Fi (registered trademark), Bluetooth (registered trademark), mobile lines such as 4G and 5G, or a plurality of communications.

[0058] (C6) In the above first embodiment, the HUB50 and the PC60 are separate from the PLC30. As another embodiment, the PLC30 may have the functions of the HUB50 and the functions performed by the PC60. Specifically, the PLC30 may include a measurement unit that measures the reception required time and a setting unit for setting the communication parameter information 35. In this case, this measurement unit acquires data such as the reception required time data. In this case, this setting unit performs a first step, a second step, and a third step. The first step is an arithmetic process for determining the timeout time. Note that the timeout time is a time including at least one of a first timeout time, a second timeout time, and a third timeout time. The second step is an arithmetic process for determining the communication parameter information so as to be the determined timeout time. The third step is a process of setting the determined communication parameter information.

[0059] (C7) Also, in the above first embodiment, the communication parameter setting process is performed by the administrator. As another embodiment, the communication parameter setting process may be performed by the PLC30. In this case, the PLC30 may start the communication parameter setting process, for example, when a start command is input. The start command is an input by an operator using the operation panel 47, a signal periodically emitted by being programmed in advance, an abnormal signal, or the like. Also, the mutual connection between the PC60, the AP10, the HUB50, and the PLC30 in the measurement system 101 may be a USB connection.

[0060] (C8) The information terminal device 70 may be configured to include the PLC30 and the display unit 71. Then, the operating status of the facility 40 may be displayed on the display unit 71.

[0061] (C9) The control unit of the PLC30 or the NC device 42 may be provided inside the control panel 46, or the wireless slave unit 20 may be provided inside the PLC30 or inside the control panel 46.

[0062] The present disclosure is not limited to the above-described embodiments, and can be implemented in various configurations without departing from the gist thereof. For example, the technical features of the embodiments corresponding to the technical features in each of the forms described in the summary of the invention can be appropriately replaced or combined in order to solve some or all of the above-described problems or to achieve some or all of the above-described effects. Further, if the technical feature is not described as essential in this specification, it can be appropriately deleted.

Description of Signs

[0063] 1…PLC system, 10…AP, 20…Wireless slave unit, 30…PLC, 30A…Target PLC, 30B…Other PLC, 32…Processor, 34…Memory, 35…Communication parameter information, 36…Communication unit, 40…Equipment, 42…NC device, 44…Peripheral device, 46…Control panel, 47…Operation panel, 48…Display unit, 50…HUB, 60…PC, 70…Information terminal device, 71…Display unit, 80…Server, 101…Measurement system, DT…Communication volume, IA…Radio interference amount, INT…Internet, RS…Radio intensity

Claims

1. A method for communication setting of a PLC system, comprising: The PLC system includes: A target PLC capable of LAN communication, An access point connected to the target PLC via a wireless LAN, And an information terminal device capable of LAN communication connected via the wireless LAN, The target PLC includes: A memory for storing communication parameter information for setting a timeout time for packet communication in the wireless LAN, A processor for performing a communication reset process for resetting the wireless LAN communication when the packet communication fails within the timeout time, The communication parameter information includes timeout time information for setting the timeout time, The method for communication setting of the PLC system includes: A first step of determining the timeout time, A second step of determining the communication parameter information so that the determined timeout time is obtained, A third step of setting the determined communication parameter information. A method for communication setting of a PLC system.

2. The method for communication setting of a PLC system according to claim 1, wherein: The PLC system is another PLC different from the target PLC and further includes another PLC capable of LAN communication, The timeout time includes: First timeout time information associated with control information used in a manufacturing process using the target PLC, and being the first timeout time which is the timeout time used for communication of the control information, for setting the first timeout time, Second timeout time information associated with operation information of the manufacturing process, and being the second timeout time which is the timeout time used for communication of the operation information, for setting the second timeout time, In the second step, the communication parameter information is determined so that the second timeout time is longer than the first timeout time. A method for communication setting of a PLC system.

3. The method for communication setting of a PLC system according to claim 2, wherein: The access point is connected to the Internet, The control information is information communicated between the target PLC and the other PLC, The operation information is information communicated between the target PLC and the information terminal device. The communication parameter information is third timeout time information associated with server information communicated between the target PLC and a server connected to the Internet, and further includes third timeout time information for setting a third timeout time, which is the timeout time used for communication of the server information. In the second step, the third timeout time is further determined to be longer than the second timeout time. In the third step, the communication parameter information is further set so as to be the determined third timeout time, which is a communication setting method of a PLC system.

4. A communication setting method of a PLC system according to claim 2, before the first step, further having an acquisition step of acquiring measured data of the reception required time from the first packet transmission to packet communication success in each packet communication of all the packet communications in a predetermined measurement period. In the first step, the first timeout time is statistically determined using the measured data, which is a communication setting method of a PLC system.

5. A communication setting method of a PLC system according to claim 2, before the first step, further having an acquisition step of acquiring the communication amount in the wireless LAN. In the first step, using a prediction formula obtained in advance between the communication amount in the wireless LAN and the maximum reception required time, which is the maximum value of the reception required time from the first packet transmission to packet communication success in the packet communication, the first timeout time is determined using the maximum reception required time corresponding to the acquired communication amount in the wireless LAN, which is a communication setting method of a PLC system.

6. A communication setting method of a PLC system according to claim 4, the access point is connected to the Internet, the control information is information communicated between the target PLC and the other PLC, the operation information is information communicated between the target PLC and the information terminal device, the communication parameter information is third timeout time information associated with server information communicated between the target PLC and a server connected to the Internet, and further includes third timeout time information for setting a third timeout time, which is the timeout time used for communication of the server information. In the acquisition step, the communication volume of the control information, the communication volume of the operation information, and the communication volume of the server information are acquired respectively. The communication setting method of the PLC system is as follows: A first determination step of determining whether the communication volume in the wireless LAN, which is performed between the acquisition step and the first step, is smaller than a predetermined reference communication volume; In the first determination step, when it is determined that the communication volume in the wireless LAN is equal to or greater than the reference communication volume, a fourth step of determining to restrict the communication of the server information; A communication setting method for a PLC system, which performs the first step, the second step, and the third step when it is determined in the first determination step that the communication volume in the wireless LAN is smaller than the reference communication volume.

7. A communication setting method for a PLC system according to claim 6, A second determination step of determining whether the total communication volume of the control information and the operation information, which is performed after the fourth step, is smaller than the reference communication volume; In the second determination step, when it is determined that the total communication volume is equal to or greater than the reference communication volume, A third determination step of determining whether the communication volume of the control information is smaller than the communication volume of the operation information; In the third determination step, when it is determined that the communication volume of the control information is smaller than the communication volume of the operation information, a fourth determination step of determining whether the communication volume of the control information is smaller than the reference communication volume; In the fourth determination step, when it is determined that the communication volume of the control information is smaller than the reference communication volume, a fifth step of determining to use the wireless LAN for the communication of the control information and use the wired LAN for the communication of the operation information; In the third determination step, when it is determined that the communication volume of the control information is equal to or greater than the communication volume of the operation information, a fifth determination step of determining whether the communication volume of the operation information is smaller than the reference communication volume; A communication setting method for a PLC system, further comprising: in the fifth determination step, when it is determined that the communication volume of the operation information is smaller than the reference communication volume, a sixth step of determining to use the wired LAN for the communication of the control information and use the wireless LAN for the communication of the operation information.

8. A PLC system, comprising: A target PLC capable of LAN communication; An access point connected to the target PLC via a wireless LAN, and the target PLC includes a memory for storing communication parameter information for setting a timeout time for packet communication in the wireless LAN, and a processor for performing a communication reset process for resetting the wireless LAN communication when the packet communication fails within the timeout time, and has the communication parameter information includes timeout time information for setting the timeout time, a PLC system.

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