Slave device, communication cable evaluation system, and communication cable evaluation method

Abstract

To realize a master device capable of easily determining deterioration of a communication cable between slave devices.SOLUTION: A communication unit (103) communicates with a plurality of slave devices (21a to 21e) via a communication network. A control unit (101) receives information on the signal quality of communication cables (61 to 66) from the plurality of slave devices (21a to 21e) via the communication unit (103), evaluates the quality of the communication cable (61 to 66) on the basis of the information on the signal quality, and notifies a user of the degree of deterioration of the quality of the communication cables (61 to 66).SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a master device, a slave device, a communication cable evaluation system, a communication cable evaluation method, and a computer program. [Background technology]

[0002] In the field of factory automation (FA), various types of devices that share the work process are controlled. In order to link various controllers, remote I / O, and manufacturing devices used for work in a certain area such as a factory facility, industrial network systems, also called field networks, are constructed to connect these devices.

[0003] A typical industrial network system uses a master-slave network consisting of various slave devices and a master device. The slave devices are devices that control or collect data from equipment installed in a factory. The master device is a device that centrally manages these slaves, such as a device called a PLC (Programmable Logic Controller). EtherCAT (registered trademark) and Ethernet / IP (registered trademark) are examples of such industrial network system types (Ethernet: registered trademark). In such industrial network systems, communication cables are stretched between each device to create a network.

[0004] A related technique is disclosed in the following Patent Document 1. Patent Document 1 relates to a method and an apparatus for determining network quality. In this method, at least two evaluation indexes reflecting network parameters in at least two different protocol layers of a communication network are determined, the at least two evaluation indexes are compared with respective thresholds, and a service quality for the network is determined based on the comparison of the at least two evaluation indexes with the respective thresholds. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Special Publication No. 2010-506457 Summary of the Invention [Problem to be solved by the invention]

[0006] For example, when the slave device is provided on a movable part of a robot, the communication cable connected to the slave device is bent, twisted, or otherwise deformed as the robot moves, and therefore the communication cable connected to the slave device is prone to deterioration.

[0007] However, since communication cables are laid out between each device, it is difficult to visually determine which communication cable has deteriorated. Even if the technology disclosed in the above-mentioned Patent Document 1 is used, such a problem cannot be solved.

[0008] The present invention has been made in consideration of the above problems, and has an object to provide a master device or the like that is capable of easily determining deterioration of a communication cable between slave devices. [Means for solving the problem]

[0009] In order to solve the above problems, the present invention employs the following configuration.

[0010] A master device according to one aspect of the present invention includes a communication unit that communicates with a plurality of slave devices via a communication network, and a control unit that receives information regarding signal quality of a communication cable from the plurality of slave devices via the communication unit, evaluates the quality of the communication cable based on the information regarding the signal quality, and notifies a user according to the degree of deterioration of the quality of the communication cable.

[0011] According to the above configuration, the control unit evaluates the quality of the communication cable based on the information on the received signal quality, so that the user can easily determine the deterioration of the communication cable between the slave devices.

[0012] A slave device according to one aspect of the present invention includes a communication unit that communicates with a master device via a communication network, and a control unit that acquires information regarding the signal quality of a connected communication cable, evaluates the quality of the communication cable based on the information regarding the signal quality, and notifies a user via the master device depending on the degree of deterioration in the quality of the communication cable.

[0013] According to the above configuration, a user can easily determine deterioration of the communication cable between the slave devices by receiving an evaluation result of the quality of the communication cable from the slave device.

[0014] In the slave device according to the aforementioned aspect, the control unit calculates an average value of information relating to the signal quality of the communication cable for a predetermined number of times, and evaluates the quality of the communication cable based on the average value.

[0015] According to the above configuration, the control unit evaluates the quality of the communication cable based on the average value, so that it is possible to reduce the influence of sudden noise and the like.

[0016] In the slave device according to the aforementioned aspect, the control unit uses information relating to the signal quality immediately after system startup as a reference value, and evaluates the quality of the communication cable according to the difference between the reference value and an average value.

[0017] According to the above configuration, the control unit uses the information on the signal quality immediately after the system is started as the reference value, so there is no need to determine and store the reference value in advance.

[0018] In the slave device according to the aforementioned aspect, the control unit notifies the master device, via the communication unit, of the port number to which the communication cable having degraded quality is connected.

[0019] According to the above configuration, the master device can easily identify a communication cable whose quality has deteriorated.

[0020] In the slave device according to the aforementioned aspect, the information relating to the signal quality of the communication cable is acquired by the physical layer control circuit.

[0021] According to the above configuration, since the function of the physical layer control circuit is used, a new circuit or the like is not required.

[0022] A communication cable evaluation system according to one aspect of the present invention is a communication cable evaluation system comprising a master device, a plurality of slave devices, and a terminal device, each of the plurality of slave devices including a first communication unit that communicates with the master device via a communication network, and a first control unit that acquires information relating to the signal quality of a connected communication cable, evaluates the quality of the communication cable based on the information about the signal quality, and transmits an evaluation result of the communication cable quality to the master device via the first communication unit, and the master device includes a second communication unit that communicates with the plurality of slave devices and the terminal device via the communication network, and a second control unit that receives the evaluation results of the communication cable quality from the plurality of slave devices via the second communication unit and notifies the terminal device according to the degree of degradation in the quality of the communication cable via the second communication unit.

[0023] According to the above configuration, the terminal device receives the evaluation result of the quality of the communication cable from the master device, so that the user can easily determine the deterioration of the communication cable between the slave devices.

[0024] A communication cable evaluation method according to one aspect of the present invention includes a step of a slave device acquiring information regarding the signal quality of a communication cable to be connected, a step of evaluating the quality of the communication cable based on the information regarding the signal quality, and a step of notifying a user according to the degree of deterioration of the quality of the communication cable.

[0025] According to the above configuration, by receiving the evaluation result of the quality of the communication cable from the slave device, the user can easily determine the deterioration of the communication cable between the slave devices.

[0026] A computer program according to one aspect of the present invention is a computer program for causing a computer to execute a communication cable evaluation method, the evaluation method including the steps of acquiring information regarding the signal quality of a connected communication cable, evaluating the quality of the communication cable based on the information regarding the signal quality, and notifying a user according to the degree of degradation in the quality of the communication cable.

[0027] According to the above configuration, by receiving the evaluation result of the quality of the communication cable from the slave device, the user can easily determine the deterioration of the communication cable between the slave devices. Effect of the Invention

[0028] According to any one of the master device according to an aspect of the present invention, the slave device according to an aspect of the present invention, the communication cable evaluation system according to an aspect of the present invention, the communication cable evaluation method according to an aspect of the present invention, and the computer program according to an aspect of the present invention, it becomes possible to easily determine deterioration of the communication cable between the slave devices. [Brief description of the drawings]

[0029] [Figure 1] 1 is a block diagram showing a functional configuration of a master device included in the communication cable evaluation system according to the first embodiment of the present invention. [Diagram 2] FIG. 10 is a diagram illustrating the acquisition of the SQI values ​​of each slave device by the master device. [Diagram 3] 1 is a diagram showing a schematic configuration of a communication cable evaluation system including a master device according to a first embodiment of the present invention. [Figure 4] 10 is a flowchart illustrating a processing procedure of the master device. [Diagram 5]11 is a flowchart for explaining a processing procedure of a PC or an HMI. [Figure 6] FIG. 11 is a block diagram showing a functional configuration of a slave device included in a communication cable evaluation system according to a second embodiment of the present invention. [Figure 7] 10 is a flowchart illustrating a processing procedure of a slave device according to a second embodiment of the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0030] [Embodiment 1] Hereinafter, an embodiment according to one aspect of the present invention (hereinafter, also referred to as "the present embodiment") will be described with reference to the drawings.

[0031] §1 Examples of application 1 is a block diagram showing a functional configuration of a master device 10 included in a communication cable evaluation system 1 according to a first embodiment of the present invention. The communication cable evaluation system 1 includes the master device 10, a hub device 17, slave devices 21a to 21e, and a PC (Personal Computer) 30.

[0032] The master device 10, the slave device 21a, and the PC 30 are connected by a communication network such as EtherCAT (registered trademark), Ethernet / IP (registered trademark), etc. In this embodiment, a case where these devices are connected to an Ethernet / IP (registered trademark) communication network will be described, but is not limited to this. The communication network may be, for example, a network system such as Mechatrolink (registered trademark), CC-Link (registered trademark), etc.

[0033] In EtherCAT (registered trademark), a protocol such as CoE (CAN application protocol over Ethernet) is added on top of the physical layer (including the MAC layer) of Ethernet (registered trademark), realizing ultra-high-speed cyclic communication by PDO (Process Data Object), high-speed event communication by SDO (Service Data Object), and safety communication on the same network. In this embodiment, the communication between the master device 10 and the PC 30 is performed by Ethernet / IP (registered trademark), and the communication between the master device 10 and the slave device 21a and the communication between the slave devices 21a to 21e is performed by EtherCAT (registered trademark).

[0034] 1, master device 10 and slave device 21a are connected by a communication cable 61. Similarly, slave device 21a and slave device 21b are connected by a communication cable 62, and slave device 21b and hub device 17 are connected by a communication cable 63. Hub device 17 and slave device 21c are connected by a communication cable 64, hub device 17 and slave device 21d are connected by a communication cable 65, and hub device 17 and slave device 21e are connected by a communication cable 66. Slave devices 21a to 21b are connected by a daisy chain connection, and slave devices 21c to 21e are connected by a star connection.

[0035] The slave devices 21a to 21e each have a physical layer control circuit (hereinafter referred to as a PHY circuit) for controlling the physical layer, and are capable of acquiring an SQI (Signal Quality Indicator) (information related to the signal quality of the communication cable) value of the communication cable connected by the PHY circuit.

[0036] The master device 10 includes a control unit 101, a storage unit 102, and a communication unit 103. The communication unit 103 is connected to the slave device 21a and the PC 30 via a communication network such as Ethernet / IP (registered trademark). Note that communication between the communication unit 103 and the slave devices 21a to 21e is performed by cyclic communication.

[0037] The storage unit 102 is configured with a RAM (Random Access Memory), a flash memory, a hard disk, etc., and stores data referenced by the control unit 101 and is used as a primary storage area.

[0038] At system startup, control unit 101 receives an SQI value from each of the slave devices 21a to 21e and stores the SQI value as a reference value in storage unit 102. Thereafter, control unit 101 periodically receives the SQI values ​​from slave devices 21a to 21e and stores them in storage unit 102.

[0039] For example, control unit 101 receives an SQI value from each of slave devices 21a-21e at a 100 ms cycle (predetermined cycle) and sets the average of 100 SQI values ​​(predetermined number of times) as the SQI value of each slave device. Then, control unit 101 compares the SQI value (average value) with a reference value stored in storage unit 102 for each of slave devices 21a-21e to evaluate the quality of the communication cable.

[0040] Note that the average of 100 SQI values ​​is used as the SQI value of each slave device, but this is not limited to this. Generally, if a communication cable deteriorates, the SQI value will continue to deteriorate, so the average of 100 SQI values ​​is used to reduce the effects of sudden noise, etc. Therefore, the number of times the average SQI value is calculated may be increased or decreased depending on the cycle for acquiring the SQI value, etc.

[0041] Furthermore, instead of using the SQI values ​​received from each of the slave devices 21a to 21e at the time of system startup, a predetermined value stored in the storage unit 102 may be used as the reference value. This predetermined value is, for example, "70," and the quality of the communication cable is evaluated based on this predetermined value.

[0042] Each of the slave devices 21a to 21e is provided with an input port and an output port, and a communication cable is connected to each port. The slave devices 21a to 21e can acquire the SQI value of either the input port or the output port. Therefore, it may be determined in advance for each slave device which communication cable's SQI value to acquire, or when transmitting an SQI value to the master device 10, information (port number) relating to whether it is an input port or an output port may be added and transmitted. This allows the master device 10 to determine which communication cable the SQI value received from the slave devices 21a to 21e belongs to.

[0043] As described above, communication between master device 10 and slave devices 21a to 21e is performed by cyclic communication, with master device 10 transmitting a packet to slave device 21a. Upon receiving the packet, slave device 21a acquires an SQI value, writes the SQI value in the packet, and transmits the packet to slave device 21b. In the same manner, packets are transmitted to the slave devices in sequence, and after the last slave device 21e writes an SQI value in the packet, the packet is transmitted to master device 10. In this manner, each of slave devices 21a to 21e writes an SQI value in one packet in sequence and transmits the packet, so that master device 10 can acquire the SQI values ​​of each of slave devices 21a to 21e at high speed.

[0044] The control unit 101 transmits the evaluation results of the quality of each of the communication cables 61 to 66 to the PC 30 or the HMI 40 via the communication unit 103. Then, the PC 30 or the HMI 40 described later displays the evaluation results of the communication cables on the display unit. Note that the notification to the user is not limited to this, and for example, the control unit 101 may notify another device used by the user of the evaluation results of the communication cables. Furthermore, the notification to the user may include information indicating to what extent the quality of the communication cables has deteriorated compared to a reference value, for example, information indicating the degree of deterioration of the communication cables.

[0045] 2 is a diagram showing a schematic diagram of the acquisition of the SQI values ​​of each of the slave devices 21a to 21e by the master device 10. The slave device 21a measures the SQI value of the communication cable 61 connecting the master device 10 and its own slave device 21a. The SQI value at this time is "89", and the slave device 21a transmits this SQI value to the master device 10. The slave device 21a also obtains an SQI value of "73" of the communication cable 62 connecting its own slave device 21a and slave device 21b, and transmits this to the master device 10.

[0046] Slave device 21b obtains the SQI value "97" of communication cable 63 connecting slave device 21b itself to hub device 17, and transmits it to master device 10. Note that the measurement of the SQI value of communication cable 62 connecting slave device 21a to slave device 21b may be performed by either slave device 21a or 21b.

[0047] Slave device 21c obtains an SQI value of "35" for communication cable 64 connecting its own slave device 21c and hub device 17, and transmits this to master device 10. Slave device 21d obtains an SQI value of "82" for communication cable 65 connecting its own slave device 21d and hub device 17, and transmits this to master device 10. Similarly, slave device 21e obtains an SQI value of "74" for communication cable 66 connecting its own slave device 21e and hub device 17, and transmits this to master device 10.

[0048] For example, if the reference value of the communication cable 64 connecting the slave device 21c and the hub device 17 is "70," then since the current SQI value is "35" lower than the reference value, it is determined that the communication cable 64 is severely deteriorated.

[0049] §2 Configuration example (Overview of Communication Cable Evaluation System 1) 3 is a diagram showing a schematic configuration of a communication cable evaluation system 1 including a master device 10 according to the first embodiment of the present invention. The communication cable evaluation system 1 includes the master device 10, hub devices 15-17, slave devices 21a-21e, 22a-22c, and 23a-23c, a PC (terminal device) 30, and an HMI (Human Machine interface) (terminal device) 40.

[0050] The network system constituting the communication cable evaluation system 1 may be, for example, a field network system constituted by a group of manufacturing devices in a factory. Furthermore, the master device 10 may be, for example, a device such as a PLC.

[0051] Master device 10 is connected to a plurality of slave devices 21a to 21c, 22a to 22c, and 23a to 23c through a communication network via hub devices 15 and 16. Furthermore, slave device 21b is connected to slave devices 21c to 21e through hub device 17. For example, the plurality of slave devices 21a to 21b, 22a to 22c, and 23a to 23c are connected by a daisy chain connection, and slave devices 21c to 21e are connected by a star connection.

[0052] The PC 30 and the HMI 40 are connected to the master device 10 via the hub device 15, and transmit instructions to the master device 10 and receive the evaluation results of the quality of the communication cable from the master device 10. The PC 30 and the HMI 40 display the evaluation results of the communication cable on the display unit. The PC 30 and the HMI 40 are also called terminal devices.

[0053] For example, the PC 30 or HMI 40 refers to the evaluation results of the communication cable received from the master device 10, and if the value obtained by subtracting the current SQI value from the reference value is less than "10", it displays a message such as "Normal: cable quality is normal."

[0054] In addition, if the value obtained by subtracting the current SQI value from the reference value is greater than or equal to "10" and less than "20," the PC30 or HMI40 will display a message such as "Warning: Cable quality is deteriorating. Please prepare a replacement cable."

[0055] In addition, if the value obtained by subtracting the current SQI value from the reference value is greater than or equal to 20 and less than 30, the PC30 or HMI40 will display a message such as "Warning: Cable quality is deteriorating. Please replace the cable at the next maintenance."

[0056] In addition, if the value obtained by subtracting the current SQI value from the reference value is 30 or greater, the PC30 or HMI40 will display a message such as "Danger: Cable quality is poor. Replace the cable immediately."

[0057] The user may change the evaluation criteria for displaying each message by operating the PC 30 or the HMI 40. For example, the criterion for determining whether the SQI value is normal (the value obtained by subtracting the current SQI value from the reference value) may be changed from "10" to "5," or the criterion for determining whether the SQI value is normal may be changed from "10" to "15."

[0058] §3 Example of operation 4 is a flowchart for explaining the processing procedure of the master device 10. First, after starting up the system, the control unit 101 receives the SQI values ​​(reference values) from the slave devices 21a to 21e and stores them in the storage unit 102 (S1).

[0059] Next, the control unit 101 judges whether or not a predetermined time has elapsed (S2). This predetermined time is, for example, 100 ms. If the predetermined time has not elapsed (S2, No), the process of step S2 is repeated.

[0060] If the predetermined time has elapsed (S2, Yes), control unit 101 receives the current SQI value from each of slave devices 21a-21e and stores it in storage unit 102 (S3). Then, control unit 101 evaluates the quality of each cable by referring to the SQI value stored in storage unit 102 (S4).

[0061] For example, the control unit 101 evaluates the quality of the communication cable by calculating the average value of the most recent 100 SQI values ​​stored in the storage unit 102 and comparing it with a reference value. Note that the number of SQI values ​​used to calculate the average value is not limited to this. Also, instead of the average value, a maximum value or a median value may be used. This process is performed for all communication cables 61 to 66.

[0062] Next, the control unit 101 transmits the evaluation results of the quality of each of the communication cables 61-66 to the PC 30 or the HMI 40 via the communication unit 103 (S5). This process may be performed when a transmission request is received from the PC 30 or the HMI 40, or the master device 10 may periodically transmit the evaluation results to the PC 30 or the HMI 40.

[0063] Finally, the control unit 101 judges whether or not to end the process (S6). For example, if an instruction to stop the system is received, it judges that the process is to be ended. If the process is not to be ended (S6, No), the process returns to step S2 and the subsequent processes are repeated. If the process is to be ended (S6, Yes), the process is ended as it is.

[0064] 5 is a flowchart for explaining the processing procedure of the PC 30 or the HMI 40. First, the PC 30 or the HMI 40 determines whether or not the cable quality display function has been enabled by the user (S11). If the cable quality display function has not been enabled (S11, No), the processing ends.

[0065] Furthermore, if the cable quality display function is enabled (S11, Yes), the PC 30 or the HMI 40 determines whether or not the cable quality evaluation result has been received from the master device 10 (S12). If the cable quality evaluation result has not been received from the master device 10 (S12, No), the process of step S12 is repeated.

[0066] Furthermore, if the evaluation result of the cable quality has been received from the master device 10 (S12, Yes), the PC 30 or the HMI 40 displays the evaluation result of the cable quality on the display screen (S13).

[0067] Finally, it is determined whether or not the process is to be ended (S14). If the process is not to be ended (S14, No), the process returns to step S12 and the subsequent processes are repeated. If the process is to be ended (S14, Yes), the process is ended as it is.

[0068] § 4 Action and effect According to the first embodiment of the present invention, the control unit 101 of the master device 10 periodically receives the SQI value from each of the slave devices 21a to 21e and evaluates the quality of each of the communication cables 61 to 66. This makes it possible to easily determine the deterioration of the communication cables between the slave devices.

[0069] Furthermore, control unit 101 receives the SQI value from each of slave devices 21a to 21e at a predetermined cycle, and sets the average of the SQI values ​​for the predetermined number of times as the SQI value for each slave device. If the communication cable deteriorates, the SQI value will continue to deteriorate, so by calculating the average value for the predetermined number of times, it is possible to reduce the influence of sudden noise, etc.

[0070] Furthermore, when the system is started up, the control unit 101 receives the SQI value from each of the slave devices 21a to 21e and sets the SQI value as the reference value. This eliminates the need to determine the reference value in advance and store it in the storage unit 102.

[0071] Furthermore, the control unit 101 transmits the evaluation results of the quality of the communication cables 61-66 to the PC 30 or the HMI 40 via the communication unit 103. Therefore, the PC 30 or the HMI 40 can present the deterioration state of the communication cables 61-66 to the user.

[0072] [Embodiment 2] A communication cable evaluation system according to a second embodiment of the present invention will be described below. For ease of explanation, components having the same functions as those described in the first embodiment will be denoted by the same reference numerals, and the description thereof will not be repeated.

[0073] 6 is a block diagram showing a functional configuration of a slave device 21a' included in a communication cable evaluation system 1' according to embodiment 2 of the present invention. The communication cable evaluation system 1' includes a master device 10', slave devices 21a' to 21e', and a PC 30. Since the slave devices 21a' to 21e' have similar configurations and functions, only the slave device 21a' will be described as a representative.

[0074] Slave device 21a' includes a control unit (first control unit) 211, a storage unit 212, and a communication unit (first communication unit) 213. The communication unit 213 is connected to master device 10' and slave device 21b' via a communication network such as EtherCAT (registered trademark). Note that communication between the communication unit 213 and slave devices 21b' to 21e' is performed by cyclic communication.

[0075] The storage unit 212 is configured from a RAM, a flash memory, a hard disk, etc., and stores data referenced by the control unit 211 and is used as a primary storage area.

[0076] The control unit 211 acquires the SQI value at the time of system startup, and stores it as a reference value in the storage unit 212. Thereafter, the control unit 211 periodically acquires the SQI value of the communication cable 61, and stores it in the storage unit 212.

[0077] For example, the control unit 211 acquires the SQI value of the communication cable 61 at a period of 100 ms (predetermined period) and sets the average of the SQI values ​​acquired 100 times (predetermined number of times) as the SQI value of the communication cable 61. Then, the control unit 211 compares the SQI value (average value) with a reference value stored in the storage unit 212 to evaluate the quality of the communication cable 61.

[0078] The control unit 211 transmits the evaluation results of the quality of the communication cable 61 to the master device 10' via the communication unit 213. Note that since communication between the master device 10' and the slave devices 21a'-21e' is performed by cyclic communication, the master device 10' can obtain the evaluation results of the quality of the communication cables 61-66 from the slave devices 21a'-21e' at high speed.

[0079] The master device 10' includes a control unit (second control unit) 101', a storage unit 102', and a communication unit (second communication unit) 103'. The communication unit 103' is connected to the slave device 21a' and the PC 30 via a communication network such as Ethernet / IP (registered trademark). Note that communication between the communication unit 103' and the slave devices 21a' to 21e' is performed by cyclic communication.

[0080] The storage unit 102' is configured with a RAM, a flash memory, a hard disk, etc., and stores data referenced by the control unit 101' and is used as a primary storage area.

[0081] The control unit 101' receives the evaluation results of the quality of the communication cables from each of the slave devices 21a'-21e' via the communication unit 103' and stores them in the memory unit 102'. The control unit 101' then transmits the evaluation results of the quality of each of the communication cables 61-66 stored in the memory unit 102' to the PC 30 or the HMI 40 via the communication unit 103'. The PC 30 or the HMI 40 then displays the evaluation results of the communication cables on the display unit.

[0082] 7 is a flowchart for explaining the processing procedure of the slave device 21a' according to the second embodiment of the present invention. First, after starting up the system, the control unit 211 acquires the SQI value (reference value) of the communication cable 61 and stores it in the storage unit 212 (S21).

[0083] Next, the control unit 211 judges whether or not a predetermined time has elapsed (S22). This predetermined time is, for example, 100 ms. If the predetermined time has not elapsed (S22, No), the process of step S22 is repeated.

[0084] If the predetermined time has elapsed (S22, Yes), the control unit 211 acquires the current SQI value of the communication cable 61 and stores it in the storage unit 212 (S23). Then, the control unit 211 evaluates the quality of the communication cable 61 by referring to the SQI value stored in the storage unit 212 (S24).

[0085] For example, the control unit 211 calculates the average value of the most recent 100 SQI values ​​stored in the storage unit 212, and compares it with a reference value to evaluate the quality of the communication cable 61. Note that the number of SQI values ​​used to calculate the average value is not limited to this. Also, instead of the average value, a maximum value or a median value may be used.

[0086] Next, the control unit 211 transmits the evaluation result of the quality of the communication cable 61 to the master device 10' via the communication unit 213 (S25). This process may be performed when a transmission request is received from the master device 10', or the slave device 21a' may periodically transmit the evaluation result to the master device 10'.

[0087] Finally, the control unit 211 judges whether or not to end the process (S26). For example, if an instruction to stop the system is received, it judges that the process is to be ended. If the process is not to be ended (S26, No), the process returns to step S22 and the subsequent processes are repeated. If the process is to be ended (S26, Yes), the process is ended as it is.

[0088] The PC 30 or the HMI 40 receives the evaluation result of the communication cable from the slave devices 21a'-21e' via the master device 10', and displays the evaluation result of the communication cable on the display unit. Note that the notification to the user is not limited to this, and for example, the control unit 211 may notify another device used by the user of the evaluation result of the communication cable. The notification to the user may also include information indicating to what extent the quality of the communication cable has deteriorated compared to a reference value, for example, information indicating the degree of deterioration of the communication cable.

[0089] As described above, in slave device 21a' according to this embodiment, control unit 211 periodically acquires the SQI value of communication cable 61 and evaluates the quality of communication cable 61. Therefore, master device 10' can easily determine the deterioration of the communication cables between slave devices by receiving the evaluation results of the quality of communication cables 61-66 from slave devices 21a'-21e'.

[0090] Furthermore, the control unit 211 acquires the SQI value of the communication cable 61 at a predetermined period, and sets the average value of the SQI values ​​for the predetermined number of times as the SQI value of the communication cable 61. If the communication cable deteriorates, the SQI value will continue to deteriorate, so by calculating the average value for the predetermined number of times, it is possible to reduce the influence of sudden noise, etc.

[0091] Furthermore, the control unit 211 acquires the SQI value of the communication cable 61 at the time of system startup, and sets the SQI value as the reference value. Therefore, it is not necessary to determine the reference value in advance and store it in the storage unit 212.

[0092] [Software implementation example] The functional blocks of master device 10, 10' and slave device 21a' (particularly control units 101, 101' and 211) may be realized by a logic circuit (hardware) formed on an integrated circuit (IC chip) or the like, or may be realized by software.

[0093] In the latter case, the master device 10, 10' and the slave device 21a' are equipped with a computer that executes instructions of a program, which is software that realizes each function. The computer is equipped with, for example, one or more processors and a computer-readable recording medium that stores the program. The object of the present invention is achieved by having the processor in the computer read and execute the program from the recording medium.

[0094] The processor may be, for example, a CPU (Central Processing Unit). The recording medium may be a "non-transitory tangible medium", such as a ROM (Read Only Memory), tape, disk, card, semiconductor memory, programmable logic circuit, or the like. The computer may further include a RAM for expanding the program. The program may be supplied to the computer via any transmission medium capable of transmitting the program (such as a communication network or broadcast waves). One aspect of the present invention may also be realized in the form of a data signal embedded in a carrier wave, in which the program is embodied by electronic transmission.

[0095] The present invention is not limited to the above-described embodiments and examples, and various modifications are possible within the scope of the claims. Embodiments obtained by appropriately combining the technical means disclosed in the different embodiments and examples are also included in the technical scope of the present invention. [Explanation of symbols]

[0096] 1,1' Communication Cable Evaluation System 10,10' Master device 15~17 Hub device 21a~21e, 21a'~21e', 22a~22c, 23a~23c Slave device 30 PC 40 Human Machine Interfaces 61~66 Communication cable 101, 101', 211 Control section 102,102',212 Storage section 103, 103', 213 Communications Department

Claims

1. A communication unit that communicates with a master device via a communication network; a control unit that acquires information regarding a signal quality of a communication cable to be connected, evaluates the quality of the communication cable based on the information regarding the signal quality, and notifies a user via the master device according to a degree of deterioration in the quality of the communication cable; The control unit calculates an average value of information regarding the signal quality of the communication cable for a predetermined number of times, uses the information regarding the signal quality immediately after system startup as a reference value, and evaluates the quality of the communication cable based on the difference between the reference value and the average value.

2. 2 . The slave device according to claim 1 , wherein the control unit notifies the master device, via the communication unit, of a port number to which the communication cable having deteriorated quality is connected.

3. 3. The slave device according to claim 1, wherein the information regarding the signal quality of the communication cable is obtained by a physical layer control circuit.

4. A communication cable evaluation system including a master device, a plurality of slave devices, and a terminal device, Each of the plurality of slave devices includes a first communication unit that communicates with the master device via a communication network; a first control unit that acquires information regarding a signal quality of a communication cable to be connected, evaluates the quality of the communication cable based on the information regarding the signal quality, and transmits an evaluation result of the quality of the communication cable to the master device via the first communication unit; the master device has a second communication unit that communicates with the plurality of slave devices and the terminal device via the communication network; a second control unit that receives an evaluation result of the quality of the communication cable from the plurality of slave devices via the second communication unit, and notifies the terminal device according to a degree of deterioration of the quality of the communication cable via the second communication unit; The first control unit calculates an average value of information regarding the signal quality of the communication cable for a predetermined number of times, uses the information regarding the signal quality immediately after system startup as a reference value, and evaluates the quality of the communication cable based on the difference between the reference value and the average value.

5. a slave device acquiring information regarding the signal quality of a communication cable to which the slave device is connected; evaluating a quality of the communication cable based on the information regarding the signal quality; notifying a user of the deterioration of the quality of the communication cable according to the degree of the deterioration of the quality of the communication cable; A communication cable evaluation method, in which in the step of evaluating the quality of the communication cable, an average value of information regarding the signal quality of the communication cable for a predetermined number of times is calculated, the information regarding the signal quality immediately after system startup is used as a reference value, and the quality of the communication cable is evaluated according to the difference between the reference value and the average value.

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