JP2012112764A - Communication line inspection method and communication device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To surely detect communication failure due to attachment of refuse such as metal scrap and dust to a communication line.SOLUTION: In a communication line inspection method, by using a plurality of combinations of amplitude voltages and frequencies of communication signals, a communication line is tested. Moreover, a combination range of the amplitude voltages and the frequencies in which communication signals can be normally transmitted and received is specified based on the test results.

Description

  The present invention relates to a method for inspecting a communication line connecting communication devices, and a communication device.

  In recent years, communication interfaces for communication between LSIs (Large Scale Integration) such as QPI (Quick Path Interconnect) and PCI (Peripheral Component Interconnect) Express have been accelerated.

  As a result, the influence of printed circuit board manufacturing variations on the wiring impedance has increased. Due to the influence of this variation, there is a problem that the impedance of the wiring changes and the signal waveform is disturbed. In addition, the timing at which signals are received may be shifted due to the influence of variations in the wiring length of the communication interface. Furthermore, the higher the frequency of the communication signal is, the greater the resistance loss due to the skin effect and the dielectric loss due to the dielectric loss tangent of the substrate material, and thus the attenuation of the amplitude voltage increases. For this reason, it becomes difficult to receive a signal correctly, so that the frequency of a communication signal is high.

  In order to solve the above-described problems, it is necessary to check whether the transmitted data can be correctly received by changing the amplitude voltage of the communication interface and the signal transmission timing at the time of shipping inspection. As an example of a technique for performing this confirmation, there is communication interface inspection software (product name: Scanworks) manufactured by ASSET Intertech, which is introduced in Non-Patent Document 1 below.

  In order to check the operation of the communication interface, it is necessary to check whether data can be transmitted and received at a frequency that may be used on the communication interface at the time of shipping inspection. As an example of this inspection method, there is PCI Express GEN2 link training introduced in Non-Patent Document 2 below. In the link training, it is tested whether or not the link can be performed at 2.5 GT / s (Transfer per Second) which is a frequency defined in the specification of Non-Patent Document 2 and 5.0 GT / s.

ASSET Intertech, Fact Sheet on the IBIST QPI Tool for Scan Works, URL: “http://www.aSSet-intertech.com/pdfS/QPI_Validation_ToolSet.pdf”, search on August 30, 2010 PCI EXPRESS BASE SPECIFICATION REV 2.0 P.I. 184

  The information processing apparatus is installed not only in a data center server room with a small amount of dust and other dust, but also in an environment where there is a large amount of dust and metal dust around the home or office. The information processing apparatus takes in external air into the casing using a cooling fan prepared for cooling the casing. At this time, if dust enters the casing together with air and contacts a part of the transmission path of the communication interface, stray capacitance or a floating inductor may be generated to hinder communication.

  FIG. 11 shows the influence of dust 1104 such as metal dust or dust attached to the communication line 1101 with an equivalent circuit of the stray capacitance 1102 and the stray inductor 1103. When dust 1104 adheres to the communication line 1101, the stray capacitance 1102 and the floating inductor 1103 are formed, and the impedance of the communication line 1101 changes. As a result, the communication waveform may be distorted.

  FIG. 12 shows an example of the impedance versus frequency characteristic of the communication line 1101 in the equivalent circuit of FIG. As can be seen from FIG. 12, the impedance of the equivalent circuit of FIG. 11 greatly increases at a specific frequency. This frequency is called the resonance frequency.

  When the frequency of the signal on the communication interface is a frequency close to the resonance frequency of the equivalent circuit in FIG. 11, the amplitude voltage of the signal waveform decreases, so that the transmitted signal may not be received correctly.

  Further, the position of the dust 1104 may be shifted due to the influence of the cooling fan wind or the vibration of the information processing apparatus, and the contact state with the communication line 1101 may change. At this time, the resonance frequency of the communication line 1101 changes according to the position of the dust 1104. Accordingly, even if the frequency used on the communication interface is not close to the resonance frequency of the equivalent circuit in FIG. 11 before the dust 1104 moves, the resonance frequency is changed to the communication interface by changing the position of the dust 1104. It may be close to the frequency used above and communication may be hindered.

  In Scanworks introduced in Non-Patent Document 1, only the frequency defined on the communication interface is the inspection target. In Scanworks, the amplitude voltage of the communication interface and the transmission timing are changed simultaneously to check that the transmitted data can be received correctly. However, since only the specified frequency is inspected, if the resonance frequency is greatly deviated from the specified frequency, it may not be possible to detect that dust is attached to the communication line. For example, even if dust is attached to the communication line, depending on the position of the dust, the resonance frequency of the communication line is greatly deviated from a specified frequency, so that dust may not be detected at the time of performing the inspection by Scanworks. However, as described above, there is a possibility that the position of the dust is shifted during the operation of the device, and a communication failure that cannot be detected at the time of inspection may occur.

  In the PCI Express link training introduced in Non-Patent Document 2, data transmission / reception is performed correctly at two frequencies of 2.5 GT / s and 5.0 GT / s defined in the PCI Express specification. Check. In other words, in link training, only two types of frequencies are inspected with a constant amplitude voltage, so even if the resonance frequency is close to the specified frequency, the transmitted data may be received correctly if the attenuation of the amplitude voltage is small. . Therefore, even if link training is performed, it may not be possible to reliably detect that dust such as metal dust or dust is attached to the communication line.

  That is, in the conventional communication line inspection method, it has been difficult to reliably detect a communication failure due to dust such as metal dust or dust adhering to the communication line.

  The inventor of the present application generates a communication failure due to dust such as metal dust or dust adhering to the communication line even at an amplitude voltage and frequency different from the amplitude voltage and frequency defined by the specifications of the communication interface. In addition, it has been found that the communication failure can also occur at a specified amplitude voltage and frequency during operation of the device.

  In the communication line inspection method according to the present invention, the communication line is tested using a plurality of combinations of the amplitude voltage and the frequency of the communication signal. Moreover, the combination range of the amplitude voltage and frequency which can transmit / receive a communication signal normally is specified based on the test result.

  According to the communication line inspection method of the present invention, a communication line is tested for a combination of a plurality of amplitude voltages and frequencies, regardless of the amplitude voltage and frequency defined by the communication interface. This can identify combinations of amplitude voltage and frequency that can potentially cause poor communication.

It is a figure which shows the internal structure of the blade type | mold server system which concerns on Embodiment 1. FIG. FIG. 3 is a diagram illustrating detailed configurations of a server blade 100 and a switch module 300, respectively. 3 is a diagram illustrating a configuration example of a loopback circuit 312. FIG. The loopback circuit 312 includes switching elements 3121 and 3122. It is a table that holds a combination of amplitude voltage and frequency of a communication signal stored in the memory 124 and used in a communication test. 6 is a diagram illustrating a processing flow in which an LSI 120 performs a communication test of a communication line 401. FIG. FIG. 5 is a diagram illustrating a result of performing the communication test described in the first embodiment using the combination table of amplitude voltage and frequency described in FIG. 4. It is the figure which showed the result of the communication test which the memory 124 hold | maintains in the table format. It is a figure which shows the table which extracted only the test result whose test result is "OK" among the test results shown in FIG. It is a figure which shows the example of the result of having implemented the secondary test with respect to the combination of the amplitude voltage and frequency whose result of the primary test was "OK". It is the figure which showed the result of the secondary test illustrated in FIG. 9 in the table format. The influence given when dust 1104 such as metal dust or dust adheres to the communication line 1101 is shown by an equivalent circuit of the stray capacitance 1102 and the stray inductor 1103. 12 shows an example of impedance vs. frequency characteristics of the communication line 1101 in the equivalent circuit of FIG.

<Embodiment 1>
FIG. 1 is a diagram showing an internal configuration of a blade server system according to the first embodiment of the present invention. The blade type server system shown in FIG. 1 includes one or more server blades 100 (here, three server blades 100a, 100b, and 100c are illustrated), a relay board 200, and one or more switch modules 300 (here, three switch modules). 300a, 300b and 300c are illustrated).

  Since each server blade 100 and each switch module have the same configuration, the alphabetical suffixes are omitted for the components when they are collectively referred to below.

  The server blade 100 is a server device having a function as a server computer, and includes a CPU (Central Processing Unit) 110 and an LSI 120. The CPU 110 controls the overall operation of the server blade 100. The LSI 120 has a role as a communication device that communicates with other server blades 100.

  The switch module 300 is a device having a function as a signal relay device that connects each server blade, and includes an LSI 310. The LSI 310 serves as a communication device that relays communication signals between the server blades 100.

  Communication lines 401 to 409 connect the server blade 100 and the switch module 300 in a mesh shape. The relay board 200 is a circuit board for arranging each communication line. The specifications of the communication lines 401 to 409 can be designed as appropriate according to the communication speed required in the blade type server system. Here, it is assumed that it is configured as a differential communication path as used in PCI Express.

  FIG. 2 is a diagram illustrating detailed configurations of the server blade 100 and the switch module 300. Here, for convenience of description, only functional units corresponding to the communication line 401 shown in FIG. 1 are shown. However, it is added that the same configuration is provided for the number corresponding to the number of communication lines in practice.

  The LSI 120 includes a controller 121, an output unit 122, an input unit 123, and a memory 124. The controller 121 controls the amplitude voltage and frequency of the communication signal transmitted / received by the LSI 120. The output unit 122 transmits a communication signal via the communication line 401. The input unit 123 receives a communication signal via the communication line 401. The memory 124 holds a table describing a combination of amplitude voltage and frequency of a communication signal used when performing a communication test described later, and a test result.

  The LSI 310 includes an input unit 311, a loopback circuit 312, and an output unit 313. The input unit 311 receives a communication signal via the communication line 401. The loopback circuit 312 receives the communication signal received by the input unit 311 and outputs it to the output unit 313 as it is. The output unit 313 transmits a communication signal via the communication line 401.

  By using the loopback circuit 312, the communication signal transmitted from the LSI 120 can be returned to the LSI 120 as a response as it is. The LSI 120 transmits a communication signal describing predetermined test data to the switch module 310 and receives a communication signal describing the same test data. If there is no signal deterioration on the communication line 401, the same test data as the transmitted test data should be received. Therefore, the communication quality of the communication line 401 can be tested depending on whether or not both test data match.

  Since the loopback circuit 312 is not required except when the LSI 120 performs a communication test, the LSI 310 can turn on / off the function of the loopback circuit 312.

  FIG. 3 is a diagram illustrating a configuration example of the loopback circuit 312. The loopback circuit 312 includes switching elements 3121 and 3122. Each switching element is a switching element configured by using, for example, a MOSFET, and the connection between the input unit 311 and the output unit 313 can be turned on / off by being turned on / off. By turning on each switching element only when performing a communication test, the function of the loopback circuit 312 can be turned on only when necessary.

  In the first embodiment, the loopback circuit 312 is used to return the transmission signal to the LSI 120 as it is, but the same function may be realized using other methods. That is, if the LSI 120 can confirm that the communication signal has not deteriorated on the receiving side, other methods can be used.

  FIG. 4 is a table that stores combinations of amplitude voltages and frequencies of communication signals used in the communication test, which are stored in the memory 124. If dust adheres to the communication lines 401 to 409, the stray capacitance and the stray inductance change according to the contact state, the resonance frequency of the communication line changes, and the signal degradation characteristics change accordingly.

  Therefore, in the first embodiment, the communication test is performed in a wider range using the amplitude voltage and frequency other than the combination of the amplitude voltage and the frequency adopted by the communication standard used on the communication lines 401 to 409. It was.

FIG. 5 is a diagram illustrating a processing flow in which the LSI 120 performs a communication test on the communication line 401. Similar procedures can be used for other LSIs and other communication lines. Hereinafter, each step of FIG. 5 will be described.
(FIG. 5: Step S500)
The CPU 110 instructs the LSI 120 to perform a communication test of the communication line 401 based on an instruction from an operator of the server blade 100, for example. When the LSI 120 receives the instruction, this processing flow is started.
(FIG. 5: Step S501)
The controller 121 receives the instruction in step S500 from the CPU 110, and instructs the switch module 300 to turn on the loopback circuit 312. The LSI 310 receives the instruction and turns on the switching elements 3121 and 3122 of the loopback circuit 312.
(FIG. 5: Step S501: Supplement)
In this step, an instruction from the controller 121 to the LSI 310 may be transmitted via the communication line 401 or may be transmitted via another appropriate control interface.

(FIG. 5: Steps S502 to S503)
The controller 121 reads the table described with reference to FIG. 4 from the memory 124, and acquires the combination of the amplitude voltage and the frequency of the communication signal (S502). The controller 121 performs the following steps S504 to S507 for all combinations of amplitude voltages and frequencies acquired from the table (S503).
(FIG. 5: Step S504)
The controller 121 acquires the combination of amplitude voltage and frequency described in the table in order from the top, and instructs the output unit 122 to transmit a communication signal using the amplitude voltage and frequency.
(FIG. 5: Step S505)
The controller 121 instructs the output unit 122 to transmit predetermined test data. The output unit 122 transmits a communication signal describing the test data to the switch module 300 using the amplitude voltage and frequency received in step S504.
(FIG. 5: Step S505: Supplement)
The test data used in this step may be stored in advance in the controller 121 or the memory 124, or may be generated by the controller 121 using, for example, a random number sequence when this step is performed.

(FIG. 5: Step S506)
The input unit 123 receives the communication signal transmitted from the output unit 122 in step S505 when it returns via the loopback circuit 312. The controller 121 determines whether or not the test data transmitted in step S505 matches the test data described in the communication signal received in this step. If they match, it is determined that the communication line 401 has not caused a communication failure. If they do not match, it is determined that a communication failure has occurred in the communication line 401.
(FIG. 5: Step S507)
The controller 121 stores the determination result of step S506 in the memory 124 as a test result for the currently used amplitude voltage and frequency.
(FIG. 5: Steps S503 to S507: Supplement)
The controller 121 may transmit the test data only once for each combination of the amplitude voltage and the frequency each time the steps S503 to S507 are performed, or transmit the test data a plurality of times for the same combination of the amplitude voltage and the frequency. May be. In the latter case, if the test data does not match even once, it is determined that a communication failure has occurred for the combination of the amplitude voltage and the frequency.

(FIG. 5: Step S508)
The controller 121 instructs the switch module 300 to turn off the loopback circuit 312. The LSI 310 receives the instruction and turns off the switching elements 3121 and 3122 of the loopback circuit 312. The instruction path is the same as in step S501.
(FIG. 5: Step S509)
The controller 121 reports the result of the above communication test to the CPU 110. The CPU 110 notifies the result to the operator of the server blade 100, for example. Further, the CPU 110 may instruct the controller 121 to prohibit the use of the communication line in which the communication failure has occurred in the subsequent communication as necessary.

  The procedure for performing the communication test using a plurality of combinations of the amplitude voltage and the frequency of the communication signal has been described above. By using this method, it is possible to detect dust that cannot be detected within the range defined by the communication standard. In which range, if the dust is not found, the test is accepted. For example, the required communication quality is acceptable, for example, the test can be passed within a predetermined range including before and after the range defined in the communication standard. Appropriate criteria may be determined according to

<Embodiment 1: Summary>
As described above, according to the first embodiment, the LSI 120 performs the communication test of the communication lines 401 to 409 using a plurality of combinations of the amplitude voltage and the frequency of the communication signal. As a result, even a hidden communication failure that is difficult to detect at the time of communication using an amplitude voltage and frequency in accordance with a communication standard can be detected efficiently.

  That is, as described above with reference to FIGS. 11 to 12, depending on the position of dust adhering to the communication line, when the resonance frequency does not overlap, communication is performed using the amplitude voltage and frequency according to the communication standard. As long as this is the case, there is a possibility that deterioration of communication quality cannot be detected. According to the first embodiment, since the communication test is performed beyond the range of the amplitude voltage and the frequency according to the communication standard, the communication is performed within the range according to the communication standard as described in Non-Patent Documents 1 and 2. Even a communication failure that is difficult to detect as long as the test is performed can be detected.

<Embodiment 2>
In the first embodiment, it has been described that the communication test is performed using a plurality of combinations of the amplitude voltage and the frequency of the communication signal. On the other hand, when a communication test is performed using an extremely high frequency or an extremely low amplitude voltage, it can be said that a communication failure is likely to occur regardless of whether dust is attached to the communication line. Therefore, when carrying out a shipping inspection of an actual product, it is desirable that there is a standard as to which range should be able to communicate normally and that the inspection should be passed.

  Therefore, in the second embodiment of the present invention, the inspection method described in the first embodiment is performed on an evaluation communication line or the like, and the range of the amplitude voltage and frequency in which the product can normally communicate is determined in advance. Create standards for shipment inspection. Since the configuration and inspection procedure of each device are the same as those in the first embodiment, the following description will focus on matters specific to the second embodiment.

  FIG. 6 is a diagram illustrating a result of performing the communication test described in the first embodiment using the combination table of amplitude voltage and frequency described in FIG. Here, an example was shown in which a communication test was performed for 42 combinations of seven amplitude voltage values and six frequency values.

  Circles in FIG. 6 indicate that steps S504 to S507 are performed a plurality of times for the same combination of amplitude voltage and frequency, and the transmitted test data and the received test data match each time. In FIG. 6, “X” indicates that the test data transmitted at least at one time does not match the received test data. In general, it can be seen that communication failure tends to occur as the frequency increases and the amplitude voltage decreases.

  FIG. 7 is a diagram showing the result of the communication test held in the memory 124 in a table format. A combination corresponding to ◯ in FIG. 6 is represented by “OK”, and a combination corresponding to x in FIG. 6 is represented by “NG”. In step S509, the controller 121 reports a test result as shown in FIG.

  FIG. 8 is a diagram illustrating a table obtained by extracting only the test results “OK” from the test results illustrated in FIG. 7. When the communication test described in the first embodiment is performed on an evaluation device in which it is known in advance that dust or the like is not attached to the communication line, the device is similarly free of dust or the like. When the communication test is performed, the same result as in FIG. 8 should be obtained.

  Therefore, in the second embodiment, the communication test described in the first embodiment is performed as a primary test on the apparatus for evaluation described above, and the obtained result is used as a pass criterion for subsequent shipping inspection (secondary test). It will be used as. For example, if dust adheres to the communication line during the manufacturing process, the result of the secondary test is considered to be worse than the result of the primary test.

  The primary test procedure and the secondary test procedure may be the same. For example, the procedure described in FIG. 5 of the first embodiment can be used.

  FIG. 9 is a diagram illustrating an example of a result of performing the secondary test on the combination of the amplitude voltage and the frequency in which the result of the primary test is “OK”. For a combination in which the result of performing the primary test on an apparatus to which dust or the like is not attached is “OK”, the result of the secondary test should also be “OK”.

  As shown in FIG. 9, when a communication failure occurs in any combination of amplitude voltage and frequency in the secondary test, dust or the like causing the communication failure may be attached to the communication line. There is sex. Therefore, even if the combination of the amplitude voltage and frequency is a combination that is not used in communication specifications, the secondary test is treated as a failure.

  Even if the combination of the amplitude voltage and the frequency is a combination that is not used in communication specifications, as described in FIGS. 11 to 12, the resonance frequency of the communication line changes due to the movement of dust, etc. As a result, there is a possibility of causing communication failure in a range overlapping with the communication specification.

  FIG. 10 is a diagram showing the results of the secondary test illustrated in FIG. 9 in a table format. A combination corresponding to ○ in FIG. 9 is represented by “OK”, and a combination corresponding to x in FIG. 9 is represented by “NG”. In step S509 of the secondary test, the controller 121 reports a test result as shown in FIG.

  Although the example in which the secondary test is performed as the product shipment inspection has been described above, the same secondary test can be performed after the product shipment. For example, a communication test similar to the secondary test may be performed when the user instructs the product to perform a communication test or when the product is activated, and the result may be reported to the user. When the test result is NG, the user can attempt to resolve the problem at an early stage by cleaning the inside of the product housing or inquiring to the manufacturer support. The CPU 110 can also analyze the cause of the failure using detailed data when the test result is NG.

<Embodiment 2: Summary>
As described above, in the second embodiment, by performing a primary test using an evaluation apparatus, the range of amplitude voltage and frequency that can be normally communicated when dust or the like is not attached is specified. This is used as a reference for subsequent communication tests. As a result, the product shipment inspection can be carried out on an objective basis, so that the test can proceed efficiently.

  In addition, by configuring each device so that the secondary test described in the second embodiment can be performed even after product shipment, even if dust adheres to the communication line after product shipment, this can be effectively performed. Can be detected. Thereby, the communication failure which arises because of a user environment can be discovered at an early stage.

<Embodiment 3>
When dust adheres to the communication line, the amplitude voltage is greatly attenuated when communicating at a frequency close to the resonance frequency formed by the stray capacitance or the stray inductor. Therefore, if dust adheres to the communication line after passing the primary test described in the second embodiment, the lowest amplitude voltage is used in any of the frequencies because the secondary test is likely to fail. It becomes a combination. In addition, if the attenuation of the amplitude voltage due to the influence of dust is small, the amplitude voltage attenuated by the dust may be sufficiently high, and transmission data may be received correctly. In this case, the adhesion of dust cannot be reliably detected.

  Therefore, in the secondary test of the second embodiment, among the combinations of frequencies and amplitude voltages that have passed the primary test, a combination using the lowest amplitude voltage at each frequency may be preferentially tested. As a result, not only can dust be detected more reliably, but if dust is actually attached to the communication line, it can be detected at an early stage, so that the efficiency of the communication test can be increased.

<Embodiment 4>
In the communication test described in the first to third embodiments, the following method can be used to further enhance the test effect.
(Method 1 to increase test effect)
The combination of the amplitude voltage and the frequency for performing the communication test is a combination in a wider range than the range defined in the communication standard from the viewpoint of detecting a communication failure due to the movement of dust as described in FIGS. It is desirable to use it. In order to increase detection accuracy, it is desirable to perform a communication test in the widest possible combination range.
(Method 2 to increase test effect)
When the communication line is configured as a differential transmission path, if any of the paired communication lines is disconnected, the amplitude voltage of the communication signal is half that of the normal state. In order to reliably detect this disconnection failure, the voltage interval between the combinations of the amplitude voltages for which the communication test is performed may be set to be smaller than half of the amplitude voltage at the normal time. As a result, since a communication failure always occurs in any combination when a disconnection occurs, a disconnection failure of the differential transmission path can be reliably detected.

(Method 3 to increase test effect)
Even if the frequency range for performing the communication test is wide, it is not practical to perform the communication test by 1 T / s in a range from 1.0 GT / s to 10.0 GT / s, for example. It is necessary to set an appropriate frequency interval for performing the communication test. Therefore, assuming that the HIGH signal and the LOW signal are continuous, the frequency interval at which the communication test is performed is obtained by dividing the maximum frequency guaranteed in the communication standard by the maximum number of bits that can be continuous in the communication standard. May be set as
(Method 3 for enhancing test effect: supplement)
For example, in a communication signal of 100 MHz, it is assumed that there is a possibility that a maximum of four bits having the same value are consecutive in the communication standard. If all four bits are consecutive, the signal waveform appears to be 25 MHz in appearance. Use of this method is desirable in that a communication test can be performed in a frequency band closer to an actual signal waveform. Moreover, it can be said that it is appropriate in terms of use as an interval between frequencies at which the communication test is performed. That is, the number of tests can be reduced while ensuring the significance as a communication test, which is advantageous.

<Embodiment 5>
In the first to fourth embodiments described above, the example of testing the differential transmission line used in the blade type server system has been described. However, with respect to the other communication lines, the signal is deteriorated due to dust or the like being attached. Since it is the same, it can test | inspect using the method similar to Embodiment 1-4.

  For example, dust is relatively easily attached to a connector portion of a LAN (Local Area Network) cable included in a computer, which may cause a communication failure. The method according to the present invention is also effective when inspecting such a communication failure.

  The object to be inspected using the method according to the present invention is not limited to the differential transmission path. The communication failure caused by the adhering of dust is the same in other types of communication lines. Also for these communication lines, adhesion of dust can be detected by testing using a plurality of combinations of amplitude voltage and frequency.

  As mentioned above, the invention made by the present inventor has been specifically described based on the embodiment. However, the present invention is not limited to the embodiment, and various modifications can be made without departing from the scope of the invention. Needless to say.

  In addition, each of the above-described configurations, functions, processing units, etc. can be realized as hardware by designing all or part of them, for example, with an integrated circuit, and the processor executes a program that realizes each function. By doing so, it can be realized as software. Information such as programs and tables for realizing each function can be stored in a storage device such as a memory or a hard disk, or a storage medium such as an IC card or a DVD.

  100: Server blade, 110: CPU, 120: LSI, 121: Controller, 122: Output unit, 123: Input unit, 124: Memory, 200: Relay board, 300: Switch module, 310: LSI, 311: Input unit 312: Loopback circuit, 3121 and 3122: switching element, 313: output unit, 401-409: communication line.

Claims (9)

A method for inspecting a communication line connecting a first communication device and a second communication device,
A first test data transmission step of transmitting a first test data signal describing test data from the first communication device to the second communication device;
A second test data transmitting step in which the second communication device receives the first test data signal and transmits a second test data signal using the received first test data signal as a response to the first communication device; ,
The first communication device receives the second test data signal, and the content of the test data described by the first test data matches the content of the test data described by the second test data. A determination step of determining communication quality of the communication line according to whether or not,
A repetition step of performing the first test data transmission step, the second test data transmission step, and the determination step using a plurality of the first test data signals having different combinations of frequency and amplitude voltage;
Based on the result of the repetition step, a range specifying step for specifying a range of the frequency and the amplitude voltage at which the contents of the test data match in the determination step;
A communication line inspection method characterized by comprising: Using the first communication device, the second communication device, and the communication line for quality evaluation, the first test data transmission step, the second test data transmission step, the determination step, the repetition step, and the A primary test step for performing a range identification step;
Within the range of the frequency and the amplitude voltage specified using the first communication device, the second communication device, and the communication line for quality evaluation, the first communication device subject to shipment inspection or after shipment, A secondary test step for executing the first test data transmission step, the second test data transmission step, the determination step, the repetition step, and the range specifying step using the second communication device and the communication line; ,
The communication line inspection method according to claim 1, further comprising: 3. The communication line inspection according to claim 2, wherein, in the repetition step executed in the secondary test step, the determination step is executed by using the lowest amplitude voltage used in combination with the frequency preferentially. Method. In the determination step,
When the content of the test data described by the first test data does not match the content of the test data described by the second test data,
Determining that the communication line does not have communication quality capable of signal transmission using the frequency and the amplitude voltage used when executing the determination step, and outputting a notification to that effect, or The communication line inspection method according to claim 1, wherein the communication line is disabled. In the secondary test step,
When the contents of the test data do not match within the range of the frequency and the amplitude voltage, it is determined that the first communication device, the second communication device, and the communication line to be inspected for shipment cannot be shipped. The communication line inspection method according to claim 2. In the repetition step,
The first test data transmission step, the second test data transmission step, and the determination step for frequencies in a wider range than the frequency range defined by the communication specifications used by the first communication device and the second communication device. The communication line inspection method according to claim 1, wherein: In the repetition step,
The first test data transmission step, the second test data transmission step, and the determination step are executed at a voltage interval smaller than a half of the amplitude voltage used by the first communication device and the second communication device. The communication line inspection method according to claim 1, wherein: In the repetition step,
The first test data at a frequency interval obtained by dividing the maximum frequency specified by the communication specification used by the first communication device and the second communication device by the maximum number of continuous bits specified by the communication specification. The communication line inspection method according to claim 1, wherein the transmission step, the second test data transmission step, and the determination step are executed. A transmission unit that transmits a first test data signal describing test data to a destination device via a communication line;
A receiving unit for receiving, from the destination device, a second test data signal using the first test data signal received by the destination device as a response;
A control unit that determines the communication quality of the communication line based on whether or not the content of the test data described by the first test data matches the content of the test data described by the second test data; ,
With
The controller is
Using the plurality of first test data signals having different combinations of frequency and amplitude voltage, repeatedly performing the transmission unit, the reception unit, and the determination,
Based on the result of the repetition, the range of the frequency and the amplitude voltage that match the content of the test data in the determination is specified.

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