JP2009122053A - Cable disconnect detector - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a cable disconnect detector which detects disconnection of a cable and contact failures of a connector, in a state where networking equipment are connected by the cable so as to be in a communication enabled state with one another. <P>SOLUTION: In the cable disconnect detector 320, a capacitor C and a secondary winding of a transformer T1a are connected in parallel between a wire 4a and one end of an existing pulse transformer 101, and a capacitor C and a secondary winding of a transformer T1b are connected in parallel, between a wire 4b and the other end of the existing pulse transformer 101. When a low-frequency signal is input from a low-frequency transmitter 30 into a primary winding of the transformer T1a, loop current 13 is excited, and induced current flows in the secondary winding of the transformer T1b. The induced current is detected by a loop current detector 11, thereby detecting that there is neither disconnect of the cable nor contact failure of the connector. In the above operation, the transmitter 30 is controlled, such that the loop current 13 and loop current 15 do not offset each other. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a technology related to a cable break detection device that detects cable breaks and poor connector contact in an environment in which network devices are connected to each other.

  When a network device is connected to a communication cable, the link pulse indicates which standard (communication speed and communication mode such as full-duplex or half-duplex) the network device of the communication partner physically connected to corresponds. To exchange information. Then, based on the exchanged information, the connected network device sets a communication speed and a communication mode so that its communication state is optimized. Such a function is called auto-negotiation.

  However, the auto-negotiation is performed on the assumption that network devices are operating normally and are properly connected to a communication cable. For this reason, in auto-negotiation, when information exchange using link pulses cannot be performed normally, this may be due to a failure of the network device, or a disconnection of the communication cable connecting the network devices or contact of the connector. It is difficult to detect whether it is caused by a defect.

Inventions for detecting disconnection of communication cables and contact failure of connectors are disclosed in Patent Document 1 and Patent Document 2.
In Patent Document 1, a LAN (Local Area Network) cable is laid on the premises, and then a resistance value of a LAN cable alone is measured using a direct current, and a high-frequency signal of 16 MHz is used between wire pairs. A method for measuring the amount of crosstalk is disclosed.
Patent Document 2 discloses that the contact resistance of the connector is obtained by comparing the voltage caused by the connector of the electronic control device and the noise removing capacitor with the reference voltage corresponding to the contact resistance of the connector being almost zero. A method for measuring whether it is within an allowable range is disclosed.
JP-A-7-301654 (see paragraphs 0006 to 0008) JP 2000-230960 A (see paragraphs 0021 to 0022, FIG. 2)

However, in the invention described in Patent Document 1, there is a problem that the disconnection of the communication cable and the contact failure of the connector cannot be detected when the LAN cable is connected to the network device.
The invention described in Patent Document 2 can be applied only when the capacitor (impedance) connected to the connector is known in advance. That is, the length of the communication cable connected to the connector changes, or a network device or the like is connected to the far end of the communication cable, which makes it difficult to apply when the impedance is different. is there.

  The present invention has been made in view of the above-described problems, and a signal for detecting disconnection of a communication cable or contact failure of a connector in a state where a network device is connected to the communication cable (LAN cable). The present invention relates to a cable disconnection detecting device including means for outputting to a communication cable and means for detecting an output signal for detecting disconnection. Then, when the cable disconnection detection devices are connected to the communication cable, it is an object to avoid a state in which the above-described disconnection detection signals cancel each other and cannot be measured.

  In order to solve the above problems, the cable break detection device in the present invention has a function of shifting the phase of the signal for disconnection detection, a function of sweeping the frequency of the signal for disconnection detection and shifting the timing of the sweep, By providing a function of switching and outputting disconnection detection signals of different frequencies at random intervals, it is possible to avoid a state in which the disconnection detection signals cancel each other and become unmeasurable.

According to the present invention, the cable break detection device or the cable break detection method can detect a disconnection of a communication cable or a contact failure of a connector in an environment in which network devices are connected to each other.
Further, according to the present invention, the cable break detection device or the cable break detection method can avoid a state in which signals for disconnection detection cancel each other and become unmeasurable.

<< First Embodiment >>
Hereinafter, a first embodiment of a cable breakage detection apparatus according to the present invention will be described with reference to FIG. FIG. 1 is a diagram illustrating a cable disconnection detection device built in a network device.

FIG. 1 shows a state where the network device A (100) and the network device B (200) are connected by a cable 400 via connectors 103 and 203, respectively.
The network device A (100) includes an existing pulse transformer 101 for reception and an existing pulse transformer 102 for transmission as part of a communication signal processing circuit. Note that a processing circuit (not shown) is omitted because it is not necessary for the description of the present invention.
Network device A (100) incorporates cable disconnection detection device 300 between existing pulse transformer 101 and connector 103 and between existing pulse transformer 102 and connector 103.
The network device B (200) includes an existing pulse transformer 201 for transmission and an existing pulse transformer 202 for reception as part of a communication signal processing circuit. Note that a processing circuit (not shown) is omitted because it is not necessary for the description of the present invention.
Then, the network device B (200), like the network device A (100), sets the cable disconnection detection device 300 between the existing pulse transformer 201 and the connector 203 and between the existing pulse transformer 202 and the connector 203. Built in.

  The existing pulse transformers 101, 102, 201, and 202 are provided for balanced connection between the network device A (100) and the network device B (200). That is, the functions of the existing pulse transformers 101, 102, 201, and 202 are the same for reception and transmission.

The cable 400 is a LAN cable, and generally includes eight (four pairs) wires. However, FIG. 1 shows only four (two pairs) wires 4a, 4b, 4c, and 4d used for communication. Examples of standards that use four wires for communication include 10BASE-T and 100BASE-TX. The wire 4a and the wire 4b are twisted to make a pair, and the wire 4c and the wire 4d are also twisted to make a pair.
The connectors 103 and 203 are a plug (RJ-45) connected to the cable 400 and a jack corresponding thereto.

  The cable breakage detection device 300 according to the first embodiment is installed between the existing pulse transformer 101 and the connector 103 and between the existing pulse transformer 102 and the connector 103. Therefore, the connection point t1 of the cable breakage detection device 300 and the existing pulse transformer 101, the connection point t2 and the wires 4a and 4b of the connector 103, the connection point t3 and the existing pulse transformer 102, and the connection point t4 and the wires 4c and 4d of the connector 103 are provided. Is connected.

Next, an internal circuit configuration of the cable disconnection detection device 300 will be described with reference to FIG. FIG. 2 is a diagram illustrating an example of a circuit configuration of the cable break detection device according to the first embodiment.
2 differs from FIG. 1 in that a detailed circuit of the cable breakage detection device 300 is shown and loop currents 13 to 16 are shown. The same circuits as those in FIG. 1 are denoted by the same reference numerals and description thereof is omitted.

First, a circuit configuration connected between the connection point t1 and the connection point t2 of the cable disconnection detection device 300 will be described.
Between the terminal above the connection point t1 (one terminal of the existing pulse transformer 101) and the terminal above the connection point t2 (one wire in the pair of wires; the wire 4a), a capacitor C (first 1 filter) is connected. The secondary winding (or primary winding) of the transformer T1a (first transformer) is connected to both ends of the capacitor C. The low-frequency transmitter 10 (signal transmitter) is connected to the primary winding (or secondary winding) of the transformer T1a, and the other end is grounded.
Further, the above-described upper terminal is connected to the lower terminal of the connection point t1 (the other terminal of the existing pulse transformer 101) and the lower terminal of the connection point t2 (the other wire in the pair of wires; the wire 4b). Similarly to the case of the terminal, the capacitor C (second filter) and the primary winding (or secondary winding) of the transformer T1b (second transformer) are connected in parallel. The loop current detector 11 (detector) is connected to the secondary winding (or primary winding) of the transformer T1b, and the other end is grounded.
Between the lower terminal of the connection point t3 (one terminal of the existing pulse transformer 102) and the lower terminal of the connection point t4 (one wire in the pair of wires; the wire 4d), the capacitor C Is connected. The secondary winding (or primary winding) of the transformer T2a is connected to both ends of the capacitor C. The low-frequency oscillator 10 is connected to the primary winding (or secondary winding) of the transformer T2a, and the other end is grounded.
Further, the lower terminal described above is also applied to the upper terminal of the connection point t3 (the other terminal of the existing pulse transformer 102) and the upper terminal of the connection point t4 (the other wire in the pair of wires; the wire 4c). Similarly to the terminal, the capacitor C and the primary winding (or secondary winding) of the transformer T2b are connected in parallel. The loop current detector 11 is connected to the secondary winding (or primary winding) of the transformer T2b, and the other end is grounded.

The low-frequency transmitter 10 outputs a low-frequency signal (a low-frequency signal lower than the frequency band used for communication by the network device) such that the inductance components of the existing pulse transformers 101, 102, 201, and 202 can be almost ignored. . The magnitude of the loop current induced thereby is such that the existing pulse transformers 101, 102, 201, 202 are not saturated.
The loop current detector 11 has a function of detecting a current induced in the secondary winding of the transformer T1b and the secondary winding of the transformer T2b. The loop current detector 11 includes an amplifier circuit, a detection circuit, and a processing circuit that processes the output of the detection circuit. Then, the loop current detector 11 displays the processed result on the display 12.

Next, the operation of the cable break detection device 300 will be described with reference to FIG.
First, the network device A (100) and the network device B (200) have the same circuit configuration, and the connection point t1-t2 side and the connection point t3-t4 side have the same circuit configuration. Therefore, the connection point t1-t2 side will be described as a representative.
The low frequency signal output from the low frequency transmitter 10 is excited (superposed) on the wire 4a by the transformer coupling of the transformer T1a. When the cable 400 is not disconnected and there is no poor contact of the connector, the loop current 13 is formed as shown in FIG. 2 via the existing pulse transformer 201 of the counterpart network device B (200). .

  When the loop current 13 passes through the transformer T1b, an induced current flows through the secondary winding on the side to which the loop current detector 11 is connected due to transformer coupling. At that time, the loop current detector 11 detects the induced current and determines that there is no disconnection of the cable 400 and there is no contact failure of the connector.

  However, if the cable is disconnected or the connector is poorly connected, the loop is not formed, and thus the loop current 13 is not formed. At that time, since the loop current detector 11 cannot detect the induced current, the loop current detector 11 determines that there is a disconnection of the cable 400 or a contact failure of the connector.

  When the loop current detector 11 detects the loop current 13, the indicator 12 is normal (the state where there is no cable disconnection or connector contact failure) by causing an LED (Light Emitting Diode) or the like to emit light. Is displayed. Or, conversely, the LED may emit light and display when there is an abnormality (a state in which the cable is disconnected or the connector is poorly connected).

In addition, the loop current 13 and a communication signal used for communication are superimposed on the cable 400. Since the communication signal has a high frequency, it cannot pass through the transformers T1a and T1b, but can pass through the capacitor C. Therefore, even if the cable disconnection detection device 300 is built in, there is no trouble in communication. Further, since the loop current 13 has a low frequency, it cannot pass through the capacitor C, but can pass through the transformers T1a and T1b. Therefore, the loop current 13 can be detected by the loop current detector 11.
Since the filter and the transformer are arranged symmetrically with respect to the pair of wires 4a and 4b, the communication cable does not lose its balance, and the network device on which the circuit of the present invention is mounted is installed. Even when connected, communication performance is not adversely affected.

  The above-described operation is the same for the connection point t3-t4, and is the same for the network device B (200). However, the flow of the loop currents 15 and 16 formed by the network device B (200) is opposite to the flow of the loop currents 13 and 14, respectively, as shown in FIG.

  Here, the loop current 13 and the loop current 15 overlap on the wires 4a and 4b. When the amplitude and frequency of the loop currents 13 and 15 are exactly the same and the phase relationship is accidentally shifted by 180 degrees, the loop currents 13 and 15 cancel each other, and the loop current does not flow. . As a result, there is a concern that it is difficult to detect disconnection normally.

  However, in actuality, the low frequency transmitters 10 of the cable breakage detection device 300 incorporated in the network devices A (100) and B (200) are operating asynchronously. Since the oscillation frequency and amplitude have an error due to the accuracy of the components to be constructed and the variation in circuit voltage, they are very rarely equal. Therefore, it is extremely rare for the signals generated by the two low-frequency transmitters 10 to be connected in a state where they are exactly 180 degrees out of phase.

  Even if the signal phase is accidentally connected by 180 degrees, as described above, each low-frequency transmitter 10 operates independently, and the oscillation frequency operates with some error. It is what you are doing. Since the waveforms of the low-frequency signals output from the respective low-frequency transmitters 10 cannot normally have completely the same period or the same amplitude, the waveforms of both of them deviate after a certain period of time. It will be. Therefore, even with the configuration of FIG. 2, disconnection detection is possible.

In order to detect disconnection more reliably, for example, a disconnection detection may be performed by adding a circuit that does not detect disconnection for a certain period of time.
Specifically, the processing circuit of the loop current detector 11 includes a counter, and the time during which the loop currents 13 to 16 can be detected and the time during which the loop currents 13 cannot be detected corresponds to how many clocks are generated at predetermined intervals. By measuring the time, the time length is determined. Further, the processing circuit of the loop current detector 11 has a time for ignoring determination as a dead zone when the number of clocks is less than a preset number (less than a predetermined time).
The processing circuit of the loop current detector 11 determines that the circuit is not disconnected when the number of clocks when the loop currents 13 to 16 can be detected is equal to or greater than a preset number (a predetermined time or more). Continue operation. Further, when the number of clocks when the disconnection detection signal cannot be detected is greater than or equal to a preset number (more than a predetermined time), the processing circuit of the loop current detector 11 causes disconnection of the cable or contact of the connector. It is determined that there is a defect.

  In addition, instead of causing the processing circuit of the loop current detector 11 to execute the above-described determination of whether or not the wire is disconnected, the network processing CPU (B) (200) for communication processing provided in advance in the network devices A (100) and B (200). Central Processing Unit) may execute.

As described above, the cable break detection device 300 is built in the network devices A (100) and B (200), so that the network device A (100) and the network device B (200) are connected with a cable. It becomes possible to detect disconnection of the cable 400 and poor contact between the connectors 103 and 203. In addition, since a loop is formed by the existing pulse transformers 101, 102, 201, and 202, the power of the network devices A (100) and B (200) is independent of the ON state or the OFF state, and the above method is used. It becomes possible to detect disconnection and poor contact of the connector.
In addition, with the configuration as shown in FIG. 2, the user can investigate the disconnection of the cable or the contact failure of the connector in the network device A (100) or the network device B (200) nearest to the network device. Therefore, there is an effect that the time for investigation can be shortened.

<< Second Embodiment >>
The case of further increasing the asynchrony of the low-frequency transmitters 10 incorporated in the network devices A (100) and B (200) described in the first embodiment will be described as a second embodiment with reference to FIG. To do. FIG. 3 is a diagram illustrating an example of enhancing the asynchronousness of the signal transmitter in the second embodiment.
3 differs from FIG. 2 in that a signal transmitter 20 is provided instead of the low-frequency transmitter 10 and a limiter circuit is provided in the loop current detector 23. Therefore, the network devices A (110) and B (210) and the cable disconnection detection device 310 are replaced by the same reference numerals, and the same circuits as those in FIG.

First, the signal transmitter 20 generates a disconnection detection signal (low frequency signal) by combining two or more oscillation circuits.
That is, as shown in FIG. 3, the signal transmitter 20 uses a first oscillator as a low frequency oscillation circuit (VCO; Voltage Controlled Oscillator) 21 to generate (sweep) a voltage signal to be input to the first oscillator. It is assumed that the second oscillator is constituted by a sweep oscillation circuit 22 (Sweep Oscillator).
The low frequency oscillating circuit (VCO) 21 has a function of changing an output frequency corresponding to the voltage of an input signal. The low-frequency oscillation circuit (VCO) 21 has a low-frequency signal (a low frequency lower than the frequency band used for communication by the network device) such that the inductance components of the existing pulse transformers 101, 102, 201, and 202 can be almost ignored. Signal). The sweep oscillation circuit 22 has a function of changing the voltage of the output signal by sweeping.
Since the low frequency oscillation circuit (VCO) 21 and the sweep oscillation circuit 22 incorporated in the network devices A (110) and B (210) all operate asynchronously, the output signals are asynchronous. That is, the low frequency oscillation circuit (VCO) 21 and the sweep oscillation circuit 22 have errors due to variations in component accuracy and circuit voltage, respectively, so that the oscillation frequency and amplitude are very equal. Few. Therefore, it is extremely rare that the phase of the signal generated by the low frequency transmitter 10 incorporated in the network devices A (110) and B (210) is just 180 degrees shifted. In addition, for each of the network devices A (110) and B (210), a signal in which the sweep range or sweep time interval of the voltage signal output from the sweep oscillation circuit 22 is changed is input to the low frequency oscillation circuit (VCO) 21. Then, the asynchronousness of the disconnection detection signal output from the low frequency oscillation circuit 21 is greatly increased as compared with the case of the low frequency transmitter 10 shown in FIG. That is, the possibility that the loop currents 13 and 15 or the loop currents 14 and 16 will accidentally cancel each other out is significantly reduced.

Next, the limiter circuit provided in the loop current detector 23 shown in FIG. 3 will be described.
The limiter circuit is a circuit that limits the amplitude and prevents the detection circuit from being adversely affected.
For example, the input signal to the loop current detector 23 is a waveform obtained by synthesizing the loop current 13 and the loop current 15 (or the loop current 14 and the loop current 16), and has a magnitude obtained by adding the maximum amplitude of both. It becomes the amplitude. Therefore, the maximum amplitude of the synthesized waveform is twice the amplitude of the loop currents 13 to 16 formed when there is one signal transmitter 20. Thus, since a signal with a large amplitude is input to the detection circuit of the loop current detector 23, it is necessary to limit the amplitude.
Note that if it is not necessary to limit the amplitude, the limiter circuit may not be provided.
Further, by using the saturation characteristic of the amplifier circuit, the same effect can be obtained even if the amplitude is limited.

  Further, the detection circuit provided in the loop current detector 23 shown in FIG. 3 has a function of performing envelope detection because the frequency of the signal input to the loop current detector 23 is a swept waveform. ing.

  As described above, by combining two or more oscillation circuits, it is possible to improve the asynchronousness of the disconnection detection signals output from the respective network devices A (110) and B (210). In an environment where network devices are connected to each other, it is possible to detect disconnection of a communication cable and poor contact of a connector.

<< Third Embodiment >>
In the third embodiment, in order to further enhance the asynchrony of the low-frequency transmitters 10 (see FIG. 2) built in the network devices A (100) and B (200) described in the first embodiment, 2 The case where the above different frequency is used is demonstrated below using FIG. FIG. 4 is a diagram illustrating an example of enhancing the asynchronousness of the signal transmitter in the third embodiment.
4 is different from FIG. 2 in that a signal transmitter 30 is provided instead of the low-frequency transmitter 10. Therefore, the reference numerals of the network devices A (120) and B (220) and the cable disconnection detection device 320 are changed, and the other circuits that are the same as those in FIG.

The signal transmitter 30 includes a random timer 31, a low frequency oscillation circuit a (32), a low frequency oscillation circuit b (33), and a signal control unit 34.
The low frequency oscillation circuit a (32) and the low frequency oscillation circuit b (33) output disconnection detection signals (low frequency signals) having different frequencies. Note that the low-frequency oscillation circuit a (32) and the low-frequency oscillation circuit b (33) are low-frequency signals (network devices) that can almost ignore the inductance components of the existing pulse transformers 101, 102, 201, and 202. (Low frequency signal lower than the frequency band used for communication) is output. In FIG. 4, two types of low-frequency oscillation circuits a (32) and b (33) are shown. However, the present invention is not limited to two types of oscillation circuits, and a single oscillation circuit has a plurality of frequencies. A signal may be generated, or three or more types may be provided for each frequency for generating an oscillation circuit.
The random timer 31 outputs a trigger signal to the signal control unit 34 at random time intervals.
Then, based on the trigger output from the random timer 31 at random time intervals, the signal control unit 34 alternately outputs the disconnection detection signal output from the low frequency oscillation circuit a (32) and the low frequency oscillation circuit b (33). ) Is switched and output.

  Next, operation | movement of the signal transmitter 30 is demonstrated using FIG. 5 (refer FIG. 4 suitably). FIG. 5 is a diagram illustrating an example of the operation of the signal transmitter in the third embodiment.

The signal transmitter 30 starts its operation when the network devices A (120) and B (220) are powered on.
First, the signal transmitter 30 maintains and outputs the output signal (disconnection detection signal) of the low frequency oscillation circuit a (32) (step S501). Next, the loop current detector 11 determines whether or not the level of the disconnection detection signal is lower than a preset threshold value in all the wires 4a to 4d (step S502). When the level of the disconnection detection signal is smaller than the threshold value for all the wires 4a to 4d (Yes in step S502), the signal transmitter 30 determines whether or not the time set by the random timer 31 has expired (step S503). ). If the set time has not ended (No in step S503), the process returns to step S501. When the set time is over (Yes in step S503), the signal control unit 34 of the signal transmitter 30 outputs an output signal (disconnection detection signal) of the low frequency oscillation circuit b (33). Switching (step S504). Then, the process returns to step S501.

In step S502, if the level of the disconnection detection signal is not lower than the threshold value for all the wires 4a to 4d, that is, if “signal level ≧ threshold value” for some wires (No in step S502), the signal transmitter 30 maintains the output signal (disconnection detection signal) (step S505). Then, the loop current detector 11 determines whether or not the level of the disconnection detection signal is lower than a preset threshold value in all the wires 4a to 4d (step S506).
When the level of the disconnection detection signal is lower than the threshold value in all the wires 4a to 4d (Yes in step S506), the process returns to step S504. When the level of the disconnection detection signal is not smaller than the threshold value for all the wires 4a to 4d, that is, when “signal level ≧ threshold value” is satisfied for some wires (No in step S506), the signal transmitter 30 is The output signal (disconnection detection signal) is determined (step S507).
Next, the loop current detector 11 determines whether or not all the wires 4a to 4d are disconnected (step S508). If all the wires 4a to 4d are disconnected (Yes in step S508), the process returns to step S501. If all the wires 4a to 4d are not disconnected (No in step S508), it is determined whether or not some of the wires 4a to 4d are disconnected (step S509).
If some of the wires 4a to 4d are disconnected (Yes in step S509), the process shown in FIG. 5 is terminated, and the process proceeds to a handling process after the disconnection is detected. If the wires 4a to 4d are not disconnected (No in step S509), the process returns to step S501.

  Note that the low-frequency oscillation circuits a (32) and b (33) may be single oscillation circuits, even if the signal oscillator 20 (the combination of the low-frequency oscillation circuit (VCO) 21 and the sweep oscillation circuit 22) shown in FIG. ). At this time, after the time determined by the random timer 31 has elapsed, the frequency of the output signal of the low-frequency oscillation circuit (VCO) 21 may be fixed by fixing the sweep voltage of the sweep oscillation circuit 22.

  Further, in the third embodiment, the case of changing the frequency has been described. However, even when the signal control unit 34 performs a process of shifting the phase by the trigger input from the random timer 31, the improvement of the asynchrony is realized. It is possible.

  As described above, in the third embodiment of the present invention, the network devices A (120) and B (220) are used to detect disconnection signals (low frequency signals) having different frequencies by the random timers that operate independently of each other. Since it is possible to increase the asynchronousness of the disconnection detection signal, it is possible to detect disconnection of the communication cable and poor connector contact in an environment in which network devices are connected to each other.

  In the first to third embodiments, the case where four wires (two pairs) are used has been described. However, the present invention is also applied to the case where eight wires (four pairs) are used. Is possible.

It is a figure which shows the cable disconnection detection apparatus incorporated in the network apparatus. It is a figure which shows an example of the circuit structure of the cable disconnection detection apparatus in 1st Embodiment. It is a figure which shows an example which improves the asynchronous property of the signal transmitter in 2nd Embodiment. It is a figure which shows an example which improves the asynchronous property of the signal transmitter in 3rd Embodiment. It is a figure which shows an example of operation | movement of the signal transmitter in 3rd Embodiment.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Low frequency transmitter 11, 23 Loop current detector 12 Display 20, 30 Signal transmitter 21 Low frequency oscillation circuit (VCO)
22 Sweep oscillation circuit 31 Random timer 32 Low frequency oscillation circuit a
33 Low frequency oscillator b
34 Signal control unit 100, 110, 120 Network device A
101, 102, 201, 202 Existing pulse transformer 103, 203 Connector 200, 210, 220 Network device B
300, 310, 320 Cable disconnection detector 400 Cable 4a, 4b, 4c, 4d Wire C Capacitor T1a, T1b, T2a, T2b Transformer

Claims (5)

A network disconnection detecting device for detecting disconnection of the cable, used in an environment where network devices including a pulse transformer that maintains a balance of cables bundled with a pair of wires are communicably connected by the cable,
A first filter, a second filter, a first transformer, a second transformer, a low-frequency oscillator, and a detector;
The first filter and the second filter have a low impedance in a frequency band used for communication by the network device, and have a high impedance in another frequency band,
The low-frequency transmitter has a function of outputting a low-frequency signal lower than a frequency band used for communication by the network device,
The detector has a function of detecting a low-frequency signal;
The first filter is connected in parallel with the primary winding or the secondary winding of the first transformer between one wire of the pair of wires and one terminal of the pulse transformer,
The second filter is connected in parallel with a primary winding or a secondary winding of a second transformer between another wire in the pair of wires and another terminal of the pulse transformer,
The low frequency oscillator is connected to a side of the first transformer where the first filter is not connected,
The detector is connected to a side of the second transformer to which the second filter is not connected;
Cable breakage detection device characterized by A network disconnection detecting device for detecting disconnection of the cable, used in an environment where network devices including a pulse transformer that maintains a balance of cables bundled with a pair of wires are communicably connected by the cable,
A first filter, a second filter, a first transformer, a second transformer, a signal transmitter, and a detector;
The first filter and the second filter have a low impedance in a frequency band used for communication by the network device, and have a high impedance in another frequency band,
The signal transmitter has a function of sweeping an output voltage and a function of changing a frequency of a low frequency signal output corresponding to the output voltage at a frequency lower than a frequency band used for communication by the network device. ,
The detector has a function of detecting a low-frequency signal;
The first filter is connected in parallel with the primary winding or the secondary winding of the first transformer between one wire of the pair of wires and one terminal of the pulse transformer,
The second filter is connected in parallel with a primary winding or a secondary winding of a second transformer between another wire in the pair of wires and another terminal of the pulse transformer,
The signal transmitter is connected to a side of the first transformer to which the first filter is not connected;
The detector is connected to a side of the second transformer to which the second filter is not connected;
Cable breakage detection device characterized by The detector has a limiter function for limiting the amplitude of the input low frequency signal to a predetermined value;
The cable disconnection detecting device according to claim 2. A network disconnection detecting device for detecting disconnection of the cable, used in an environment where network devices including a pulse transformer that maintains a balance of cables bundled with a pair of wires are communicably connected by the cable,
A first filter, a second filter, a first transformer, a second transformer, a signal transmitter, and a detector;
The first filter and the second filter have a low impedance in a frequency band used for communication by the network device, and have a high impedance in another frequency band,
The signal transmitter generates a trigger signal at random time intervals, and switches and outputs a low frequency signal having a frequency lower than a frequency band used for communication by the network device and having a different frequency by the trigger signal. With functions,
The detector has a function of detecting a low-frequency signal;
The first filter is connected in parallel with the primary winding or the secondary winding of the first transformer between one wire of the pair of wires and one terminal of the pulse transformer,
The second filter is connected in parallel with a primary winding or a secondary winding of a second transformer between another wire in the pair of wires and another terminal of the pulse transformer,
The signal transmitter is connected to a side of the first transformer to which the first filter is not connected;
The detector is connected to a side of the second transformer to which the second filter is not connected;
Cable breakage detection device characterized by The detector determines whether the magnitude of the detected low frequency signal is equal to or greater than a predetermined value,
When it is determined that the detector is greater than or equal to the predetermined value in some wires,
The signal transmitter holds the frequency of the output low frequency signal;
The cable break detection device according to claim 4.

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