JP2001127714A - Lan tester - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a LAN tester which can conduct a cable continuity test and a reverse-connection confirmation test only at one end and enables a simple operation test including a HUB. SOLUTION: With this LAN tester 1, a continuity test, a polarity test, and an operation test of LAN wiring are conducted, and the tester 1 is equipped with a power source part 2 which supplies a power source current to one signal line at one end of paired signal lines to be tested, a current detection part 3 which detects a current flowing to the other signal line, a normal polarity detection part 4 which detects plus and minus pulses from a plus signal line and a minus signal line, a reverse polarity detection part 5 which detects minus and plus pulses, a 1st changeover switch 6 which places the power source part 2 and current detection part 3 in operation in continuity test mode and the normal polarity detection part 4 and reverse polarity detection part 5 in operation in polarity test mode, and a 2nd changeover switch 7 which actualizes the operation test mode by connecting the connection terminal of a transmit signal line and the connection terminal of a receive signal line in the polarity test mode to make a return. A scanning position on the paper surface or the position right before (after) it can be always viewed by photodetection light through an optical path slanting the direction perpendicular to the paper surface.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a LAN (Local Ar
ea Network), which belongs to a test device that easily performs disconnection, short circuit, polarity check, connection test, reverse connection test, etc.

[0002]

2. Description of the Related Art Conventionally, relatively small-scale data processing devices such as personal computers have often been used alone. However, in recent years, there has been an increase in data processing capacity and a trend toward downsizing. Therefore, in order to effectively use the accumulated data, for example, a plurality of data processing devices within a specific range such as a company or a department are connected to each other via a network to configure a distributed processing system,
It is common practice to construct a simple network without performing distributed processing.

[0003] Such networks are generally LA
N, and one of the simplest LAN constructions,
There is a combination of a network OS (Operating System) and peer-to-peer 10BASE2 or 10BASE-T. Of these, 10 BASE-T
Is relatively simple, and can be performed on the user side without requiring a specialist to perform the connection. For this reason, when constructing a LAN based on 10BASE-T, the wiring is often performed by the user independently.

[0004] However, although the wiring of 10BASE-T is simple, it does not function as a network if there is a wiring error, and the number of cables increases as the scale of the LAN increases, and the wiring becomes complicated. It is becoming.
In such a state, for example, when a failure such as a broken cable or incorrect wiring occurs, as a procedure for finding out which cable has a failure, first, a folding connector is provided at both ends of each cable. By connecting, and connecting a dedicated cable tester including loop resistance, etc., and conducting a continuity test on each cable,
A method is used in which the presence or absence of disconnection or incorrect wiring is checked for each cable, and a cable in which a failure has occurred is searched for.

[0005]

However, in such a conventional method for searching for a broken cable, it is necessary to connect a folding connector to both ends of the cable to be tested. Therefore, the folding connector is connected to one end. In order to connect the return connector to the other end later, it is necessary to follow a cable having the return connector connected to one end. In other words, the task of finding which cable to connect the foldback connector to is a difficult task in complicated wiring, and the conventional continuity test requires a great deal of effort to find a fault. Becomes

In addition, the work of connecting the turn-back connector for conducting the continuity test has a problem that it causes a new trouble such as a wrong connection or a poor contact. However, there is a problem that only the test can be performed, and the connection confirmation test including the HUB and the like cannot be performed.

SUMMARY OF THE INVENTION An object of the present invention is to solve the above-mentioned problems and to provide an LA test capable of performing a cable continuity test and an erroneous wiring confirmation test only at one end and also performing a simple operation test including a HUB or the like.
N testers.

[0008]

According to the present invention, there is provided a method of conducting a continuity test on a hub having a circuit for forming a DC closed circuit or a LAN having an AUI. The LAN tester is connected to the pair of signal lines while the signal line of the pair is connected to the hub or the AUI, a current is supplied from the LAN tester to one of the pair of signal lines, and the other is connected to the other of the pair of signal lines. A method is provided, wherein whether the current returned from the DC closed circuit provided in the hub or the AUI is flowing is detected by the LAN tester.

In a LAN having a hub or an AUI,
A method for performing a polarity test of a signal from the hub or AUI, wherein a pair of signal lines are connected to the hub or AUI, and a first terminal and a second terminal of a LAN tester are connected to the pair. And the LAN from the hub or the AUI through one of the pair of signal lines.
A positive pulse is received at a first terminal of the tester, and the L level is transmitted from the hub or AUI through the other of the pair of signal lines.
When a negative pulse is received at a second terminal of the AN tester, a positive pulse is received at the first terminal, and the negative pulse is received at the second terminal, the forward polarity detection unit of the LAN tester Detecting the positive pulse received at the first terminal and the negative pulse received at the second terminal, receiving a negative pulse at the first terminal, and detecting the positive pulse at the second terminal; When receiving a pulse, the reverse polarity detector of the LAN tester detects the positive pulse received at the first terminal and the negative pulse received at the second terminal, A method is also provided, wherein determining whether a signal sent from the hub or the AUI is forward or reverse polarity.

[0010] In the above configuration, the first terminal and the second terminal of the LAN tester are connected to the third terminal and the fourth terminal of the LAN tester, and the third terminal and the fourth terminal are connected. Is connected to the hub or AUI through another pair of signal lines, whereby the positive and negative pulses received at the first terminal and the second terminal are transmitted to the third terminal and the fourth terminal, respectively. Through the terminal, as a pseudo signal, the hub or A
Returning to the UI, the first terminal of the LAN tester and the second terminal
And receiving a positive pulse and a negative pulse from the hub or AUI as a response signal in response to the pseudo signal at the terminal, thereby performing an operation test of the hub or AUI.

Also, a LAN tester connected to a LAN hub or AUI, the first terminal receiving a positive pulse from the hub or AUI through a first pair of signal lines; The hub or AU through a signal line
A second terminal for receiving a negative pulse from I, said hub or AUI when said first terminal is actually receiving a positive pulse and said second terminal is actually receiving a negative pulse.
Having a forward polarity detector for detecting a positive pulse and a negative pulse received from the first terminal, the first terminal is actually receiving a negative pulse, and the second terminal is actually receiving a positive pulse. And a forward polarity detection unit for detecting a positive pulse and a negative pulse received from the hub or the AUI when the first terminal and the second terminal are respectively connected to a third terminal and a fourth terminal. A second connector for connecting the third terminal and the fourth terminal to the hub or AUI;
And the received positive pulse and negative pulse are returned to the hub or AUI through the second pair of signal lines as a pseudo signal. A LAN tester is also provided.

[0012]

Next, an embodiment of a LAN tester according to the present invention will be described with reference to FIGS. FIG. 1 is a circuit configuration diagram showing an embodiment in which this LAN tester is implemented, and is roughly divided into a power supply unit 2, a current detection unit 3, a forward polarity detection unit 4, a reverse polarity detection unit 5, It comprises a first changeover switch (changeover switch) 6 and a second changeover switch 7 having a function of a folded connection portion. In the figure, RA, R
B is a receiving terminal, and SA and SB are transmitting terminals.

The power supply unit 2 includes a power switch SWP and a built-in battery E. The current detection unit 3 includes a bipolar transistor Q3, and light-emitting diodes LY1 and LY1, which emit yellow light.
Y2 and a plurality of resistors R1, R7, R8, R14. The resistors R7 and R8 are provided to turn on the bipolar transistor Q3, turn off the bipolar transistor Q2, and supply a power supply current to the transmission terminal SA. R1 and R14 are 560
Ω, R7 and R8 are suitably about 10 kΩ. The forward polarity detecting unit 4 includes a bipolar transistor Q4 and a field effect transistor Q5, and a light emitting diode L that lights green.
G, resistors R12, R13, R15, R16, and a capacitor C2, and the reverse polarity detection unit 5 includes a bipolar transistor Q2, a field effect transistor Q
1. Light emitting diode LR that lights up in red and resistor R
4, R5, R6, and R9, and a capacitor C1. The resistors R10 and R11 are provided to bias the bipolar transistors Q2 and Q4, and a smoothing circuit is formed by the capacitor C1 and the resistor R5, and the capacitor C2 and the resistor R15.

The resistances R6, R9, R12 and R13 are 1k
Ω, R10 is 270Ω, R11 is 4.7kΩ, resistance R
4, R16 is 500 kΩ, resistors R5 and R15 are 5 MΩ,
It is appropriate that the capacitors C1 and C2 are about 0.1 μF.
The first changeover switch 6 is, as shown in FIG.
a switch SW for turning on / off a and connecting the transmission terminal SB to either the connection terminal 2a or 2b.
As shown in FIG. 10B, the second changeover switch 7 includes a switch SW2 for connecting the transmission terminal SA and the reception terminal RA, and a connection between the transmission terminal SB and the reception terminal RB. Have been.

Next, each test using the LAN tester of the present invention will be described. FIG. 2 is a diagram showing a connection relationship with a HUB (or AUI) 20 when a continuity test is performed by the LAN tester of the present invention. FIG. 3 is a diagram for explaining an operation example in the continuity test. FIG. 3 is a circuit configuration diagram in which main parts are extracted. That is, during the continuity test, the bipolar transistor Q2 is turned off by turning on the bipolar transistor Q3, and the monitoring of pilot data is stopped. Further, when the switch SW1 (part 2b) is separated, no signal current flows through the bipolar transistor Q4, and the bipolar transistor Q4 does not operate. Therefore, the LAN tester 1 shown in FIG. 1 is equivalent to a circuit as shown in FIG.

First, when conducting a continuity test of the receiving line, FIG.
As shown in the figure, the receiving terminals RA and RB of the LAN tester 1
Is connected to the HUB 20, and the power switch SWP is turned on. When the switch SW1 is pressed in this state, if the reception line or the HUB 20 is normal, as shown in FIG. 3, the power supply current passes between the reception terminals RA and RB, and the light emitting diode LY1 → diode D1 → resistance R1 → switch. SW1
(Part 1a) → Since the current flows along the path of ground GND, the light emitting diode LY1 is lit in yellow, and the fact that the receiving line is normal is notified to the outside. Also, the receiving line or HUB 20
If there is a failure such as disconnection, the above-described current path will be interrupted, so that the light emitting diode LY1 does not turn on,
It can be seen that the reception line or the HUB 20 has an abnormality.

On the other hand, when conducting the continuity test of the transmission line, FIG.
As shown in the figure, the transmission terminals SA, SB of the LAN tester 1
Is connected to the HUB 20, and the power switch SWP is turned on. When the switch SW1 is pressed in this state, the base current of the bipolar transistor Q3 flows from the switch SW1 (1a portion) to the ground GND via the resistor R8, so that the bipolar transistor Q3 is turned on. When the bipolar transistor Q3 turns on, the transmission line or the HUB
If the switch 20 is normal, as shown in FIG. 3, the power supply current passes between the transmitting terminals SA and SB and the switch SW1 (2a
Since the current flows in a path of (part) → the resistor R14 → the light emitting diode LY2 → the ground GND, the light emitting diode LY2 lights up in yellow, and it is notified to the outside that the transmission line or the HUB 20 is normal. Further, when there is a failure such as a disconnection in the transmission line or the HUB 20, the above-described current path is interrupted, so that the light emitting diode LY2 does not turn on, and it is understood that there is an abnormality in the transmission line or the HUB 20. in this way,
The continuity test of the distribution cable is performed through a coil in the HUB or AUI without using a folding device. That is, since the folding device is not used, the operation of following the wiring cable as in the related art is not required, and the labor required for the search operation can be greatly reduced.

FIG. 4 is a diagram showing a connection relationship with the HUB 40 when a polarity test is performed by the LAN tester 1 of the present invention.
FIG. 5 is a diagram showing a connection relationship between the HUB 40 and the AUI 50 when a communication monitor is performed by the LAN tester 1 according to the present invention. FIG. 6 is a diagram for explaining an operation example in the polarity test and the communication monitor. FIG. 3 is a circuit configuration diagram in which main parts of FIG. That is, at the time of the polarity test and the communication monitor, the bipolar transistor Q3 is off, so that the bipolar transistors Q2 and Q4 are in an active state, and the switch SW1 (2b portion) is connected to the terminal SB to monitor the pilot data. Works, the LAN tester 1 shown in FIG. 1 is equivalent to a circuit as shown in FIG.

When the polarity test of the HUB 40 is performed, as shown in FIG. 4, the HUB is connected to the terminals SA and SB of the LAN tester 1.
And turn on the power switch SWP. In this state, since the switch SW1 is not pressed, no base current flows through the bipolar transistor Q3, the bipolar transistor Q3 is turned off, and the bipolar transistor Q2 is turned on based on the voltage division ratio of the power supply voltage set by the resistors R10 and R11. And a slight bias is applied to bipolar transistor Q4. In this state, a pulse signal as shown in FIG.
When a positive pulse is continuously applied to the terminal A and a negative pulse is applied to the terminal SB, the bipolar transistor Q
4, the base current flows intermittently, whereby the bipolar transistor Q4 is turned on intermittently.

When the bipolar transistor Q4 is turned on intermittently, an intermittent pulse-like voltage is applied to the field effect transistor Q5 via the resistor R16. Since the smoothing is performed by the time constant circuit constituted by the capacitor C2, the field effect transistor Q5 is turned on, the light emitting diode LG is lit in green, and it is notified to the outside that the light emitting diode LG is connected with the correct polarity (forward polarity). Is done.

On the other hand, when a negative pulse is continuously applied to the terminal SA and a positive pulse is applied to the terminal SB, a base current flows intermittently in the bipolar transistor Q2 in response to the pulse application. , Will be turned on intermittently. Bipolar transistor Q
2 turns on intermittently, an intermittent pulse-like voltage is applied to the field-effect transistor Q1 via the resistor R4. This pulse-like voltage is constituted by the resistor R5 and the capacitor C1. Since the smoothing is performed by the time constant circuit, the field effect transistor Q1 is turned on, the light emitting diode LR lights up in red, and the fact that the light emitting diode LR is connected with the wrong polarity (reverse polarity) is notified to the outside. As described above, by turning on the light emitting diode LG or the light emitting diode LR, it is possible to easily confirm the presence or absence and the polarity of the signal.

When a communication monitor is performed, the L of the present invention is used.
By inserting the AN tester 1 between the communication cables and connecting the HUB 40 and the AUI 50 as shown in FIG. 5, when the communication waveform as shown in FIG. The condition can be monitored. That is, when a waveform is applied such that a positive pulse is continuously applied to the terminal SA and a negative pulse is applied to the terminal SB, the light emitting diode LG is lit green and the terminal SA
When a waveform such that a negative pulse is applied to the terminal SB and a positive pulse is applied to the terminal SB is applied to the light emitting diode LR
Lights red, so that the signal can be easily monitored by blinking the light emitting diodes LG and LR.
The signal voltage flowing through the cable for turning on the transistors Q1 and Q5 is a very short pulse as shown in FIG.
Even if G and LR are driven and turned on, it is difficult for the naked eye to recognize them. For this reason, the width of the lighting time is set by the capacitors C1 and C2 to make it easy to see the lighting state. As described above, the polarity can be easily determined by detecting the direction of the signal pulse and blinking the two light emitting diodes LG and LR.

FIG. 9 is a diagram showing a connection relationship with the HUB 40 when a simple operation test is performed by the LAN tester 1 of the present invention, and FIG. 10 shows an operation example in a simple operation test by the LAN tester of the present invention. It is the figure which extracted the principal part of FIG. 1 for description. That is, during the simple operation test of the HUB 40, the bipolar transistors Q2 and Q4 are in the active state because the bipolar transistor Q3 is off.
Also, since the switch SW1 (2b portion) is connected to the terminal SB to perform a pilot data monitoring function, the LAN tester 1 shown in FIG. 1 is equivalent to a circuit as shown in FIG. Become. Further, FIG.
As shown in (1), the terminals RA and SA and the terminals RB and SB are connected for turning back by turning on the switch SW2.

When performing a simple operation test of the HUB 40,
As shown in FIG. 9, by pressing the switch SW2,
The terminals SA and SB of the LAN tester are connected to the terminals RA and RB, respectively, and the power switch SWP is turned on. As a result, a pseudo signal is generated by transmitting a pulse on the transmission line to a pulse on the reception line. That is, as shown in FIG. 9, when the LAN tester 1 of the present invention is connected to a HUB, the HUB again outputs a signal voltage serving as response data to the transmission line based on the folded signal. As in the case of the operation example of the communication monitor, a simple operation test can be performed by confirming PART and LINK of the HUB 40 and by causing the light emitting diodes LG and LR to blink irregularly.
Also, when the LAN tester 1 of the present invention is connected to the AUI, similar to the case of the HUB 40, the R / L lamp of the AUI is turned on and the light emitting diodes LG and LR blink irregularly, thereby simplifying the operation. Dynamic test can be performed. That is, the connection test with the device and the simple operation test can perform their functions simply by folding back the signal lines.

As described above, the signal in the wiring is detected by the LAN tester, the presence / absence and polarity of the signal are determined, and a pseudo operation test is performed by displaying a light-emitting diode and folding back, so that the HUB and the AUI can be controlled. Simple operation test and connection confirmation between devices can be performed.
Disconnection, short circuit, polarity difference, and simple connection test of HUB and AUI in the twisted pair wire of ET can be performed. Thus, when the AUI cannot perform LAN communication, H
It is possible to easily test whether the connection between the UB, the cable, and the AUI is securely performed, and to determine the operation failure of the HUB, the contact failure, the disconnection or short circuit of the cable, the operation failure of the AUI, and the like. In addition, during the continuity test, there is no need to follow the wiring cable because no folding device such as a folding connector is used.This greatly reduces the search operation, and the test can be performed while one end is connected to the device. Confirmation, HUB and AU
The operation test of I can be easily performed.

In the above embodiment, when conducting a continuity test including a HUB or AUI, the continuity test is limited to those having a pulse transformer for forming a DC loop in the HUB or AUI. There are no limitations on other polarity tests, including simple operation tests, communication monitors, and the like.

Next, a description will be given of a case where a test for confirming the wiring connection direction is performed using the LAN tester of the present invention. FIG. 11 is a diagram showing a configuration example in the case of performing a confirmation test for the presence or absence of incorrect wiring of a general-purpose 8-pin modular jack used for LAN wiring, for example. As shown in FIG.
The N tester includes, for example, a plurality of reverse connection confirmation circuits 12a and 12 that are electrically connected to corresponding receiving terminals of a modular jack.
are provided. Reverse connection confirmation circuits 12a, 12
b is the diode D11 (D12) and the light emitting diode L
D1a (LD2a) is reversely connected.

The modular jack to be tested (M
J) One end of a paired signal line 11a, 11b is connected to No. 1 and No. 10 of one, and is connected to one signal line of this paired signal line, for example, the signal line 11a connected to the No. 1 pin of MJ10. Is configured to supply a current based on the DC voltage Ea from the power supply unit 2 described above. Further, between the signal line 11b connected to the second pin of the MJ10 and the ground line, a light emitting diode LD1b that is lit when energized is inserted and connected. The above-mentioned reverse connection confirmation circuit 12a is connected to the other ends of these signal lines 11a and 11b.

As shown in the figure, the MJ 10 is also connected to the third and sixth pins with paired signal lines 11c and 11d. Therefore, as in the case of the pair signal lines 11a and 11b, a current based on the DC current Eb is supplied to the third pin, and the light emitting diode LD2b is connected between the sixth pin and the ground line.
And a reverse connection confirmation circuit 12b is connected to the other ends of the paired signal lines 11c and 11d.

At the time of the test, the DC voltages Ea, Ea
The current based on b is separately supplied from the power supply unit 2 at different timings. The switching of the power supply timing itself can employ a known technique, and is not shown here. Further, the light emitting diodes LD1b and LD2b can use the circuit of the current detection unit 3 as it is.

Next, a specific example of a test for confirming the connection direction using the LAN tester having the above configuration will be described with reference to FIGS. FIG. 12A is a diagram illustrating a state where the wiring of the MJ 10 is normal, that is, a case where the pair signal lines 11a and 11b are connected in the forward direction. In this case, M
Since the current supplied from the first pin of J10 reaches the second pin of MJ10 through the diode D11 of the reverse connection confirmation circuit 12a, the light emitting diode LD1a is turned on.
This makes it possible to visually recognize that the wiring of the MJ 10 is normal.

FIG. 12B shows a state where the wiring of the MJ 10 is abnormal, that is, a case where the pair signal lines 11a and 11b are reversely connected. In this case, MJ10
Since the current supplied to the first pin reaches the reverse connection confirmation circuit 12a from the other signal line 11b, the light emitting diode LD1a is turned on. Also, the light emitting diode LD1
Since the current passing through a reaches the sixth pin of the MJ10, the light emitting diode LD1b is also turned on. Therefore,
In this case, it can be visually recognized that the first and second pins of the MJ 10 are connected in reverse.

The presence or absence of erroneous wiring between other signal lines in the MJ 10 can also be visually recognized by this LAN tester. For example, FIG. 13A shows that when a current is supplied to the third pin of MJ10, the light emitting diode LD
The other light-emitting diodes LD1a and LD1b are lit while 2a and LD2b are to be lit. This state means that the wiring in the MJ 10 is sequentially shifted upward as shown in the figure, so that it is possible to visually recognize that the wiring is incorrect. Further, as shown in FIG.
When the light-emitting diodes LD2a and LD2b which should not be lit when the current flows through the first pin of J10 also indicate that the wiring of MJ10 is not normal. As described above, the combination test of the power supply timing to the MJ 10 and the lighting pattern of the light emitting diodes LD1a, LD1b, LD2a, and LD2b makes it possible to easily perform a test for confirming the connection direction of the MJ10.

Although the present invention has been described with reference to a plurality of embodiments, it is needless to say that the present invention is not limited to the above embodiments. For example, the current detector 3,
Alternatively, a light-emitting diode is used in the reverse connection confirmation circuits 12a and 12b so as to detect the energized state. You may comprise so that it may notify outside.

[0035]

As is apparent from the above description, according to the present invention, it is possible to determine whether or not there is a failure such as a disconnection in a signal line based on the presence or absence of current detection by the current detection unit. Whether the signal line has the correct polarity or the reverse polarity can be confirmed based on the presence or absence of the pulse detection by the polarity detection unit and the reverse polarity detection unit. In addition, a pseudo signal can be generated by folding the pulse of the transmission signal line to the reception signal line, and the operation state of the connected HUB or AUI can be confirmed. Further, erroneous connection of the wiring and the like can be easily confirmed.

[Brief description of the drawings]

FIG. 1 is a circuit diagram showing one embodiment of a LAN tester according to the present invention.

FIG. 2 is a diagram showing a connection relationship with a HUB and an AUI when a continuity test is performed by the LAN tester of the present invention.

FIG. 3 is an essential part extracted diagram of FIG. 1 for explaining an operation example in a continuity test by the LAN tester of the present invention.

FIG. 4 is a diagram showing a connection relationship with a HUB when a polarity test is performed by the LAN tester of the present invention.

FIG. 5 is a diagram showing a connection relationship with a HUB and an AUI when a communication monitor is performed by the LAN tester of the present invention.

FIG. 6 is an essential part extracted diagram of FIG. 1 for explaining an example of an operation in a polarity test and a communication monitor by the LAN tester of the present invention.

FIG. 7 is a diagram showing a waveform example of a trigger pulse (carrier component) in FIG. 4;

FIG. 8 is a view showing an example of a waveform during communication in FIG. 5;

FIG. 9 is a diagram showing a connection relationship with a HUB or AUI when a simple operation test is performed by the LAN tester of the present invention.

FIG. 10 is an essential part extracted diagram of FIG. 1 for explaining an operation example in a simple operation test by the LAN tester of the present invention.

FIG. 11 is a diagram showing an example of a configuration in a case where a confirmation test is performed for the presence or absence of incorrect wiring of a general-purpose 8-pin modular jack used for LAN wiring.

12A is a diagram illustrating a state in which a pair signal line is connected in a forward direction, and FIG. 12B is a diagram illustrating a state in which a pair signal line is reversely connected.

13A and 13B are diagrams showing a state in which other signal lines are erroneously connected;

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 LAN tester 2 Power supply part 3 Current detection part 4 Forward polarity detection part 5 Reverse polarity detection part 6 First changeover switch (changeover switch) 7 Second changeover switch (return connection part) 10 Modular jack (MJ) 11, 11a to 11d Signal line 12a, 12b Reverse connection confirmation circuit 20, 40 HUB 50 AUI

Claims (4)

[Claims] 1. A method for conducting a continuity test with a hub having a circuit for forming a DC closed circuit or a LAN having an AUI, wherein a pair of signal lines are connected to the hub or the AUI while a pair of signal lines are connected to the hub or the AUI.
An AN tester is connected to the pair of signal lines, a current is supplied from the LAN tester to one of the pair of signal lines, and the other of the pair of signal lines is supplied from the DC closed circuit provided in the hub or AUI. A method for detecting whether or not the returned current is flowing by the LAN tester. 2. A method for performing a polarity test of a signal from the hub or the AUI in a LAN having a hub or an AUI, wherein a pair of signal lines are connected to the hub or the AUI.
A first terminal and a second terminal of the LAN tester are respectively connected to the pair of signal lines, and a positive pulse is received from the hub or the AUI at the first terminal of the LAN tester through one of the pair of signal lines. And receiving a negative pulse at a second terminal of the LAN tester from the hub or AUI through the other of the pair of signal lines, receiving a positive pulse at the first terminal, and receiving the negative pulse at the second terminal. When receiving a pulse, the forward polarity detection unit of the LAN tester detects the positive pulse received at the first terminal and the negative pulse received at the second terminal, When the negative pulse is received at the terminal and the positive pulse is received at the second terminal, the reverse polarity detector of the LAN tester detects the positive pulse received at the first terminal, Received at terminal 2 How serial detects a negative pulse, thereby characterized signal sent from the hub or AUI is and judging whether the reverse polarity or a forward polarity. 3. A first terminal and a second terminal of the LAN tester are connected to a third terminal and a fourth terminal of the LAN tester, and the third terminal and the fourth terminal are connected to each other. Connected to the hub or AUI through another pair of signal lines, whereby the positive and negative pulses received at the first terminal and the second terminal are transmitted to the third terminal and the fourth terminal, respectively. To the hub or AUI as a pseudo signal through the first terminal and the second terminal of the LAN tester as a response signal to the pseudo signal at the hub or AU.
3. The method of claim 2, wherein a positive pulse and a negative pulse are received from I to perform an operational test of the hub or AUI. 4. An L connected to a LAN hub or AUI.
An AN tester, comprising: a first terminal that receives a positive pulse from the hub or AUI through a first pair of signal lines; and a second terminal that receives a negative pulse from the hub or AUI through the first pair of signal lines. Positive and negative pulses received from the hub or AUI when the first terminal is actually receiving a positive pulse and the second terminal is actually receiving a negative pulse. And a forward polarity detection unit for detecting the signal received from the hub or AUI when the first terminal is actually receiving a negative pulse and the second terminal is actually receiving a positive pulse. A turn-back connector for connecting the first terminal and the second terminal to a third terminal and a fourth terminal, respectively. The third terminal and the fourth terminal A second pair of signal lines connected to the hub or AUI, whereby the received positive and negative pulses are transmitted as pseudo signals through the second pair of signal lines to the hub or the AUI. A LAN tester returned to the AUI.