JPH08237292A - Link testing system for transmission line - Google Patents

Abstract

PURPOSE: To provide a link testing system for a transmission line in which the normality of a transmission line link can be confirmed and the distance from a master device to a slave one can be measured by the use of a simple monitor circuit on the side of the master device without requiring any dedicated machine and occupancy of channel. CONSTITUTION: In the case where the master device 1 inputs a prescribed pulse from the slave device 20 through the under-mentioned transmission line 40 within a prescribed time limit after it transmits a generated link test pulse to the slave device 20 through one transmission line 40, it judges the transmission line 40 including the slave device 20 to be normal; while, in the case where the prescribed time limit is exceeded, it judges the device to be abnormal. On the other hand, in the case where the slave device 20 inputs the prescribed pulse from the master device 1 through one transmission line 40, it returns the pulse generated by prescribed procedure to the master device 1 through the transmission line 40. Besides, the master device 1 measures the response time of this pulse, and calculates the distance to the slave device 20 from this response time.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a transmission for connecting a master device for exchanging data to a master device, which is formed by connecting a plurality of slave devices accommodating data terminals, to each other for connecting the master device and the slave devices. Link test method of transmission line to test path, especially link test method of transmission line that can test transmission line including multiple slave devices without special special equipment connection and with simple circuit of master device Regarding

[0002]

2. Description of the Related Art Conventionally, in a link test method for a transmission line of this type, as shown in FIG. 5, each of a plurality of line circuits 910 included in a master device 91 is, for example, a LAN.
(Local Area Network) A slave device 920 accommodating a terminal 930 is connected via a transmission line 40.

This link test is performed from the line circuit 910 of the master device 91 to the slave device 920, and vice versa.
This is performed by sending predetermined link test pulses from the slave device 920 to the line circuit 910 and checking the normality of the input link test pulse in the device / circuit on the other side. In the master device 91, the result of this test is notified from the line circuit 910 via the control bus 12 to the man-machine interface 94 via the central control circuit 93, and is displayed as a lamp. On the other hand, in the slave device 920, the test result is
The terminal interface 205 is notified and displayed in a lamp.

The line circuit 910 shown in FIG. 5 includes a line receiver 101, a line driver 102, an internal bus transmitter 105, an internal bus receiver 106, a link test pulse generator 913, and a link test pulse detector 91.
4 On the other hand, the slave device 920 includes a line driver 201, a link test pulse generation unit 921, a link test pulse detection unit 203, a line receiver 204, and a terminal interface 205.

The plurality of line circuits 910 are the master device 91.
Internally connected by the internal bus 11 and the control bus 12, the data received by the line receiver 101 is sent to the internal bus 11 by the internal bus transmission unit 105. On the other hand, the internal bus receiving unit 106 takes out data from the internal bus 11 and transmits the data to the transmission line 40 via the line driver 102.
Send to.

The slave device 920 is connected to the LAN terminal 930 by the terminal interface 205.

Next, the line test will be described.

The link test pulse generator 913 of the line circuit 910 is connected to the line driver 102, and when no data is transmitted to the transmission line 40, that is, the link test pulse is generated and transmitted during an idle period of the transmission line 40. Road 4
Send to 0. In the slave device 920, the link test pulse detection unit 203 detects the link test pulse from the signal received by the line receiver 204, whereby the normality of the transmission line 40 is confirmed, and the result is displayed on the terminal interface 205.

On the other hand, the link test pulse generator 921 of the slave device 920 is connected to the line driver 201 and generates a link test pulse when no data is transmitted to the transmission line 40, that is, in the idle period of the transmission line 40. And transmits it to the transmission line 40. In the line circuit 910, the link test pulse detection unit 914 detects the link test pulse from the signal received by the line receiver 101, whereby the normality of the transmission line 40 is confirmed, and the result is the control bus 12 and the central control circuit. It is displayed on the man-machine interface 94 via 93.

In this example, the normality of the link test from the slave device to the master device is confirmed on the master device side, while the normality of the link test from the master device to the slave device is confirmed on the slave device side. , The normality of a set of transmission line links will be confirmed by another device.

On the other hand, as a means for solving this problem,
A technique in which a loopback module is connected to a relay point on a transmission line and a master device confirms the normality of a transmission line link is described in, for example, Japanese Patent Laid-Open No. 62-100046. In this method, a loopback module is connected to a relay point on the transmission path, and when the master device sends a test frame, it checks the content of the response frame returned from the loopback module to confirm the normality of the link. ing.

In addition, a technique of separately providing a measuring device and a signal returning device on a transmission line to turn a signal back and calculate the distance of the transmission line is disclosed in, for example, Japanese Patent Laid-Open No. 1-17542.
No. 8 publication. In this method, one of the transmission lines is provided with a measuring device, and the other end is connected with a headend modulator as a return device that receives an upstream carrier signal, converts this frequency into a frequency of the downstream carrier signal, and returns the frequency. With this configuration, unused 1
Using a channel, the measuring device calculates the distance of this transmission line by measuring the time until the signal sent from the measuring device is returned by the headend remodulator and reaches this measuring device.

[0013]

Among the above-mentioned conventional link test systems for transmission lines, Japanese Patent Laid-Open No. 62-100046 has been proposed.
In the method described in the publication, it is necessary to connect a dedicated folding module to the relay point on the transmission line.
Since a test frame is formed and the contents of this frame are checked, the check circuit becomes complicated.

Also in the method described in Japanese Patent Laid-Open No. 1-175428, it is necessary to connect a head end remodulator of a dedicated device to one end of the transmission line.
There is a practical problem in that a transmission channel is required only for testing.

An object of the present invention is to use a pulse for a link test, generate a pulse on the slave device side in synchronization with a pulse for a link test received from a master device, and generate the pulse for the link test. By sending back to, without dedicated equipment, and without occupying the channel,
Another object of the present invention is to provide a link test method for a transmission line, which can confirm the normality of the transmission line link with a simple monitoring circuit on the master device side.

[0016]

In the link test method for a transmission line according to the present invention, when one master device sends a generated link test pulse to a slave device through one transmission line, it is within a predetermined time limit. When a link test pulse is input from the slave device to the slave device via the transmission line, the transmission line including the slave device is determined to be normal, and if the predetermined time is exceeded, it is determined to be abnormal, and the other slave device is determined. When a link test pulse is input from the master device via one transmission path, the link test pulse generated in a predetermined procedure is returned to the master device via the transmission path.

[0017]

Next, the present invention will be described with reference to the drawings.

FIG. 1 is a functional block diagram showing an embodiment of the present invention. In the link test method of the transmission line shown in FIG. 1, each of the plurality of line circuits 10 of the master device 1 transmits to and receives from each of the slave devices 20 accommodating the LAN terminal 30, a transmission line formed of one or more transmission media. It is assumed that each of the 40 is connected to form a star LAN.

The line circuit 10 in the master device 1 is connected by an internal bus 11 for data transmission, and sends and receives data between the line circuits 10. Further, control information, status information, etc. of the line circuit 10 are transmitted via the control bus 12 to the central control circuit 1
3 is accessed. The central control unit 13 is connected to the maintenance terminal 2 via the man-machine interface 14, reads the status information from the line circuit 10 and sends it out when requested by the maintenance terminal 2, and displays the screen on the maintenance terminal 2 and prints it out. And so on.

The line circuit 10 includes a line receiver 10
1, the line driver 102, the link test pulse generator 103, the link test pulse detector 104, the internal bus transmitter 105, and the internal bus receiver 106, in addition to the components shown in FIG. And a response time holding unit 108. The link test pulse generator 103 and the link test pulse detector 104 are different in function from the components having the same names shown in FIG.

The slave device 20 includes a line driver 20.
1, a link test pulse generating section 202, a link test pulse detecting section 203, a line receiver 204, and a terminal interface 205. The link test pulse generating section 202 has the same components as those shown in FIG. Functions are different.

At the time of data communication, the transmission data from the LAN terminal 30 is converted by the line driver 201 via the terminal interface 205 into a signal format suitable for the medium of the transmission line 40, and sent to the transmission line 40. The line receiver 101 of the line circuit 10 extracts a signal from the transmission line 40, and when the extracted signal is normal data, passes the extracted data to the internal bus transmission unit 105. The internal bus transmission unit 105 sends the received data to the internal bus 11 at a predetermined timing and sends it to another line circuit.

On the other hand, the data on the internal bus 11 is received by the internal bus receiving section 106, and the line driver 102 is received.
Passed to. The line driver 102 converts the received data into a signal format suitable for the connected transmission medium and sends it to the transmission line 40. The line receiver 204 of the slave device 20 extracts the signal from the transmission line 40, and when the extracted signal is normal data, sends the extracted data to the LAN terminal 30 via the terminal interface 205.

Next, the transmission line 40 including the slave device 20.
Link test of.

First, the link test pulse generator 103 of the master device 1 generates a pulse signal for link test, for example, after a lapse of a predetermined time from the end of data transmission,
In addition to sending it to the line driver 102, it also notifies the link test pulse detection unit 104 and the response time monitoring unit 107.

The link test pulse detector 104 monitors the signal received from the transmission line 40 via the line receiver 101. When a prescribed link test pulse is received, the link test pulse detector 104 detects this and detects a normal test result. Of the link test pulse, the response time monitoring unit 107 is notified of the normal detection of the link test pulse. Further, when the link test pulse detection unit 104 receives and detects the data signal before the link test pulse is detected after the generation of the link test pulse notified from the link test pulse generation unit 103, the link test pulse detection unit 104 performs time monitoring. Response time monitoring unit 1
07 has been notified.

Further, the link test pulse detector 104
Holds the abnormality of the link state internally when the link test pulse cannot be detected within a predetermined time after the generation of the link test pulse notified from the link test pulse generation unit 103.

The response time monitoring unit 107 measures the time from the generation of the link test pulse notified from the link test pulse generation unit 103 to the notification of the detection of the link test pulse from the link test pulse detection unit 104,
When the detection notification of the link test pulse is received with the measurement time information as the response time value, the response time holding unit 108 is notified and held together with the response time latch signal.

When the response time monitoring unit 107 receives a cancel signal for time monitoring from the link test pulse detection unit 104, the response time monitoring unit 107 stops measuring time, and measures time information and response time to the response time holding unit 108. Stop the notification of the latch signal, and then the link test pulse generator 10
These stoppages are released by the generation of the link test pulse notified from the above item 3.

The response time holding unit 108 holds the measurement time information received from the response time monitoring unit 107 together with the response time latch signal as the response time.

The central control circuit 13 receives a command from the maintenance terminal 2 via the man-machine interface 14, and the response time holding unit 1 of the line circuit 10 is received by this command.
08 or the link test pulse detector 104 can be accessed to read the response time or link status information. The read information is notified to the maintenance terminal 2 via the man-machine interface 14, and is output to the maintenance terminal 2 by screen display, printing or the like.

Further, the central processing circuit 13 can calculate the distance to the slave device connected to the line circuit 10 by using the following equation (1) based on the information read from the response time holding unit 108.

L = 0.5 × (T1−T2) × S (1) Here, L is the distance from the master device 1 to the slave device 20, and T1 is the response time value read from the response time holding unit 108. , T2 is the delay time value due to the signal processing of the single device independent of the transmission distance, and S is the propagation speed of the signal in the transmission path 40 used. In addition, the central control circuit 13
Is to promptly determine the abnormality of the transmission line 40 connected to each line circuit 10 with the response time value T1 calculated back from the maximum allowable distance as the upper limit of the response time in the specifications of the device. You can

The link test pulse detection unit 204 of the slave device 20 is connected to the transmission line 4 via the line receiver 204.
The signal extracted from 0 is monitored, and when the signal defined as the link test pulse is received, the normal detection of the link test pulse is notified to the link test pulse generator 202 and the terminal interface 205.

The link test pulse generator 202 outputs the link test pulse when it receives the notification of normal detection of the link test pulse from the link test pulse detector 204 except when the slave device 20 receives an alarm of abnormality. It is generated and sent to the transmission line 40 via the line driver 201. When there is no data to be transmitted to the transmission line 40, the line driver 201 converts the received link test pulse into a signal format suitable for the transmission medium of the transmission line 40 to be transmitted and transmits the signal.

Further, when the terminal interface 205 receives the notification of normal detection of the link test pulse from the link test pulse detection unit 204, it displays the state of the link by turning on / off the lamp.

Next, referring to FIG. 1 and FIG. 2 and FIG. 3 together, the operation procedure relating to the link test of the line circuit 10 will be described.

The link test pulse generator 103 generates a line test pulse p at a prescribed time (YES in step S11) and sends it to the line driver 102.
The occurrence is notified to the link test pulse detection unit 104 and the response time monitoring unit 107. When the data is not being sent (NO in step S12), the line driver 102 sends the received pulse p to the transmission line 40 (step S13).

When the link test pulse detection unit 104 receives the notification of the transmission of the pulse p from the link test pulse generation unit 103, the link test pulse detection unit 104 checks the status of response time monitoring (step S1).
4) Then, in the case of monitoring cancellation (YES in step S15), the response time monitoring unit 107 deletes the monitoring cancellation signal being sent (step S16), and starts measuring the input monitoring time limit of the pulse p (step S17). ) Do. Step S16
Since the cancel signal for monitoring is erased by, the response time monitoring unit 107 starts measuring the response time (step S18).
Then, the input of the pulse p of the link test is checked (step S19).

If the step S15 is "NO" and there is no monitoring cancel signal, the step skips "S16" and
Directly go to "S17".

If the pulse p is input while the link test pulse detector 104 is checking the input of the pulse p in step S19 (YES in step S21), the link test pulse detector 104 is reporting an abnormal state of the link ( Step S
If YES, then this abnormality report is canceled (procedure S
23) and input the pulse p to the response time monitoring unit 1
Notify 07.

The response time monitoring unit 107 receives the input notification of the pulse p, sends the measured value of the response time of the pulse p to the response time holding unit 108 together with the response time latch signal, and measures the response time in the response time holding unit 108. Hold value (step S24)
At the same time, the measured value of the response time is updated, and the value is returned to zero (step S25) to return to the initial state.

If step S22 is "NO" and there is no abnormality report, the procedure skips "S23" and proceeds to "S24".

If the link test pulse detection unit 104 is checking the input of the pulse p in step S19, and the data is input (YES in step S31) before the pulse p is input in step S21 when "NO", the link test is performed. The pulse detection unit 104 generates a cancellation signal for response time monitoring (step S32) and sends it to the response time monitoring unit 107.

When the link test pulse detection unit 104 is checking the input of the pulse p by the step S19, the step S21 is "NO" and the pulse p is not input, and the step S31 is "NO" and the data is not input. The link test pulse detection unit 104 checks the measurement of the input monitoring time limit of the pulse p (step S41).

The link test pulse detection unit 104, which has checked the measurement of the input monitoring time limit in step S41, detects the time limit over because the slave device 20 cannot receive the pulse p input due to an abnormal fault, for example (YES in step S42). In this case, the link test pulse detection unit 104 outputs an abnormality in the link status via the control bus 12 (step S43), notifies the central control circuit 13 of the abnormality, and cancels the measurement of the monitoring time period (step S44) to initialize. Return to the state.

Steps S25, S32 and S44 are step S11.
Return to and repeat the above procedure. If step S42 is "NO" and the time limit is not exceeded, the procedure is "S1.
Then, the procedure returns to "9" and the procedure after "S20" is repeated.

Next, with reference to FIG. 1 and FIG. 4 together, the operation procedure relating to the link test of the slave device 20 will be described.

First, the link test pulse detector 204 of the slave device 20 monitors the signal extracted from the transmission line 40 via the line receiver 204, and checks the input of the signal defined as the pulse p for the link test ( In step S51, a normal pulse p is input (Y in step S52).
S) is detected and notified to the link test pulse generator 202 and the terminal interface 205.

When the link test pulse generator 202 receives the input notification of the pulse p, the link test pulse generator 202 checks whether there is an abnormality in the slave device 20 (step S53). If there is no abnormality (NO in step S54), the link test pulse generator 20
2 generates a prescribed pulse p and sends it to the line driver 201.

The line driver 201 is used for the LAN terminal 30.
The presence or absence of the data from (step S55), and if the data is not transmitted (NO in step S56), the received pulse p is converted into a signal format suitable for the transmission medium of the transmission path 40 and transmitted (step S55). Perform step S57).

If the step S54 is "YES", the slave device 2
If 0 is abnormal, if there is data transmission in step S56 with "YES", and if the pulse p is transmitted in step S57, the procedure ends.

In the above description, only the LAN is targeted, but other similar small range networks, for example,
It can also be applied to a part of a wide area network, a small area or a private area.

In the above description, the measurement of the input monitoring time limit of the link test pulse is performed by the link test pulse detecting section, but it may be performed by the response monitoring section. Also, the procedure S
Although it is described that the time measurement of the pulse input monitoring in step S41 is checked after the presence or absence of data input in step 31, the procedure may be reversed. Thus, the separation, merging, and movement of the functional arrangements of the illustrated and described blocks, the movement before and after the operation procedure, the parallel operation, and the like are free as long as the above functions are satisfied, and the above description relates to the present invention. Is not limited.

[0055]

As described above, according to the present invention, when one master device sends the generated link test pulse to the slave device via one transmission line, the transmission line is transmitted within a predetermined time period. When a link test pulse is input from the slave device via the, the transmission line including this slave device is judged to be normal, while if it exceeds the predetermined time, it is judged to be abnormal, and the other slave device is When a link test pulse is input from the master device via the transmission line, a link test method of a transmission line in which a link test pulse generated in a predetermined procedure is returned to the master device via the transmission line can be obtained. With this configuration, it is possible to obtain a transmission line link test method in which there is no dedicated device, the channel is not occupied, and the normality of the transmission line link can be confirmed by a simple monitoring circuit on the master device side.

[Brief description of drawings]

FIG. 1 is a functional block diagram showing an embodiment of the present invention.

FIG. 2 is a time chart based on the embodiment of FIG.

FIG. 3 is a flowchart showing an example of an operation procedure on the master device side in FIG.

FIG. 4 is a flowchart showing an example of an operation procedure on the slave device side in FIG.

FIG. 5 is a functional block diagram showing a conventional example.

[Explanation of symbols]

 1 Master Device 2 Maintenance Terminal 10 Line Circuit 11 Internal Bus 12 Control Bus 13 Central Control Circuit 14 Man-Machine Interface 20 Slave Device 30 LAN Terminal 40 Transmission Line 101, 204 Line Receiver 102, 201 Line Driver 103, 202 Link Test Pulse Generator 104, 203 Link test pulse detection unit 105 Internal bus transmission unit 106 Internal bus reception unit 107 Response time monitoring unit 108 Response time holding unit 205 Terminal interface

Claims (4)

[Claims] 1. A link test method of a transmission line for testing a transmission line between the master device and a slave device forming a star network by connecting a plurality of slave devices accommodating data terminals to a master device for exchanging data. In one of the cases, when one of the master devices sends the generated link test pulse to the slave device via one transmission line, when the link test pulse is input from the slave device via the transmission line within a predetermined time period, , The transmission line including the slave device is determined to be normal, and when the predetermined time is exceeded, it is determined to be abnormal, and the other slave device is set to 1
When a link test pulse is input from a master device via one transmission line, a link test pulse generated in a predetermined procedure is returned to the master device via the transmission line, . 2. The master device according to claim 1, wherein:
A link test method for a transmission line, wherein when data is input from the slave device via the transmission line within the predetermined time period, monitoring by the predetermined time period is canceled. 3. The transmission according to claim 1, wherein the slave device stops transmission of a link test pulse returned to the master device via the transmission path while an abnormality is occurring. Road link test method. 4. The master device according to claim 1, wherein:
The link test pulse is sent to the slave device via one transmission path and then returned via the transmission path,
A link test method for a transmission line, which measures the time until the input and calculates the distance of the transmission line from the measured time.