JPH0245862B2 - - Google Patents

Description

Detailed Description of the Invention (Technical Field of the Invention) The present invention relates to a communication line control system, particularly a system in which a plurality of terminal devices are serially connected to two pairs of communication lines consisting of a working line and a backup line. , relates to a communication line control system that automatically configures a loop when a fault occurs in a line or the like.

(Technical background and issues) In order to improve the reliability of communication lines, preparations are made to connect to the current line that is actually in use and to form a loop when a failure occurs. There is a reserve line.

The working line normally sends out a data signal including a flag, and the working line, terminal device, repeater, etc. is monitored, and when some kind of failure occurs, for example, the device where the failure has occurred is monitored. The system is configured to receive notification from the next device that a failure has occurred.

On the other hand, the backup line is monitored by constantly sending out a predetermined signal.

Conventionally, in a communication line system equipped with the working line and the protection line, when some kind of fault occurs in the working line, the working line and the protection line are used to form a loop in order to avoid the fault as described later. It is necessary to switch to the so-called "one-stroke writing" state. The switching was done manually so as to form a loop within the control device of the center managing the communication system. Therefore, when a failure occurs, the administrator goes to the location where the control device of the center is located and switches the working line and backup line to form a loop.
Even when the failure is restored, the user must go out and switch the system back to its original state, which sometimes results in the user forgetting the operation or being unable to perform the operation at the site where the restoration is to be performed.

(Object and Structure of the Invention) An object of the present invention is to solve the above-mentioned problems, and to provide a system in which a plurality of terminal devices are serially connected to two pairs of communication lines consisting of a working line and a backup line. To quickly and reliably configure a loop when a failure occurs in a communication line by automatically detecting the failure and configuring a working line and a backup line into a loop when a failure occurs in a line, etc. It is in. Therefore, the communication line control method of the present invention is a control device in which terminal devices are serially connected to a working line and a standby backup line, each connected in a loop, so that when a failure occurs in the line or the terminal device, In the communication line control method in which a loop is configured using the working line and the protection line, a test pattern sending unit sends a monitoring signal to the sending end of the protection line, and the test pattern sending unit sends out a signal for monitoring. a backup line monitoring section that monitors the backup line by detecting the signal transmitted from the receiving end of the backup line; a loopback detection unit that detects from the reception end of the backup line; and when the specific pattern is detected by the loopback detection unit, the reception end and the transmission end of the backup line are connected, and the specific pattern is detected. The present invention is characterized in that it includes a switching circuit that disconnects the receiving end and the transmitting end of the backup line and sends out the monitoring signal to the transmitting end of the backup line when the backup line is not operated.

(Embodiments of the Invention) The present invention will be described in detail below with reference to the drawings.

1 and 2 are conceptual explanatory diagrams explaining the concept of the present invention, FIG. 3 is a configuration diagram of a conventional example, FIG. 4 is a configuration diagram of one embodiment of the present invention, and FIGS. FIG. 4 is an explanatory diagram illustrating one embodiment of the present invention.

In the figure, 1 is the working line, 2 is the control device, 3 is the backup line, and 4 is the ELB (emergency loop).
back) switch, 5 and 10 are test pattern generators, 6 and 6-1 are switching circuits, and 7 and 7-1 are
DV circuit, 8 and 8-1 are RV circuits, 9 is a counter B, 11 is a sampling circuit, 12 is a clock generator, 13 is a decoder, 14 is a flag detection circuit,
15 represents a counter A, and 16 represents a controller.

In FIG. 1, reference numeral 1 denotes a working line, which transmits signals necessary for various communications from the control device 2 to the illustrated terminal devices Tm, Tn, etc., or transmits signals from each terminal to the control device 2. It is intended for transmission to. The current line may be a coaxial cable or any other form of optical cable capable of transmitting signals.

Reference numeral 3 in the figure is a backup line, which is used to form a loop when a failure occurs in the working line or the like.

JBX (junction box) 1 or
JBX3 connects the terminal devices Tm, Tn, etc.
It can switch to form a loop in the event of a failure, or has a lightning protection function.

In the figure, "failure" indicates a state in which the working line itself is disconnected or a fault has occurred in the terminal device Tm due to some cause. If a failure occurs in the illustrated active line, control is performed to avoid it as shown in FIG.

As shown in FIG. 2A, in order to avoid a fault that occurred in the working line shown in FIG. 1, the switching devices in JBX1 and JBX2 before and after the fault occurred
For example, the state shown in FIG. 2B (normal communication state) is switched to the state shown in FIG. 2C (loopback state), and the working line and backup line of the communication line are connected to perform loopback. Then, within the control device 2, the working line and the standby line are connected to form one loop as a whole. In this way, even if some kind of failure occurs in the working line system, communication reliability is maintained by constructing a loop as a whole using the backup line.

In Figure 3, the illustrated ELB (emergency
When the loop back switch 4 is in the "NORMAL position" (normal communication state), the signal generated from the test pattern generator 5 at the lower end of the figure is sent to the backup line via the switching circuit 6 and the DV circuit 7. It is being sent out. The backup line is monitored by this signal.

On the other hand, if some kind of failure occurs in the working line system, a notification to that effect is sent from the next terminal device Tm, Tn, etc. where the failure occurred, as described above. When the administrator switches the ELB switch 4 to the "LOOP position" based on the notification, the signal from the test pattern generator 5 is no longer sent to the backup line. Then, the signal received from the receiving end of the backup line is sent to the backup line via the illustrated RV circuit 8, switching circuit 6, and DV circuit 7, forming a so-called "one-stroke" loop state illustrated in FIG. .

However, in the past, in order to switch the signal received from the receiving end of the backup line to be sent from the transmitting end within the control device 2, the administrator had to go out of his way to the location where the control device 2 is located and perform the above-mentioned switching operation. Because of this, it was not possible to perform quick switching operations, and it was also impossible to switch from the site where the failure occurred as necessary.

Therefore, the present invention detects the occurrence of a failure in the current line system or the like and automatically performs the switching within the control device 2 described above. This will be explained in detail below.

In FIG. 4, reference numeral 6-1 is a switching circuit, which receives a signal of "L level" from the counter B9 under normal communication conditions, so that the test pattern generated by the test pattern generator 10 is is sent out from the transmission end of the protection line via the DV circuit 7-1. On the other hand, if a failure occurs in the working line system, etc., the counter B9 supplies an "H level" signal, so the test pattern generator 10 does not send out the signal.
The signal received from the receiving end of the backup line sampled by the sampling circuit 11 is automatically sent out via the switching circuit 6-1 and the DV circuit 7-1. This creates the loop shown in the second figure, and the fault is automatically avoided. Furthermore, when the counter B9 no longer receives a predetermined signal (signal that should form a loop) as described later, the counter B9 automatically returns to the "L level" signal. switching circuit 6
-1. Then, the switching circuit 6-1
sends a signal used for monitoring the backup line during normal operation to the backup line via the DV circuit 7-1.

FIG. 5 shows an example of a signal waveform sent out from the DV circuit 7-1 in a normal state, and the configuration diagram of one embodiment of the present invention shown in FIG. 4 will be explained using this example of the signal waveform.

Shown in the figure are signals generated by the clock generator 12 shown in FIG.

The figure shows NRZ data, “…0000000…”
This is a signal string consisting of all values of "0". The figure shows the NRZ data in the form of a signal.

The figure shows NRZi data, which is a value that is inverted when the value of the NRZ data is "0". The figure shows the NRZi data in the form of a signal, which is generated by the test pattern generator 10 shown in FIG. The NRZi signal is then input to the DV circuit 7-1 via the switching circuit 6-1. The DV circuit 7-
1 converts the NRZi signal into an output signal consisting of a 50% duty RZ bipolar signal and sends it out from the sending end of the backup line. By converting to a bipolar signal, the DC component is eliminated and it can be treated as an AC signal.

FIG. 6 shows an example of a signal waveform converted by the RV circuit 8-1 in a normal state based on a signal received from the receiving end of the protection line. A configuration diagram of a first embodiment will be explained.

The clock shown in the figure is extracted from the received signal by the clock generator 12 shown in FIG.

The figure shows a received signal, which is a signal in the form of "...01010..." received by the RV circuit 8-1 shown in FIG. The received signal is sampled by a sampling circuit 11 to obtain a unipolar signal such as the sampling signal shown in the drawing, and then the sampling signal is converted into the NRZi signal shown in the drawing.

The figure shows an NRZ signal, which is obtained by decoding the NRZi signal by the decoder 13 shown in FIG. The NRZ signal is expressed in the form of "...00000..." as shown in the illustrated NRZ data.

As explained above with reference to FIGS. 5 and 6, in normal communication conditions, the value decoded by the decoder 13 of the received signal detected from the backup line is always in the form "...00000...". For this reason,
Since the flag detection circuit 14 shown in FIG. 4 does not detect the flag described later, the counter B9 is at "L level".
The signal is sent to the switching circuit 6-1. As a result, the switching circuit 6-1 sends out the signal from the test pattern generator 10 in the form of "...010101..." via the DV circuit 7-1.

FIG. 7 shows an example of a signal waveform converted based on a signal received by the RV circuit 8-1 in a state where a fault has occurred in the communication line. A configuration diagram of a first embodiment will be explained.

The figure shows the signal extracted by the clock generator 12 shown in FIG.

The figure shows an example of a received signal received by the RV circuit 8-1, which is a signal consisting of all zeros. The received signal is, for example, a signal generated when a backup line is disconnected. Further, even if part of the value of the received signal becomes different from the output signal for some reason, it is also possible to detect that at least a fault has occurred in the backup line.

The figure shows a sampling signal. When the sampling signal is converted into an NRZ signal by the decoder 13, it is detected as a value "111111" as shown in the NRZ data. Since this is different from the value detected in the normal state shown in FIG. 6 (all zeros), the occurrence of the fault can be easily detected by, for example, the counter A15 shown in FIG. 4.

FIG. 8 is an explanatory diagram illustrating a state in which a loop is automatically formed due to a failure occurring in the working line system.

FIG. 8A shows an example of a signal being sent to the working line. This signal sends signals such as address information, command information, data, and CRC check to the area surrounded by FLAG and FLAG. The FLAG information has a value of "...01111110...", for example, as shown in FIG. 8B. Since the FLAG information is always sent to the working line, if some fault occurs in the working line system and a loop as shown in FIG. 2A is formed, the FLAG information is transmitted by the decoder 13 shown in FIG. will be decoded. The decoded FLAG information is detected by the flag detection circuit 14, and the counter B
9 and is counted by a counter A15 for a predetermined period of time, for example, one minute, and if it is greater than the predetermined value, the controller 16 is notified that a fault has occurred in the working line or backup line. As a result, it is detected that a failure has occurred, and a loop is then constructed using the backup line.

When the FLAG information is input to the counter B9, the counter B9 is set. As a result of this setting, an "H level" signal is sent to the switching circuit 6-1. As a result, the switching circuit 6-1 interrupts the output signal shown in FIG.
For example, as shown in FIG. 8A, the signal detected by the circuit 1 is switched to be sent out via the sampling circuit 11, the switching circuit 6-1, and the DV circuit 7-1. Then, when the FLAG information is no longer detected by the flag detection circuit 14, the counter B9 is reset. At this time, even if a predetermined period of time has elapsed after the counter B9 is set by the FLAG information, for example, a period slightly longer than the cycle at which the next FLAG information is detected, the counter B9 is set again by the FLAG information.
If not set by FLAG information, it is automatically reset.

Due to the reset, the switching circuit 6-1 sends out the signal from the original test pattern generator 10 via the DV circuit 7-1. As explained above, when FLAG information is detected, connections are automatically made to form a loop, and when FLAG information is no longer detected, the loop is released and the backup line is monitored. signals can be sent automatically.

(Effects of the Invention) As explained above, according to the present invention, in a system in which a plurality of terminals are serially connected to two pairs of communication lines consisting of a working line and a backup line, a failure occurs in the working line system, etc. When a failure occurs, it automatically detects the fault and configures the working line and backup line into a loop, eliminating the need for humans to operate the center control device and configure the loop, as was the case in the past. A loop can be automatically configured and can be automatically restored at the time of restoration.

[Brief explanation of drawings]

1 and 2 are conceptual explanatory diagrams explaining the concept of the present invention, FIG. 3 is a configuration diagram of a conventional example, FIG. 4 is a configuration diagram of one embodiment of the present invention, and FIGS. FIG. 4 is an explanatory diagram illustrating one embodiment of the present invention. In the figure, 1 is the working line, 2 is the control device, 3 is the backup line, and 4 is the ELB (emergency loop).
back) switch, 5 and 10 are test pattern generators, 6 and 6-1 are switching circuits, and 7 and 7-1 are
DV circuit, 8 and 8-1 are RV circuits, 9 is a counter B, 11 is a sampling circuit, 12 is a clock generator, 13 is a decoder, 14 is a flag detection circuit,
15 represents a counter A, and 16 represents a controller.

Claims (1)

[Scope of Claims] 1. A control device in which a terminal device is serially connected to a working line and a standby standby line, each connected in a loop, so that when a failure occurs in the line or the terminal device, the working line In a communication line control system in which a loop is configured using a backup line and a backup line, a test pattern sending unit sends a monitoring signal to a sending end of the backup line, and a signal sent by the test pattern sending unit is transmitted. a backup line monitoring unit that detects from the receiving end of the backup line and monitors the backup line; and a backup line monitor unit that detects from the receiving end of the backup line and monitors the backup line; a loopback detecting section that detects from the end; and a loopback detecting section that connects the receiving end and the transmitting end of the protection line when the specific pattern is detected by the loopback detecting section; A communication line control system comprising: a switching circuit that separates a receiving end and a transmitting end of a protection line and transmits the monitoring signal to the sending end of the protection line. 2. A loop holding section is provided which maintains the receiving end and the transmitting end of the backup line in a connected state for a predetermined period of time after the specific pattern is detected by the loopback detecting section. A communication line control system according to claim 1, characterized in that: 3 The state of the signal changes alternately in synchronization with the clock signal by the test pattern sending section.
A disconnection notification that transmits an NRZi-converted monitoring signal, decodes a signal detected from the receiving end of the backup line by the backup line monitoring unit, and determines the disconnection state of the backup line based on the decoded signal. 2. The communication line control system according to claim 1, further comprising a section.