JPH0433434A - Line concentrator for local area network - Google Patents

Abstract

PURPOSE:To keep the communication function of a normal section by operating an input bypass means so as to disconnect an input connector from an internal loop when a DC current reaches a specific current or below. CONSTITUTION:When a broken line fault takes place in a ring cable 16 and no DC current flows to DC signal transmission line (22,24,23), a current in a coupler 4 of a subordinate line concentrator 1b reaches a current B or below, an input bypass means of the coupler 4 is activated. That is, the coupler 4 of the subordinate line concentrator 1b reaches the bypass state in which a sub signal transmission line 11 and a main signal transmission line 14 are connected thereby disconnecting the ring cable 16 from an internal loop of the line concentrator lb. Thus, a faulty point is automatically disconnected from the network to maintain the communication function.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a line concentrator for local area networks based on IEEE802.5 and similar thereto, and particularly to failure countermeasures for local area networks.

[Prior Art] An example of the configuration of a local area network (LAN) based on IEEE802.5 is shown in FIG.
(a, b, c) and communication terminals 20 connected radially to each line concentrator 1 by branch cables 19, and the line concentrator 1 connects each communication terminal 20 in a ring shape as a whole. It is coupled to cable 16.

The ring cable 16 has a main signal transmission path and a sub-signal transmission path that constitute two information transmission paths, for example in the form of twisted wire pairs, and under normal conditions, the former main signal transmission path is used as an information transmission path, and is free from failures. Sometimes the latter sub-signal transmission path is used as a loopback information transmission path.

During normal operation, the line concentrator 1 connects the main signal transmission path of the ring cable 16 to the branch cable 19, forming one ring-shaped information transmission path as a whole. Thereby, the transmission signal is relayed from one communication terminal 20 to another communication terminal 20.

The internal configuration of the line concentrator 1 is shown in FIG.

The line concentrator J has an inner loop 30 formed by connecting a plurality of coupling units 5 in a ring shape via the main signal transmission line 14, which control the joining and leaving of the communication terminals 20 to the network, and an inner loop 30 that is left unused during normal times. The sub-signal transmission line 11 is connected to the sub-signal transmission line 11. Each coupling unit 5 in the line concentrator 1 is connected to a branch cable connector 15, and controls joining and detachment of the communication terminal 20 from the network.

The main signal transmission line 14 forming the inner loop 30 is connected to the first signal terminals (main signal terminals) a, a of the ring cable input connector 2 and the ring cable output connector 3, and and is connected to the main signal transmission path of the two information transmission paths of the ring cable 16. Further, the sub signal transmission line 11 is connected to second signal terminals (sub signal terminals) b, b of the ring cable input connector 2 and the ring cable output connector 3, and is connected to the ring cable 16 via the terminals. It is connected to the sub signal transmission path of the two information transmission paths. Therefore, during normal times, the sub-signal transmission line 11 is not associated with the coupling unit 5 and the like, and is left in an unused state.

In normal times, the main line of the network is such that each line concentrator 1 connects the main signal transmission line 14 of the inner loop 30 to the main signal transmission line of the ring cable 16 in a ring shape, forming one ring-shaped information transmission line as a whole. Consists of forming. As a result, during normal times, transmission signals flow through the line concentrator 1 as shown by solid arrows in FIG.
The communication terminal 20 is then relayed to another communication terminal 20 .

A communication terminal 20 that wishes to perform data communication using the LAN applies current directly to the branch cable 19. This direct current operates the coupling unit 5 to connect the branch cable 19 to the network. When no direct current flows, the coupling unit 5 disconnects the branch cable 19 from the network, and the transmission signal is transferred to the coupling unit 5.
Bypassed in Therefore, even if a fault such as a short circuit or disconnection occurs in the branch cable 19, direct current will no longer flow, and the cable 19 in which the fault has occurred will be disconnected in the coupling unit 5, and the network will be maintained.

[Problems to be Solved by the Invention] However, as described above, the conventional line concentrator has sufficient recovery capability against a fault in the branch cable 19, but it has a sufficient recovery function against a fault in the ring cable 16. In other words, when a failure occurs, a person must search for the point of failure and remove the failed ring cable 16 from the concentrators at both ends.

Connect the ring cable 16 to the output connector 3. Input connector 2
When the connector is removed from the connector, the main signal transmission line 14 and the sub signal transmission line 11 are short-circuited in both open connectors, thereby forming a new loop as shown by the dotted line in FIG. 5, thereby recovering from the fault.

As described above, the conventional line concentrator requires a recovery operation by a human, so there is a problem in that recovery takes time.

Another problem is that reliability decreases when a large-scale network is configured.

The purpose of the present invention is to solve the problems of the prior art described above,
To provide a line concentrator for a local area network capable of automatically separating a fault point from a network in response to a fault in a ring cable and maintaining the communication function of a normal part.

[Means for Solving the Problems] The present invention provides means for applying a DC voltage to the main signal terminal of a ring cable output connector in a local area network concentrator that performs communication control based on IEEE 802.5 or similar. and output-side feedback means connected to the sub-signal terminal of the output connector to feed back the DC current, and monitoring the current flowing through the main signal transmission path or the sub-signal terminal, and detects that the current value deviates from a specific current range A. a monitoring means for detecting that the output connector is connected to the input connector; The input side feedback means connects the input connector to the inner loop by means of the DC current, and when the DC current becomes below a specific current value B, a bypass operation is performed to connect the input connector from the inner loop. This configuration includes an input-side bypass means for disconnecting.

In this line concentrator, the input-side feedback means and the input-side bypass means can have the same configuration as a coupling unit that controls non-joining and disconnection of communication lines in the line concentrator.

[Function] The DC voltage applying means applies a DC voltage to at least one of the main signal terminals of the ring cable output connector.

When the ring cable is normal, the ring cable main signal transmission path, the downstream line concentrator, and the ring cable sub signal transmission path form the DC signal transmission path, so there is no direct current in this DC signal transmission path. Current flows. The flow of this direct current operates the input side bypass means connected to the input connector of the downstream line concentrator, thereby coupling the input connector to the inner loop. When the monitoring means detects that a normal DC current is flowing, the output side bypass means of the upstream line concentrator connects the output connector to its own internal loop.

However, if some kind of fault occurs in the ring cable, such as a disconnection fault, the direct current flowing through the transmission path becomes small or stops flowing, so the input side bypass means of the downstream line concentrator enters the bypass state and disconnects the ring cable from the inner loop. Also in the upstream concentrator, the monitoring means detects that the direct current is out of the normal range, and the output side bypass means enters the bypass state, so that the ring cable is disconnected from the inner loop.

In this way, since the signal is looped back at the line concentrators at both ends of the ring cable where the fault has occurred, a new loop is formed using the sub-signal transmission path, and the information transmission function is maintained. The same applies to short circuit faults.

[Example] Hereinafter, the present invention will be explained based on illustrated embodiments.

In the line concentrator 1 shown in FIG. 1, 2 is a ring cable input connector, 3 is a ring cable output connector,
Input connector 2.15 indicates a branch cable connector. A ring cable 16 consisting of a transmission medium capable of passing a direct current is connected to each output connector 3, and a communication terminal 20 is connected to the connector 15 via a branch cable 19. Build an area network.

Here, as already mentioned, the ring cable 16 has two information transmission paths, and each of these information transmission paths has a third information transmission path.
It is configured as a set of a main signal transmission line 22 and a sub signal transmission line 23 shown in the figure. Each transmission path is a pair of two conductors, but in FIG. 1, this pair is represented as one transmission path.

The main signal transmission path 22 is formed by a twisted pair of conductors 221 and 222, and the sub signal transmission path 23 is also formed by a twisted pair of conductors 231 and 23.
Although the transmission medium is composed of two pairs of twisted wires, any transmission medium that can flow a direct current may be used, and the twisted wires are not necessarily required.

The internal configuration of the line concentrator 1 is basically the same as that shown in FIG. 14
An inner loop 30 connected in a ring shape is connected to the inner loop 30, and a sub-signal transmission line 11 is connected between the sub-signal terminals S and B of the input connector 2 and the output connector 3.

However, as shown in FIGS. 1 and 3, a coupling device 4 having the same configuration as a coupling unit 5 that controls joining and detachment of a communication terminal 20 is provided on the ring cable input connector 2 side. On the cable output connector 3 side, there are a signal bypass section 6, voltage application sections 81, 82 . DC voltage detection sections 71 and 72 and DC feedback sections 171 and 172 are provided.

Specifically, on the input connector 2 side, a coupling device 4 is provided between the sub signal transmission line 11 and the main signal transmission line 14, and the coupling device 4 connects the sub signal transmission line 11 and the main signal transmission line via the coupling device 4. 14 are the main signal terminals a of the input connector 2,
Connected to the sub signal terminal. Further, on the output connector 3 side, a signal bypass section 6 is provided between the sub signal transmission line 11 and the main signal transmission line 14, and the sub signal transmission line 11 and the main signal transmission line 14 are connected via the bypass section 6, respectively. The sub signal terminal b9 of the output connector 3 is connected to the main signal terminal a. Main signal transmission line iot, 10 from the signal bypass section 6 to the main signal terminal a l + a 2 of the output connector 3
2, there is a DC voltage application section 8 that applies a DC voltage.
1.82 is provided. On the other hand, the main signal terminal bb2 of the output connector 3 is connected to a DC feedback section 1 that serves as an output-side feedback means that returns the DC current to ground the signal in a DC manner.
71.172 is connected to a DC current monitoring unit 71.72 that monitors DC current.

The DC voltage application parts 81 and 82 are connected to two differential signal lines for transmission connected to the output connector 3 (this is one of the twisted wires used for the main signal transmission line 22 and the sub signal transmission line 23). ,
Conductors 221 and 231. It is made up of conductors 222 and 232. ) It functions as a DC voltage applying means that applies a DC voltage independently to each of the DC voltages. The DC current monitoring units 71 and 72 are DC current monitoring means for monitoring the current flowing through each of the conductors 231 and 232 of the sub-signal transmission path 23, and detecting that the current value of one or both of them deviates from a specific current range A. This function is as follows.

In this embodiment, the DC voltage applying means applies a DC voltage V between the conductors 221 and 222 of the main signal transmission path 22 and the ground potential of the DC feedback section 171 and 172, as shown in FIG. By doing so, two information transmission paths (main signal transmission path 2
2 conductor 221° 222 and conductor 2 of the sub signal transmission line 23
31°232), voltages are applied independently to each of them. Further, when the DC current monitoring means detects that the current value flowing in this state is outside the specific current range A, it provides a detection signal to that effect to the signal bypass section 6.

When this signal bypass section 6 receives a detection signal indicating that the current value is out of a specific current range A from the DC current monitoring means, the internal loop 3 connected to the output connector 3
0 main signal transmission line 14 to the sub signal transmission line 11 and input connector 21! 1, and serves as an output-side bypass means for bypassing the output connector 3.

As already mentioned, the coupling device 4 has the same configuration as the coupling unit 5, and has the following two functions. The first is to transfer the DC current flowing through the signal transmission terminals al and az of the input connector 2 to the signal return terminals b+ and b of the input connector 2.
The function as an input side feedback means to feed back to i, that is,
This function is to feed back the DC current flowing through each of the two conductors 221 and 222 of the two signal transmission paths 22 of the ring cable 16 to each of the two conductors 231 and 232 of the ring cable 16. Second, the DC current connects the main signal transmission line 13 of the signal transmission terminal a of the input connector 2 to the internal loop 30 of the line concentrator 1 as shown by the solid arrow in FIG. When the current value is below B, the sub signal transmission line 1 is
1゜ Performs a bypass operation to connect between the main signal transmission lines 14 and connects the inner loop 30 to the sub signal transmission line 12 of the input connector 2.
．． It functions as an input-side bypass means for disconnecting from the main signal transmission line 13.

In the case of this embodiment, the coupling device 4 has the same configuration as the coupling unit 5 connected to the plant cable connector 15, but it does not necessarily have to be a unit with the same configuration. If it has a function,
Any configuration may be used.

Next, the operation of the line concentrator configured as described above will be explained using FIGS. 2 and 3.

Here, for convenience of explanation, two line concentrators 1 connected by a ring cable 16 are shown as upstream side 1a and downstream side Ill.
! Distinguished as Jib.

In normal times, the inner loop 30 of the concentrator 1 is connected to the coupling device 4. It is connected between the main signal terminals a, a of the input connector 2 and the output connector 3 via the signal bypass section 6 and the DC voltage application section 8. And upstream and downstream line concentrators 1a.

When the ring cable 16 interposed between Ib and Ib is normal (normal time), the DC voltage application section 81 of the upstream concentrator 1a
．． 82 through the main signal transmission path 22 of the ring cable 16 to the coupling device 4 of the downstream line concentrator W, ib, and a DC return path 24 by the input side feedback means of the coupling device 4 in the downstream line concentrator lb. , and a DC feedback path that returns from the downstream concentrator 1b to the DC current feedback sections 171, 172 of the upstream concentrator 1a through the sub-signal transmission path 23 of the ring cable 16, forming a DC signal transmission path.

In this case, the DC voltage application section 81 of the upstream line concentrator 1a.
Due to the DC voltage V applied at 82, a DC current flows through the DC signal transmission path (22, 24, 23).

This direct current is transmitted to the input connector 2 of the downstream concentrator ib.
operating the coupling device 4 of the inner loop 30 connected to
The coupling device couples the signal transmission terminal a of the input connector 2 of the concentrator 1b to the inner loop 30. Also, on the upstream line concentrator la side, the DC current monitoring units 71 and 72 detect a normal value of DC current (flow range A), so the signal bypass unit 6 of the line concentrator 1a The main signal terminal a of the output connector 3 is connected to the loop 30.

In this way, the concentrator 1f at both ends of the ring cable 16
The la and lb inner loops 30 form one loop via the ring cable 16, and this cable 16 is used as a data transmission path.

Next, assuming that a disconnection fault has occurred in the ring cable 16, the DC signal transmission path (22°24.23
), and the current in the coupling device 4 of the downstream line concentrator 1b becomes less than the current value B, so the input side bypass means of the coupling device 4 works, that is, the coupling device of the downstream line concentrator 1b 4 is a sub-signal transmission line 11.4 as shown by a dotted arrow on the right side of FIG. A bypass state is established in which the main signal transmission lines 14 are connected, and the ring cable 16 is disconnected from the internal loop 30 of the line concentrator 1b.

Also in the upstream line concentrator 1a, the DC current monitoring means of the DC current monitoring sections 71 and 72 detects that the DC current is outside the normal range A, and in response to this detection signal, the output side bypass means of the signal bypass section 6 In other words, the signal bypass section 6 of the upstream line concentrator 1a is connected to the sub signal transmission line 11. as shown by the dotted arrow on the left side of FIG. A bypass state is established in which the main signal transmission lines 14 are connected, and the ring cable 16 is disconnected from the internal loop 30 of the line concentrator 1a.

In this way, the ring cable 1 where the disconnection fault occurred
6 is the upstream and downstream line concentrator 1a.

1b is disconnected from both inner loops 30. As a result, the signal is looped back at the concentrators 1a and lb at both ends of the ring cable 16 where the fault has occurred, and a new trunk ring is formed using the sub-signal transmission path and the sub-signal transmission line, and the information transmission function is restored. maintained. The same applies to short circuit faults.

[Effects of the Invention] As described above, according to the line concentrator of the present invention, it is possible to realize the function of automatically disconnecting the fault point from the network and maintaining the communication function in the event of a fault in the ring cable. can. This feature allows you to configure a highly reliable network.

[Brief explanation of drawings]

Fig. 1 is a configuration diagram showing an embodiment of the line concentrator of the present invention, Fig. 2 is a diagram showing the state in which the line concentrators are connected by a ring cable together with the information route, and Fig. 3 is a diagram showing the route of the DC signal. FIG. 4 is a block diagram of a local area network to which the present invention is applied, and FIG. 5 is a block diagram of a line concentrator according to the prior art. In the figure, 1. la and lb are line concentrators, 2 is a ring cable input connector, 3 is a ring cable output connector,
4 is a coupling device, 5 is a coupling unit, 6 is a signal bypass section, 7.71.72 is a DC current monitoring section, 8, 81.82 is a DC current application section, 9.91.92.11.12 is a sub signal Transmission lines, 10, 101, 102, 13.14 are main signal transmission lines, 15 is a branch cable connector, 16 is a ring cable, 171.172 is a direct current return section, 19 is a branch cable, 20 is an information terminal, 21 is a ring cable signal transmission path, 22 is a main signal transmission path, 23 is a sub signal transmission path, 24 is a DC return path, 30 is an internal loop, a,
a, a2 are main signal terminals, and b, b+, b2 are sub signal terminals. Patent applicant: Hitachi Cable Co., Ltd. Representative Patent Attorney Nobuo Kinutani

Claims (1)

[Claims] 1. In a local area network concentrator that performs IEEE802.5 or similar communication control, means for applying a DC voltage to the main signal terminal of a ring cable output connector; output-side feedback means connected to the sub-signal terminal to feed back the DC current; monitoring means for monitoring the current flowing through the main signal terminal or the sub-signal terminal and detecting that the current value deviates from a specific current range A; output-side bypass means that performs a bypass operation to disconnect the output connector from the inner loop when the monitoring means performs a detection operation; and an input that returns the direct current flowing through the main signal terminal of the ring cable input connector to the sub-signal terminal of the input connector. side feedback means, the direct current connects the input connector to the inner loop, the direct current is at a specific current value B;
A line concentrator for a local area network, comprising input-side bypass means that performs a bypass operation to disconnect the input connector from the inner loop when the following conditions occur. 2. The line concentrator according to claim 1, wherein the input side feedback means and the input side bypass means have the same configuration as a coupling unit that controls joining and detachment of communication terminals in the line concentrator. Network concentrator.