JPS62247649A - Duplex communication equipment - Google Patents

Abstract

PURPOSE:To attain surely loop-back despite a fault occurred at a point near a connection area by providing a line receiver, a line driver and a loop-back control means at a joint part between a duplicated circular transmission line and a node. CONSTITUTION:The communication nodes ST1-STi are connected to circular transmission lines LW1 and LW2 set opposite to each other via line connection parts LC1-LCi. Each part LCi contains line receivers 11 and 12 to receive the signals from the upstream side and line drivers 21 and 22 to send signals to downstream side. Then loop-back control parts 31 and 32 are set between those line receivers and drivers together with a loop control/external connection control part 4. Thus the loop-back is secured at the line connecting parts LC2 and LC4 if the faults occur at circuits A1 and A2, for example, set in the same section. While the loop-back is secured at the connecting parts LC2 and LC4 with the faults occurring at the circuits A2, B1, for example, set in different sections. Thus the loop-back is surely secured even with faults occurring at a point near a connecting part.

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Application Field) The present invention relates to a duplex communication device that performs data communication between a plurality of communication nodes connected via a duplex loop dataway. .

(Conventional technology) FIG. 6 is a conceptual diagram of the structure of the duplex communication device U.

In the figure, STI, ST2, . . . are a plurality of distributed communication stations between communication nodes), and LW is a duplex loop-type dataway that connects each communication node.

Each communication node sequentially transmits and relays the signals it receives to the next communication node, and one LWI and the other LW2 of the duplexed loop dataway transmit signals in opposite directions. configured to be transmitted.

In a communication device with such a configuration, points AI and A are now connected.
If an accident occurs in which the dataway LW is disconnected at two locations, communication node ST2 will be unable to receive a signal from communication node ST3. Similarly, communication node ST3 becomes unable to receive a signal from communication node ST2.

Here, the communication node ST2 and the communication node ST3 are
AI of data ways LWI and LW2 via data way LW on the side where the wire is not disconnected.

The downstream communication node is notified that an abnormality has occurred at point A2. This notification is sequentially transmitted to the communication nodes on the downstream side, and finally the notification sent from communication node ST2 is sent to communication node ST3, and the notification sent from communication node ST3 is sent to communication node ST2 by 5 rJa. As a result, each communication node ST2. ST3 is data way LWI.

Recognizing that both LW2 are disconnected, communication node ST
2 sends a signal from one data way LW2 to the other data way LWI, and communication node ST3 sends a signal from data way LW2 to the other data way LWI.
A loopback operation is performed so that the signals from the WI are looped back to the data way LW2.

This loopback operation reconfigures the ring-shaped transmission path and continues the dataway.

(Problems to be Solved by the Invention) In the conventional communication device, for example, in FIG. 6, when the point A2 and the point B1 on the data way LW are disconnected, the communication node ST3
Both WI and LW2 are used to report disconnection information at points A2 and B1 to the downstream communication node, but these reports disappear at points Bl and A2, respectively, and are not received until communication node ST3. not reached. For this reason, there was a problem in that a loop by loopback was not formed, making it impossible to pass through.

FIG. 7 is a conceptual diagram of a connection between a communication node and a duplex dataway (communication cable) that connects to a second communication node.

Each communication node is connected by a communication cable laid in the duct DT, and the disconnection at points A1 and A2 in FIG. 6 corresponds to the disconnection in the duct DT in FIG.
Moreover, the disconnection at point A2 and point B1 corresponds to a disconnection near the connection point between the communication node and the communication cable.

SUMMARY OF THE INVENTION An object of the present invention is to realize a redundant communication device that has a communication recovery function using a loopback operation even in the event of a disconnection accident near a connection point between a communication node and a communication cable.

(Means for Solving the Problems) The present invention achieves this object in a communication device that performs data communication between a plurality of communication nodes each connected to a duplicated loop dataway via a line coupling section. , the line coupling section includes a line receiver coupled to each of the duplicated data ways, a line driver, a loopback control means that inputs a signal from the line receiver and performs a loopback operation when a loop break is detected; A loop control/external connection control unit is provided between each line receiver and each line driver to control the loop and exchange data with communication nodes, and the loop control/external connection control unit receives data from each line receiver. It is characterized by having means for monitoring signals and interrupting signal transmission from each line driver to the output transmission path connected thereto if an abnormality occurs in both of the input transmission paths connected to these line receivers. do.

(Actual Example) FIG. 1 is a conceptual diagram of a communication system to which the present invention is applied. In the figure, LCI, LC2 to LCn are line coupling units, and each communication node STI to STn is connected to a duplexed loop dataway L via a corresponding coupling unit.
Connected to W. Signals between communication nodes that are in +a contact are transmitted in opposite directions to one LWI and the other LW2 of the duplexed data way.

FIG. 2 is a block diagram of the main parts of each line coupling unit LCI to LCn. In Figure 2, 11.12 is a line receiver, 21.22 is a line driver, and 31.32 is a line receiver.
is a loopback control circuit, which is a duplicated loop type data way L W 1 .

When coupled to LW2 and detecting loop breakage, it performs a loopback operation. 4 is a loop control/external connection control unit provided between each line receiver and line driver, which is connected to a computer or terminal as a fi node, and controls the loop and connects each communication node. exchange of data.

41 is a signal transmission interrupting means, and the line receivers 11 and 12
If an abnormality occurs in both of the input transmission paths leading to these line receivers and it becomes impossible to receive signals from the upstream communication node, output transmission from the two line drivers 21 and 22 is performed. Road LW1. LW2
is configured to interrupt signal transmission to.

This function is realized, for example, by a program using a microprocessor.

The operation of the apparatus configured as described above will now be described with reference to FIGS. 3 to 5.

Now, in Fig. 3, A of one data way LWI
If a wire breakage accident occurs at one point, the loop of the external data way LW2 is normal, so data communication is performed using this loop.

Further, in FIG. 4, the data way LWI.

If a disconnection accident occurs at points A1 and A2 of LW2, loopback is performed at each line coupling section LC2 and LC3 to enable data communication.

The above operation is the same as that of the conventional +A position.

Next, in FIG. 5, if a disconnection accident occurs at point B1 of data way LWI and point A2 of data way LW2, line coupling part LC3
It becomes impossible to receive signals from both LW2 and LW2. In this case, the signal transmission interrupting means 41 in this line coupling unit LC3 detects that the signal cannot be received, and each line driver 21.22
signal transmission to each output transmission path is interrupted. As a result, each line coupling part LC2 and LC4 on the downstream side is
Each line coupling part LCI respectively.

The signal from LC2 becomes unreceivable, and information indicating this is reported to the downstream side. This notification eventually reaches the line coupling parts LC4 and LC2, respectively, and each line coupling part LC
The loopback control sections 4 and LC2 each perform a loopback operation, and a loop is formed excluding the line coupling section LC3, thereby enabling communication.

(Effects of the Invention) As explained above, according to the present invention, it is possible to continue the communication function by loopback operation even in the event of a disconnection accident near the connection point between the communication node (line coupling part) and the communication cable. Therefore, it is possible to realize a highly reliable communication device against data way disconnection in the communication system.

[Brief explanation of drawings]

Figure 1 is a conceptual diagram of the configuration of a communication system to which the present invention is applied;
The figure is a block diagram of the main part of each line coupling section in Figure 1, Figures 3 to 5 are explanatory diagrams of operations when the dataway is disconnected, Figure 6 is a conceptual diagram of the configuration of the duplex communication device, and Figure 7 is FIG. 2 is a conceptual diagram of a connection between a communication node and a communication cable. LW...Data way, STI, ST2...Communication node, LCI, LC2...Line coupling unit, 11°12
... Line receiver, 2122 ... Line driver, 31.32 ... Loopback control section, 4 ... Loop control/external connection system? ! 1lffl, 41...Signal transmission interrupting means.

Claims (1)

[Claims] In a communication device that performs data communication between a plurality of communication nodes each connected to a duplicated loop data way via a line coupling section, the line coupling section includes a line receiver coupled to each of the duplicated dataways. , a line driver, a loopback control means that inputs a signal from the line receiver and performs a loopback operation when a loop break is detected, and a loop control and communication node provided between each of the line receivers and each line driver. and a loop control/external connection control unit that exchanges data with the line receiver, and the loop control/external connection control unit monitors signals from each line receiver and detects an abnormality in both input transmission paths connected to these line receivers. A duplex communication device characterized by comprising means for interrupting signal transmission from each line driver to an output transmission line connected to the line driver when the line driver does not operate.