JPS62213343A - Coaxial lan node - Google Patents

Abstract

PURPOSE:To prevent the entire system from being stopped even if a fault takes place by terminating or disconnecting of a coaxial cable having the fault, in case the fault takes place in the coaxial cable. CONSTITUTION:If a fault such as a damage takes place in the coaxial cable 11, a fault detection circuit 22 of a network controller 20 detects reflection from transmission/reception data (a) and outputs a fault signal (b) to a coaxial cable control circuit 23. Then the circuit 23 outputs a control signal Ca to termination circuits 12a, 14a and a disconnection circuit 13a in one direction of a transceiver 10 to apply termination/disconnection of the cable 11 and the data detects whether or not a reflection comes from a data (a). Since it is detected which direction of the cable 11 is faulty in the cable 11, the cable 11 of said direction is terminated or disconnected. Thus, the inter-node communication connected to the cable 11 not terminated/disconnected is attained. If the circuit 22 applies reflection detection at all times or periodically, the communication of all network is restarted just after the recovery of damage.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a coaxial LAN node having a transceiver and a network controller in a coaxial LAN (local area network).

2. Description of the Related Art Conventionally, this type of device uses a trunker 2 for transmitting and receiving data to and from a coaxial cable l, as shown in FIG. 2(a).
and a network controller 3 having a circuit 3a for controlling communication, and the network is shown in FIG.
As shown in Figure 3, a plurality of nodes were connected via a coaxial cable 1, and a termination circuit 4 was installed at the end of the coaxial cable 3 to prevent data reflection.

Problems to be Solved by the Invention However, with this configuration, if the coaxial cable 3 is damaged, the electrical signal will be reflected at the damaged location,
There is a problem in that communication becomes impossible not only between nodes on both sides of the coaxial cable 3 at the damaged location but also between all nodes, and the entire system stops operating.

SUMMARY OF THE INVENTION In view of the above problems, it is an object of the present invention to provide a coaxial LAN node in which the entire system does not stop operating even if the coaxial cable is damaged or the damage has not yet been repaired.

Means for Solving the Problems In order to solve the above problems, the present invention provides a termination circuit for opening or terminating the coaxial cables connected to both sides of a transceiver, respectively, for the transceiver, and for other transceivers. A termination circuit that opens or terminates the coaxial cable and a cutoff circuit that connects or disconnects the coaxial cable are provided, and if there is an abnormality in the coaxial cable, it is possible to detect which direction of the coaxial cable of the transceiver there is an abnormality,
This device is configured to terminate and cut the coaxial cable in the direction of the abnormality.

Effect of the Invention The present invention has the above-mentioned configuration, so that when an abnormality occurs in the coaxial cable, in order to terminate and disconnect the coaxial cable in the direction in which the abnormality occurs, communication between nodes connected to the coaxial cable in the direction in which the abnormality does not occur is performed. is possible, and the entire system does not stop operating.

EXAMPLES Hereinafter, the present invention will be described in detail with reference to the drawings. FIG. 1(A) is a block diagram showing an embodiment of a coaxial LAN node according to the present invention, and FIG. 1(B) is a block diagram of a system constituted by the nodes of FIG. 1(A).

The coaxial cable 11 to which both ends of the transceiver 1o of this coaxial LAN node are connected has termination circuits 12a and 12b that open or terminate the coaxial cable 11 in the direction of the transceiver 10, and connect or disconnect the coaxial cable 11. Breaking circuit 13a.

13b, and termination circuits 14a and 14 for opening or terminating the coaxial cable 11 in the direction of other transceivers 10.
b is placed.

The network controller 2o includes a communication control circuit 21, a coaxial cable abnormality detection circuit 22 that detects damage to the coaxial cable 11 based on transmission/reception data a from the transceiver 10, and outputs an L-tl-coaxial cable abnormality signal. It has a coaxial cable control circuit 23 which outputs coaxial cable control signals Ca and Cb for controlling the termination circuits 12a, 12b, 14a, 14b and the cutoff circuits 13a, 13b in the respective directions in response to a coaxial cable abnormality signal from the coaxial cable.

FIG. 1(b) shows a block diagram in which a network is constructed using a plurality of coaxial LAN nodes shown in FIG. 1(a), and each node is connected in series via a coaxial cable 11.

Next, the operation of the coaxial LAN node configured as described above will be explained.

First, when the coaxial cable 11 is normal, the abnormality detection circuit 22 of the network controller 20 does not detect the reflection of the signal to the transceiver IO, and therefore the coaxial cable control circuit 23
14a and 14b open the coaxial cable 11,
And the cutoff circuit 13a + 13b is the coaxial cable 11
control to connect. At this time, communication is possible between all nodes.

On the other hand, if an abnormality such as damage occurs to the coaxial cable 11,
The abnormality detection circuit 22 of the network controller 2o is
The reflection is detected from the transmitted/received data a, and an abnormality signal is output to the coaxial cable control circuit 23.

Next, the coaxial cable control circuit 23 connects the transceiver l
A control signal Ca is output to the one-way termination circuit 12a * 14a and the cutoff circuit 13a to terminate and disconnect the one-way coaxial cable 11, and the abnormality detection circuit 22 detects whether there is any reflection from the transmitted/received data a. To detect. Further, similar operations are performed in other directions of the coaxial cable 11.

Through the above operation, it is possible to detect which direction of the coaxial cable 11 connected to the transceiver IO is abnormal, and the coaxial cable 1 in the direction of the abnormality can be detected.
1 termination circuit 12 a e 14 a or 12b, 14
b. By controlling the cutoff circuit 13a or 13b, the cable 11
Terminate and cut. Therefore, communication is possible between the nodes connected to the coaxial cable 11 that is not terminated and disconnected.

In addition, the abnormality detection circuit 2 of the network controller 20
If the cable 11 detects the reflection of data constantly or at fixed time intervals by scanning or the like, communication of the entire network can be restarted when the damage to the cable 11 is recovered.

As explained above, the present invention provides a termination circuit for opening or terminating the coaxial cable and a cutoff circuit for connecting or disconnecting the coaxial cable on both sides of the transceiver. The configuration is configured to detect in which direction an error occurs in the coaxial cable, and terminate and cut off the coaxial cable in the direction in which the error occurs, allowing communication between all nodes even if an error occurs in the coaxial cable. The entire system will not stop working due to failure.

[Brief explanation of drawings]

FIG. 1(A) is a block diagram showing a coaxial LAN node according to an example of the present invention, and FIG. 1(B) is a block diagram of a system configured by the coaxial LAN node of FIG. 1(A). , FIG. 2(a) is a block diagram of a conventional coaxial LAN mate, and FIG. 2(a) is a system block diagram constituted by the coaxial LAN node of FIG. 2(a). 10... Transceiver, 11... Coaxial cable, 1
2a, 12b, 14a, 14b... termination circuit, 13a
, 13b... Cutoff circuit, 22 Coaxial cable abnormality detection circuit, 23... Coaxial cable control circuit. Name of agent: Patent attorney Toshio Nakao and one other person Figure 2 (O)

Claims (1)

[Claims] A first termination circuit that opens or terminates a coaxial cable connected to both ends of a transceiver with respect to the direction of the transceiver, and opens or terminates a coaxial cable with respect to another transceiver to which the transceiver is connected. a second termination circuit, and a cutoff circuit that connects or disconnects the coaxial cables at both ends of the transceiver, respectively;
a circuit for detecting an abnormality in a coaxial cable; and a circuit for detecting which direction of the coaxial cable of the transceiver is abnormal when the detection circuit detects an abnormality in the coaxial cable, and detecting the first and second coaxial cables in the direction of the abnormality. A coaxial LA having a termination circuit that terminates the coaxial cable and a circuit that controls the cutoff circuit in the direction of the abnormality to cut the coaxial cable.
N node.