JPH088945A - Loop network equipment - Google Patents

Abstract

PURPOSE:To allow the loop network equipment to detect isolation of a slave equipment whose communication is disable with a center equipment from a center equipment quickly CONSTITUTION:A center equipment 11 has a center existing signal transmission circuit 16 and a slave equipment 12(13, 14, 15) has a center existing signal relay/ delete circuit 17(18, 19, 20) in the loop network consisting of one center equipment and the plural slave equipments. The center existing signal relay/delete circuit of a slave equipment detecting a fault of a transmission line deletes a center existing signal. The slave equipment has an isolation discrimination circuit 21(22, 23, 24) discriminating isolation based on the presence of the center existing signal.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a loop type network device used in a local area network or the like.

[0002]

2. Description of the Related Art FIG. 4 shows a configuration example of a conventional loop type network device.

In FIG. 4, 41 is a center device, 42,
Reference numerals 43, 44, and 45 are slave devices, and the center device 41 and the slave devices 42, 43, 44, and 45 are two transmission lines 46 and 47 that transmit data in opposite directions.
Are connected by loop type.

In this conventional example, when no failure occurs in the transmission lines 46 and 47, the data synchronized with the reference timing generated by the center unit 41 is transmitted to the slave unit 4.
The data is transmitted clockwise from 2 to the flavor device 45 in order, and by circulating around the center device 41 again, communication between arbitrary devices is enabled.

Next, the operation of the loop type network device when a failure occurs in the transmission line will be described with reference to FIG.

FIG. 5 shows a center device 41 and a slave device 4.
A case where a failure occurs simultaneously in the transmission lines 46 and 47 between the two and the transmission lines 46 and 47 between the slave device 44 and the slave device 45 is shown.

In FIG. 5, the slave device 42, which has detected a transmission line failure with the center device 41, operates a turn-back switch in the slave device 42 so as to send out counterclockwise transmission line data to the clockwise transmission line. Switch.

Similarly, the center device 41, which has detected a transmission line failure with the slave device 42, switches the loopback switch in the center device 41 so as to send the clockwise transmission line data to the counterclockwise transmission line.

Similarly, the slave device 44 and the slave device 45 also perform a loopback operation so as to disconnect the transmission line in which the failure is detected.

As a result, the network is divided into two loops, a loop loop including the center apparatus 41 and a loop loop not including the center apparatus 41 (hereinafter, an isolated loop), to perform communication.

[0011]

However, in the above-mentioned conventional example, when a transmission line failure such as a loopback loop not included in the center device 41 occurs as shown in FIG. Devices 42, 4
In 3 and 44, the possibility of communication with the center device 41 cannot be promptly known.

The present invention is to solve the above-mentioned conventional problems, and it is possible for each slave device forming an isolated loop to promptly detect that communication with the center device has become impossible, in a loop type network. The purpose is to provide a device.

[0013]

According to the present invention, in order to achieve the above object, one center device and a plurality of slave devices are connected in a loop type by two transmission lines that are transmitted in opposite directions. In the network, the center device is provided with a center presence signal sending circuit for sending the presence signal of the center device to the transmission line, and the slave devices are provided with the center presence signal when the state of the transmission line is normal. A center presence signal relay / erase circuit that relays to the device of the next stage and erases the center presence signal sent to the device of the next stage when the status of the transmission line is abnormal, and an output signal from the center presence signal relay / erase circuit. An isolation determination means for determining isolation from the loop based on the above is provided.

[0014]

Therefore, according to the present invention, when a transmission line failure occurs in the network, the center presence signal relay / elimination circuit erases the center presence signal and relays it to the next stage device. Then, based on this center presence signal, the isolation determination means promptly detects that communication with the center device has become impossible.

[0015]

An embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 is a schematic configuration diagram of a loop type network device according to the present invention. In FIG. 1, 11 is a center device, and 12, 13, 14, and 15 are slave devices, respectively.

The center device 11 includes a clockwise center presence signal generation circuit 16 and a counterclockwise center that transmit a center presence signal to both the clockwise and counterclockwise transmission lines 30 and 31 by superimposing the center presence signal on the transmission line data. Presence signal generation circuit 17
Have. Further, the slave devices 12, 13, 14, 15
Is a center presence signal relay / elimination circuit for clockwise 18, which relays / eliminates a center presence signal according to the state of the transmission line to which the device is connected, and a center presence signal relay / elimination for counterclockwise rotation. It has circuits 22, 23, 24 and 25, respectively.

Further, the slave devices 12, 13, 14,
Reference numeral 15 denotes an isolation determination circuit 26 which receives the output signals of the center presence signal relay / erase circuits 18 to 21 for clockwise rotation and the output signals of the counter presence signal relay / erase circuits 22 to 25 for counterclockwise rotation, which are respectively provided. , 27, 28, 29.

The center presence signal relay / elimination circuit erases the center presence signal which is transmitted clockwise and counterclockwise from the self device in the slave device which has detected the transmission line fault, and has not detected the transmission fault. In the device, the transmission line 3 is provided for each of the clockwise and counterclockwise directions.
The center presence signal received from 0 and 31 is relayed.

Each of the isolation determination circuits determines that it is an isolated loop when the inputs from the two center presence signal relay / erase circuits are erased.

FIG. 3 is a block diagram showing the internal structure of each slave device in the embodiment. In FIG. 3, the slave device 311 includes a clockwise data receiving circuit 312, a clockwise center presence signal relay / erase circuit 313 including a logical product circuit, a clockwise data transmitting circuit 314, a counterclockwise data receiving circuit 315, and a logical product circuit. A counterclockwise center presence signal relay / erase circuit 315, a counterclockwise data transmission circuit 317, and an isolation determination circuit 318 composed of a logical sum circuit.

The center presence signal and the transmission line state signal extracted from the data received by the clockwise data receiving circuit 312 are input to the center presence signal relay / erasure circuit 313, and the logical product of these two signals is relayed / erased by the center presence signal. Circuit 313
Output from This center presence signal relay / elimination circuit 3
13 outputs the logic "1" only when the logic of the reception center presence signal from the clockwise data receiving circuit 312 is "1" and the state of the transmission line is normal, and when the state of the transmission line is normal. The center presence signal is relayed and the center presence signal is erased when the status of the transmission line is abnormal.

The clockwise data transmission circuit 314 multiplex-combines the center presence signal and other transmission data and sends it to the next slave device or the center device.

The counterclockwise data reception circuit 315, the counterclockwise center presence signal relay / erasure circuit 316, and the counterclockwise data transmission circuit 317 relating to counterclockwise data perform the same operations as in the clockwise direction.

The isolation determination circuit 318 is a clockwise / counterclockwise center presence signal relay / erase circuit 313, 316.
If the outputs of both are logical "0", the slave device 31
It is determined that 1 is isolated and a logic "0" is output, and if it is not isolated, a logic "1" is output.

Next, the operation of this embodiment will be described with reference to FIGS. As shown in FIG. 1, when there is no transmission path failure in the network, the center presence signal sent by the center device 11 is relayed without being erased by any of the slave devices 12, 13, 14, 15 on the network. To be done.

That is, the center presence signal sent from the sensor device 11 is a logic "1", which is sent to the clockwise and counterclockwise transmission lines 30 and 31, respectively.

Here, the slave devices 12, 13, 14,
The clockwise and counterclockwise center presence signals in 15 are respectively the center presence signal relay / erasure circuits 18 to 21.
And received as a logical "1" at 22-25,
Since it is sent out as a logic "1", all the slave devices receive "1" as the center presence signal and each of the isolation determination circuits 26 to 29 determines that the device itself is not isolated.

Next, as shown in FIG. 2, the center device 11
Transmission lines 30 and 31 between the slave device 12 and the slave device 12, and a transmission line 30 between the slave device 14 and the slave device 15,
A case will be described in which 31 simultaneously fails.

In this case, since the transmission lines 30 and 31 between the center device 11 and the slave device 12 have a failure,
The slave device 12 erases the center presence signal from the logic “1” to the logic “0” by the center presence signal relay / erasure circuit 18 for the clockwise transmission line 30 and relays the center presence signal.

Similarly, since a failure has occurred in the transmission lines 30 and 31 between the slave device 14 and the slave device 15, the slave device 14 erases the counterclockwise center presence signal.

Therefore, in the slave devices 12, 13, and 14 forming the isolated loop, both the clockwise and counterclockwise center presence signals are received as logic "0", and communication with the center device 11 becomes impossible. It can be promptly detected. As a result, the service status of the network can be notified to the outside.

[0033]

As is apparent from the above embodiments, the present invention can promptly and accurately know the inability to communicate with the center device on the isolated loop side when an isolated loop occurs due to a transmission line failure. The effect is that the service status of the network can be promptly notified to the outside.

[Brief description of drawings]

FIG. 1 is a block diagram showing a schematic configuration of a loop type network device according to an embodiment of the present invention.

FIG. 2 is a schematic block diagram when an isolated loop occurs due to a transmission line failure in the loop type network device of the present embodiment.

FIG. 3 is a block diagram showing an internal configuration of a slave device according to the present embodiment.

FIG. 4 is a block diagram showing a schematic configuration of a conventional loop type network device.

FIG. 5 is a schematic block diagram in the case where an isolated loop occurs due to a transmission line failure in a conventional loop type network device.

[Explanation of symbols]

 11 Center Device 12 to 15 Slave Device 16 Clockwise Center Presence Signal Generation Circuit 17 Counterclockwise Center Presence Signal Generation Circuit 18 to 21 Clockwise Center Presence Signal Relay / Erase Circuit 22 to 25 Counterclockwise Center Presence Signal Relay / Erase Circuit 26-29 Isolation determination circuit 311 Slave device 312 Clockwise data receiving circuit 313 Clockwise center presence signal relay / erasing circuit 314 Clockwise data transmitting circuit 315 Counterclockwise data receiving circuit 316 Counterclockwise center presence signal relay / erasing circuit 317 Counterclockwise data transmission circuit 318 Isolation determination circuit

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Ken Miyakoshi 4-3-1, Tsunashima-higashi, Kohoku-ku, Yokohama-shi, Kanagawa Matsushita Communication Industrial Co., Ltd.

Claims (1)

[Claims] 1. A network in which one center device and a plurality of slave devices are connected in a loop by two transmission lines that are transmitted in opposite directions, and the center device has the center device. A center presence signal transmission circuit for transmitting a signal to the transmission line is provided, and each slave device relays the center presence signal to the next stage device in a normal state of the transmission line, and when the state of the transmission line is abnormal. A center presence signal relay / erase circuit for erasing the center presence signal to be sent to the next stage device, and an isolation determination means for determining isolation from a loop based on an output signal from the center presence signal relay / erase circuit are provided. A loop type network device characterized by the above.