JPH08116330A - Lan system - Google Patents

Abstract

PURPOSE: To provide a LAN system capable of continuing communication be tween terminal equipment even when a fault occurs in a transceiver. CONSTITUTION: A packet as a signal for check is transmitted from a control, circuit 4 to terminals 3a, 3b via a LAN cable 1, and fault information is stored in fault memory 6 by a response signal from the terminal equipment 3a, 3b. The control circuit 4 drives the relay 7a or 7b of a switching means 21 or 22 by the fault information, and separates a faulty transceiver by switching a contact 8a or 8b.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a LAN (Local Area Network) system, and particularly to LA
It relates to the elimination of transceiver failures in N systems.

[0002]

2. Description of the Related Art FIG. 11 is a block diagram showing a conventional LAN system. In the figure, 1 is a LAN cable for transmitting communication data, 2a, 2b, ... Transceivers 3a, 3b,
... 3z is a terminal device (hereinafter referred to as a terminal) that joins this LAN system, 12 is a terminator connected to both ends of the LAN cable 1, and terminates the signal path with the same resistance value as the characteristic impedance of the LAN cable 1. This prevents signal reflection.

Next, the operation will be described. In FIG. 11, for example, the terminal 3a is connected to the LAN via the transceiver 2a.
This LAN is connected by using the cable 1 as a data transmission line.
Data is exchanged between the terminals 3b via the cable 1.

[0004]

Since the conventional LAN system is configured as described above, if a transceiver connected to a terminal fails, the terminal can be used even if the terminal is operating. There were problems such as disappearance.

The present invention has been made to solve the above problems, and an object thereof is to continue the use of the terminal device even if a transceiver connected to the terminal fails. Further, it is an object of the present invention to make the LAN system continue to operate even when one of the LAN cables is broken by duplicating the LAN cable portion.

[0006]

A LAN system according to the present invention is a LAN system in which a plurality of terminal devices are connected to one LAN (local area network) through a transceiver, and the above LAN is provided for one terminal device. A plurality of transceivers connected to the terminal device, and first switching means for selectively switching one of the plurality of transceivers to connect to the terminal device; and sending a check signal to the terminal device through the LAN. However, a monitoring means for sending a switching command signal to the first switching means in response to a response signal from the terminal is provided.

In a LAN system in which a plurality of terminal devices are connected to one LAN (local area network) via transceivers, a plurality of transceivers connected to the LAN are provided for one terminal device, A transceiver having first switching means for selectively switching one of the plurality of transceivers to connect to the terminal device, the transceiver having signal generating means for generating a check signal and transmitting the check signal to the connected LAN. Further, there is provided a monitoring means for receiving the checking signal and transmitting a switching command signal to the first switching means in accordance with the received information.

A plurality of transceivers connected to the LAN are provided for the monitoring means, and a second switching means for selectively switching one of the plurality of transceivers to connect to the monitoring means is provided. The monitoring means is means for sending a switching command to at least one of the first and second switching means in accordance with the received information of the check signal.

Further, the monitoring means sends a switching command to the second switching means when the received information of the check signal is the failure information of all terminals, and the received information of the check signal is other than the failure information of all terminal devices. If the failure information is, the switching command is sent to the first switching means of the terminal device corresponding to the failure information.

Further, the LAN is a plurality of LANs, and a plurality of transceivers on the side of the terminal device and a plurality of transceivers on the side of the monitoring means are arranged so as to correspond to the plurality of LANs, respectively, and the monitoring means transmits the check signals. It is a means for sending a switching command to the first and second switching means so as to select a sound LAN from among the plurality of LANs according to the received information.

In a LAN system in which a plurality of terminal devices are connected to one LAN (local area network) via transceivers, a plurality of transceivers connected to the LAN are provided for one terminal device, The transceiver is provided with third switching means for selectively switching one of the plurality of transceivers to connect to the terminal device, and the transceiver is a transceiver having signal generating means for generating a check signal. It is provided with a monitoring means which is installed and which receives the check signal and sends a switching command signal to the third switching means according to the received information.

Further, the LAN is a plurality of LANs, and a plurality of transceivers are arranged so as to correspond to the plurality of LANs, respectively, and the monitoring means determines the health of the plurality of LANs according to the reception information of the check signal. It is a means for sending a switching command to the third switching means so as to select a different LAN.

As the check signal, a heartbeat signal transmitted from the transceiver when the transceiver is healthy is used.

Further, there is provided a manual switching command means for manually sending a switching command to the first and second switching means.

[0015]

In the LAN system of the present invention, the L means is connected to the monitoring means.
A check signal is sent to the terminal device through the AN, a switch command signal is sent to the first switching means in response to a response signal from the terminal, and the first switching means switches the transceiver.

Further, a plurality of transceivers connected to the LAN are arranged for one terminal device, and a signal generating means of the transceiver generates a check signal and sends it to the connected LAN. The monitoring means receives the check signal, sends a switching command signal to the first switching means in accordance with the received information, and the switching means switches the transceiver.

Further, a plurality of transceivers connected to the LAN are provided for the monitoring means, and the monitoring means switches at least one of the first and second switching means according to the received information of the check signal. Sends a switching command to the first
And the second switching means switches the transceiver according to the switching command.

Further, the monitoring means sends a switching command to the second switching means when the received information of the check signal is the failure information of all terminals, and the received information of the check signal is other than the failure information of all terminals. If it is the failure information, the switching command is sent to the first switching means of the terminal corresponding to the failure information.

Further, the monitoring means sends a switching command to the first and second switching means so as to select a sound LAN among the plurality of LANs according to the reception information of the check signal, and the first switching means
And the second switching means switches the transceiver according to the switching command.

Further, the transceiver generates a check signal from the signal generating means, and the monitoring means installed in each terminal device receives the check signal and switches to the third switching means according to the received information. The command signal is transmitted, and the third switching means switches the transceiver.

Further, the monitoring means sends a switching command to the third switching means so as to select a sound LAN among a plurality of LANs in accordance with the reception information of the check signal, and the third switching means switches the transceiver. .

As the check signal, a heartbeat signal transmitted from the transceiver when the transceiver is healthy is used.

Further, the manual switching command means for manually sending the switching command to the first and second switching means is used.

[0024]

【Example】

Example 1. Embodiment 1 of the present invention will be described below with reference to the drawings. In FIG. 1, 1 is a LAN cable, 2a, 2
b, 2c, 2d, ... 2z are transceivers connected to the LAN cable 1 and 3a and 3b are transceivers 2.
LAN cable 1 via a, 2b or 2c, 2d
Connected to the terminal 4, a control circuit for managing failure of the transceivers 2a to 2d, 5 a LAN interface controlled by the control circuit 4, and 6 a transceiver 2
Fault memories 7a and 7b for storing fault information a to 2d
Is a relay operated by the output of the control circuit 4, 8a, 8b
The transceivers 2a, 2 due to the operation of the relays 7a, 7b.
b, 2c, a contact for switching the connection state with 2d, 9a,
9b is a contact point 21 indicating the operating state of the relays 7a and 7b,
Reference numeral 22 is a switching circuit, and 31 is a monitoring device.

Next, the operation will be described with reference to the flowchart of FIG. In FIG. 1, each of the terminals 3a and 3b is connected to one transceiver, for example, depending on the state of the contacts 8a and 8b.
It is connected to 2a and 2c. The control circuit 4 is periodically set to L
A check signal (operation confirmation packet signal) is transmitted to the terminals 3a and 3b via the AN interface 5 (step S1, step is omitted hereinafter), and the terminals 3a and 3b are transmitted.
Then, it is confirmed whether or not there is a normal response (S2). Terminal 3
If there is no response from a or 3b, the LAN interface 5 stores transceiver failure information in the failure memory 6 (S3). Whether all terminals have been checked (S4)
Steps S1 to S until all terminals are checked
Repeat 4.

When the check of all terminals is completed, the control circuit 4 reads the contents of the failure memory 6 and checks whether or not there is a failure. For example, if failure information of the transceiver 2a exists (S5), the relay will be relayed. Output is performed so that 7a is in an operating state opposite to the operating state determined from the input state of the contact 9a. With this output, the relay 7a operates and the contact 8
a is switched to be connected to the transceiver 2b, and the terminal 3a is continuously connected to the LAN cable 1 and the operation can be continued (S6). As described above, even if there is only one LAN interface (not shown, necessary for cable connection with the transceiver) of the terminal, the reliability is the same as that of duplexing.

In the description of this operation, the operation confirmation packet is individually transmitted from the control circuit 4 to each terminal to confirm the response. However, when the operation confirmation packet is transmitted from the control circuit 4, the broadcast transmission (the destination is It is also possible to use a signal that is transmitted to all connected terminals without specifying (without an address). In this case, when each terminal receives the broadcast signal, the terminal transmits a response signal to which the address of each terminal is added to the monitoring device 31.

Embodiment 2 FIG. In this embodiment, a plurality of transceivers are also provided on the monitoring device 31 side. FIG. 3 is a diagram showing the configuration, and FIG. 4 is a flowchart of the operation.

In FIG. 3, transceivers 2y and 2z are provided on the monitoring device 31 side, and the relay 7z of the switching circuit 41 switches and connects the transceivers 2y and 2z by the operation of the contact 8z. The contents of the fault memory 6 include the transceivers 2a, 2
When the failure of c is stored, the relay 7z is connected to the contact 9
Operate so as to be the opposite of the state recognized by z, and
The N interface 5 is connected to the LAN cable 1.
In this state, the transmission to the transceivers 2a and 2c is performed again, and each transceiver connected to the terminal is checked.

In this way, the LAN interface 5
It is possible to avoid a communication failure due to a failure of the transceiver 2y or 2z connecting the LAN cable 1 to the LAN cable 1. In the flowchart of FIG. 4, steps S1 to S6 are the same processes as those in the first embodiment. If all the terminals fail in step S7, the transceiver 2y is regarded as a failure, the state of the relay 7z is inverted, and the transceiver 7z is inverted. Switch from 2y to 2z.

Example 3. In the second embodiment, the relays 7a, 7
Although the operation output of b and 7z is performed by the response of the terminals 3a and 3b, in this embodiment, as shown in FIG. 5, the manual switches 10a, 10b and 1 input to the control circuit 4 are input.
Switch group 5 with built-in 0c, 10d, 10y, 10z
1, the manual switch 10a, 10b, 10
By closing c, 10d, 10y and 10z, the control circuit 4 outputs the operation output of the relays 7a, 7b and 7z.

By doing so, the transceivers 2a, 2
When performing maintenance of b, 2c, 2d, 2y, 2z, the desired transceiver can be disconnected,
The transceiver can be inspected, repaired, removed, etc. without hindering the communication of the terminals 3a and 3b and the LAN interface 5.

Example 4. In the first embodiment, the monitoring device 31 checks each terminal and the transceiver, but in this embodiment, a control circuit is provided on each terminal side to check.

The structure of this embodiment is shown in FIG. As shown, control circuits 11a and 11b are provided in the switching circuits 23 and 24, and the control circuits 11a and 11b are connected to the terminals 3a and 3b.
Heartbeat signal output from each transceiver in units of transceivers 2a, 2b and transceivers 2c, 2d connected to (a signal output to the terminal side after data transmission to notify that its own transceiver is normal) Is detected, and if there is an abnormality, the relay 7a or 7b is operated.

In this way, it is possible to easily switch between the transceivers 2a and 2b or between the transceivers 2c and 2d without the control circuit 4 of the first embodiment, so that an inexpensive device can be provided.

Example 5. In the first and second embodiments, the control circuit 4
Although the packet is transmitted from the device through the LAN interface 5, this embodiment does not provide a monitoring device separately but provides a control circuit on the terminal side.

FIG. 7 shows the configuration. As shown in the figure, the packet transmission circuit 14 that transmits specific packets at regular intervals
a, 14b, 14c, 14d and a transmission buffer 13 for receiving the specific packet and transmitting it to the LAN cable 1.
a, 13b, 13c, and 13d are provided in each transceiver, and the control circuit 4 receives this packet and determines whether the transceiver is normal or not.

In this way, even if there is no response to the packet transmitted by the control circuit 4, it is possible to specify whether the faulty portion is located in the terminal or the transceiver when the transceiver transmits the packet.

Example 6. In the above embodiments, the LAN
However, in the present embodiment, multiple LANs are used to form a redundant multiplex system. FIG. 8 shows the configuration of this embodiment. As shown
It consists of two LAN cables 1a and 1b, the transceivers 2a, 2c and 2y are connected to the LAN cable 1a, the transceivers 2b, 2d and 2z are connected to the LAN cable 1b, and the terminals 3a and 3b and the LAN interface 5 are always connected.
Are connected to one of the same LANs.

When the failure of either of the transceivers 2a, 2c is detected, the control circuit 4 outputs an operation output to the relays 7a, 7b, 7z so that the states of the contacts 8a, 8b, 8z are reversed, and the terminals 3a, 7b. 3b, the LAN interface 5 is connected to the LAN cable 1b. By doing so, it is possible to avoid a system failure due to a disconnection or short circuit of the LAN cable 1a as well as a transceiver failure.

Example 7. In the sixth embodiment, the relays 7a, 7
The operation outputs of b and 7z were output by the control circuit 4 by detecting the failure of the transceivers 2a and 2c, but in this embodiment, as shown in FIG. 9, the manual switches 10a, 10b, 10c, which are input to the control circuit 4, are input. 10d, 10y, 10z
Switch group 51 with built-in switch, manual switch 1
By closing 0a, 10b, 10c, 10d, 10y and 10z, the control circuit 4 outputs the operation output of the relays 7a, 7b and 7z.

The terminal 3a is the LAN cable 1a and the terminal 3b
To the LAN cable 1b and connect each LAN cable 1
It is possible to reduce the communication volume of a and 1b. In addition, one of the LAN cables 1a and 1b is connected to the terminal 3a,
3b, the LAN interface 5 can be switched to the non-connected state to perform maintenance of the entire LAN.

Embodiment 8 FIG. In the sixth and seventh embodiments, the case where the failure monitoring of the transceivers 2a, 2b, 2c and 2d is performed by the control circuit 4 and the relays 7a and 7b are operated has been described, but in this embodiment, as shown in FIG. , 3b connected to the transceivers 2a and 2b and the transceivers 2c and 2d in units of heartbeat signals (output to the terminal side after data transmission in order to inform that the own transceiver is normal) signal)
When a failure is detected in the transceiver 2a, a separate control circuit 11a for operating the relay 7a is provided, and at the same time, the other control circuit 11b is instructed to switch. By doing so, it is possible to manufacture an inexpensive device capable of changing the connection between the LAN cables 1a and 1b without the control circuit 4.

Example 9. In the third and seventh embodiments, a manual switch is provided for switching, but this can also be applied to the first and fifth embodiments. Further, manual switches may be provided for the control circuits provided for each terminal as in the fourth and eighth embodiments.

Example 10. In the fifth embodiment, the packet is transmitted from each transceiver to the monitoring device. In this case, two transceivers are arranged on the monitoring device side. It can also be applied in cases. Further, the fifth embodiment can be applied to a plurality of LANs like the sixth embodiment.

Example 11. In the sixth, seventh and eighth embodiments, the example in which the LAN is applied to the dual LAN is described, but the LAN may be triple or more, that is, the LAN can be applied to the multiple LAN. Although the LAN has been described as a bus type LAN, a ring type LAN can also be applied.

Example 12 In the first, second, third, sixth, seventh and the like, the check signal is sent using a packet, but the present invention can be applied to communication means other than the packet, which uses the packet from the transceiver as in the fifth embodiment. The same applies to the case of a check signal that is sent out as a signal. Further, other checking signals may be used instead of the heartbeat signals of the fourth and eighth embodiments.

[0048]

Since the present invention is constructed as described above, it has the following effects.

Since a plurality of transceivers of the terminal device are switched and used, there is an effect that even if a transceiver fails, another transceiver can be used to continue communication.

Since the check signal is transmitted from the transceiver, there is an effect that the failure classification of the transceiver and the terminal device can be clarified.

By connecting the monitoring means to the LAN with a plurality of transceivers, there is an effect that the monitoring means can switch its own transceiver to continue communication even if the transceiver of the monitoring means fails.

Since the second switching means is switched to the failure information of all terminals and the first switching means is switched to the failure information other than the failure information of all terminals, the communication can be continued. effective.

By making the LAN a multiplexed structure,
There is an effect that not only the transceiver but also another LAN cable can be used to continue the communication even when a trouble such as a short circuit occurs in the LAN cable.

By providing each terminal device with the function of monitoring the check signal from the transceiver and eliminating the dedicated monitoring means, it is possible to economically monitor and switch the transceiver.

By providing each of the plurality of LANs with the function of monitoring the check signal from the transceiver for each terminal device and eliminating the dedicated monitoring means, the transceivers can be monitored and switched economically. In addition to the transceiver, the effect of being able to continue is that the communication can be continued by using another LAN cable not only for the transceiver but also for a problem such as a short circuit in the LAN cable due to the multiplexing structure of the LAN. There is.

Since the heartbeat signal from the transceiver is used as the check signal, no separate transmitting means is required, which is economically effective.

Since the manual switching command means for operating the switching of the transceiver is provided, there is an effect that maintenance and replacement work can be performed without interrupting the operation of the LAN.

[Brief description of drawings]

FIG. 1 shows a configuration diagram of a LAN system according to a first embodiment of the present invention.

FIG. 2 is a flowchart showing the operation of the first embodiment of the present invention.

FIG. 3 shows a configuration diagram of a LAN system according to a second embodiment of the present invention.

FIG. 4 is a flowchart showing the operation of the second embodiment of the present invention.

FIG. 5 shows a configuration diagram of a LAN system according to a third embodiment of the present invention.

FIG. 6 shows a block diagram of a LAN system according to a fourth embodiment of the present invention.

FIG. 7 shows a block diagram of a LAN system according to a fifth embodiment of the present invention.

FIG. 8 shows a configuration diagram of a LAN system according to a sixth embodiment of the present invention.

FIG. 9 shows a configuration diagram of a LAN system according to a seventh embodiment of the present invention.

FIG. 10 shows a configuration diagram of a LAN system according to an eighth embodiment of the present invention.

FIG. 11 is a configuration diagram of a conventional LAN system.

[Explanation of symbols]

1, 1a, 1b LAN cable, 2a-2z transceiver, 3a-3z terminal device, 4 control circuit, 5 L
AN interface 10a to 10z Manual switch, 11a, 11b
Control circuit, 12 terminator, 13a to 13d transmission buffer, 14a to 14d packet transmission circuit, 2
1, 22, 23, 24, 41 Switching circuit (switching means) 31 Monitoring device (monitoring means), 51 switch group (manual switching command means).

Claims (9)

[Claims] 1. In a LAN system in which a plurality of terminal devices are connected to one LAN (local area network) via transceivers, a plurality of transceivers connected to the LAN are provided for one terminal device, First switching means for selectively switching one of the plurality of transceivers to connect to the terminal device, and a check signal to the terminal device through the LAN, and the first signal corresponding to the response signal from the terminal. 1 is provided with a monitoring means for sending a switching command signal to the LAN.
system. 2. In a LAN system in which a plurality of terminal devices are connected to one LAN (local area network) via transceivers, a plurality of transceivers connected to the LAN are provided for one terminal device, A first switching means for selectively switching one of the plurality of transceivers to connect to the terminal device, the transceiver generating a check signal and connecting the LA;
A transceiver having signal generating means for transmitting to N,
A LAN system comprising: a monitoring unit that receives the check signal and sends a switching command signal to the first switching unit according to the received information. 3. The method according to claim 1, wherein a plurality of transceivers connected to the LAN are provided for the monitoring means, and one of the plurality of transceivers is selectively switched to be connected to the monitoring means. A LAN system characterized in that two switching means are provided, and the monitoring means is means for transmitting a switching command to at least one of the first and second switching means in accordance with the reception information of the check signal. . 4. The monitoring device according to claim 3, wherein the reception information of the checking signal is failure information of all terminal devices.
If the received information of the check signal is failure information other than the failure information of all terminal devices, the switching instruction is sent to the first switching means of the terminal corresponding to the failure information. A LAN system characterized by the above. 5. The LAN according to claim 3, wherein the LAN comprises a plurality of LAs.
N, and the plurality of transceivers on the terminal device side and the plurality of transceivers on the monitoring means side are the plurality of LANs.
And monitoring means for sending a switching command to the first and second switching means so as to select a sound LAN from the plurality of LANs according to the received information of the check signal. LAN system characterized by the above. 6. In a LAN system in which a plurality of terminal devices are connected to one LAN (local area network) via transceivers, a plurality of transceivers connected to the LAN are provided for one terminal device, The transceiver is provided with third switching means for selectively switching one of the plurality of transceivers to connect to the terminal device, and the transceiver is a transceiver having signal generating means for generating a check signal. Installed,
A LAN system comprising a monitoring means for receiving the checking signal and transmitting a switching command signal to the third switching means in accordance with the received information. 7. The LAN according to claim 6, wherein the LAN comprises a plurality of LAs.
N, and the plurality of transceivers are connected to the plurality of LAs.
The monitoring means is arranged corresponding to each N, and the monitoring means is a sound LAN among the plurality of LANs according to the received information of the check signal.
A LAN system characterized in that it is a means for sending a switching command to the third switching means so as to select. 8. The LAN system according to claim 6, wherein the check signal is a heartbeat signal transmitted from the transceiver when the transceiver is healthy. 9. The method according to any one of claims 1 to 8,
A LAN system comprising a manual switching command means for manually sending a switching command to the first and second switching means.