JP2928019B2 - Data communication system - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION This invention connects the optical repeater to each of the coaxial cable in which a plurality of communication control apparatuses are connected to each of the light repeater mutually communication system connected by an optical cable It is about.

[0002]

2. Description of the Related Art FIG. 4 is a block diagram showing a conventional data communication system disclosed in, for example, JP-A-2-120970. In the figure, 1 is an A-system coaxial cable, 2 is B
Reference numeral 3 denotes a terminating resistor terminating the coaxial cables 1 and 2. Reference numeral 4 denotes a plurality of communication control devices connected to the A-system and B-system coaxial cables, 5 denotes a communication control unit in the communication control device 4, and 6 denotes an application control unit. Reference numeral 7 denotes a processor of the communication control unit 5, reference numeral 8 denotes a memory in which data to be transmitted / received is read and written, and reference numeral 9 denotes data between the A-system coaxial cable 1 and the B-system coaxial cable 2 under the control of the processor 7. This is a communication function for exchanging data. Reference numeral 10 denotes each application in the application control unit 6.

Next, the operation will be described. In a normal state, data having different communication modes is input and output from the communication control device 4 to the coaxial cables 1 and 2 of both the A and B systems. The application 10 may write and read data corresponding to each communication mode to and from a predetermined area of the memory 8. On the other hand, the communication function 9 in the communication control unit 5 has a function of detecting an abnormality of the coaxial cable 1 or 2 to which it is connected. 10 to that effect. Therefore, when the application 10 receives this notification, the application 10 may change the access to the data on the remaining transmission path using the normal coaxial cable 1 or 2, and the communication connected to the normal coaxial cable 1 or 2. The control unit 5 notifies another communication control device 4 connected to the coaxial cable 1 or 2 that an abnormality has occurred in the coaxial cable 1 or 2.

Here, in the above data communication system, since a coaxial cable is used as a transmission line, the applicable range of the system is restricted by the transmission line limit length of the coaxial cable. Therefore, when the system is constructed in a range exceeding the transmission line limit length of the coaxial cable, subsystems are respectively constructed by the data communication system within the range of the transmission line limit length. Are connected by an optical cable via an optical repeater device.
FIG. 5 shows an example in which an optical cable is used to connect subsystems using an optical repeater device in which an optical signal transmission / reception function is added to a repeater device conforming to “JIS X5252-1990”.
FIG. 2 is a configuration diagram illustrating a conventional data communication system.

In the figure, 1 is a coaxial cable, 4 is a communication control device, 11 is an optical repeater device connected to the coaxial cable 1 in each subsystem, and 12 and 13 are via these optical repeater devices 11. This is an optical fiber of an optical cable connecting between the two subsystems. Further, in the optical repeater device 11, reference numeral 14 denotes an electric transceiver for controlling transmission and reception of data by an electric signal to and from the connected coaxial cable 1, and reference numeral 15 denotes an electric transceiver connected to an optical cable composed of optical fibers 12 and 13. The communication data based on the electric signal from the transceiver 14 is converted into an optical signal and transmitted to the optical fiber 12 (13), and the communication data based on the optical signal received from the optical fiber 13 (12) is converted into an electric signal and converted into an electric transceiver. 1
Reference numeral 16 denotes an optical transceiver for sending to the optical repeater 4;

Next, the operation will be described. During normal times,
The communication control device 4 and the other communication control device 4 are coaxial cable 1
Communication is performed via the optical fibers 12 and 13. Here, when an abnormality occurs in the coaxial cable 1 of one of the subsystems as indicated by the mark x in FIG. 5, the optical repeater device 11 connected to the coaxial cable 1 in which the abnormality has occurred operates as specified. After the electrical transceiver 14 detects the abnormality and converts it into an optical signal under the control of the control unit 16, the optical transceiver 15 notifies the optical repeater device 11 of the other party via the optical fiber 12 (13). In the optical repeater device 11 on the other side, the optical transceiver 1
After receiving the signal at 5, the controller 16 outputs a jam signal to the coaxial cable 1 to which the optical repeater device 11 is connected via the electric transceiver 14.
With this jam signal, the communication control device 4 connected to the coaxial cable 1 can recognize a communication error of the system.

However, the current optical repeater device 11
Has a function of detecting an abnormality of the coaxial cables 1 and 2, but when an abnormality occurs in the optical fibers 12 and 13, the communication control device 4 cannot recognize the abnormality of the optical cable because there is no detection function. . Therefore, when an abnormality occurs in the optical cable, the communication control devices 4 in different subsystems include a device that can receive communication data and a device that cannot receive communication data.

[0008]

Since the conventional data communication system is configured as described above, the optical fibers 12, 13 of the optical cable connecting the coaxial cables 1 of the two subsystems and the optical repeater are connected. When an abnormality occurs in the device 11, the communication control device 4 in each subsystem
There are devices that can receive communication data and devices that cannot receive communication data between them, causing a problem that plant control becomes dangerous.

SUMMARY OF THE INVENTION The present invention has been made to solve the above problems, and does not cause mismatching of received data between communication control devices of subsystems even when an optical cable or the like becomes abnormal. an object of the present invention to provide a data communication system.

[0010]

Means for Solving the Problems The data communication system according to the first aspect of the present invention, an optical repeater device, an optical cable
Error of the optical repeater device on the other side
Then, the occurrence of the abnormality is notified to multiple
Communication control device, and the communication control
If the communication control unit with the highest priority in the device
Switching to the coaxial cable of the
In a different subsystem than other communication controllers in the system
A shall be notified to the communication control device.

Further, the data according to the second aspect of the present invention.
The communication system connects the optical repeater device to a coaxial cable.
Control transmission and reception of communication data by electrical signals
An electrical transceiver and an electrical cable connected to an optical cable
Communication data by electrical signal from transceiver is converted to optical signal
After conversion and transmission to the optical cable,
The communication data based on the received optical signal is converted to an electrical signal.
Optical transceiver that sends the
Monitors the optical signal received by the transceiver, and
Error of the optical repeater device of the other
When a normal occurrence is detected, the coaxial cable is
Optical reception monitoring that outputs a signal indicating an optical signal abnormality
And a unit .

[0012]

The optical repeater device according to the first aspect of the present invention detects an abnormality in the optical cable or the optical repeater device on the opposite side, notifies the communication control device of the abnormality, and transmits the transmission path to the coaxial cable connected by the normal optical cable. By switching to a cable system, a data communication system is realized in which, even if an abnormality occurs in an optical cable or the like, a device that can receive data between communication control devices and a device that cannot receive data do not occur.

The optical reception monitoring unit according to the second aspect of the present invention monitors the presence or absence and validity of an optical signal received by the optical transceiver, and detects the invalidity of the optical signal.
By transmitting a signal indicating this to the coaxial cable via the electric transceiver, an optical repeater device that can reliably notify each communication control device of an abnormality in an optical cable or the like is realized.

[0014]

[Embodiment 1] Hereinafter, a first embodiment of the present invention will be described with reference to the drawings. FIG.
Is a block diagram showing an embodiment of a data communication system according to the invention of this. In the figure, 1 is an A-system coaxial cable,
Reference numeral 2 denotes a B-system coaxial cable, reference numeral 3 denotes a terminating resistor, and reference numeral 4 denotes a communication control device. Reference numeral 17 in FIG. 5 designates that a monitoring function of an optical cable and an optical repeater device on the other side and a function of outputting a signal for notifying an abnormality to the coaxial cable 1 or 2 are provided. Are different optical repeater devices. Reference numeral 18 denotes an A-system optical cable, and 19 denotes a B-system optical cable, which is constituted by a pair of optical fibers denoted by reference numerals 12 and 13 in FIG. Reference numeral 20 denotes a message command transmitted to the coaxial cable 2 from the optical repeater device 17 that has detected an abnormality.
(In this case, the reference numeral 4s is assigned) is a switching command for instructing another communication control device 4 to switch the transmission path.

[0015] FIG. 2 is used in the above data communication system is a block diagram showing an embodiment of an optical repeater according to this invention. In the figure, 2 is a B-system coaxial cable, 12 and 13 are optical fibers constituting the B-system optical cable 19, 14 is an electric transceiver, and 15 is an optical transceiver, which are denoted by the same reference numerals in FIG. It is the corresponding part. 22 monitors the optical signal received by the optical transceiver 15 so that the optical cable 1
9 and occurrence of abnormalities in the optical repeater 17 on the other side
Then, when the occurrence of the abnormality is detected, the optical reception monitoring section outputs the message command 20 indicating the occurrence to the coaxial cable 2 via the electric transceiver 14.

Next, the operation will be described. During normal times,
Communication data based on the electric signal output from the communication control device 4 to the coaxial cable 2 is received by the electric transceiver 14 of the optical repeater device 17, sent to the optical transceiver 15, converted into an optical signal, and transmitted to the optical fiber 12. Is done. On the other hand, the communication data based on the optical signal sent via the optical fiber 13 is converted into an electric signal by the optical transceiver 15 of the optical repeater device 17 and sent to the electric transceiver 14, and the electric transceiver 14 transmits the electric signal to the coaxial cable 2. Sent out. During the transmission of the communication data from the coaxial cable 2 to the optical fiber 12, for example, if an abnormality such as a disconnection occurs in the optical fiber 13 of the B-system optical cable 19 marked X in FIG. This hinders communication between the communication control devices 4 of the subsystems, and thus the communication function performed via the B-system coaxial cable 2 and the optical cable 19 is lost.

Therefore, the optical repeater device 17 monitors the optical signal received by the optical transceiver 15 from the optical fiber 13 by the optical reception monitoring unit 22, and the optical signal received by the optical fiber 13 is lost due to the disconnection of the optical fiber 13. When this is detected, a message command 20 for notifying the abnormality of the optical cable 19 is issued to the coaxial cable 2 via the electric transceiver 14 while the communication data exists. The message command 20 is received by all the communication control devices 4 connected to the coaxial cable 2 and is recognized by the communication control device 4s having a higher priority among the communication control devices 4. The communication control device 4 s recognizing the message command 20 issues a switching command 21 for supporting the switching of the transmission path to the A-system coaxial cable 1 connected by the normal optical cable 18. This switching command 21 is sent to the other communication control devices 4 connected to the coaxial cable 1 and all the communication control devices 4 connected to the coaxial cable 1 connected thereto by the optical cable 18.

Therefore, the optical fiber 13 of the optical cable 19
Is transmitted to the communication control device 4 connected to the coaxial cable 2 of the other subsystem via the normal optical fiber 12, but the communication control device 4 After receiving the command 21, the B
Ignore the communication data received from the system transmission line. The communication data output from the communication control device 4 to the coaxial cable 2 in the partner subsystem does not reach the coaxial cable 2 of the subsystem due to the abnormality of the optical fiber 13 of the optical cable 19, but the communication data of the subsystem is not transmitted. The communication control device 4 discards the communication data by receiving the switching command 21, so that the identity of the received data can be reliably maintained. All of the communication control devices 4 are switched by the A-system transmission path by the coaxial cable 1 connected by the normal optical cable 18 thus switched.
Can operate the lost communication function.

Embodiment 2 FIG. In the above embodiment, the case where one optical repeater device is connected to one coaxial cable 1 (2) and two subsystems are connected by the optical cable 18 (19) has been described. As shown, a plurality of optical repeaters 17 may be connected to one coaxial cable 1 (2). With such a configuration, many subsystems can be combined into one, so that a data communication system having such a redundant communication function can be widely applied.

[0020]

As described above, according to the first aspect of the present invention, the optical repeater device is provided with an optical cable or a mating device.
When an abnormality of the optical repeater device is detected,
Notify live to multiple communication controllers in the subsystem
And the priority order among the plurality of communication controllers that received the notification.
The communication control device with the highest rank is the coaxial cable of another normal system.
Switching to another communication control within the subsystem.
To multiple communication control devices in a subsystem different from the control device
Since the notification is configured, even if an error occurs in the optical cable or the like, it is possible to reliably prevent the occurrence of a device that can receive data and a device that cannot receive data between the communication control devices in each subsystem , and reliability. There is an effect that a data communication system with a high level can be obtained.

According to the second aspect of the present invention, the light
Connect the repeater device to an electric signal by connecting it to a coaxial cable.
Transceiver controlling transmission and reception of communication data by
And connected to the optical cable, from the electrical transceiver
Converts communication data using electrical signals into optical signals and converts them into optical cables.
Optical signal transmitted from the optical cable
Communication data into electrical signals and
Optical transceiver to send to and receive with this optical transceiver
Monitor the incoming optical signal and the optical cable and optical
Detects the occurrence of abnormalities in data equipment and detects the occurrence of the abnormalities
And an optical signal to a coaxial cable via an electrical transceiver
Since it is composed of the optical reception monitoring unit that outputs the signal indicating the abnormality, there is an effect that an optical repeater device that can reliably notify each communication control device of the abnormality of the optical cable or the like can be obtained.

[Brief description of the drawings]

FIG. 1 is a configuration diagram showing a data communication system according to an embodiment of the present invention.

FIG. 2 is a block diagram showing an optical repeater device according to one embodiment of the present invention.

FIG. 3 is a configuration diagram showing a data communication system according to another embodiment of the present invention.

FIG. 4 is a configuration diagram showing a conventional data communication system.

FIG. 5 is a configuration diagram showing a conventional data communication system in which subsystems are connected by an optical cable using an optical repeater device.

[Explanation of symbols]

 1, 2 coaxial cable 4, 4s communication control device 14 electric transceiver 15 optical transceiver 17 optical repeater device 18, 19 optical cable 22 optical reception monitoring unit

──────────────────────────────────────────────────続 き Continued on front page (51) Int.Cl. ⁶ Identification code FI H04L 29/14

Claims (2)

(57) [Claims] A plurality of coaxial cables are provided for each of a plurality of systems.
Connect a number of communication controllers to form a subsystem,
An optical repeater device for each of the coaxial cables of the subsystem
To connect the coaxial of a plurality of subsystems of each subsystem
The cable is connected to the optical cable via the optical repeater.
The communication control devices are configured to
Detects an error in the axis cable, and
Notifying the communication control device of the occurrence of an abnormality and
Data with a function to switch to the coaxial cable
In a communication system, the optical repeater device includes the optical repeater.
Abnormal occurrence of the cable or the optical repeater on the other side
When a failure is detected, the occurrence of the abnormality is detected in the subsystem.
Notify the plurality of communication control devices, and
Communication control units having a higher priority among a plurality of the communication control devices.
The control device switches to the normal coaxial cable of another system.
That the other communication control device in the subsystem
A plurality of said communication control devices in said subsystem different from
Data communication system which is characterized that you notice in. 2. An optical repeater device , comprising: an electric transceiver connected to a coaxial cable for controlling transmission and reception of communication data by an electric signal ; and an optical repeater connected to the optical cable to convert communication data by the electric signal from the electric transceiver into an optical signal. While converting and transmitting to the optical cable, the optical transceiver that converts the communication data by the optical signal received from the optical cable to an electrical signal and sends it to the electrical transceiver, and monitors the optical signal received by the optical transceiver ,
Check for abnormalities in the optical cable and the optical repeater
And an optical reception monitoring unit that outputs a signal indicating an optical signal abnormality to the coaxial cable via the electric transceiver when the abnormality is detected.
The data communication system according to claim 1, wherein