JP3076219B2 - Sequential propagation type transmission system - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a sequential transmission system in which data is sequentially transmitted between a plurality of devices connected by a transmission line.

[0002]

2. Description of the Related Art In a sequential propagation type transmission system for sequentially transmitting data between a plurality of devices having arbitrary functions, each device is continuously connected by a bidirectional transmission path capable of transmitting data in both directions. I have. Each device is provided with a route switching circuit for switching data transmission / reception and switching the transmission direction connected to the bidirectional transmission path, and data transmission with other devices is possible via the route switching circuit. It has become.

In a conventional sequential propagation type transmission system, each device only switches between transmission and reception with respect to a bidirectional transmission line by a route switching circuit.

[0004]

However, in the conventional sequential propagation type transmission system as described above, when a plurality of devices are continuously connected, a failure occurs in one of the bidirectional transmission lines. However, it was difficult to identify where the failure occurred.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems of the prior art, and it is an object of the present invention to provide a sequential propagation type transmission system which specifies a location of a failure and facilitates maintenance work. Aim.

[0006]

In order to achieve the above object, a sequential propagation type transmission system according to the present invention is characterized in that a plurality of devices are connected by a transmission line capable of bidirectional data transmission, and the transmission device is connected to the plurality of devices respectively. In a sequential propagation type transmission system including a route switching circuit that switches between transmission and reception of data to and from a transmission direction, a control line through which a control signal for detecting occurrence of a failure is transmitted,
A main transmission control unit that is respectively connected to the plurality of devices by the control line, and periodically outputs a maintenance operation instruction signal that instructs the plurality of devices to execute a failure detection process; anda clock signal to the control line. Clock generating means for transmitting the data, the first, second, and third data tank circuits, the data comparing circuit, and the clock adjusting means when the maintenance operation instruction signal is in an active state. The data currently held by the route switching circuit is stored in the first data tank circuit, the data is received from one device connected next by the transmission line, and the data is transferred to the second data tank circuit. And the data stored in the first data tank circuit is transmitted to the other device connected next to the second data tank circuit. The stored data is returned to the original device as it is, the data transmitted to the other device is received as it is, stored in the third data tank circuit, and then stored in the first and third data tank circuits. And a control unit for transferring data to the data comparison circuit and performing control for receiving a comparison result from the comparison circuit.

[0007]

[0008]

In the sequential propagation type transmission system of the present invention configured as described above, the main transmission control unit issues a maintenance operation instruction signal to issue an instruction to execute a failure detection process, and the failure point isolation circuit is placed adjacent to the transmission line by a transmission line. When data from one connected device is received, the data is returned to the other device as it is.

[0009] Further, the fault point isolation circuit transmits the data currently held by the route switching circuit to the other device connected next by the transmission line, and transmits when the data is returned from the other device. Compare the data with the returned data.

[0010] At this time, since the failure point isolation circuits provided in each device perform the same operation, the data transmitted earlier is returned as it is from the other device. Therefore, by comparing the transmitted data with the returned data, it can be determined that a failure has occurred between the transmission paths with the other device when the two data do not match.

[0011]

Next, an embodiment of the present invention will be described with reference to the drawings.

FIG. 1 is a diagram showing a configuration of a sequential propagation type transmission system according to the present invention. FIG. 1A is a block diagram of the entire system, and FIG. 1B is a block diagram of a fault location isolation circuit. FIG. 2 is a timing chart showing the operation of the fault location isolation circuit shown in FIG.

As shown in FIG. 1A, in this embodiment, a first device 1, a second device 2, and a third device 3 having arbitrary functions as devices constituting a sequential propagation type transmission system. Is exemplified. Each device is connected by a bidirectional transmission line 5 capable of transmitting data in both directions, and a control line 6 for transmitting a control signal for collectively managing a data transmission state is connected to each device.

Each device has a route switching circuit 7 for switching data transmission and reception and a transmission direction to and from the bidirectional transmission path 5, and a fault location isolation circuit 8 for specifying a failure location. The main transmission control unit 4 that outputs a control signal for controlling each of the fault location isolation circuits 8 is connected to the control line 6.

In FIG. 1B, each fault location isolation circuit 8 is adjacent to a first data tank circuit 11 for holding data currently held by a route switching circuit 7 by a bidirectional transmission path 5. A second data tank circuit 12 for holding data from one device connected to the second device and a third data tank circuit 13 for storing data from the other device connected to the next device by the bidirectional transmission line 5. A comparison circuit 15 for comparing data held in the first data tank circuit 11 and the third data tank circuit 13, a first data tank circuit 11, a second data tank circuit 12,
It comprises a third data tank circuit 13 and control means 14 for controlling the operation of the comparison circuit 15.

In such a configuration, FIG.
As shown in FIG. 2, the operation of the fault location isolation processing of the sequential transmission system will be described with reference to FIG. 2 in the case where a fault occurs between the second device 2 and the third device 3 as an example. . In the following description, the operation of the fault location isolation circuit 8 of the second device 2 is described as an example, but each device performs the same operation as the second device 2 on both adjacent devices.
Further, the maintenance operation for specifying the fault location is executed by the fault location isolation circuit 8 of each device according to the instruction of the maintenance operation instruction signal S periodically sent from the main transmission control unit 4 to each device via the control line 6. You.

As shown in FIG. 2, when the main transmission control unit 4 sets the maintenance operation instruction signal S to the active state of "1" and transmits the signal to each device, the failure point isolation circuit 8 is not shown in the figure via the control line 6. The process of isolating a fault location is executed in accordance with the following procedure every time the system clock CLK transmitted from the clock generating means of the first embodiment rises.

First, at the first rise of the system clock CLK (a in FIG. 2), the control means 14 of the fault locating circuit 8 stores the data currently held by the route switching circuit 7 in the first data tank circuit 11. To accumulate.

Next, at the second rising edge of the system clock CLK (FIG. 2b), the data held in the first data tank circuit 11 is transmitted to the third device 3, and at the same time, the first device The data sent from 1 is stored in the second data tank circuit 12.

Next, at the third rising edge of the system clock CLK (c in FIG. 2), the data held in the second data tank circuit 12 is returned to the first device 1 as it is.
At the same time, the data sent from the third device 3 is stored in the third data tank circuit 13. At this time, the third device 3
Sent from the third device 3 is the data that was previously sent back to the third device 3 as it is.

Finally, at the fourth rising of the system clock CLK (d in FIG. 2), the first data tank circuit 11
And the data held in the third data tank circuit 13 are transferred to the comparison circuit 15, which compares the two data and returns the comparison result to the control means 14.

Here, when a failure has occurred between the second device 2 and the third device 3 as shown in FIG.
The comparison circuit 15 of the second device 2 detects a mismatch between the two data as a comparison result. At this time, the control means 14 of the second device 2 determines that a failure has occurred between the second device 2 and the third device 3, and determines the result as the control line 6
To the main transmission control unit 4 via

The main transmission control unit 4, which has received the notification of the occurrence of the failure from the second device 2, notifies the system control unit (not shown) of the occurrence of the failure and the location of the failure, and the instruction of the system control unit (not shown). The occurrence of the failure and the location of the failure are displayed on a display device or the like.

On the other hand, when the main transmission control unit 4 sets the maintenance operation instruction signal S to the non-active state of “0”, each device transmits and receives normal data using the first data tank circuit 11. Do.

Therefore, it is possible to specify a fault location in the sequential propagation type transmission system with a simple circuit configuration,
Maintenance work becomes easier. In addition, since the fault location can be specified with a few clocks, the process can be completed in a short time.

In this embodiment, three devices are described as an example of the sequential propagation type transmission system. However, the number of devices is not limited to three, and four or more devices are connected. This embodiment can be applied even if it is.

Also, in this example, the occurrence of a fault is detected by comparing data transmitted from the second device 2 to the third device 3 with data returned from the third device 3 to the second device 2. As described, the data transmission direction is from the second device 2 to the third device.
Not only when the data is transmitted to the third device 3 but also when the data transmitted from the second device 2 to the first device 1 and the data returned from the first device 1 to the second device 2 are compared with each other. The occurrence may be detected. In this case, the second device 2 and the third device 3
The fault that has occurred during the period is detected by the third device 3.

[0028]

Since the present invention is configured as described above, the following effects can be obtained.

The apparatus has a main transmission control unit for periodically outputting a maintenance operation instruction signal for instructing execution of a failure detection process to each device. When receiving data from one connected device, the data is returned to one device as it is, and the data currently held by the route switching circuit is transferred to the other device connected next by the transmission line. When the data is transmitted and the data is returned from the other device, the transmitted data is compared with the data returned from the other device, and when the comparison result does not match, a failure point that notifies the main transmission control unit that a failure has occurred. By providing the separation circuit in each device, it is possible to sequentially identify a failure point in the propagation type transmission system with a simple circuit configuration, and maintenance work is facilitated.

[Brief description of the drawings]

FIG. 1 is a diagram showing a configuration of a sequential propagation type transmission system according to the present invention. FIG. 1A is a block diagram of the entire system, and FIG. 1B is a block diagram of a fault location isolation circuit.

FIG. 2 is a timing chart showing an operation state of the fault location isolation circuit shown in FIG.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 1st apparatus 2 2nd apparatus 3 3rd apparatus 4 Main transmission control part 5 Bidirectional transmission line 6 Control line 7 Route switching circuit 8 Fault location isolation circuit 11 First data tank circuit 12 Second data Tank circuit 13 Third data tank circuit 14 Control means 15 Comparison circuit CLK System clock S Maintenance operation instruction signal

Continuation of the front page (56) References JP-A-6-282454 (JP, A) JP-A-4-336645 (JP, A) JP-A-52-113639 (JP, A) JP-A-59-100927 (JP) , A) JP-A-57-52933 (JP, A)

Claims (1)

(57) [Claims] A plurality of devices are connected by a transmission path capable of bidirectional data transmission, and a path switching circuit for switching transmission / reception of data to / from the transmission path and switching of a transmission direction to each of the plurality of apparatuses. In the sequential propagation type transmission system provided, a control line through which a control signal for detecting occurrence of a failure is transmitted, and the control line is connected to each of the plurality of devices, and the plurality of devices execute failure detection processing. A main transmission control unit that periodically outputs a maintenance operation instruction signal to be instructed, and a clock generation unit that sends a clock signal to the control line.
It has a step, to the plurality of devices, a first, a second, and a third data tank circuit, data
A comparator circuit, and when the maintenance operation instruction signal is in an active state,
In accordance with the lock signal, the data currently held by the route switching circuit is stored in the first
Stored in the data tank circuit of
Receives data from one of the connected devices and
Is held in the second data tank circuit and
Connect the data stored in the first data tank circuit to the next
The second data tank circuit
Return the data held in
The data transmitted to the other device is received as it is and a third
The data stored in the data tank circuit is then stored in the first and third data tanks.
Transfer the data stored in the link circuit to the data comparison circuit
A control means for performing control for receiving a comparison result from the comparison circuit.
And a failure point isolation circuit having a stage .