JPH0282834A - Loop back control system - Google Patents

Abstract

PURPOSE:To enable communication by loop back control independently of distinct of master station or slave station by incorporating a buffer memory circuit in a loop back circuit and holding the subordinate synchronization of an inter- network clock. CONSTITUTION:The communication between a master station equipment 1 and a slave station equipment 2 is implemented normally through transmission lines 4-1, 4-2 and loop back circuits 3-1, 3-2 reflect respectively a reception signal to an opposite equipment at the time of loop back instruction. When the slave station equipment 2 receives a loop back instruction and the loop back circuit 3-2 is active, the loop back circuit 3-2 writes the reception signal in a buffer memory according to a subordinate clock from the master station equipment 1, read out by an output clock of the slave station equipment 2 and sent to an opposite equipment as a transmission signal. Moreover, the operation of the loop back circuit 3-1 of the master station equipment 1 is similar to above, the reception signal from the slave station equipment 2 is written in the buffer memory of the loop back circuit 3-1, read out by a transmission clock of the master station equipment 1 and folded to the slave station equipment 2.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a loopback control method, and more particularly to a loopback control method for a device applied to a slave synchronous network to an opposite device side.

[Conventional technology]

An example of a conventional foldback control method is shown in FIG. 2 and will be described.

Conventionally, this type of loopback control method is a method in which a signal from an opposite device is looped back within its own device, and as shown in FIG. -1.7-2 are looped back via transmission lines 8-1 and 8-2, and constitute the flow of slave clocks shown by dotted lines.

[Issues that the company is trying to solve]

In the conventional loopback control method described above, the circuit loops back the signal from the opposite device, so when the master station loops back the signal to the slave station, the source of the slave clock disappears, that is, normally The slave device operates using the master station device's clock signal as the slave clock, but when the master station device loops back, the slave device's own device's output clock becomes its own device's input clock, and communication due to loopback is not possible. The problem was that it was no longer possible.

[Means to solve the problem]

The loopback control method of the present invention includes a buffer memory circuit built into the loopback circuit that loops back to the opposite device side of a device constituted by a slave synchronization network to maintain slave synchronization of clocks within the network. This is what I did.

[Effect]

In the present invention, the signal from the opposing device is not simply looped back, but is buffered and sent via the backup memory circuit using the same transmission port as in the normal state where loopback is not performed.

〔Example〕

Hereinafter, embodiments of the present invention will be described in detail based on the drawings.

FIG. 1 is a block diagram showing an embodiment of the loopback control method according to the present invention.

In the figure, 1 is the main station device, 2 is the slave station device, 3-1.3
Reference numeral 2 denotes a return circuit, and each of the return circuits 3-1 and 3-2 has a built-in buffer memory circuit (not shown), and is configured to maintain slave synchronization of the clock within the network. 4-1.4-2 is a transmission line.

Next, the operation of the embodiment shown in FIG. 1 will be explained.

First, normally, communication between the main station device 1 and the slave station device 2 is carried out via transmission paths 4-1, 4-2, and return circuits 3-1.
3-2 each takes a configuration in which the received signal is returned to the opposing device when a return instruction is given. The dotted line in the figure shows the flow of the dependent clock.

Next, the first slave station device 2 receives a loopback instruction, and the loopback circuit 3
-2 is operated, this folding circuit 3-2 writes the received signal into the backup memory using the slave clock from the master station device 1, reads it out using the output clock of the slave station device 2, and sends it as a transmission signal to the opposing device.

Similarly, the operation of the loopback circuit 3-1 of the master station device 1 is similar to that of the loopback circuit 3-1 when receiving a signal from the slave station device 2.
The data is written in the backup memory of No. 1, read out using the transmission clock of master station device 1, and sent back to slave station device 2.

〔Effect of the invention〕

As explained above, the present invention realizes a loopback circuit with a built-in backup memory circuit, thereby making it possible to communicate by loopback control without distinguishing between master and slave stations, and providing excellent functionality in terms of maintenance and operation. This has the effect of providing a highly reliable system.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing an embodiment of a loopback control method according to the present invention, and FIG. 2 is a block diagram showing an example of a conventional loopback control method. 1. Fist...Main station device, 2...Slave station device, 3-1.3
-2...-Return circuit, 4-1.4-2@...Transmission line. Figure 1

Claims (1)

[Claims] A loopback control characterized in that, in a loopback circuit that loops back to the opposite device side of a device constituted by a slave synchronization network, a buffer memory circuit is incorporated in the loopback circuit to maintain slave synchronization of clocks within the network. method.