JPH0653979A - Ring-like data communication system - Google Patents

Abstract

PURPOSE:To automatically switch a synchronous clock at a high speed by turning the connection delivery of the clock back to normal when transmission terminals except a master detect the arrival of correct identifiers for the directions of respective transmission lines. CONSTITUTION:When a fault detection means 11 detects recovery, the transmission of data is instructed to a clock switching means 13 using the clock from the internal clock of the current station. Also simultaneously, the instruction is transmitted to an identifier insertion means 14 to insert the identifier of the received data instead of adding the current station identifier and transmit the data. Then, an identifier detection means 12 detects the identifier inserted by an upstream station and transmits the instruction to the clock switching means 13 to use the identifier for data transmission when the identifier is other than FFh. Thus, the connection delivery of the clock can be automatically switched back to a normal state at a high speed and manual work is unnecessitated.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention is used for clock switching at the time of transmission line failure in a system in which all transmission devices having a synchronous network ring structure are operated in synchronization with one clock. The present invention relates to a ring-shaped data communication system capable of automatically and rapidly switching clocks at the time of transmission line failure without requiring human intervention.

[0002]

2. Description of the Related Art Conventionally, when a failure occurs in a data transmission system having a synchronous network ring structure, the failure is detected because the clock of the master device is supplied to the devices after the transmission device in which the failure is detected. The device clock after the transmission device was switched to be extracted from the data of the opposite direction.

However, when the transmission line failure is restored, the transmission line clock cannot be switched back. Therefore, either the clockwise or the counterclockwise signal must be turned off for maintenance work of the device. If the master
The clock was manually switched so that it was supplied to all devices in a fixed direction.

[0004]

In such a conventional clock switching system, it is necessary to manually control the clock switching when the transmission line failure is recovered, and therefore, the switching requires manpower.

The present invention solves such a problem by automatically switching the synchronous clock when a transmission line failure occurs.
It is also an object of the present invention to provide a ring-shaped data communication method that can be performed at high speed.

[0006]

According to the present invention, three or more transmission devices are connected in a dual ring by bidirectional transmission paths, one of the transmission devices is set as a master, and two transmission devices are transmitted from this master. Another identifier (00,
FF), the transmission device includes a means for extracting a clock signal from a signal received from the transmission path and synchronizing the clock signal with its own device. It is characterized in that it is provided with means for automatically returning the connection / delivery of the clock to a normal state when it is detected that a correct identifier has arrived for each direction of the road.

[0007]

Operation: The identifier detecting means detects the inserted identifier,
The identifier inserting means and the clock switching means are controlled.
According to this control, the clock switching means switches between the clockwise and counterclockwise reception clocks to be used as the transmission clocks, as well as whether to use the internal clock of the own station or the reception clocks. To do. The identifier sent by the master for each direction is received, and the switchback is performed when this identifier matches the correct one assigned in advance for each direction.

Thus, when the failure of the transmission path is recovered, the clock can be automatically switched back to operate as a normal synchronous network.

[0009]

Embodiments of the present invention will now be described with reference to the drawings. FIG. 1 is a block diagram showing a main part of a transmission device according to the embodiment of the present invention, and FIG. 2 is a block diagram showing a configuration of the transmission device according to the embodiment of the present invention.

According to the embodiment of the present invention, the transmission devices 0 to 5 are connected in a dual ring by bidirectional transmission lines, the transmission device 0 is set as a master, and the transmission lines sent from the master are divided into two directions. The identifiers "00" and "FF" are transmitted, and each of the transmission devices 0 to 5 is provided with means for extracting a clock signal from the signal received from the transmission path and synchronizing it with its own device. The transmission device other than the master automatically switches the connection / delivery of the clock to the normal state when it detects that the correct identifier arrives in each direction of the transmission lines, and the state in which the clock is switched. Failure detection means 11 for detecting the recovery of the transmission path when switching back with the recovery of the failure, identifier detection means 12 for detecting the identifier from the received signal, and detection output of the identifier detection means 12. Therefore, it is provided with the identifier insertion means 14 for switching the insertion of the identifier.

Next, the operation of the embodiment of the present invention thus constructed will be described.

Fault detection means 11 for detecting a fault in the main signal
When the recovery of the fault is detected, the clock switching means 13
A command is sent to the device to transmit data clockwise and counterclockwise using a clock that is clockwise from its own internal clock. At the same time, instead of adding the own station identifier to the identifier inserting means 14, a command is sent to insert the identifier of the received data and transmit the data.

The identifier detecting means 12 detects the identifier inserted by the upstream station, and when this identifier is other than FFh, the clock of the clockwise received data is used to transmit the clockwise and counterclockwise data. Switching means 13
Send a command to.

The switching procedure in the embodiment of the present invention will be described below with reference to FIGS.

FIG. 3 shows a clock switching state when a line fault occurs when a fault has occurred between the transmission devices 1 and 2. All the clocks are supplied by the master transmission device 0. The data transmission is performed in synchronization with the transmission devices 0 to 5. Here, the transmission device 1 transmits data in a clockwise direction, and the transmission devices 2, 3, 4, 5 transmit data in synchronization with a counterclockwise clock signal. In addition, the transmission device 1 has an identifier 0
0 (hexadecimal number) is transmitted as transmission line data, and the transmission devices 2, 3, 4, and 5 transmit the identifier FF (hexadecimal number) as transmission line data.

FIG. 4 shows the restoration of the transmission line fault between the devices 1 and 2, and FIG. 5 shows that the device 2 which has detected the restoration of the transmission line transmits from the internal clock to the clockwise reception clock. The clock is switched, and 0 is the identifier of the received data.
It shows a state in which 0 (hexadecimal number) is transmitted as data on the transmission path. Similarly, FIG. 6 similarly shows a state in which the transmission devices 3 and 4 are transmitting the identifier 00 (hexadecimal number) clockwise and counterclockwise. Further, in FIG. 7, the switching of the clock is completed, and all the transmission devices 0 to
5 operates in synchronization with one clockwise master clock, and 00 (hexadecimal number), which is the identifier of the master transmission apparatus 0, is transmitted as the transmission path identifier.

[0017]

As described above, according to the present invention, it is possible to perform automatic and high-speed switching of synchronous clocks without requiring humans to switch clocks when a transmission line fails in a synchronous network ring configuration system. There is an effect that can be.

[Brief description of drawings]

FIG. 1 is a block diagram showing a main part of a transmission device according to an embodiment of the present invention.

FIG. 2 is a block diagram showing a configuration of a transmission device according to an embodiment of the present invention.

FIG. 3 is a diagram for explaining a clock switching state when a line failure occurs in the embodiment of the present invention.

FIG. 4 is a diagram for explaining failure recovery in the embodiment of the present invention.

FIG. 5 is a diagram explaining an operation at the time of restoration detection in the embodiment of the present invention.

FIG. 6 is a diagram for explaining an identifier transmission state in the embodiment of the present invention.

FIG. 7 is a diagram for explaining the operation after clock switching in the embodiment of the present invention.

[Explanation of symbols]

 0-5 transmission device 11 failure detection means 12 identifier detection means 13 clock switching means 14 identifier insertion means

Claims (1)

[Claims] 1. Three or more transmission devices are connected in a dual ring by bidirectional transmission lines, one of the transmission devices is set as a master, and another identifier is provided to the transmission lines in two directions sent from this master. (00, FF) is transmitted, and in the ring-shaped data communication method, the transmission device includes means for extracting a clock signal from a signal received from the transmission path and synchronizing the clock signal with its own device. Is a ring-shaped data communication system, which is provided with means for automatically switching the clock connection / delivery back to a normal state when it detects that a correct identifier has arrived for each direction of each transmission path.