JPH06164608A - Synchronism settling system for serial transmission line - Google Patents

Abstract

PURPOSE:To improve the fault resistance of a system and also to improve the clock precision by eliminating the variance of clocks among the nodes of a serial transmission line and also to prevent the occurrence of the working fault of each node despite the fault of a master node. CONSTITUTION:Each of plural nodes connected to a serial transmission line is provided with a clock transmitter means 9 which transmits the clock of its own node, a clock switching signal output means 5 which outputs a clock switching signal from the optional one of those nodes connected to the serial transmission line by an independent synchronization system, and a clock switching means 7 which receives the clock switching signal from the means 5 and switches the independent synchronization system to a subordinate synchronization system which works by the reception clock sent from an optional node by the clock transmitted from the means 9. In such a constitution, the variance of clocks is eliminated among the nodes of the transmission line and also it is possible to prevent the occurrence of the working fault of each node despite the fault of a master node.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to serial transmission in which a plurality of nodes are connected to a serial transmission line and which has an independent synchronous system which operates by the clock of its own node and a slave synchronous system which operates by a received clock. Among the path synchronization establishment methods, in particular, by eliminating the variation in the clock between the nodes in the serial transmission path and preventing the failure of the operation of each node even if the master node fails, The present invention relates to a synchronization establishment method for a serial transmission line, which improves fault tolerance and clock accuracy.

[0002]

2. Description of the Related Art In a conventional serial transmission line, a signal receiving side operates in synchronization with a transmitting side, and an independent synchronization method is performed by a clock generated by the node connected to the serial transmission line when transmitting. And the dependent synchronization method in which the node uses the clock received from the reception side as the transmission clock.

When the serial transmission line is formed in a LAN ring shape, the node has a signal receiving side and a signal transmitting side. When the independent synchronization method is used for the ring type, the receiving side of each node of the serial transmission line formed in the ring type operates in synchronization with the transmitting side of the upstream node. The receiving side of each node depends on the clock of each node. That is, the clocks in the entire ring are not completely identical in phase or frequency.

On the other hand, when the slave synchronization system is used for the ring type serial transmission line, all the nodes connected to the serial transmission line operate by the clock transmitted from the master node on the ring of the serial transmission line. . In this case, the clocks of the entire ring are the same, and if the master node is synchronized with the clock from the outside, the connection with the synchronization network is facilitated.

[0005]

By the way, when the independent synchronization system is used for the ring type serial transmission line, the clock frequency of the entire ring is not constant and the phase is not the same due to the variation of the clocks among the nodes. Therefore, there was a problem in connectivity with the synchronization network outside the ring.
On the other hand, in the case of using the subordinate synchronization method, if the master node fails, the nodes of the entire ring cannot operate, communication of the serial transmission line becomes impossible, and there is a risk that the processing capability will be reduced.

The present invention has been made in order to solve such a conventional problem, and an object thereof is to eliminate a variation in clocks between nodes in a serial transmission line and to prevent a failure in a master node. It is an object of the present invention to provide a synchronization establishment method for a serial transmission line that improves the fault tolerance of the system and the clock accuracy by preventing the operation failure of each node even if it occurs.

[0007]

In order to achieve the above object, the present invention provides a clock transmitting means for transmitting a clock of its own node to a plurality of nodes connected to a serial transmission line, and a serial by the independent synchronization method. Clock switching signal output main means for outputting a clock switching signal from an arbitrary node among a plurality of nodes connected to the transmission line, and when the clock switching signal is received by the clock switching signal output means, it is transmitted from the clock transmitting means. And a means for switching to the slave synchronization system which operates by a reception clock transmitted from the arbitrary node.

[0008]

With the above configuration, a plurality of nodes are connected to the serial transmission line, and any one of the plurality of nodes connected to the serial transmission line by the independent synchronization system that operates by the clock of the own node. To output a clock switching signal. When the clock switching signal is received, the clock switching signal output means transmits the clock of its own node to a plurality of nodes connected to the serial transmission line. The reception clock transmitted from the arbitrary node from the clock transmitted from the clock transmission means. By switching to the subordinate synchronization system which operates according to the above, it is possible to eliminate the clock variation between the nodes in the serial transmission line and prevent the operation failure of each node even if the master node fails.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 is a block diagram showing an embodiment of a synchronization establishment system for a serial transmission line according to the present invention.

The synchronization establishment method for the serial transmission line is based on the receiving circuit 1, the receiving interface 3, and the clock controller 5.
Incorporating an independent synchronization method that operates by the clock generated by each node when the power is turned on or the ring is reconfigured and starts operation when synchronization is established and operates as a transmission clock using the reception clock as the transmission clock Is.

The receiving circuit 1 separates the data and the clock contained in the signal received from the serial transmission line, and outputs the data to the receiving interface 3 and the clock to the receiving interface 3 and a clock switching circuit 7 described later. To do. The reception interface 3 outputs the data input from the reception circuit 1 to an internal bus (not shown) and the clock control unit 5. The clock control unit 5 switches from the independent synchronization system of the ring type serial transmission line to the dependent synchronization system, and therefore, the master clock node 17 (not shown)
A clock switching command transmitted from the receiving circuit 1 is received by the receiving circuit 1 and is received via the receiving interface 3.
Further, the clock control unit 5 outputs the received clock switching command to the clock switching circuit 7 described later to receive the clock used by the transmission interface 11 and the reception circuit 13 described later from the clock of the own-node clock oscillator 9. Switch to the receive clock received by circuit 1.

The serial transmission line synchronization establishment method is as follows:
It is provided with a clock switching circuit 7, a clock transmitter 9 for its own node, a transmission interface 11 and a transmission circuit 13. When the clock switching command is input from the clock control circuit 5, the clock switching circuit 7 switches the clock used for the transmission interface 11 and the transmission circuit 13 from the clock of its own node clock transmitter 9 to the reception clock. Clock transmitter for own node 9
Supplies the clock of its own node to the clock switching circuit 7 when operating in independent synchronization and when its own node is the master clock node. The transmission interface 11 outputs the data input from the clock control unit 5 to the transmission circuit 13 in synchronization with the transmission clock. The transmission circuit 13 transmits the data input from the transmission interface 11 to the downstream node in synchronization with the transmission clock.

FIG. 2 shows a system in which a plurality of the nodes described in FIG. 1 are connected to the ring-shaped serial transmission line 15. The ring-shaped serial transmission line 15 has a master clock node 17, a node 19 and a node 21.
Are connected. In the above configuration, when switching from the independent synchronization system to the dependent synchronization system, the master clock node 17 transmits a clock switching command to the downstream node 19. Node 1 that received this clock switching command
The node 9 switches from its own node clock transmitter 9 to the reception clock and resynchronizes with the downstream node 21.
When the node 19 is synchronized with the node 21, the node 19 outputs a clock switching command to the node 21 after waiting for the data transmission. The node 21, which has received this clock switching command, switches the clock for its own node to the reception clock and transmits the clock switching command, similarly to the node 19. The clock switching command transmitted from the node 21 is the master clock node 17
To be received. When the master clock node 17 receives the clock switching command, it outputs a slave synchronization establishment signal to the downstream node 19 to complete the slave synchronization of the ring.

FIGS. 3 and 4 are block diagrams showing details of the synchronization establishment system of the serial transmission line of the present invention shown in FIG. 1, FIG. 3 shows the case of the independent synchronization system, and FIG. The method is shown.

In the figure, DMUX 23 indicates a unit equipped with a microprocessor, which decodes a frame transmitted by the ring-shaped serial transmission line 15 and outputs data to LAB 25 and a reception clock to a clover switch 43 described later. To do. Since the LAB 25 matches the timings of the serial transmission line and the frame, the LAB 25 absorbs the mismatched portion. The FIFO 27 outputs the data from the LAB 25 to the selector 29 by the first-in first-out method. The selector 29 receives the received data whose timing is matched by the LAB 25 or the DRV / RCV 31 described later.
The transmission data input from is selected. D
The RV / RCV (driver / receiver) 31 is a circuit that inputs and outputs data to and from the selector 29 and, for example, an HX bus (not shown).

FIF connected to the selector 29
The O33 outputs the data from the selector 29 to the MUX 35 described later by the first-in first-out method. MUX35
Are CMDcont37 and Cye Gene3, which will be described later.
The frame or the like input from the device 9 is transmitted to the serial transmission line via the transmission circuit 13. The CMDcont 37 operates under the control of a microprocessor (not shown) and sets an IDLE pattern and a slave synchronization command in a frame. The Cye Gene (cycle generator) 39 transmits a frame with a 25 μs cycle structure and a signaling sequence symbol from an FDDI control interface (not shown) on a frame that follows the cycle structure. The OSC 41 is the same as the self-node clock oscillator 9 described above, and generates a clock for transmitting data by the independent synchronization method. The crossbar switch 43 is controlled by a microprocessor (not shown), and the OSC is used when transmitting data by an independent synchronization method.
When the data is transmitted by the subordinate synchronization method to the 41 side, it is switched to the DMUX 23 side which receives the reception clock and outputs it to the MUX 35.

As described above, when the crossbar switch 43 shown in FIG. 3 is a contact on the OSC 41 side, the independent synchronization method for synchronizing with the clock from the OSC 41 is established. This independent synchronization method is established at the time of power-on or ring reconfiguration, and the master clock node Cyc Gene 39 is
A command transmission request for slave synchronization is issued to the CMD cont 37. After the command transmission request, the CMD cont 37 sets the IDLE pattern command and the subordinate synchronization command in the frame and transmits the frame from the MUX 35. When the frame reaches the master clock node after going around the ring, the crossbar switch 43 is switched from the OSC 41 side to the MUX 35 side by the microprocessor (not shown) and transmits the data in synchronization with the reception clock received by the DMUX 23. A dependent synchronization method is established. FIG. 4 shows the case where this subordinate synchronization method is established. MUX35
Transmits data on the ring in synchronization with the reception clock received by the DMUX 23.

Next, the operation of this embodiment will be described.

First, after turning on the power to the apparatus, the crossbar switch 43 is connected to the OSC 41 side, and the clock switching circuit 7 is set to send the clock of the OSC 41 to the transmission circuit 13 to establish the independent synchronization system. Then, when all the nodes start up, data can be transmitted and received between the nodes.

When the ring is switched to the subordinate synchronization, the Cyc Gene 39 of the master clock node 17 transmits a clock switching command, which is a command transmission request for subordinate synchronization, to the node 19. Master clock node 1
The node 19 that received the clock switching command from 7
A clock switching command is transmitted from the receiving circuit 1 to the clock control unit 5 via the receiving interface 3. The clock control unit 3 that has received this clock switching command
Outputs a switching signal to the clock switching circuit 7, and the microprocessor (not shown) switches the crossbar switch 43 to the DMUX 23 side. After the switching, the node 19 resynchronizes with the node 21 and waits until the data transmission is possible, and then the clock control unit 5 causes the transmission interface 11 and the transmission circuit 1 to operate.
A clock switching command is transmitted to the node 21 via 3. Node 21 that received this clock switching command
Executes a process similar to that of the node 19 and transmits a ring switching command to the master clock node 17. Ring 1
When the clock switching command that goes around 5 returns to the master clock node, the master clock node 17 determines that the slave synchronization method of transmitting data by the received clock is established, and the clock control unit 5 outputs a slave synchronization establishment signal to the node 19. And complete the subordinate synchronization of the ring. After that, the nodes 19 and 21 transmit data on the ring 15 in synchronization with the master clock transmitted from the master clock node 17.

As a result, when the transmission line is established, such as when the power is turned on, transmission is possible for each node and transmission line unit by the independent synchronization system, and thereafter, the slave node is switched to the slave synchronization system by an instruction from the master node. It becomes possible to transmit in ring form without a master clock by
An accurate clock can be used in the slave synchronization method.

Conventionally, for example, in the case of a failure of the master clock node 17, the operation of the entire ring 15 is disabled. However, since the ring can be constructed by the independent synchronization system, the selection of the master clock node 17 and the By the instruction, it is possible to prevent the deterioration of the data transmission processing capacity.

Although the present embodiment has been described as applied to the ring type serial transmission line, the present invention is not limited to the ring type, but can be applied to a star type or a tree type in which the entire system makes one round.

[0025]

As described above, according to the present invention, when the transmission path is established, the transmission is enabled in each node and transmission path unit by the independent synchronization method, and then the slave node is switched to the slave synchronization method by the instruction from the master node. By eliminating the clock variation between each node in the serial transmission line and preventing the failure of the operation of each node even if a failure occurs in the master node, the fault tolerance of the system is improved and the clock accuracy is improved. Improvement can be realized.

[Brief description of drawings]

FIG. 1 is a configuration diagram showing an embodiment according to a synchronization establishment system of a serial transmission line of the present invention.

FIG. 2 is a schematic diagram in which the present invention is applied to a ring LAN.

FIG. 3 is a detailed configuration diagram of the present invention.

FIG. 4 is a detailed configuration diagram of the present invention.

[Explanation of symbols]

 1 receiver circuit 5 clock control unit 7 clock switching circuit 9 clock generator for own node 13 transmitter circuit 17 master clock node 19 node 21 node 23 DMUX 35 MUX 37 CMDcont 39 Cyc Gene 41 OSC 43 crossbar switch

Claims (1)

[Claims] 1. A synchronization establishment method for a serial transmission line, comprising a plurality of nodes connected to a serial transmission line, the independent synchronization method operating according to the clock of the node, and the dependent synchronization method operating according to a reception clock. A clock transmitting means for transmitting a clock of its own node to a plurality of nodes connected to the serial transmission line, and a clock switching from an arbitrary node among the plurality of nodes connected to the serial transmission line by the independent synchronization method. Clock switching signal output means for outputting a signal, and the subordinate synchronization operated by a reception clock transmitted from the arbitrary node from a clock transmitted from the clock transmission means when the clock switching signal is received by the clock switching signal output means It is equipped with a means to switch to the system. Serial transmission line synchronization establishment method to.