JPH0744557B2 - Loop fault handling method - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a loop fault handling system, and more particularly to a loop fault handling system in a loop communication system of a data communication system.

(Prior Art) A loop data communication system including one master node and a plurality of slave nodes transmits data in synchronization with a synchronization signal output from the master node. Therefore, if the master node becomes inoperable due to a failure, the entire communication system goes down. Conventionally, in order to recover from such a failure, one of the slave nodes is selected and manually started as an alternative master node (backup master node), or a plurality of slave nodes are selected based on a complicated algorithm logic. The slave nodes competed, and one of them automatically became the alternate master node to recover the loop.

(Problems to be Solved by the Invention) However, the method of selecting one from slave nodes and manually starting it as a master node has a drawback that it takes time to restore. Further, in a method in which a plurality of slave nodes compete to determine the master node, the recovery time until the loop is restored becomes long because the logic of the algorithm for determining the master node is complicated. Further, the slave node has a drawback that it cannot easily distinguish between the failure of the master node and the failure of the loop transmission.

The present invention solves the above-mentioned drawbacks of the conventional technology, shortens the loop recovery time when a master node fails, simplifies the logic of the algorithm for determining the master node, and speeds up the detection of the master node failure. The object is to provide a loop fault handling method.

(Means for Solving Problems) In order to solve the above problems, the present invention forms a loop transmission line by a first master node and a plurality of slave nodes, and outputs the loop transmission line from the first master node. A loop failure processing method of a loop type data communication system in which data communication is performed by a loop transmission line in synchronization with a synchronization signal is performed by a slave node adjacent to a first master node that can directly receive the synchronization signal from a first master node. If either one is set as the second master node in advance and the first master node cannot output the synchronization signal due to a failure,
The second master node, instead of the first master node, outputs the synchronization signal to restore the loop of the data communication system.

(Operation) According to the present invention, when the first master node cannot output the synchronization signal due to a failure, the monitoring means of the second master node detects that the synchronization signal is not sent from the first master node. Then, the time of the sync signal interruption is counted. When the counted time reaches the failure detection time, the monitoring means outputs a loop failure output to the processing means. The processing means of the second master node determines that the first master node has a failure based on the loop failure output and outputs a synchronization signal to restore the loop of the data communication system.

(Embodiment) Next, an embodiment of the loop fault processing method according to the present invention will be described in detail with reference to the accompanying drawings.

FIG. 1 shows an embodiment of a network of a loop type data communication system to which the loop fault processing method according to the present invention is applied. As shown in the figure, in this embodiment, the master node 10 for controlling the network and this node
It is composed of slave nodes 20 to 23 which perform data transmission in synchronization with a master clock output from 10 described later. The data communication system according to the present embodiment is a duplex loop type data communication system capable of forming loops in opposite directions, and communication is normally performed in either one of the duplex loops. .

The master node 10 is connected to the slave node (# 0) 20 via the signal line 202 of loop # 1 and the signal line 100 of loop # 2.
And to the slave node (# 2) 22 via the signal line 102 of loop # 1 and the signal line 220 of loop # 2. The master node 10 is a node that controls communication of the entire system. Master node 10 is a clock oscillator
The master clock, which is a synchronization signal that synchronizes the entire system generated by 600, is output to loop # 1 via output 100.
Further, the output 102 outputs it to each of the loops # 2.

The slave node 20 is arranged to the left of the master node 10 and is connected to the slave node 21 (#
Connected to 1). The slave node 22 is connected to the signal line 22.
It is connected to the slave node 23 (# 3) via 2 and 230. Slave node 21 and slave node 23 are connected by signal lines 232 and 210. In this way, the loop type communication system of the present embodiment is configured, and the slave nodes 20 to 23 perform data communication in synchronization with the above master clock.

Slave node 20 arranged to the left of master node 10
Also, one of the slave nodes 22 arranged on the right side of the master node 10 can be set in advance as an alternative master node that supplies a master clock to the entire system instead of the slave node 22 when the master node 10 fails. For example, if slave node 20 is set as an alternative master node, data transmission is performed by loop # 2 so that output 100 of master node 10 can be directly received, and if slave node 22 is set as an alternative master node, Data transmission is performed in loop # 1 so that the output 102 of the master node 10 can be directly input.

FIG. 2 shows a node device 5 which is a functional block diagram of each of the master node 10 and the slave nodes 20 to 23. As shown in the figure, in the node device 5 according to the present embodiment, a processing device 500, a monitoring circuit 502, a counter 504, and a selector (SEL) 508 are provided in loop # 1 and loop # 2, respectively. It has a clock oscillator 600 that supplies a clock.

The monitoring circuit 502 is connected to the input side of the loop # 1 via a signal line 552. The monitoring circuit 502 is a circuit that confirms the operation of the master node 10 and detects a loop transmission line failure. That is, the monitoring circuit 502 monitors whether or not the master clock of the master node 10 is transmitted in loop # 1.
Normally, the output of the monitoring circuit 502 is off, and when the master clock cannot be detected in loop # 1, the output 554 is turned on from on to inform the counter 504 that the master clock cannot be detected. When the master clock is detected again in loop # 1, the output 554 is turned from on to off.

The counter 504 counts the turn-on time of the output 554, and outputs a loop fault output 556 to the processing device 500 when the counted time reaches the fault detection time set semi-fixed in advance. If the output 554 turns off before the failure detection time is reached, the counting time counted up to now is cleared and output again.
When 554 is turned on, counting is performed from the beginning.

When the node device 5 is other than the alternative master node, the processing device 500 operates according to a predetermined failure processing program in the processing device 500 of each node device 5 when the master node 10 goes down. Therefore, the alternative master node sets the failure detection time to a sufficiently large value as compared with the master node 10 and other slave nodes. this is,
The alternate master node outputs the master clock that performs loop recovery processing to the loop when the master node 10 goes down, preventing it from becoming the alternate master node due to a cause other than the down of the master node 10, and other slave nodes are the alternate master nodes. This is to prevent the master clock output from the master node from being mistaken for the master clock of the master node 10. The down of the master node 10 in the present embodiment means a state in which the master node 10 cannot output the master clock to both loop # 1 and loop # 2.

The processor 500 is connected to the output side of the loop # 1 via a signal line 550. The processing device 500 is a processing device that processes the signal transmitted in the loop # 1, and may be either a communication device such as an exchange, a key telephone device or a transmission device, or an information device such as a computer or a word processor. The signal processed by the processing device 500 is sent to the selector 508 via the output 560 and to the selector 508 on the loop # 2 side via the loopback output 562. Further, the processing device 500 is connected via a signal line 590 to a clock oscillator 600 which is a signal source of a master clock which is a synchronization signal of the communication system network. Further, the processor 500 on the loop # 1 side receives the loop # 2 via the signal line 800.
It is connected to the processing device 500 on the side.

When the processing device 500 on the loop # 1 side inputs the loop fault output 556 from the counter 504, the processing device 500 on the loop # 2 side similarly checks whether the loop fault output 576 is received via the signal line 800. When the processing device 500 on the loop # 2 side receives the loop failure output 576, each processing device 500 determines that the master node 10 has gone down, and the built-in failure processing when the master node 10 goes down is performed. Recovery processing is performed by the program. For example, when the alternate master node becomes the master node, the processor 500 outputs the clock input from the clock oscillator 600 as the master clock. Further, when the processing device 500 on the loop # 2 side does not receive the loop failure output 576, each processing device 500 determines that there is a transmission path failure in loop # 1 and determines the loop for data transmission from loop # 1 to loop # 2. Switch to. Each processing device 500 exchanges fault information with each other via a signal line 800.

The selector 508 on the loop # 1 side inputs the output 560 of the processing device 500 on the loop # 1 side and the loopback output 582 of the processing device 500 on the loop # 2 side, and outputs one of the outputs to the loop # 1. It is an output switch. The output switching of the selector 508 on the loop # 1 side is performed by the control output 558 of the processing device 500 on the loop # 1 side. Normally, the selector 508 on the loop # 1 side outputs the output 560 of the processing device 500 on the loop # 1 side.
Is output to the loop # 1, and when a failure occurs, the slave node is controlled to output the loopback output 582 of the processing device 500 on the loop # 2 side to the loop # 1.

The input side of loop # 2 is connected to the processor 500 via the output 570, and the processor 500 is connected to the selector 508 via the output 580. The processor 500 is also connected to the selector 508 via the control output 578. Selector 508 loops #
It is connected to the loopback output 562 of the processing device 500 on the one side. The monitoring circuit 502 is also connected to the input side of loop # 2 via the output 572, and the output 574 of the monitoring circuit 502 is connected to the counter 504. The counter 504 is connected to the processor 50 via the output 576.
Connected to 0. The clock oscillator 506 is connected to the processor 500 on the loop # 2 side via the output 592, and the output 590
The same clock as is supplied to this processing device 500.

The operation of the data communication system according to this embodiment when the slave node 20 is used as an alternative node will be described with reference to FIGS. 1 and 2. As described above, the loop # 2 using the slave node 20 as an alternative node is used, and the master node 10-
Slave node 20-Slave node 21-Slave node
23-A loop is formed in the route of the slave node 22 and data transmission is performed.

Normally, each processing device 500 of the master node 10-
The clock received from the clock oscillator 600 is output to loop # 1 and loop # 2 as a master clock. As a result, even if a transmission line failure occurs in loop # 2, for example, each slave node can receive the master clock by loop # 1, and therefore each slave node can determine that there is a transmission line failure.

FIG. 3 shows a system diagram when the master node 10 goes down, and FIG. 4 shows a system diagram when the loop of the data communication system is restored after the master node 10 goes down. There is. When the master node 10 goes down, the master clock is not output to loop # 1 and loop # 2. Therefore, the monitoring circuits 502 of the slave nodes 20 to 23 detect that the master clock is not transmitted to the loop # 1 and the loop # 2 and turn on the loop fault outputs 554 and 574, respectively.

The counter 504 on the loop # 1 side starts counting when the output 554 is turned on, and outputs the loop invitation output 556 to the processing device 500 when the count value reaches the failure detection time. Similarly, the counter 504 on the loop # 2 side also sends a loop fault output 576 to the processor 500. Upon receiving the loop fault output, each processing device 500 informs each other via the signal line 800 that they have received the loop fault output, and determines that the master node 10 is down.
It should be noted that as the communication system becomes larger, each processing unit 50
At 0 there is an error in the time to receive the loop fault output,
The processing device 500 determines whether the master node 10 is down in consideration of this error.

When the slave node 20, which is the alternative master node, confirms that the master node 10 is down, the processing device on the loop # 2 side
The control output 578 of 500 switches the output of the selector 508 on the loop # 1 side from the output 580 of the processing device 500 on the loop # 1 side to the loopback output 562 of the processing device 500 on the loop # 2 side. Then, the processing device 500 on the loop # 1 side becomes the master node by outputting the clock 590 input from the clock oscillator 600 to the loop # 2 as the master clock. Loop connected to master node #
The processing device 500 on the second side does not output a signal to the loops # 1 and # 2, so even if noise is input from the master node 10, it does not adversely affect the entire system.

In the slave nodes 21 to 23 other than the slave node 20, the failure detection time of the counter 504 is shorter than that of the slave node 20.
For this reason, it is determined that the master node 10 has gone down earlier than the node 20, and after failure processing is performed, waits for the master clock to be sent from the alternate master node. Then, when the master clock is sent from the alternative master node, the loop is restored as shown in FIG.

When the slave node 22 determines that the master node 10 is down, the output of the selector 508 on the loop # 1 side is changed from the output 560 of the processor 500 on the loop # 1 side to the processor 50 on the loop # 2 side.
Switch to 0 loopback output 582. Slave node 21
And 23 detect an input failure as a transient state when the master node 10 goes down, but when a master clock is input from the alternate master node, loop # 1 and loop # 2 are used to return to the data communication state. That is, after the master node 10 goes down, as shown in FIG. 4, the alternative master node 20-signal line 200-slave node 21-signal line 210-slave node 23-signal line 230-slave node 22-signal line 2
22-Slave node 23-Signal line 232-Slave node 21
-Signal line 212-A loop is formed by the route of the alternative master node 20 and data communication is performed.

As described above, according to the present embodiment, the algorithm for determining the alternative master node when the master node 10 is down is set simply by setting one of the left and right slave nodes adjacent to the master node 10 as the alternative master node in advance. Therefore, the loop recovery time can be shortened. Further, since each slave node has a simple algorithm for determining an alternative master node, it is possible to easily distinguish whether the master node 10 is down or a loop transmission line failure.

Note that the slave nodes 21 and 23 can also be alternative master nodes. However, if there is another slave node between the alternate master node and master node 10, it will determine whether the master node is down, the line is faulty, or the slave node between it and the master node is faulty when a loop fault is detected. The algorithm becomes complicated because it must be done. Further, the number of slave nodes is not limited to four as shown in this embodiment, and the present invention can be advantageously applied to a data communication system having a larger scale than that of this embodiment. Furthermore, in the present embodiment, two processing devices 500 are provided in the node device 5, but the present invention is not limited to this. That is, one processing device 500 is provided,
Monitoring circuit 502 for each of loop # 1 and loop # 2
It is also possible to provide counters 504 connected to the circuit 502 and output loop fault outputs of the counters 504 to one processing device 500.

As described above, according to the present invention, any slave node adjacent to the first master node is set in advance as the second master node, that is, the alternative master node.
This simplifies the algorithm for determining the alternative master node that outputs the synchronization signal when the first master node goes down, and shortens the loop recovery time. Further, since each slave node has a simple algorithm for determining the alternative master node, it is possible to easily distinguish whether the failure of the first master node is a loop transmission path failure.

[Brief description of drawings]

FIG. 1 is a system configuration diagram of a data communication system to which an embodiment of a loop fault processing method according to the present invention is applied, and FIG. 2 is a functional block diagram showing an embodiment of a node device in the communication system of FIG. FIG. 3 is a system configuration diagram showing that the master node is down in the data communication system of FIG. 1, and FIG. 4 is a signal flow when the loop is restored after the master node is down in the data communication system of FIG. It is a system configuration diagram showing. Explanation of main part code 10 …… Master node 20-23 …… Slave node 500 …… Processor 502 …… Monitoring circuit 504 …… Counter 508 …… Selector 600 …… Clock oscillator # 1, # 2 …… Loop

Continuation of front page (56) References JP 62-53335 (JP, A) JP 59-81943 (JP, A)

Claims (3)

[Claims] 1. A first master node that sends a synchronization signal and a plurality of slave nodes that communicate in synchronization with the synchronization signal are connected to two loop transmission lines, and the two loop transmission lines are connected. In a loop fault handling method of a loop type data communication system in which data communication between nodes is performed by one of the slave nodes, the fault handling method is such that the first master node of the plurality of slave nodes is adjacent to the first master node in advance. A second master node which directly sends a synchronization signal to one of the slave nodes instead of the first master node when a failure occurs in the first master node;
The master node of the second master node, and the first master node sends synchronization signals to both of two loop transmission lines when communicating with each other. Slave node monitors the synchronization signal supplied from each of the two loop transmission lines, and if the synchronization signal from one of the loop transmission lines is not detected for a predetermined time or longer, the slave transmission line When it is determined that a failure has occurred, the loop is restored by switching to the other loop transmission line, and the second master node cannot detect any synchronization signal from both loop transmission lines of two systems for a predetermined time or longer. In addition, it is determined that a failure has occurred in the first master node, and a synchronization signal is sent instead of the first master node to restore the loop of the data communication system. Loop failure processing method to be. 2. The loop fault processing method according to claim 1, wherein when a fault occurs in the first master node and a synchronization signal is transmitted in the second master node, the first fault occurs. The slave node adjacent to the other side of the master node returns the synchronization signal received from the second master node via one loop transmission line to the other loop transmission line, and returns to the plurality of loop nodes other than the first master node. A loop fault handling method characterized by forming a loop between slave nodes. 3. The fault processing method according to claim 1, wherein the fault detection time of the second master node is the second
Loop failure processing method, wherein the failure detection time is longer than the failure detection time of the plurality of slave nodes excluding the master node.