JPH09298552A - Communication equipment - Google Patents

Abstract

PROBLEM TO BE SOLVED: To detect a faulty section of a communication line in a communication system in which respective nodes are connected to each other via a communication line in a loop. SOLUTION: A fault detection section 14 monitors a token frame from a communication line, discriminates it to be an occurrence of a fault when the token frame is not detected within a set time and informs the fault to node control sections 15, 22. The node control section 15 of each node receiving the notice starts a fault information packet generating section 18 after the elapse of a set time of a timer counter 16 to send a 1st packet with the node number provided thereto to a master node from a medium connection section 12b via a data transmission reception section 13 and a transceiver 11b in a signal transmission reception section 10b. A fault detection section 14 of the master node detects a fault and a defect information packet identification section 21 monitors the reception of the 1st packet sent from each node within a set time. A fault block of the communication line is detected depending whether or not the 1st packet sent from each node is received within the set time.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a communication device capable of detecting a failure of a communication path in a local area network (hereinafter referred to as LAN).

[0002]

2. Description of the Related Art A conventional communication path failure detection method in a LAN is disclosed in Japanese Patent Laid-Open No. 2-277341. FIG. 9 shows a configuration example of a LAN in a conventional communication device. In FIG. 9, 1a to 1d are nodes forming a LAN (hereinafter, referred to as a node 1 when describing a node), and 2a to 2d are communication paths connecting each node 1 in a loop (hereinafter, the communication path will be described. 3a to 3d are communication channels having a transmission direction different from that of the communication channel 2 (hereinafter, referred to as the communication channel 3 when describing the communication channel). Also, a loopback test is possible in the input / output unit (not shown) to which the communication paths 2 and 3 of each node 1 are connected. Each node 1 normally uses only one communication path 2 and the other communication path 3 is put on standby as a backup.

In a state where all of the nodes 1 have stopped communication, a token frame indicating that the communication path 2 is idle is circulated in the communication path 2, and the node 1 that has made a communication request , Occupies the communication path 2 by capturing the token frame, and sends out to the communication path 2 an information frame for transferring information to the desired node 1. When the desired communication is completed, the node 1 collects the transmitted information frame, and again transmits the token frame indicating the empty state,
Orbit the communication path 2.

As shown in FIG. 9, a specific node 1d of the four sets of nodes 1 also serves as a monitoring node for monitoring the operating state of this LAN. The monitoring node monitors the token frame circulating on the communication path 2 and detects that an abnormality has occurred on the communication path 2 when the token frame cannot be detected within a preset time. By this detection, the communication path 2 and the communication path 3 are transmitted to the other nodes 1.
A loopback test by an inquiry is performed using both of the above, and the failure section is detected by the presence or absence of a response from each node 1.

[0005]

However, in such a conventional LAN communication path failure detection method, as is clear from the above description, in order to identify the failure section of the communication path in which the failure has occurred, There was a problem of requiring a pair of communication channels.

The present invention is to solve the above-mentioned problems of the prior art. In a communication system in which nodes constituting a LAN are connected in a loop through a set of communication paths, a faulty section of the communication path is present. It is an object of the present invention to provide a communication device capable of detecting the.

[0007]

In order to achieve this object, a communication device according to the present invention is a communication system in which a plurality of nodes and a master node for system management are connected in a loop through a communication path. In each of the nodes, failure detection means for detecting the occurrence of a failure in the node or the communication path when a signal from the communication path is not received, and after the preset time has elapsed after the failure detection means detects the failure, Fault information signal transmitting means for transmitting a fault information signal including the node number information given to the node to the master node, fault detecting means in the master node, and a preset time after the fault detecting means detects the fault. And a fault information signal receiving means for detecting reception of a fault information signal from each node.

Further, when receiving a failure detection signal from the master node, each node switches the transmission / reception direction of the signal transmission / reception unit connected to the communication path after a preset time has passed, first transmission / reception direction switching means. Fault information signal transmitting means for transmitting a fault information signal including the node number information given to the node to the master node after a lapse of a preset time by switching the transmitting and receiving directions by the first transmitting and receiving direction switching means, When the master node detects a failure in each node or communication path when it does not receive a signal from the communication path, and when a failure is detected by the failure detection means, a failure detection signal is sent to each node. And a failure detection signal transmitting means for transmitting to the communication device and switching the transmission / reception direction of the signal transmission / reception unit connected to the communication path after transmitting the failure detection signal. Comprising a second transceiver direction switching means, in the failure detecting means time set in advance to detect a fault, a fault information signal receiving means for detecting the reception of the fault information signals from each node.

Further, failure detection means for detecting the occurrence of a failure in each node or the communication path when each node does not receive a signal from the communication path, and when the failure detection means detects a failure, or the master Fault information signal transmitting means for transmitting a fault information signal including the node number information given to the node to the master node when a fault detection signal from the node is received, and a fault from the master node. When a detection signal is received, a first transmission / reception direction switching unit that switches the transmission / reception direction of a signal transmission / reception unit connected to the communication path after a preset time has elapsed, the master node includes the fault detection unit, and the fault. When a failure is detected by the detection means, a failure detection signal transmission means for sending a failure detection signal to each node and a failure detection signal are sent. Comprises a second transceiver direction switching means for switching the transmitting and receiving direction of the signal transmission and reception unit connected to the communication path, and a fault information signal receiving means for receiving fault information signals from each node.

Further, failure detection means for detecting a failure in each node or communication path when a signal from the communication path is not received in each node, and failure is detected by the failure detection means and set in advance. Failure alarm signal transmitting means for sending a failure alarm signal to an adjacent node after a lapse of time, and failure alarm signal reception for detecting reception of a failure alarm signal after a lapse of a preset time by detecting a failure by the failure detection means Means, a failure information signal transmitting means for sending a failure information signal including the node number information given to the node to the master node, a failure detecting means, a failure alarm signal transmitting means, and a failure alarm signal receiving means for the master node And a failure information signal receiving means for receiving the failure information signal from each node.

According to the above configuration, the failure section can be detected by the failure information signal received by the master node and the failure information signal not received within a preset time.

Also, after the transmission / reception direction is switched by the first and second transmission / reception direction switching means according to the failure information signal from each node due to the failure detection of the failure detection means and the failure detection signal from the master node, The fault section can be detected by the fault information signal of.

Further, the fault information signal transmitting means of the node which has not detected the fault alarm signal can send the fault information signal to the master node to detect the fault section.

..

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. FIG. 1 is a diagram showing a configuration of a communication system of a communication device according to Embodiment 1 of the present invention, in which 1 is a node, 4 is a master node, and 5 is a communication path. In FIG. 1, the nodes 1a, 1b, 1c and the master node 4 are connected in a loop by communication paths 5a, 5b, 5c, 5d.

FIG. 2 shows a communication device according to the first embodiment, in which (a) is a block diagram showing an internal configuration of each node,
(b) is a block diagram showing an internal configuration of the master node. In FIG. 2, 10a and 10b are signal transmitting / receiving units, and 11a and 11b.
Is a transceiver, 12a and 12b are media connection units connected to a communication path, 13 is a data transmission / reception unit of each node, 14 is a failure detection unit, 15 is a node control unit of each node, and 16 is a preset time counting unit. Timer counter, 17 is a node number register, 18 is a failure information packet generator, 19 is a terminal interface for connection with a terminal device, 20 is a master node data transceiver, 21 is a failure information packet generator 18 of each node. A fault information packet identification unit that detects an information packet,
Reference numeral 22 is a node control unit of the master node. In this embodiment, the signal transmitting / receiving unit 10a and the transceiver 11a are set for signal reception, and the signal transmitting / receiving unit 10b and the transceiver 11b are set for signal transmission. Furthermore, FIG. 3 shows a fault information signal.
It is a figure which shows the format example of (1st packet).

The operation of the first embodiment will be described with reference to FIG. Each node and the master node are connected to a communication path (not shown) by the media connection units 12a and 12b, and are connected to a terminal device (not shown) by a terminal interface 19. Each node or master node is connected to the transceiver 11 in the media connection unit 12a and the signal transmission / reception unit 10a from the communication path.
From a, a token frame that indicates that the communication path is received via the failure detection unit 14 as a failure detection unit in the data transmission / reception units 13 and 20 and is detected is detected. Now, when a transmission request is generated from the terminal device, each node or master node divides the data transmitted from the terminal device into the set length, and outputs the node numbers etc. assigned to the self node and the destination node, respectively. The added information packet is configured, and the data transmitting / receiving units 13 and 20 to the signal transmitting / receiving unit 10b
The data is sent to the communication path via the transceiver 11b and the media connection unit 12b.

Further, each node and the master node have 1
The data length to be transmitted at a time is limited, and it is prohibited for a specific node to occupy a communication path for a long time. Therefore, if an information packet with a data length within the allowable amount is sent, the data transmission / reception circulates on the communication path, collects the information packet that arrives at the own node again, and then sends the token frame indicating the empty state to the communication path. Terminate communication.

On the other hand, the failure detection unit 14 monitors the token frame arriving from the communication path, and if it does not detect the token frame within a preset time, it judges that a failure has occurred in the communication path. , Notifies the node control units 15 and 22 of the failure.

A node control unit of each node that has received a failure notification
Reference numeral 15 denotes a failure information packet generator 18 which is failure information signal transmitting means after a lapse of time preset in the timer counter 16.
The first packet (see FIG. 3), which is a fault information signal including fault 1 detection (packet identifier), is assigned to the node number of the fault detected (stored in the node number register 17). The data is sent from the media connection unit 12b to the master node to the communication path via the transceiver unit 13 and the transceiver 11b in the signal transceiver unit 10b.

Further, the timer counter 16 of each node that has detected a failure, for example, a value based on the arrangement sequence information of the corresponding node in the communication path, so that the first packet sent by each node does not collide with the communication path. Is set in advance.

At the same time, the master node also detects a failure by the failure detection section 14, and the failure information packet identification section 21 and the node control section 22 which are failure information signal receiving means set a time (each node is set in advance in the timer counter 16). After the failure is detected, the failure information packet identifying unit 21 sends the first packet to the master node, and then the transceiver 11a of the signal transmitting / receiving unit 10a is connected to the master node by a time sufficient to reach the master node. Via, it is monitored whether the first packet sent by each node that has detected a failure has been received. Therefore, by the first packet of each node received,
Since the first packet is not received within the preset time, it is possible to detect in which section of the communication path the failure has occurred.

Next, FIG. 4 is a communication device according to the second embodiment of the present invention, (a) is a block diagram showing the internal configuration of each node, and (b) is a block diagram showing the internal configuration of the master node. . Further, in each of the following drawings, the same reference numerals are given to those having the same operation and effect corresponding to the constituent portions described in FIG. In FIG. 4, 10a and 10b are signal transmission / reception units, 11a and 11b are transceivers, 12a and 12b are media connection units, 13 is a data transmission / reception unit, 14 is a failure detection unit, 15 is a node control unit, 16 is a timer counter, 17 Is a node number register, 18 is a failure information packet generation unit, 19 is a terminal interface, 20 is a data transmission / reception unit, 21 is a failure information packet identification unit, 22 is a node control unit, 23 is a failure detection packet generation unit,
Reference numeral 24 is node array data indicating each node number connected to the communication path, and 25 is a failure detection packet identification unit for detecting the information packet from the failure detection packet generation unit 23 of the master node. FIG. 5 is a diagram showing a format example of the failure detection signal (second packet).

The operation of the second embodiment will be described with reference to FIG. The master node monitors the token frame arriving from the communication path in the failure detection unit 14, and if the token frame cannot be detected within a preset time, it is determined that a failure has occurred in the communication path. Notify the control unit 22 of the failure. Node controller 22 that received the notification
Is a fault detection packet generator that is a fault detection signal transmitting means
23 is started and the node array data 24, etc.
A second packet, which is a failure detection signal of a format having a failure 2 detection (packet identifier) as shown in, is communicated from the media connection unit 12b via the data transmission / reception unit 20 and the transceiver 11b in the signal transmission / reception unit 10b. Send to the road. After transmitting the second packet, the master node switches the input / output direction of the transceiver 11b in the signal transmission / reception unit 10b, which is the second transmission / reception direction switching means, according to an instruction from the node control unit 22, and transmits the signal from the communication path to the media. It can be received from the connection unit 12b.

Each node detects a failure in the data transmitter / receiver 13 by sending the second packet, which is a failure detection signal from the master node, from the communication path through the media connection unit 12a and the transceiver 11a in the signal transmitter / receiver 10a. The packet identification unit 25 detects and notifies the node control unit 15. Upon receiving this notification, the node control unit 15 switches the transmission / reception direction of the transceiver 11a in the signal transmission / reception unit 10a, which is the first transmission / reception direction switching means, and enables transmission from the media connection unit 12a to the communication path.

After that, after a predetermined time elapses in the timer counter 16 in the node control section 15 (for example, in order to prevent the first packet sent from each node from colliding with the communication path, for example, the arrangement of the corresponding nodes in the communication path) It is a fault information signal with a node number (stored in the node number register 17) added thereto by activating the fault information packet generator 18 which is a fault information signal sending means. The first packet (see FIG. 3) is sent from the media connection unit 12a to the master node to the communication path via the data transmission / reception unit 13 and the transceiver 11a in the signal transmission / reception unit 10a.

As described above, the master node transmits the first packet addressed to the master node from each node to the media connection unit.
The fault information packet identification unit 21 of the data transmission / reception unit 20 detects this from 12b via the transceiver 11b in the signal transmission / reception unit 10b. Since the first packet from each of these nodes does not receive the first packet within a preset time, it is possible to detect in which section of the communication path the failure has occurred.

Next, FIG. 6 is a communication device according to the third embodiment of the present invention, (a) is a block diagram showing an internal configuration of each node, and (b) is a block diagram showing an internal configuration of a master node. In FIG. 6, 10a and 10b are signal transmission / reception units, and 11a and 1b.
1b is a transceiver, 12a and 12b are media connection units, 13 is a data transmission / reception unit, 14 is a failure detection unit, 15 is a node control unit, 16
Is a timer counter, 17 is a node number register, 18 is a failure information packet generation unit, 19 is a terminal interface, 20 is a data transmission / reception unit, 21 is a failure information packet identification unit, 22 is a node control unit, and 23 is a failure detection packet generation unit. , 24 is node array data, and 25 is a failure detection packet identification unit.

The operation of the third embodiment will be described with reference to FIG. The third embodiment has both the first embodiment and the second embodiment. First, when the failure detection unit 14 of each node detects the occurrence of a failure in the communication path, the node control unit 15 notifies the failure information. The packet generator 18 is activated, the node number that detected the fault (stored in the node number register 17) is given, and the first packet (see FIG. 3), which is the fault information signal, is sent to the data transmitter / receiver 13 and the signal. The data is sent from the media connection unit 12b to the master node via the transceiver 11b in the transmission / reception unit 10b to the communication path.

Further, the master node detects a failure by the failure detection unit 14, activates the failure detection packet generation unit 23, and sends a second packet, which is a failure detection signal, to the data transmission / reception unit 20 by the node array data 24 and the like. The signal is transmitted from the media connection unit 12b to the communication path via the transceiver 11b in the signal transmission / reception unit 10b. After transmitting the second packet, the master node switches the input / output direction of the transceiver 11b in the signal transmission / reception unit 10b according to an instruction from the node control unit 22 so that the signal from the communication path can be received from the media connection unit 12b.

Each node sends a second packet, which is a failure detection signal from the master node, from the communication path to the failure detection in the data transmission / reception section 13 via the media connection section 12a and the transceiver 11a in the signal transmission / reception section 10a. The packet identification unit 25 detects and notifies the node control unit 15. Upon receiving this notification, the node control unit 15 switches the transmission / reception direction of the transceiver 11a in the signal transmission / reception unit 10a, which is the first transmission / reception direction switching means, and enables transmission from the media connection unit 12a to the communication path.

After that, after a lapse of time preset in the timer counter 16 in the node controller 15, the failure information packet generator 18 is activated and the first packet with the node number in which the failure is detected is sent to the data transmitter / receiver. 13 and signal transmitting / receiving unit 10a
The data is sent to the communication path from the media connection unit 12a to the master node via the internal transceiver 11a.

As described above, the first packet from each node is sent from the node next to the failure point to the master node in the forward direction in which a normal information packet passes through the communication path. Further, upon reception of the second packet from the master node, the node in front of the failure point sends the first packet from the reverse direction to the master node. With each of the first packets sent from each of these nodes in the forward and reverse directions,
It is possible to detect in which section of the communication path the failure has occurred.

Next, FIG. 7 is a communication device according to the fourth embodiment of the present invention, (a) is a block diagram showing the internal configuration of each node, and (b) is a block diagram showing the internal configuration of the master node. . In FIG. 7, reference numerals 10a and 10b denote signal transmitting / receiving units, and 11
a, 11b are transceivers, 12a, 12b are media connection parts, 13
Is a data transmission / reception unit, 14 is a failure detection unit, 15 is a node control unit, 16 is a timer counter, 17 is a node number register, 18
Is a fault information packet generator, 19 is a terminal interface,
20 is a data transmission / reception unit, 21 is a failure information packet identification unit, 22
Is a node control unit, 24 is node array data, 26 is a fault alarm signal generation unit that generates a fault alarm signal by the fault detection of the fault detection unit 14, and 27 is a fault alarm signal identification unit that detects a fault alarm signal. FIG. 8 is a diagram showing a format example of the fault alarm signal.

The operation of the fourth embodiment will be described with reference to FIG. Each node and the master node monitor the token frame arriving from the communication path, and if the token frame is not detected within a preset time, it is determined that a failure has occurred in the communication path and the node control unit 15 , 22 is notified of the failure. The node control units 15 and 22 that have received the notification are the failure alarm signal generation unit that is the failure alarm signal transmission means.
26 is started, and the data transmission / reception units 13 and 20 and the signal transmission / reception unit 10b
For example, a fault alarm signal as shown in FIG. 8 is sent to the communication path to the adjacent node via the transceiver 11b in the inside. At the same time, each node and the master node are connected to the fault alarm signal identifying section 27 in the data transmitting / receiving sections 13 and 20.
Detects a fault alarm signal from an adjacent node.

A node that does not detect a failure alarm signal from an adjacent node after sending the failure alarm signal activates the failure information packet generator 18 which is means for sending failure information signal,
The data transmitting / receiving unit 13 and the signal transmitting / receiving unit 13 send the first packet (see FIG. 3), which is the fault information signal to which the node number (stored in the node number register 17) in which the fault is detected, is added.
Media connection 12 via transceiver 11b in 10b
It is sent from b to the master node to the communication path. With this first packet, it is possible to detect in which section of the communication path the failure has occurred.

[0036]

As described above, according to the present invention,
Even in a communication system in which a set of communication paths is configured in a loop, failure information when a failure occurs in a communication path is aggregated in a master node that manages the system, and which section of the communication path It is possible to detect whether or not a failure has occurred.

[Brief description of drawings]

FIG. 1 is a diagram showing a configuration of a communication system of a communication device according to a first embodiment of the present invention.

FIG. 2 is a communication device according to the first embodiment of the present invention,
(a) is a block diagram showing an internal configuration of each node, and (b) is a block diagram showing an internal configuration of a master node.

FIG. 3 is a diagram showing a format example of a failure information signal (first packet).

FIG. 4 is a communication device according to the second embodiment of the present invention,
(a) is a block diagram showing an internal configuration of each node, and (b) is a block diagram showing an internal configuration of a master node.

FIG. 5 is a diagram showing a format example of a failure detection signal (second packet).

FIG. 6 is a communication device according to a third embodiment of the present invention,
(a) is a block diagram showing an internal configuration of each node, and (b) is a block diagram showing an internal configuration of a master node.

FIG. 7 is a communication device according to a fourth embodiment of the present invention,
(a) is a block diagram showing an internal configuration of each node, and (b) is a block diagram showing an internal configuration of a master node.

FIG. 8 is a diagram showing a format example of a fault alarm signal.

FIG. 9 is a diagram showing a configuration example of a LAN in a conventional communication device.

[Explanation of symbols]

1a, 1b, 1c, 1d ... nodes, 2a, 2b, 2c, 2d,
3a, 3b, 3c, 3d, 5a, 5b, 5c, 5d ... communication path,
4 ... Master node, 10a, 10b ... Signal transmitting / receiving unit, 11
a, 11b ... Transceiver, 12a, 12b ... Media connection part,
13, 20 ... Data transmission / reception unit, 14 ... Failure detection unit, 15,
22 ... Node control unit, 16 ... Timer counter, 17 ... Node number register, 18 ... Fault information packet generation unit, 19
... Terminal interface, 21 ... Fault information packet identifying section, 23 ... Fault detecting packet generating section, 24 ... Node array data, 25 ... Fault detecting packet identifying section, 26 ... Fault alarm signal generating section, 27 ... Fault alarm signal identifying section.

Claims (4)

[Claims] 1. A communication system in which a plurality of nodes and a master node for system management are connected in a loop through a communication path, wherein each node receives no signal from the communication path. Alternatively, a failure detection means for detecting the occurrence of a failure in the communication path, and a failure information signal including node number information given to the node after a predetermined time has elapsed after the failure detection means detects the failure. Fault information signal transmitting means for transmitting to the master node, the fault detecting means for the master node, and the fault from each node within a preset time after the fault detecting means detects the fault. Failure information signal receiving means for detecting reception of the information signal, and receiving the failure information signal within a preset time together with the failure information signal received by the master node. A communication device characterized in that a faulty section is detected by not communicating. 2. A communication system in which a plurality of nodes and a master node that performs system management are connected in a loop through a communication path, when each node receives a failure detection signal from the master node, A first transmission / reception direction switching unit that switches the transmission / reception direction of the signal transmission / reception unit connected to the communication path after a preset time has elapsed, and the transmission / reception direction is switched by the first transmission / reception direction switching unit. Fault information signal transmitting means for transmitting a fault information signal including node number information given to the node to the master node after a lapse of time, and each node when the master node does not receive a signal from the communication path. Alternatively, when a failure is detected by the failure detection means for detecting that a failure has occurred in the communication path, the failure detection means Failure detection signal transmitting means for transmitting an output signal to each of the nodes, and second transmission / reception direction switching means for switching the transmission / reception direction of the signal transmission / reception unit connected to the communication path after transmitting the failure detection signal. A fault information signal receiving unit that detects reception of the fault information signal from each node within a preset time by the fault detecting unit detecting the fault, and the fault received by the master node. A communication device, wherein a failure section is detected by not receiving the information signal and the failure information signal within a preset time. 3. A communication system in which a plurality of nodes and a master node that performs system management are connected in a loop via a communication path, wherein each node receives no signal from the communication path. Alternatively, when a failure detection means for detecting the occurrence of a failure in the communication path and the failure detection means detects a failure, or when a failure detection signal is received from the master node, after a preset time has elapsed Fault information signal transmitting means for transmitting a fault information signal including node number information given to the node to the master node, and, when a fault detection signal is received from the master node, the communication is performed after a preset time elapses. A first transmission / reception direction switching means for switching the transmission / reception direction of a signal transmission / reception unit connected to the path; Means, a failure detection signal transmitting means for sending the failure detection signal to each of the nodes when a failure is detected by the failure detection means, and a connection for connecting to the communication path after sending the failure detection signal. Second transmission / reception direction switching means for switching the transmission / reception direction of the signal transmission / reception section, and failure information signal reception means for receiving the failure information signal from each node, wherein each of the nodes by failure detection by the failure detection means From the master node and the failure detection signal from the master node, the first and second transmission / reception direction switching means switch the transmission / reception direction, and then the failure section is detected from the failure information signal from each node. A communication device characterized by the above. 4. A communication system in which a plurality of nodes and a master node for system management are connected in a loop through a communication path, wherein each node receives no signal from the communication path. Alternatively, failure detection means for detecting the occurrence of a failure in the communication path, and failure alarm signal transmission for sending a failure alarm signal to an adjacent node after a preset time has elapsed by detecting the failure by the failure detection means Means, failure alarm signal receiving means for detecting the reception of the failure alarm signal after a preset time has elapsed after the failure is detected by the failure detection means, and a failure information signal including node number information given to the node. Fault information signal transmitting means for transmitting to the master node, the fault detecting means, and the fault alarm signal to the master node Receiving means, the failure alarm signal receiving means, and failure information signal receiving means for receiving the failure information signal from each of the nodes, wherein the failure information signal transmitting means of the node that has not detected the failure alarm signal According to the communication device, the fault information signal is sent to the master node to detect a fault section.