JP2000244520A - Diagnosis method for redundant network - Google Patents

Abstract

(57) [Summary] [PROBLEMS] To provide a method for promptly switching to a standby network when an abnormality occurs in a primary network. A communication interface (3) connected to a standby network (5) periodically transmits a message of a diagnostic command to a communicating partner station, and (2) checks for the presence or absence of a diagnostic response from the partner station. (3) If the diagnostic response from the partner station is received, it is determined that the network components such as the partner station and the communication cable are normal. (4) If the diagnostic response from the partner station is not received, The standby network 5 is diagnosed by the procedure of determining that the network components such as the partner station and the communication cable are abnormal, and (5) notifying the upper information processing unit 1 of the abnormality.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for diagnosing an industrial network having a redundant transmission line, and more particularly to a method for diagnosing an abnormality in a standby network which is switched when a main network is abnormal.

[0002]

2. Description of the Related Art Conventionally, when communication is performed between devices connected to a network, communication cannot be performed if there is an abnormality in the network. When communicating on a duplicated network,
It is general that the primary network is used when the network is normal and the standby network is switched to the standby network when the primary network is abnormal.

[0003]

However, in such a duplicated network, when the main network becomes abnormal and switches to the standby network, the communication partner connected to the standby network is down, If an error occurs in a standby network component such as a communication cable, communication using the standby network cannot be performed, and the entire network system may be down.This is a problem in safe operation. I was Therefore, the present invention has been made in view of such a problem, and a communication interface connected to the standby network is provided with a network diagnostic function to constantly monitor the standby network for abnormalities, and to quickly monitor the abnormalities of the main network. It is another object of the present invention to provide a method for switching to a standby network.

[0004]

In order to solve the above-mentioned problems, a method for diagnosing an error in a duplicated network according to the present invention performs communication on a main network in a normal state and a standby system in an abnormal state of the main network. When switching to a network for communication, a communication interface connected to the standby network diagnoses the standby network according to the following procedure. (1) A diagnostic command message is periodically transmitted to the communicating partner station, (2) the presence or absence of a diagnostic response from the partner station is checked, and (3) a diagnostic response from the partner station is received. It is determined that the network components such as the partner station and the communication cable are normal. (4) If no diagnostic response is received from the partner station, the network components such as the partner station and the communication cable are determined to be abnormal. , (5) Notify the upper information processing unit of the abnormality. Since the diagnosis is performed according to the above-described procedure, it is possible to reliably switch to the standby network in the event of an abnormality in the primary network, and to continue communication without interruption.

[0005]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a configuration diagram of a duplex network to which the method of the present invention is applied. FIG. 2 is a view for explaining the contents of diagnostic communication parameters held in the standby communication interface. FIG. 3 is a flowchart showing a processing procedure of the standby communication interface in the present invention. FIG. 4 is a diagram showing a communication state of the network when all the networks are normal. FIG. 5 is a diagram illustrating a network communication state when the standby network is abnormal.

In FIG. 1, reference numeral 4 denotes a main network, 5 denotes a standby network, ST # 1 and ST # denote stations connected to the main network 4 and the standby network 5, and these stations are duplicated. It forms a network system. 1 is an information processing device provided in each station, 2 is a main communication interface provided in each station and connected to a main network 4 for communication, and 3 is provided in each station and connected to a standby network 5 for communication. The communication interface is a standby communication interface that performs communication between the stations ST # 1 and ST # 1.
# 2. The information processing device 1 has a function of controlling switching of communication between the main network 4 and the standby network 5. When the main network 4 is normal, the main communication interface 2 is used to perform communication. In the event of an abnormality in 4, communication is performed using the standby communication interface 3. The communication cables of the main network 4 and the standby network 5 are independently extended.

FIG. 2 shows the contents of diagnostic communication parameters held in the standby communication interface 3. The communication parameters for diagnosis are
Is passed from the information processing apparatus 1 to the standby communication interface 3 at the time of startup. The diagnostic communication parameters include a diagnostic ST number indicating the number of stations to be diagnosed and an ST address indicating the address of each station.

FIG. 3 is a flow chart showing the processing procedure of the method for diagnosing abnormality in a duplicated network according to the present invention. When the diagnosis is started, it is first determined whether there is a diagnosis ST (S1). Here, if there is no diagnosis ST, the diagnosis ends, but if there is a diagnosis ST, a diagnosis message is transmitted (S
2) It is determined whether there is a normal response (S3).
If there is a normal response, the process returns to (S1), and the above procedure is repeated until there is no ST to be diagnosed. If there is no normal response, an abnormality determination is made (S4), and if not, a diagnostic message is transmitted again (S6), and the procedure returns to (S2) to repeat the above procedure. If there is no normal response even after the retransmission (S6) is repeated, it is determined that the response is abnormal, an abnormality notification is made to the host information processing device (S5), and the procedure returns to (S1) and the above procedure is repeated.

FIG. 4 shows a communication state of the network when both the main network 4 and the standby network 5 are normal when the diagnosis is performed by the above means. When both networks are normal, the stations ST # 1 and ST # 2 exchange normal command messages and response messages with the main communication interface 2. In the standby communication interface 3, a network diagnosis function is activated at a constant cycle. And FIG.
A network diagnostic message is transmitted to a station registered in the diagnostic communication parameter according to the information on the diagnostic communication parameter shown in (1), and a response from the partner station is awaited. The station receiving the diagnostic message transmits a return response message to the transmitting station. The station that has transmitted the diagnostic message checks whether a response message is returned from the partner station at a certain time. When the response message is returned from the partner station, it is determined that the partner station and the network component are normal, and the information processing apparatus 1 is notified that the network component is normal.

FIG. 5 shows a communication state of the network when an abnormality has occurred in the standby network while the diagnosis is being performed by the above-mentioned means. In this case, similarly to FIG. 4, a diagnostic message is transmitted to the partner station in accordance with the diagnostic communication parameters. If no response is returned from the other party, the diagnostic message is transmitted again. If the response message is not returned even after the transmission has been performed a certain number of times, it is determined that the partner station or the network component reaching the partner station is abnormal, and the information processing apparatus 1 is notified of the abnormality. When the cause of the network abnormality is removed, the normality is detected by the next activation of the network diagnostic function, and the information processing apparatus 1 is notified of the normality. In this case, the communication is performed on the main network 4 as long as the main network 4 is normal. Since the operation is performed as described above, even when the main network is operating normally, if the standby network is abnormal, it can be detected that the network is abnormal, and the system can quickly return. .

[0011]

As described above, according to the present invention, while the main network is normal, the standby communication interface periodically transmits and receives diagnostic messages to and from the communication partner to change the status of the standby network. Since the monitoring is performed, the abnormality can be immediately reported to the information processing device and the operator can be notified of the abnormality when the standby network is abnormal. Therefore, it is possible to quickly cope with an abnormal factor on the network, and it is possible to avoid a problem that both the main network and the standby network go down at the same time and affect the entire system. .

[Brief description of the drawings]

FIG. 1 is a configuration diagram of a network to which a method of the present invention is applied;

FIG. 2 is a communication parameter for diagnosis.

FIG. 3 is a flowchart showing a processing procedure of the method of the present invention.

FIG. 4 is a diagram showing a network communication state in a normal state.

FIG. 5 is a diagram showing a communication state of a network at the time of an abnormality 1 information processing device 2 main communication interface 3 standby communication interface 4 main network 5 standby network

Claims (1)

[Claims] (1) Under normal conditions, communication is performed on the main network,
In a duplexed network for switching to a standby network when the primary network is abnormal, a communication interface connected to the standby network diagnoses the standby network in the following procedure. Network error diagnosis method. (1) A diagnostic command message is periodically transmitted to the communicating partner station, (2) the presence or absence of a diagnostic response from the partner station is checked, and (3) a diagnostic response from the partner station is received. It is determined that the network components such as the partner station and the communication cable are normal. (4) If no diagnostic response is received from the partner station, the network components such as the partner station and the communication cable are determined to be abnormal. , (5) Notify the upper information processing unit of the abnormality.