JPH0795217A - System for detecting transmission line fault part - Google Patents

Abstract

PURPOSE:To specify a transmission line fault part by assigning a number to each transceiver, connecting terminations, connecting/disconnecting the terminals according to an instruction from a host, and judging the normality/abnormality of a transmission line. CONSTITUTION:A number is assigned to each communication controller of an LAN system or transceiver 4-a-4-n connected with each terminal equipment 3 in the order of the short length of a transmission line from a host 1. Each transceiver 4-a-4-n is provided with a termination T, and the terminal T and the transmission line are connected/disconnected by a changeover switch 6 according to the instruction from the host 1. When a control part 2 detects the generation of the transmission line, entire communication in a system is stopped, the termination T is connected by controlling the switch 6 through an inter-transceiver control part 5 of the transceiver nearest to the host 1, and the following transmission lines are disconnected. Then, the control part 2 judges the normality/abnormality of the transmission line, and when it is normal, the control part 2 successively judges the normality/abnormality in the order of the number of the transceiver.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION The present invention relates to an L connected in a bus type.
The present invention relates to a method of detecting a transmission path failure occurrence point in an AN system.

[0002]

2. Description of the Related Art In the prior art, an L connected in a bus type is used.
When a transmission line failure occurs in the AN system, the transmission line is used not only in communication between the communication control device and the terminal device between the places where the transmission line failure occurs, but also in communication between all communication control devices and terminal devices in the LAN system. A fault is reported.

That is, in a LAN system connected in a bus type, the state of the transmission line is in an electrically balanced state even if a transmission line fault occurs, and means for identifying the location of the transmission line fault is provided. There was no

[0004]

In the above-mentioned prior art, when a transmission line failure occurs in a LAN system connected in a bus type, the state of the transmission line is electrically balanced.
Even if the communication between all the devices is used, there is a problem in that the location of the failure cannot be identified.

An object of the present invention is to provide an LA connected in a bus type.
It is an object of the present invention to provide a method of specifying a failure occurrence point when a failure occurs in a transmission line in the N system.

[0006]

In order to achieve the above object, in a bus-type LAN system, a host has a system control unit for controlling and monitoring the entire LAN system, and each communication control device, Numbers are assigned to the transceivers connected to the respective terminal devices in the ascending order of the transmission paths from the host, and each transceiver is provided with a termination.

Each transceiver has a function of connecting / disconnecting a terminal and a function of connecting / disconnecting a transmission line of a number after the eye transceiver.

When a failure occurs in the transmission path, the end of the transceiver is connected according to the number assigned in ascending order of the transmission path from the host, and further communication is performed between the host and the device connected to the transceiver, resulting in an abnormal communication. It is possible to solve the problem by providing a function of identifying the location where the transmission path failure has occurred, based on the presence or absence of the message and the number assigned to the transceiver.

[0009]

According to the present invention, in a LAN system connected in a bus type, a number is assigned to each transceiver connected to each communication control device and each terminal device, and a termination is connected to each transceiver to terminate it. On /
By providing the function of turning off and the function of connecting / disconnecting the bus after the transceiver, it functions to control the formation of the transmission path.

By communicating between the specified terminal device and the host and judging whether the transmission line is normal or abnormal,
It is possible to identify the location where the transmission line failure has occurred.

The system control unit of the host performs communication using the transmission line formed with the terminal device, confirms the normality of the transmission line based on the presence / absence of a communication error, and specifies the location of the transmission line failure. To do.

[0012]

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

FIG. 1 shows an example of a LAN system connected in a bus type, in which a transceiver connected to each communication control device and each terminal device under the transmission path of the LAN system transmits data from a host. Numbers are assigned in ascending order of path.

Each transceiver has a termination, and has a control unit for receiving an instruction from the host and executing the instruction.

Further, each transceiver has a function of connecting / disconnecting a terminal according to an instruction from a host and a function of connecting / disconnecting a transmission line after the eye transceiver (changeover switch).
Have.

The host also has a system control unit for controlling and monitoring the entire system.

Now, assuming that a transmission line failure has occurred between the transceiver 2 and the transceiver 3, the transmission line failure is reported between the communication control device and the terminal device which are communicating at that time, and the system control unit of the host , Detects that a failure has occurred in the transmission path in the system.

The system control unit of the host, which has detected the transmission line failure, gives an instruction to stop all communication in the system.
Send to each communication control device and each terminal device, connect the terminal to the control unit of the transceiver with the shortest transmission path distance from the host (transceiver with the smallest assigned number), and perform subsequent transmission. Send the instruction to disconnect the road.

The control unit of the transceiver which has received the instruction is
Connect the terminal end as instructed by the system control unit of the host, switch the selector switch to the terminal side to disconnect the transmission line after the eye transceiver from the system, and when the switching is completed, switch to the system control unit of the host Report completion.

When the system control unit of the host recognizes that the changeover switch of the transceiver which has sent the instruction is switched to the terminal side, it sends polling to the communication control device or the terminal device connected to the transceiver. .

The communication control device or the terminal device returns a response to the polling, and the system control unit of the host judges normality / abnormality of the transmission line of the route by this pair of communications.

When the state of the transmission line is normal, the system control unit of the host sends an instruction to the transceiver to disconnect the terminal and connect to the subsequent transmission line.

The control unit of the transceiver which has received the instruction is
Disconnect the end as instructed by the system control unit of the host,
The changeover switch is switched to the transmission line side to connect to the subsequent transmission lines, and when the switching is completed, the completion of the switching is reported to the system control unit of the host.

When the system control unit of the host recognizes that the change-over switch of the transceiver which has sent the instruction is switched to the transmission line side, it transmits to the next numbered transceiver (transceiver having the second shortest transmission line route from the host). To connect the terminal and disconnect the bus after the eye transceiver.

The control unit of the transceiver which has received the instruction is
Connect the terminal as instructed by the host system controller, switch the selector switch to the terminal side in order to disconnect the transmission path after the eye transceiver from the system, and when the switching is completed, switch to the host system controller. Report completion.

When the system control unit of the host recognizes that the changeover switch of the transceiver that has sent the instruction has been switched to the terminal side, it sends polling to the communication control device or terminal device connected to that transceiver. .

The communication control device or the terminal device returns a response to the polling, and the system control unit of the host judges normality / abnormality of the transmission line of the route by this pair of communications.

When the state of the transmission line is normal, the system control unit of the host sends a command to the transceiver to disconnect the terminal and connect to the subsequent transmission line.

In the same procedure, the system control unit of the host successively judges whether the transmission path is normal or abnormal, and identifies the transmission path failure occurrence point.

[0030]

According to the present invention, L connected in a bus type
Even if a transmission line failure occurs in the AN system, the transmission line state is in an electrically balanced state, and the location where the transmission line failure has occurred cannot be identified, each transceiver with the assigned number and termination in the system A device that communicates with the host can be specified by means for connecting / disconnecting the terminal according to an instruction from the host.

Further, by the means for judging the normality / abnormality of the transmission path between the host and the device connected to the transceiver in the order of the assigned transceiver numbers, the location of the transmission path failure can be specified. .

[Brief description of drawings]

FIG. 1 is an example of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Host, 2 ... System control part, 3 ... Communication control device or terminal device, 4 ... Transceiver, 5 ... Transceiver control part, 6 ... Transceiver changeover part (changeover switch), T ... Terminator (terminal), a ... n ... Logical number.

Claims (1)

[Claims] 1. In a bus-type connected LAN system, a transceiver for connecting a communication control device and a terminal device to the system has a number and a termination assigned in the system, and the termination is from a host. The means to connect / disconnect according to the instruction, and the above according to the instruction from the host,
In the order of the assigned transceiver numbers, the transmission path between the host and the device connected to that transceiver is normal / normal.
A transmission line failure occurrence point detection method, characterized by having a means for judging an abnormality and identifying a transmission path failure occurrence point.