JPH11168487A - Loop communication method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a communication method with which both transmission lines can be effectively utilized although a loop communication system conventionally uses one of two transmission lines duplexed to ensure fault tolerance of a loop or node as while keeping the other line a reserve when these two transmission lines are provided. SOLUTION: In a loop communication system for mutually transmitting data of plural terminals 61 and 62 connected to a plurality of nodes through the loop while having the plurality of nodes 21-26 and two transmission lines of 0 system transmission line 11 for oppositely connecting these nodes in loop and of reserve 1 system transmission line 122, a transmission frame to be distributed along two transmission lines is provided with data validity display A and data number display DN as control data for transmission/reception data, and is provided with transmission line system display L and loop back display LB as control data for the frame.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a communication method in a loop communication system, and more particularly to a loop communication method suitable for effectively using two duplex transmission paths.

[0002]

2. Description of the Related Art In a conventional loop communication system,
For example, a loop LAN described in JP-A-1-64436
The transmission line is duplicated in order to prepare for the failure of the transmission line and the node as described above, but it is easy to make effective use of the two transmission lines without using the transmission line that becomes the standby system during normal operation. Could not be realized.

[0003]

In the above-mentioned conventional loop communication system, in order to transmit half of the data to be transmitted using the backup transmission line, the transmission delay due to the difference in the length of the transmission loop is required. It was necessary to assemble the data divided in half by correcting the difference.

When a failure occurs in a transmission line or a node and a loop enters a loop-back state, it is necessary to detect the loop-back state and reduce the transmission to half for communication.

[0005] It is an object of the present invention to provide a loop communication method capable of effectively utilizing a duplicated transmission line in a loop communication system having a duplicated transmission line.

[0006]

In order to achieve the above object, a data valid display (A) and a data number display (DN) are provided as control data of transmission / reception data in a transmission frame of a loop communication system. The data is divided into two transmission lines in half and transmitted in a frame that goes around the loop. At this time, the data validity display (A) is made valid and the same serial number is displayed on the data number display (DN) of the two transmission lines. Is transmitted, and at the time of reception, only data for which the data valid display (A) is valid display is received, and the data number display (DN) of the data received from the two transmission paths is compared to assemble half the data. Therefore, a function is provided in which the difference in delay between two transmission paths is corrected, data is reassembled correctly, and transmitted to the partner terminal.

[0007] Further, a transmission line system display (L) and a loopback display (LB) are provided as frame control data. When a failure occurs in a transmission line or a node and the loop enters a loopback state, the loopback is displayed. The display (LB) is set to the loopback state display, and in the case of the loopback state, a function is provided to stop transmission / reception on the first system side and to degrade to only the zero system to continue communication.

[0008]

Embodiments of the present invention will be described below in detail with reference to the drawings.

FIG. 1 shows a system configuration of the embodiment. The nodes 21 to 26 are connected to the transmission line 1 in which data circulates in the opposite direction.
1 and the transmission path 12 are connected in a loop, and terminals 61 to 62 are connected to the nodes, respectively, to constitute a system.

FIG. 2 shows a loop-shaped transmission line 11 and a transmission line 1.
2 shows a configuration of a transmission frame that circulates at a period of 125 μs on the second frame. The transmission frame has a synchronization pattern (SYN) for synchronizing the frame of the transmission frame, a transmission line system indication (L) indicating a transmission line system in which the frame circulates, and a loop in a loopback state due to a loop failure or the like. The data on the frame has a loop-back display (LB) indicating that the transmitted / received data is valid (A), and the data used when assembling the data from the terminal in half. Each area of the number display (DN) is provided, and loops around the transmission path 11 and the transmission path 12 in a facing direction (reverse direction).

FIG. 3 is a diagram showing a data flow when a failure occurs in a loop. When a failure occurs in the loop, the loop is looped back at the node before the loop to bring the loop into a loopback state. At this time, the two transmission paths are used as one transmission path, and the circulating frames are limited to the zero-system frames.

FIG. 4 shows a configuration diagram of a node. The node includes two transmission path access units 3 and a data transmission / reception unit 4 (transmission circuit / reception circuit).

FIG. 5 shows a configuration diagram of the transmission path access unit.

FIG. 6 shows a configuration diagram of a receiving circuit of the data transmitting / receiving unit 4 of the node.

FIG. 7 shows a configuration diagram of a transmission circuit of the data transmission / reception unit 4 of the node.

The detailed operations of the terminal for transmitting data to the loop and the terminal for receiving data from the loop will be described below.

First, an operation of transmitting data from a terminal to a loop will be described.

In FIG. 6, control data and audio data are fetched from a reception data (transmission frame) passed from the transmission path access unit into a reception buffer, and a transmission path system display (L) and a loopback display (LB) are checked.
When receiving from the transmission line access unit of the first system, the transmission line system display (L) is the first system display (L = “1”), and the loopback display (LB) is the non-loopback state display (LB = ”).
0 "), and when the transmission line system display (L) and the loopback display (LB) are normal, the data valid display (A) is valid (A =" 1 "). Only the data is written to the reception data assembling buffer.

When writing data, the write address is determined by operating the receive data counter in accordance with the data number indication (DN) given to the receive data.
The transmission delay differs between the transmission via the transmission line of the system 0 and the transmission via the transmission line of the system 1, so that the timing of reception from the transmission line access unit is different. Since the display (DN) is given,
By writing to the reception data assembling buffer in accordance with the data number indication (DN), the divided data can be correctly reassembled and transmitted to the terminal.

When there is no more valid data to be received from the loop, the data to be transmitted to the terminal is data of blockage data (valid display is busy). Similarly, when the loop is in the loopback state and the data is compressed, half of the compressed data is transmitted to the terminal as blockage data (valid display is busy).

Next, the data transmission operation will be described.

In FIG. 7, data from the terminal is written in a transmission data division buffer. The data written in the transmission data division buffer is alternately read in data division units, and the time-divided data is given the same data number indication (DN) to transmit the data at a predetermined position of the circulating transmission frame. I do.

At this time, when transmitting to the transmission line access unit of the first system, the transmission line system display (L) checked by the receiving circuit is the first system display (L = “1”) and the loop back display (L). LB) indicates the non-loopback state display (LB = "
0 ”), the data is transmitted at a predetermined position in the transmission frame that circulates the data.

The transmission line system display (L) is changed to the 1 system display (L = "
1 ") and the loopback indication (LB) is not the non-loopback status indication (LB =" 0 "), the transmission circuit transmitting to the transmission line access unit of the first system transmits the transmission to the circulating transmission frame. Only the transmission circuit that stops and transmits to the transmission line access unit of system 0 continues transmission.

With the above operations, the system shown in FIG. 1 can be realized.

[0026]

(1) A data validity indication (A) and a data number indication (DN) are provided as control data of transmission / reception data in a transmission frame of a loop LAN, and data from a terminal is halved to two transmission paths. And send it to the frame that goes around the loop. At this time, data valid display (A)
Is displayed as an effective display, and data numbers of two transmission lines are displayed (D
N), the same serial number is added to the data, and the data is transmitted. When the data is received, only the data for which the data valid display (A) is valid is received. The data number display (DN) of the data received from the two transmission paths is compared. By assembling half of the data,
By correcting the difference between the respective delays when passing through two transmission paths, it is possible to reassemble the data correctly and transmit the data to the partner terminal, thereby realizing the effective use of the spare transmission path.

(2) A transmission line system display (L) and a loopback display (LB) are provided as control data of a frame. When a failure occurs in a transmission line or a node, the loop becomes loopback state. The back display (LB) is set to the loop back state display, and when the loop back state is entered, transmission and reception on the first system side is stopped, and communication is continued with only the 0 system being reduced.

[Brief description of the drawings]

FIG. 1 is a diagram showing a configuration of a loop communication system according to an embodiment of the present invention and a data flow when there is no failure in a loop.

FIG. 2 is a diagram showing a configuration of a transmission frame in one embodiment of the present invention.

FIG. 3 is a diagram showing a data flow when a failure occurs in a loop.

FIG. 4 is a configuration diagram of a node according to an embodiment of the present invention.

FIG. 5 is a configuration diagram of a transmission line access unit of a node according to an embodiment of the present invention.

FIG. 6 is a configuration diagram of a reception circuit of a data transmission / reception unit of a node according to an embodiment of the present invention.

FIG. 7 is a configuration diagram of a transmission circuit of a data transmission / reception unit of a node according to one embodiment of the present invention.

[Explanation of Symbols] 2 nodes, 3 transmission line access unit, 4 data transmission / reception unit, 11 and 12 transmission lines, 21 to 26 nodes, 61,
62 ... Terminal.

Claims (2)

[Claims] 1. A plurality of nodes and two transmission lines of a system 0 transmission line and a standby system 1 transmission line through which data flows in opposite directions by connecting them in a loop, and are connected to the plurality of nodes. In a loop communication system for mutually transmitting data of a plurality of terminals via a loop, a data valid display (A) and a data number display (DN) are provided as control data of transmission / reception data in a transmission frame circulating through two transmission paths. , The data from the terminal is divided into two transmission paths in half and transmitted in a frame that goes around the loop. At this time, the data validity display (A) is made valid and the data numbers of the two transmission paths are displayed (DN) The same serial number is added to the data and transmitted. At the time of reception, only the data whose data valid display (A) is valid is received, and the data number display (DN) of the data received from the two transmission paths is compared. Half of the data Te By assembling,
By compensating for the difference between the respective delays when passing through two transmission lines, it is possible to reassemble the data correctly and transmit it to the partner terminal, thereby effectively using the 1-system transmission line as a spare transmission line. A loop communication method characterized in that it can be used. 2. A transmission line system display (L) and a loopback display (LB) are provided as control data of a frame. When a failure occurs in a transmission line or a node and the loop is in a loopback state, loopback is performed. The display (LB) is set to the loop-back state display, and when the loop-back state is entered, transmission / reception on the system 1 side is stopped, and only the system 0 is reduced so that communication can be continued. The loop communication method according to claim 1.