JPS632183B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a dual loop transmission system for transmitting data between a plurality of devices via a loop-shaped transmission line.

In explaining the present invention, an example of a double loop transmission system is shown in FIG. 1 as a premise.

It has a loop 1 and a loop 2 for transmitting data,
Transmission control devices 11, 12, 13 are connected to loop 1, and these devices 11, 12, 13 are connected to loop 2.
transmission control devices 21, 22, paired with each of 13;
23 are connected. each pair of devices 11 and 21;
12 and 22, 13 and 23 are detour transmission lines 100, 200, 3, which are capable of transmitting data in both directions, respectively.
00, and transmitting/receiving terminal 3
1, 32, and 33, terminal transmission lines 311 to 313, and 321 to which data can be transmitted bidirectionally, respectively.
323. Transmitting/receiving terminal 31,
32 and 33 exchange data with each other using only these devices 11 to 13 and loop 1 when devices 11, 12, 13 and loop 1 are normal. If there is a failure in any of the devices 11 to 13 or loop 1, these terminals 31 to 33 will fail to connect to devices 21 to 23, transmission line 100, or
200, 300 and loop 2 are used to mutually exchange data.

Therefore, the transmission control devices 11, 12, 13
During normal operation, the function transmits data on loop 1 and receives data on loop 1, and when there is an abnormality in the transmission system of loop 1, it transmits data on transmission lines 100, 200, and 300, respectively. It is also configured to have a function of receiving data on this transmission path.

In the conventional dual loop transmission system, data from the transmitting/receiving terminals 31 to 33 is always transmitted to one loop or to both loops at a constant rate. In other words, the purpose of the duplex system is to control transmission control devices 11-13, 21-23 and loop 1.
It is mainly used for backup in the event of an abnormality such as a failure as described in (2) above, and has the disadvantage that it tends to cause an imbalance in the amount of traffic in the loops of both systems, resulting in a lot of waste in terms of transmission capacity and speed.

An object of the present invention is to provide an efficient transmission system by averaging the amount of traffic in both systems.

The present invention is characterized in that the transmitting/receiving terminal issues test data at regular time intervals and transmits it to the loop of the system that completed the loop first, thereby averaging the amount of traffic in both systems.

Hereinafter, specific examples will be described using FIGS. 1 to 3.

Figure 2 shows the data format. As shown in the figure, the data includes a flag F to indicate the beginning and end of the data, a function code FC to determine whether each transmission control device should receive the data,
It is composed of a center address SA indicating an address unique to each transmission control device, a control byte indicating detour information, etc., an actual data section DATA, and a frame check sequence FCS for error checking.

Next, the concept of the transmission control device will be explained with reference to FIGS. 1 and 3. Transmission control device 11-13, 21-
Reference numeral 23 controls a transmission system having a double loop configuration, and transmits data from the transmitting/receiving terminals 31 to 33.

The transmission control devices 11 to 13 and 21 to 23 have two modes: a through mode in which only reception is performed, and a store and forward mode in which transmission and reception are performed simultaneously. As shown in FIG. 3, in the through mode, the switch 61 is switched to the a side, and the data is taken into the reception buffer and simultaneously sent to the next transmission control device. In the store and forward mode, the switch 61 is
or c, and the data in the reception buffer 4 or transmission buffer 5 is transmitted. Also, by turning on the switch 62, the received data can be taken into the transmitting/receiving terminal 31 via the terminal transmission line 311.

The reception buffer data is determined by its function code as to whether it is necessary for the transmitting/receiving terminal.
By switching the switches 61 and 62, it is connected to the transmitting terminal or loop 1.

When there is a large amount of data to be transmitted, each transmission control device enters store-and-forward mode.
Transmission speed will be slower. Therefore, there is a proportional relationship between transmission speed and traffic amount.

In the case of normal control data transmission, the transmitting/receiving terminals 31 to 33 transmit to the transmission control device on the loop 1 or loop 2 side, but only in the case of test data, they transmit to both loops simultaneously. . It is assumed that the data function code can be received only by the own transmission control device, and the data that has gone around the loop is returned from the transmission control device of loop 1 or loop 2 to the transmitting/receiving terminal. The sending/receiving terminal determines that the amount of traffic in the loop that returned first is smaller, and
Transmission is performed to the transmission control device on that loop. That is, the transmitting/receiving terminal 31 includes (1) a means for generating a command to make one round of test data to each loop at a fixed time interval, and (2) a means for generating a command to make one round of test data to each loop at a fixed time interval, and (2) a means for generating a command to send test data to each loop in response to reception of the test data, whichever has a shorter one round time. (3) means for issuing a control data transmission command to a transmission control device corresponding to a loop with a short round trip time. If this operation is performed at regular time intervals, the amount of traffic in both systems will be averaged out.

According to the present invention, the amount of traffic in the double loop can be averaged, the transmission capacity can be approximately twice that of the single loop, and efficient transmission can be achieved.

[Brief explanation of the drawing]

FIG. 1 is a diagram for explaining a dual loop transmission system, FIG. 2 is a diagram for explaining a data format, and FIG. 3 is a diagram for explaining the concept of a transmission control device. 1, 2...Loop, 11-13, 21-23...
...Transmission control device, 31-33...Transmission/reception terminal, 1
00,200,300...Detour transmission line, 311
~313...Terminal transmission line, 321~323...
Transmission line for terminal, 4... Reception buffer, 5... Transmission buffer, 61, 62... Changeover switch, F
...Flag, FC...Function code, SA...Sender address, C...Control byte, DATA
...Data, FCS...Frame check sequence.

Claims (1)

[Claims] 1. First and second transmission control devices that are respectively connected to a plurality of transmitting and receiving terminals and transmit and receive information, and first and second loop-shaped devices that connect these first and second transmission control devices in a loop shape, respectively. In a dual loop transmission system equipped with a transmission line, means is provided in the transmitting/receiving terminal and generates a command to make one round of test data to each loop at a fixed time interval, and a means for generating a command to make one round of test data to each loop according to reception of the test data. 1. A data transmission method comprising: means for determining a short loop; and means for issuing a control data transmission command to a transmission control device corresponding to the short loop.