JPH0522317A - Loop communication system - Google Patents

Abstract

PURPOSE:To facilitate the line connection of the loop and to reduce a connection delay due to collision. CONSTITUTION:Line exchanging system interfaces IFs are provided on a control station 21 and transmission stations 22-26 respectively and one or plural broadcasting paths are provided from a host terminal equipment 28 to respective terminal equipment 29-40. Furthermore, one or plural limes from respective terminal equipment 29-40 toward a host terminal equipment 21 are provided. Then a line exchanging system interface IF has the function of sending a call request from each of the terminal equipment 29-40 through a control path, recognizing the presence of a call from a terminal equipment based on the call request and opening a MAP to the loop, and also has the function of operating a control level line among the terminal equipment 29-40 through the control path and enabling the transmission of a data of the terminal equipment.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a multi-drop modem conventionally used by using a circuit switching interface in communication between terminal devices used in a local area network (LAN) or the like. The present invention relates to a loop communication system that realizes equivalent functions.

[0002]

2. Description of the Related Art A conventional data communication network system, which is a kind of local area network, connects one or more host terminal devices and a plurality of terminal devices in a bus form via a modem, and connects them on a transmission line. This is a communication system.

FIG. 5 is a diagram showing a connection form of a modem used in a conventional computer system to the loop network system, in which a host terminal device 1 and a plurality of terminal devices 2 to 9 are modems 10 to 10. It is connected to the bus by 17.

In this system, the host terminal device 1 broadcasts to each terminal device 2 to 9 and the address of the terminal device to which the host terminal device wants to connect is put in the data to make the target terminal device. The request data is transmitted to.

On the other hand, the terminal devices whose addresses do not match each other are processing for discarding the received data. However, conversely, when it is desired to communicate from each terminal device 2 to 9 to the host terminal device 1, each terminal device 2 to 2 is used as N: 1 communication.
9 may output a connection request to the host terminal device 1, and in that case, it can be said that a collision occurs on the transmission path and connection takes time.

However, in this case, since the host terminal device needs to have the LAN set up a communication path with a terminal device that does not communicate, connection processing on the LAN side becomes complicated and processing time is long.

[0007]

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned problems of the prior art, and makes it very easy to perform loop line connection processing, and further, there is little connection delay due to collision. Is intended to provide.

[0008]

In a loop communication system of the present invention, a plurality of stations including a control station are connected in a loop through a transmission line, a frame is circulated on the transmission line, and a circuit switching area is provided. In a time division multiplexing loop communication system for performing 1: N communication from a terminal device connected to each of the stations and a terminal device serving as a host among them, Each of the stations is provided with a circuit switching interface, one or a plurality of broadcast paths are provided from the host terminal device to each terminal device, and one or a plurality of lines from each terminal device to the host terminal device are provided. A line is provided, and the circuit switching interface has a function of transmitting a call request from each terminal device on the control path, and the terminal device is requested by the call request. Has a function to recognize that a call has been made from the terminal and open the MAP for the loop, and to operate the control level line between each terminal device on the control path to permit the data transmission on the terminal device side. It is characterized by having.

[0009]

With the above-mentioned structure, the function equivalent to that of the conventional multi-drop type modem can be realized, so that the loop line connection processing becomes very easy and the connection delay due to the collision is significantly reduced. Become.

[0010]

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

1 to 3, one control station 2
One and a plurality of transmission stations 22 to 26 are connected by a transmission line 27 in a loop. The control station 21 has host terminal devices 28 and 29, the transmission station 22 has terminal devices 30, 31, 32, the transmission station 23 has terminal devices 33, 34, and the transmission station 24 has terminal devices. 35, 36
However, a terminal device 37 is connected to the transmission station 25, and terminal devices 38, 39, 40 are connected to the transmission station 26, respectively.

When communication is performed between the stations 21 to 26, the control station 21 generates a transmission frame as shown in FIG. 4 and circulates the transmission frame on the transmission path 27 so that the respective stations communicate with each other. Is becoming

Each of the stations 21 to 26 has a circuit switching interface IF. Further, one or a plurality of broadcast paths P1 are provided from the host terminal device 28 to each of the terminal devices 29 to 40, and
One or a plurality of lines P2 from each of the terminal devices 29 to 40 to the host terminal device 28 are provided.

The stations 21 to 26 are respectively connected to the terminal devices 2
It has a function of receiving the RS line ON signal (call request) Ron from 9 to 40 and opening the MAP Mb on the transmission side for the loop. Note that the MAP Ma on the receiving side is always open. Then, from the host terminal device 28 to each terminal device 29-
40, the host terminal device 28 broadcasts to the respective terminal devices 29 to 40, and the respective terminal devices 29 to 40 are transmitted.
From the host to the host terminal device 28, one path is fixedly set in advance.

Now, when the host terminal device 28 wants information on the terminal device, the host terminal device 28 uses the data communication area of the transmission frame shown in FIG. Request information. At this time, since data is transmitted by broadcast from the host terminal device 28, the terminal device 30 connected to each transmission station 22-26.
~ 40 receive data at the same time. However, terminal devices other than the target terminal device do not transmit anything because the addresses are different. On the other hand, only the target terminal device transmits its own information to the host terminal device 28.

The circuit switching interface IF has a function of transmitting a call request from each of the terminal devices 29 to 40 on the control path, and recognizes that there is a call from the terminal device by the call request. And the sending MA for the loop
It has a function of opening PMb, and further has a function of operating the control level line between the terminal devices 29 to 40 on the control path to permit data transmission on the terminal device side. As a result, since a fixed path is set on the loop side, each transmission station 2
2 to 26, the host terminal device 28 side can receive.

2 and 3 are for explaining the operation. FIG. 2 shows a case where data is transmitted from the host terminal device 28 to the terminal device 36, for example.
Shows a case where data is transmitted from the terminal device 36 to the host terminal device 28, for example.

[0018]

As described in detail above, according to the present invention, since the function equivalent to that of the conventional multi-drop type modem can be realized, the line connection processing of the loop becomes very easy, and moreover, due to the collision. A loop communication system with significantly reduced connection delay can be provided.

[Brief description of drawings]

FIG. 1 is a schematic configuration diagram of a loop communication system according to an embodiment of the present invention.

FIG. 2 is a diagram illustrating an operation when data is transmitted from a host terminal device to a terminal device.

FIG. 3 is a diagram illustrating an operation when data is transmitted from a terminal device to a host terminal device.

FIG. 4 is a diagram showing an example of a format of a transmission frame.

FIG. 5 is a schematic configuration diagram of a conventional system.

[Explanation of symbols]

21 ... Control station, 22-26 ... Transmission station, 27 ... Transmission line, 28 ... Host terminal device, 29-40 ... Terminal device, IF ... Circuit switching interface, P1 ... Broadcast path, P2 ... Line, Ma ... MAP on receiving side, Mb ...
… Sending MAP.

Claims (1)

Claim: What is claimed is: 1. A plurality of stations including a control station are connected in a loop through a transmission line, and a frame is circulated on the transmission line.
Communication is performed using the circuit switching area, and a time division multiplex loop system for performing 1: N communication from a terminal device connected to each station and a terminal device serving as a host among them In the communication system, each of the stations is provided with a circuit switching system interface, and the host terminal device provides 1 to each terminal device.
A book or a plurality of broadcast paths are provided, and one or a plurality of lines from each terminal device to the host terminal device are provided. The circuit switching interface controls a call request from each terminal device. In addition to having a function of transmitting by the above, it has a function of recognizing that there is a call from the terminal device by the call request and opening a MAP for the loop.
And operate the control level line between each terminal device on the control path,
A loop communication system having a function of permitting data transmission on a terminal device side.