JPH0628355B2 - Data communication method - Google Patents

Description

The present invention relates to a data communication system between arbitrary devices connected to a commonly accessible data transmission path.

(B) Conventional technology A large number of devices are connected to one data transmission line,
When data transfer is performed between any of these devices, generally, a connection relationship is set between those devices, transparent data transfer is performed using the relationship, and the connection relationship is released. To do. However, in such a data communication method, after the data transfer between the devices is completed, if the connection relationship is maintained without data transmission / reception, the connection from the other device to one of the currently connected devices is established. I cannot connect even if there is a request. Therefore, conventionally, when a state in which transmission / reception is not performed continues for a certain period of time or more, the connection relation is released regardless of the presence or absence of a connection request.

(C) Problems to be solved by the invention However, in such a method, the current connection relationship is released even when there is no connection request from others. It is necessary to reset the connection relationship. Further, after the connection relation is released, it is necessary to newly set the connection relation to return to the connection state before the connection relation is set.

The present invention has been made in view of such circumstances, and an object of the present invention is to provide a data communication system that freely sets connection relationships between devices by a simple procedure.

(D) Means for solving the problem Therefore, in this method, the current state is only available when there is a connection request from another device after there is no transmission / reception between the devices to which the connection relationship is set for a certain period of time. It releases the connection relation of and maintains the current connection relation when there is no connection request.

(E) Example An example of the present invention will be described below with reference to the drawings.

FIG. 1 is a connection example of a personal computer by a terminal server which is an embodiment of the present invention. In FIG. 1, (11), (12) and (13) are personal computers used as terminals, and (14), (15) and (16) are connected to the personal computers (11), (12) and (13). Computer
(11) (12) A terminal server that controls the communication of (13), (17)
Is a limited area transmission line connecting these terminal servers (14), (15) and (16).

Generally, in such a limited area transmission system, the buckets as shown in FIG. 2 are exchanged to connect / disconnect the devices and transfer the data.

In Fig. 2, the set connection relationship is the connection identification number.
It is managed by a certain number called (21). The exchanged packets are identified by the identifier (22) and classified into connection request packets, connection response packets, rejection response packets, disconnection request packets, disconnection response packets, interrupt connection request packets, data packets, and the like.

To set the connection relationship between the devices, first, a connection request packet is transmitted to the device that wants to have the connection relationship. The device that has received the connection request responds with a rejection response packet if the connection relationship with another device has already been set. After the connection relation is set, data is transmitted / received by a data packet, and after the data transmission / reception is completed, the connection relation is released by a disconnection request / disconnection response packet according to the necessity of disconnecting the connection relation.

FIG. 3 is a block diagram of the terminal server. Reference numerals (31) and (32) denote an input unit and an output unit that perform input / output with a terminal device, a personal computer, or the like by a general-purpose interface such as RS-232C. (33) and (34) are limited area transmission systems, and are the first between other terminal servers.
A packet transmitting unit and a packet receiving unit that transmit and receive packets as shown in the figure. (35) is a connection information storage unit that stores information about the current connection state, for example, the address of the other terminal server in the connection relationship, the connection identification number, and the like, and (36) packets are transmitted and received within a certain period of time. It is a no-call monitoring timer that monitors whether or not. (37) rewrites the connection information in the connection information storage section (35) by an input section, a command from the packet receiving section and an interrupt from the silent call monitoring timer (36), and the input section
(31) is a transmission / reception processing unit that delivers data from the packet reception unit (34) to the packet transmission unit (33) and the output unit (32) according to the connection information. Next, an operation example will be described.

In FIG. 1, when data is transferred between the personal computers (11) and (12), the terminal server (14) and
Set the connection relation of (15). Therefore, the command from the personal computer (11) can be used to
(14) sends a connection request packet with a connection request command as a packet identifier to the terminal server (15). Terminal server that received the connection request packet (15)
The transmission / reception processing unit (37) checks the connection information storage unit (35) to find that it is not currently connected, and establishes a new connection relationship with the terminal server (14). That is, the reception processing unit (3
At 7), a connection identification number is randomly generated, and the address of the terminal server (14) is stored in the connection information storage section (35) in correspondence with the connection identification number. After that, the connection response packet is transmitted to the terminal server (14) in association with the connection identification number. Upon receiving the connection response packet, the terminal server (14) knows that the connection request has been accepted, and stores the address of the terminal server (15) in the connection information storage unit (35) in association with the connection identification number. . As a result, a connection relationship is set between the terminal servers (14) and (15), and data can be transferred between these by simply inputting data from the personal computers (11) and (12).

The feature of this embodiment resides in the change of the connection relation when there is no transmission / reception for a certain period of time or more.

Now, in FIG. 1, when the connection relation is set between the personal computer (11) and the personal computer (12) and data is given by the personal computer (11) (12), the terminal server (14) (15) In (), the address of the other party is added and the data is transmitted to the personal computer (12) (11). If the data transfer between the personal computer (11) and the personal computer (12) is interrupted,
Each time the terminal server (14) (15) idle call monitoring timer
(36) is activated, and upon restarting the data transfer, these silent call monitoring timers (36) are set again. When the data transfer is completed, the silent call monitoring timer (36) works again, and after a predetermined count, the timer (36) times out, and it is stored in the connection information storage unit (35) that the silent call monitoring state is set. (4th
(Figures A, C). In this state, the current connection relationship is not released, but when there is a connection request from another, the current connection relationship can be released and a new connection relationship can be set.

When the data transfer between the personal computers (11) and (12) is restarted in the no call monitoring state, both terminal servers (14)
The inside of the connection information storage unit (35) of (15) is returned to the connected state (FIG. 4B). On the other hand, when it becomes necessary to connect from the personal computer (13) to the personal computer (11), a command from the personal computer (13) sends a connection request bucket to the terminal server (14), and the server (14) Releases the connection relationship with the terminal server (15) and newly establishes the connection relationship with the terminal server (16) (Fig. 4D). If the connection request from the personal computer (13) is an interrupt connection request, the connection relationship between the personal computers (11) and (13) is released, and then the personal computer (11) is connected again.
The connection relationship between (12) is restored (Fig. 5).

That is, in the connection information storage unit (35) of each terminal server (14) (15) (16), the address of the destination of the interrupt request is stored in addition to the connection address area that stores the normal connection destination address. When there is an interrupt address area and there is an interrupt request, the address of this interrupt destination is stored in the interrupt request address, data is transmitted to the interrupt destination, and when the interrupt processing is completed Erase the address of.

(F) Effects of the Invention As described above, in the communication method of the present invention, the connection relationship is set between the devices, and after a state where no data is transmitted / received for a certain period of time, there is a connection relationship from another device. Only when necessary, a new connection relationship is set, and the current connection relationship is maintained while there is no connection request from others, so the connection relationship is unduly occupied even if data is not sent or received. There is no such thing, and there is no case that the connection relationship is unreasonably released.

Further, in the communication system of the present invention, an interrupt connection request can temporarily set a connection relationship with a device in a connected state, and after the data transfer is completed, the connection relationship can be restored. Therefore, even if a device used in daily work has a connection relationship with another device, the device can be temporarily borrowed, and daily work can be smoothly performed.

[Brief description of drawings]

FIG. 1 is a block diagram of a limited area transmission system in which the data communication system of the present invention is implemented, and FIG. 2 is a schematic diagram showing a form of a packet exchanged in the limited area transmission system of the present invention, and FIG. FIG. 4 is a block diagram of the terminal server, FIG. 4 is an operation explanatory diagram for explaining a connection relation changing operation by the no-call monitoring timer, and FIG. 5 is a connection relation changing operation by an interrupt connection request. FIG. 8 is an explanatory diagram of an operation for doing so. (11) (12) (13) …… Personal computer, (14) (15) (1
6) …… Terminal server, (17) …… Transmission line, (35)…
… Connection information storage, (36) …… No call monitoring timer, (37)…
… Transmit / receive processor.

Claims (2)

[Claims] 1. A method of transparently transferring data in a communication between devices connected to a commonly accessible data transmission path by using a preset connection relationship between arbitrary two devices. , If a connection request is made from another device after a state in which data is not sent and received for a certain period of time between the devices to which the connection relationship has been set, a new connection relationship is automatically set. Characteristic data communication method. 2. In the above data communication system according to claim 1, when a device to which a connection relationship is set has an interrupt connection request from another device, the requested device makes a request. A data communication method characterized in that a connection relationship is set with the device that performed the operation, and when the connection relationship ends, the connection relationship before the interrupt connection request was made is restored.