JPH0714190B2 - Computer network - Google Patents

Description

The present invention relates to a computer network in which a general-purpose computer as a host computer and a terminal computer at a remote place are connected using a telephone line.

[Conventional technology]

A basic procedure between a general-purpose computer and a terminal computer at a remote place, etc., by using a telephone line [Basic Mode Data Transmission Control Procedu
res: JIS standard copy X5002-1975] As a link control method when connecting with a public line, that is, a switched line system assuming a subscriber telephone network (including a private telephone network) and a dedicated line (including a private line) A direct line system based on the premise is known.

Among these, as the circuit control method of the direct line method, a polling selection method is used, in which a general-purpose computer asks each terminal in turn whether it can send or receive, and as the circuit control method of the switched line method. Is a contention system in which the side transmitting the data calls the other party for communication, and the person who calls the other party earlier has the transmission right.

In this way, the circuit control method is completely different between the case of using the subscriber telephone network and the case of using the leased line, and as the software for performing each procedure, in the case of the subscriber telephone network, IBM's BSC2 or I if Hitachi's HSC2 is a dedicated line
BM's BSC3 and Hitachi's HSC3 are used. (Hereinafter, the procedure for the subscriber telephone network is referred to as BSC2, etc., and the procedure for the leased line is referred to as BSC3.) On the other hand, a computer network that uses the leased line is used when the security that prevents the intrusion of a third party is the subscriber telephone network. Needless to say, the polling selection method can be adopted, so that it is possible to control traffic from the general-purpose computer side to give information to terminals.

[Problems to be Solved by the Invention]

For example, a dedicated line is often used in a network between a large-scale computer and a general-purpose computer, or a general-purpose computer interconnecting a head office in Tokyo and a branch office in a local metropolis.

When a general-purpose computer and a terminal computer (such as a personal computer) at a remote place are connected by a basic procedure using a telephone line to expand the network, the general-purpose computer and the terminal computer are connected to each other. Regardless of whether a dedicated line is already provided between them, it is very expensive to add a new dedicated line, and therefore it is desirable to use the subscriber telephone network.

Since the procedure BSC2 of the subscriber telephone network and the procedure BSC3 of the leased line are completely different from each other, it has never been considered to communicate with the subscriber telephone network using the BSC3 or the like. This is because when a large number of terminals are connected to one general-purpose computer in such a subscriber telephone network, which terminal is connected to the general-purpose computer in BSC3 etc., which uses the polling selection method,
This is because the host cannot recognize it. Therefore, if you decide to do this using a normal modem, the procedure for the dedicated line is that the terminal identification (station address, unit address) is unique to the terminal in BSC3 etc. It is impossible to freely connect a plurality of terminals to the terminal identification information. Therefore, the one-to-one relationship between the general-purpose computer and the terminals is limited, and it is not possible to freely connect a large number of terminals to one general-purpose computer.

As a communication procedure, in addition to BSC2 etc. and BSC3 etc., there is also a communication procedure called HDLC, which is widely used in the world of large computers, but it is hard to introduce it.
It costs a lot in terms of software.

It is an object of the present invention to solve the above-mentioned inconvenience of the conventional example, and to use a dedicated line procedure BSC3 or the like to provide a computer network capable of connecting a large number of terminals to one general-purpose computer in a subscriber telephone network. To provide.

[Means for Solving the Problems]

In order to achieve the above-mentioned object, the present invention, when a general-purpose computer and a terminal computer at a remote place or the like are connected by a basic procedure using a telephone line, the telephone line is provided by a telephone station that provides a telephone network. An exchange uses a subscriber telephone network with a representative telephone function to automatically select and connect to a vacant line from multiple lines, and its control is such that one control station assigns unique addresses to multiple slave stations. By using the transmission control procedure for the dedicated line that adopts the polling selection method, which is a method of attaching and communicating, a plurality of slave stations arbitrarily jump from the vacant line by the representative telephone function between the general-purpose computer and the modem, and the address A converter that exchanges addresses, which is a function to allow a general-purpose computer to recognize the fixed address of a virtual slave station in order to prevent it from being determined. Connecting to fix the terminal address information from a plurality of lines to the general-purpose computer, and to divide the general-purpose computer into a plurality of connection ports, and a modem through a converter that exchanges addresses for each branch connection port. The main point is to connect.

[Action]

According to the present invention, when connecting a plurality of terminals, first, the same address is given as the station address of each terminal (this can be done by normal terminal preparation work). Next, on the host side, the function of the address converter according to the present invention works for each telephone line, and a station address that is consistent with the general-purpose computer is repeated. Be able to identify.

As a result, a plurality of terminals can be freely connected to each other through a plurality of modems on the side of a general-purpose computer using a subscriber telephone network only when needed.

〔Example〕

FIG. 1 is a block circuit diagram showing an embodiment of a computer network of the present invention. In the figure, 1 is a general-purpose computer as a host computer, 2a, 2b, 2c are terminals of a personal computer class, 3 is a subscriber telephone network, At least the installation side of the general-purpose computer 1 has a representative telephone function 3a that receives the representative telephone number and sends it to each telephone.

The representative telephone function is that the telephone exchange of the NTT station that provides the subscriber telephone network 3 has a plurality of lines (in the example shown in FIG.
This is a function to automatically select a free line from 3 lines) and connect to the company.

Modems 4 and 5 are connected to the general-purpose computer 1 and the terminals 2a, 2b and 2c, respectively, in order to connect them by a telephone line.
As is well known, the modems 4 and 5 are modulation / demodulation devices that perform modulation for converting digital signals into AC signals and demodulation for converting AC signals into digital signals.

The present invention is a converter 6a for exchanging addresses between the general-purpose computer 1 and the modem 4 when the general-purpose computer 1 and the terminals 2a, 2b, 2c are connected via the modems 4 and 5 in the subscriber telephone network 3. , 6b, 6c are provided.

It should be noted that the address exchange is for causing the general-purpose computer 1 to recognize a fixed address of a virtual slave station in order to prevent a plurality of slave stations from jumping arbitrarily from a vacant line by the representative telephone function to determine an address. Is.

That is, the converters 6a, 6b, 6c are address converters that correspond to the leased line procedure BSC3, etc., and when the terminals 2a, 2b, 2c are viewed from the host side, each terminal having the same address is It has a station address conversion function that allows the host to recognize different station addresses regardless of which telephone line is connected.
In this embodiment, a personal computer 9801 manufactured by NEC Corporation is used, and the personal computer is provided with a mechanism for exchanging data with the general-purpose computer 1.

Although the general-purpose computer 1 may have only one connection port, as shown in FIG. 1, the converters 6a, 6b are branched into a plurality of connection ports 1a, 1b, 1c so as to accommodate a large number of terminals. , 6c and the modem 4 are connected to each of the branch connection ports 1a, 1b, 1c.

Next, the operation will be described.

The terminals 2a, 2b, 2c have station addresses according to the procedure BSC3 of the leased line, but they are set to the same (for example, D).

On the other hand, the general-purpose computer 1 carries information by polling / selection method using BSC3 or the like.

When the address information is input from the terminal, the converters 6a, 6b, 6c convert the addresses to A, B, C respectively and send them to the general-purpose computer 1, and, on the contrary, from the general-purpose computer 1 to A, B, C. 2a, 2 when the address information of
It is converted to the address D set in b and 2c and sent to the terminal. In this way, the connection port of the representative telephone, which is the connection port on the terminal side, is set so that any connection port can be regarded as a dedicated terminal connection port of the station address D.

First, considering the case where the converters 6a, 6b, and 6c are not provided, naturally communication with a terminal having the same terminal address is not normally performed.

However, in the present invention, for example, when connecting from the terminal 2a to a general-purpose computer, the converters 6a, 6b, and 6c provide the unique addresses of the converters regardless of which of the representative telephone lines is connected to the modem. Both the general-purpose computer and the terminal can operate normally because they are converted for communication.

As a result, the subscriber telephone network can be used to freely connect a plurality of terminals only when necessary.

〔The invention's effect〕

As described above, the computer network of the present invention is the use of an inexpensive subscriber telephone network for a general-purpose computer and a terminal computer at a remote place, etc., when the telephone line is used for basic connection. Only the dedicated line procedure BSC3, which cannot support the conventional subscribed telephone network procedure BSC2, can be used, so the software resources of the general-purpose computer are not wasted, and the telephone line receiving port is not changed at all. It is possible to connect multiple terminals freely and only when necessary.

[Brief description of drawings]

FIG. 1 is a block circuit diagram showing an embodiment of a computer network of the present invention, and FIG. 2 is a block diagram showing an application example. 1 ... General-purpose computer, 1a, 1b, 1c ... Connecting port 2a, 2b, 2c ... Terminal, 3 ... Subscribed telephone network 3a, 3b, 3c ... Representative telephone, 4,5 ... Synchronous modem for telephone 6a , 6b, 6c …… Address converter, 7 …… Branching device

Claims (2)

[Claims] 1. When a general-purpose computer and a terminal computer at a remote place are connected by a basic procedure using a telephone line, a plurality of telephone exchanges of telephone stations providing a telephone network are connected to this telephone line. A system that uses a subscriber telephone network that has a representative telephone function that automatically selects and connects to a free line from the lines, and its control is a system in which one control station assigns unique addresses to multiple slave stations for communication. By using the dedicated line transmission control procedure that adopts the polling selection method described above, a plurality of slave stations can arbitrarily jump in from the vacant line by the representative telephone function between the general-purpose computer and the modem and the address is not fixed. To prevent this, connect a converter that performs address exchange, which is a function to make a general-purpose computer recognize the fixed address of a virtual slave station, Computer networks, characterized in that to fix the terminal address information from multiple circuits into computer. 2. The computer network according to claim 1, wherein the connection port of the general-purpose computer is branched into a plurality, and the modem is connected through a converter for exchanging an address for each branch connection port.