JPH118625A - Data communication system and data communication method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a data communication system and its method by which problems of interference and security are improved in the case of transmitting data by means of a radio wave and the procedure of registration of each device is simplified. SOLUTION: A radio LAN is built up by connecting a radio communication adaptor to each computer. Each radio communication adaptor is provided with memories 16A-16C storing a group identification code and with group identification code setting switches 3A-3C. In the case that the two radio communication adaptors of the same group are connected and the group identification code setting switches 3A-3C are depressed and no group identification code is in existence in both devices, one device generates the group identification code and the code is set to both devices. In the case that the identification code has been in existence in one device, the identification code of the device is transferred to the other device and stored therein.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a wireless LAN (Local Area Network) for connecting a plurality of computers wirelessly.
The present invention relates to a data communication device and a data communication method suitable for use in constructing k).

[0002]

2. Description of the Related Art With the rapid spread of computers, computer network technology has become very important. Already, companies, universities and the like having a plurality of computers are actively connecting computers to share resources and files and exchange mails. In recent years, computers have been widely used in homes, and many people own many computers, such as desktop computers and portable computers. As described above, when a home has a plurality of computers, a desktop computer and a portable computer are connected to exchange data, and a plurality of computers share a printer or the like. To connect multiple computers.

Conventionally, LA has been connected to a plurality of computers.
In the case of constructing N, computers are often connected by wire using a coaxial cable, a twisted pair cable, or an optical fiber. However, when a computer network is constructed by connecting a plurality of computers by wire, there is a problem that construction is required and wiring is routed, so that a computer network cannot be easily constructed. Therefore,
Wireless LANs that perform wireless data communication between computers have attracted attention.

[0004]

However, wireless LANs
Then, mutual interference and security problems are likely to occur. For example, as shown in FIG.
Assume that two computer networks N1 and N2 are located in close proximity.

[0005] The computer network N1 comprises computers 101A, 101B and 101C, and each of the computers 101A, 101B and 101C communicates with a wireless communication unit 102A, 101A for transmitting and receiving data wirelessly.
02B and 102C are attached respectively. By attaching the wireless communication units 102A, 102B, 102C to the respective computers 101A, 101B, 101C, data can be transferred between the computers 101A, 101B, 101C on the same computer network N1.

The computer network N2 is composed of computers 111A, 111B and 111C. Each of the computers 111A, 111B and 111C has a wireless communication unit 112A, 1
12B and 112C are attached. Each computer 1
By attaching the wireless communication units 112A, 112B, 112C to the respective computers 11A, 111B, 111C, data can be transferred between the computers 111A, 111B, 111C on the same computer network N2.

In such a wireless LAN, the computer network N1 and the computer network N2 are close to each other, and the wireless communication units 102A, 102B and 102C on the computer network N1 and the wireless communication units 102A and 102A on the computer network N2
If the distance between the radio waves 102B and 102C is within the reach of the radio wave, there is a risk of causing interference with each other.

In the wireless LAN, when data is sent to the other computer, for example, the data is packetized and sent with the destination of the other party. Since the destination address can be freely assigned, the same address may be assigned in adjacent computer networks. If the same address is assigned to the computers of the adjacent computer networks N1 and N2, there is a risk that data is erroneously transferred between the computer networks N1 and N2.

[0009] Further, if not only problems caused by coincidence of addresses but also mutual interference and security problems are not taken into consideration, there is a risk that data may be intentionally intercepted or stolen.

[0010] Therefore, it is conceivable to encrypt and transmit the data. Conventionally, when encrypting and transmitting data, it is common for a user to determine an encryption key and register this encryption key in a device used in a network.

However, the encryption key is determined as described above,
The task of registering each device is not easy. In addition, the user often forgets the encryption key set by the user.

SUMMARY OF THE INVENTION It is therefore an object of the present invention to provide a data communication apparatus and method capable of improving the problem of interference and security when data is transmitted wirelessly and simplifying the operation of registering devices.

[0013]

SUMMARY OF THE INVENTION According to the present invention, there is provided a data communication apparatus for transmitting data to another terminal wirelessly and receiving data from the other terminal, comprising: an input means for setting an identification code; Has an identification code distributing means for distributing an identification code for enabling data communication only to the device, and an identification code storage means for storing the identification code. When setting the identification code, data communication is permitted. Devices that belong to the same group are connected to each other, and when an input for setting an identification code is given from the input unit, the identification code exists in the identification code storage unit of both devices. If not, one device generates an identification code, stores the generated identification code in the identification code storage means of one device, and transfers it to the other device. The identification code which has been transferred to the other device and stored in the ID code memory means of the other devices,
If the identification code already exists in the identification code storage unit of one device, the identification code already stored in the identification code storage unit of one device is transferred to the other device and transferred to the other device. Controls the stored identification code to be stored in the identification code storage means of the other device, distributes the same identification code to devices belonging to the same group, and enables data communication only between devices belonging to the same group A data communication device characterized in that:

By connecting a wireless communication adapter to the computer, data communication can be performed wirelessly. Each wireless communication adapter includes a memory storing a group identification code and a group identification code setting switch. When two wireless communication adapters in the same group are connected and a group identification code setting switch is pressed, a common group identification code is set in the same group.

[0015]

Embodiments of the present invention will be described below with reference to the drawings. The present invention is suitable for use in constructing a wireless LAN by transmitting data between a plurality of computers by radio waves as shown in FIG. In FIG. 1, 1A, 1B and 1C are computers. A serial communication port is derived from each of the computers 1A, 1B, and 1C. These computers 1A,
The wireless communication units 2A, 2B, and 2C are connected to the serial communication ports 1B and 1C, respectively.

By connecting the wireless communication units 2A, 2B and 2C to the computers 1A, 1B and 1C, the computers 1A, 1B and 1C can perform wireless data communication between the respective computers. .
When transmitting data, the transfer data is packetized, the destination of the destination is added, and the data is transmitted by radio waves. At the other end, the data transmitted by radio waves is received, and the baseband data is demodulated. Then, the destination of the packet is detected, and if the packet is of its own destination, the packet is received. If the packet is successfully received, an acknowledgment packet is returned to the sender. On the sending side, it is confirmed from the acknowledge packet whether or not the data transfer has been correctly performed.

The radio communication units 2A, 2B and 2C have
In order to enable such wireless data communication,
A baseband data processing unit for packetizing data to be transmitted and disassembling received packets, and a transmission / reception unit for converting the transmitted data and transmitting the data at a predetermined frequency, and receiving a signal to demodulate the baseband data. Are provided.

As a modulation / demodulation method for performing wireless data communication, for example, a spread spectrum method is used. Spread spectrum uses PN (Pseudorandom)
(Noise) code is superimposed to perform communication, and has an advantage that it has excellent interference resistance and is hardly disturbed. Further, in the spread spectrum, the same PN code as in the transmission is required to perform despreading at the time of reception. Therefore, the confidentiality is high.

Thus, each of the computers 1A, 1B,
By connecting the wireless communication units 2A, 2B, and 2C to 1C, a wireless LAN can be constructed. Such a wireless L
The AN transfers data between the computers 1A, 1B, and 1C, and can share resources and files and exchange mails.

In such a wireless LAN, mutual interference and security problems are likely to occur. Therefore, the wireless communication units 2A, 2B, 2C to which the present invention is applied
Include group identification code setting switches 3A, 3B, 3
C is provided. The group identification code setting switches 3A, 3B, and 3C are used to distribute a common identification code to devices on a common network so that data communication can be performed only within the same group. Each of the wireless communication units 2A, 2B, and 2C has an EE-PROM 16A for storing a group identification code,
16B and 16C are provided.

When performing the process of distributing the group identification code, as shown in FIG.
C are connected two by two, and one of the wireless communication units 2A to 2A
The 2C group identification code setting switches 3A to 3C are pressed.

That is, the radio communication units 2A, 2B,
When 2C is used in the same computer network, two of them, for example, as shown in FIG. 2A, a wireless communication unit 2A and a wireless communication unit 2B are connected by a cable 5. Then, the group identification code setting switch 3A of the wireless communication unit 2A is pressed.

When the group identification code setting switch 3A of the wireless communication unit 2A is pressed, the group identification code is generated by the wireless communication unit 2A unless the group identification code is stored in the EE-PROM 16A of the wireless communication unit 2A. The group identification code is written into the EE-PROM 16A, and the group identification code is sent to the wireless communication unit 2B.
The data is written to the EE-PROM 16B of the wireless communication unit 2B. Thereby, a common group identification code is set between the wireless communication unit 2A and the wireless communication unit 2B.

Then, as shown in FIG. 2B, the wireless communication unit 2A and the wireless communication unit 2C are connected, and the group identification code setting switch 3A of the wireless communication unit 2A is pressed. When the group identification code setting switch 3A of the wireless communication unit 2A is pressed, the group identification code stored in the EE-PROM 16A of the wireless communication unit 2A is sent to the wireless communication unit 2C, and the EE-PROM 16C of the wireless communication unit 2C is sent. Is written to. Thereby, a common group identification code is set between the wireless communication unit 2A and the wireless communication unit 2C.

As shown in FIG. 2A, when the wireless communication unit 2A and the wireless communication unit 2B are connected and the group identification code setting switch 3A is pressed, the wireless communication unit 2A and the wireless communication unit 2B are shared. Is set. Then, by connecting the wireless communication unit 2A and the wireless communication unit 2C and pressing the group identification code setting switch 3A, a common group identification code is set between the wireless communication unit 2A and the wireless communication unit 2C. Thereby, the wireless communication units 2A to 2A to within the same computer network
This means that a common group identification code has been set between 2C.

Note that the wireless communication units 2A to 2C are provided with clear switches 4A to 4C, and the group identification code once set is cleared by the clear switches 4A to 4C.
You can clear it by pressing.

When a common group identification code is set between the wireless communication units 2A to 2C in the same computer network, the group identification code becomes a kind of encryption, and the common group identification code is set. Data communication can be performed only between the wireless communication units, and the problem of interference with the computer network due to adjacent wireless communication and the problem of security can be improved.

As described above, when data is transmitted with spread spectrum, the group identification code can be made to correspond to the PN code. That is, to despread the spread spectrum data, the same P
N codes are required. Therefore, if the same PN code is set for devices in the same group, data communication will be performed only with devices in the group.

Of course, encryption may be performed such that the group identification code is used as an encryption key.

It is desirable that the group identification code generated by the wireless communication unit in the initial state is unique. Therefore, it is conceivable to generate a group identification code using a manufacturing serial number for each device.
Since the production serial number for each unit is unique, if a group identification code is generated using the production serial number, a unique group identification code can be automatically generated. For example, by combining a serial number and a random number generated at that time, a group identification code whose contents change each time it is generated and which does not match another key and a code can be generated.

In the above example, when distributing a common group identification code for each group, the wireless communication units 2A to 2C are connected to each other by the cable 5, but radio waves are transmitted between the wireless communication units 2A to 2C. May be used to send the group identification code. Note that the wireless communication unit 2
When sending a group identification code by radio between A and 2C,
It is conceivable to lower the output power than usual so that the group identification code does not affect other computer network devices. Further, the group identification code may be distributed by optical communication such as infrared communication.

FIG. 3 shows such a wireless communication unit 2.
2A to 2C show an example of the configuration. In FIG. 3, a wireless communication unit 2 includes a CPU (Central Proc).
essingUnit) 11 is provided. A bus 13 is led from the CPU 11. The bus 13 has a ROM (Read
Only Memory) 14, RAM (Rndom Access Memory)
15. EE-PROM (Electrically Erasable Progra
mable ROM) 16 is connected.

An interface circuit 17 and a baseband signal processing circuit 18 are connected to the bus 13. From the interface circuit 17, the computer 1
An I / O port 19 for connecting to A to 1C is derived. This I / O port 19 is also used to connect the wireless communication units 2A to 2C to each other and transmit the group identification code when distributing the group identification code. A transmission / reception circuit 20 for wirelessly transmitting / receiving data is connected to the baseband data processing circuit 18. Further, the CPU 11 is supplied with inputs from the group identification code setting switch 3 and the clear switch 4 and various displays are displayed on the display 12.

When performing data communication, the I / O ports 19 of the wireless communication units 2A to 2C are connected to the serial communication ports of the computers 1A to 1C. When transmitting data from each of the computers 1A to 1C, data from each of the computers 1A to 1C is input from the I / O port 19 and supplied to the interface circuit 17. The output of the interface circuit 17 is supplied to a baseband data processing circuit 18.

In the baseband data processing circuit 18, the CP
The transmission data is packetized into a predetermined packet under the control of U11. The output of the baseband data processing circuit 18 is supplied to the transmission / reception circuit 20. In the transmitting / receiving circuit 20,
This data is multiplied by a PN code and spread spectrum. Note that the PN code at this time is EE-PROM1
6 is set according to the group identification code stored in. Then, the signal is converted to a predetermined transmission frequency, power-amplified, and output from the antenna 23.

At the time of data reception, a reception signal from the antenna 23 is supplied to the transmission / reception circuit 20. Transmission / reception circuit 2
At 0, the received signal is amplified and converted to a predetermined intermediate frequency signal, and the spectrum code is despread. Despreading is performed by multiplying by the same PN code as at the time of transmission. The PN code at this time is EE-PROM
16 is set according to the group identification code stored. The output of the transmitting / receiving circuit 20 is supplied to the baseband data processing circuit 18.

The baseband data processing circuit 18 decomposes the received packet and demodulates the baseband data. The output of the baseband data processing circuit 18 is supplied to the interface circuit 17. The output of the interface circuit 17 is output from the I / O port 19 and sent to the serial communication ports of each of the computers 1A to 1C.

When distributing the group identification code,
Via the I / O port 19, the wireless communication units 2A to 2C
Are connected to each other. Then, the group identification code setting switch 3 of one of the wireless communication units 2A to 2C is pressed. Thus, an encryption key distribution process as shown in the flowchart of FIG. 4 is performed, and the group identification code is stored in the EE-PROM 6.

FIG. 4 is a flowchart showing an encryption key distribution process for connecting two wireless communication units 2 and distributing a group identification code. In FIG. 4, it is determined whether or not the clear switch 4 has been pressed (step ST1). If clear switch 4 is pressed, EE-
The contents of PROM 16 are erased (step ST2).
Then, an indication of successful registration is made (step ST3),
The process ends.

If the clear switch 4 has not been pressed in step ST1, it is determined whether or not the group identification code setting switch 3 has been pressed (step ST4).
If the group identification code setting switch 3 is pressed,
A connection confirmation message is sent (step ST5).
If the registration processing has been performed without any problem, when the connection confirmation message is sent, a response message is returned from the other party. It is determined whether or not this response message has been received (step ST6). If no response message is received, registration failure is displayed (step ST).
7), the process ends.

When the response message is received in step ST6, it is determined whether or not the group identification code has already been written in EE-PROM 16 (step ST6).
8). If the group identification code is not written in the EE-PROM 16, a new group identification code is generated, and the generated group identification code is used as the EE-PR.
The data is written to the OM 16 (step ST9). Then, the group identification code written in the EE-PROM 16 is transmitted to the other party (step ST10). In step ST8, the group identification code is already EE-PROM.
When it is determined that the group identification code has been written in the EE-PROM 16, the group identification code written in the EE-PROM 16 is transmitted to the other party.

If the registration processing has been performed without any problem, the group identification code is sent out, and the other party returns the group identification code set in the other party as a response message. It is determined whether or not this response message has been received (step ST11). If a response message has not been received, the process goes to step ST7, where a message indicating that registration has failed is displayed, and the process ends. Step ST11
When the response message is received in the EE-PROM 16
It is determined whether or not the group identification code written in (1) matches the group identification code sent as the response message from the other party (step ST1).
2). If the group identification codes match, the process goes to step ST3, where the display of registration success is performed, and the process ends. If the group identification codes do not match, the process proceeds to step ST7, where registration failure is displayed, and the process ends.

If it is determined in step ST4 that the group identification code setting switch 3 has not been pressed,
It is determined whether or not a connection confirmation message has been received (step ST13). If no connection confirmation message has been received, the process ends.

When the connection confirmation message is received in step ST13, a response message is transmitted (step ST14). Then, it is determined whether or not a group identification code is received (step ST15). If no group identification code has been received, the process ends.

When the group identification code is received in step ST15, it is determined whether there is a group identification code already written in the EE-PROM (step ST16). If there is no group identification code, the received group identification code is written into the EE-PROM (step ST17), and the received group identification code is sent out as a response message (step ST1).
8).

If it is determined in step ST16 that there is a group identification code already written in the EE-PROM, the group identification code written in the EE-PROM 16 is sent out as a response message (step ST16). ST19).

For example, FIG. 5 shows a process in a case where a group identification code is distributed, and both wireless communication units 2D and 2E do not have a group identification code.

When the group identification code setting switch 3 of the wireless communication unit 2D is pressed, the wireless communication unit 2D
Sends a connection confirmation message to the wireless communication unit 2E (step ST5).

Upon receiving the connection confirmation message, the wireless communication unit 2E returns a response message to the wireless communication unit 2D (step ST14).

Since the wireless communication unit 2D has not previously stored the group identification code, the wireless communication unit 2D receives the response message, generates a group identification code, and stores the generated group identification code (step ST9). ) And sends it to the wireless communication unit 2E (step ST10).

Since the wireless communication unit 2E does not previously store the group identification code, when receiving the group identification code, the wireless communication unit 2E stores the transmitted group identification code (step ST1).
7), the group identification code is sent to the wireless communication unit 2D as a response message (step ST18).

Upon receiving the response message, radio communication unit 2D compares the group identification code set in radio communication unit 2D with the group identification code returned as the response message (step ST1).
2).

The wireless communication unit 2E sets the group identification code sent from the wireless communication unit 2D and sends it as a response message. Therefore, the group identification code set in the wireless communication unit 2D and the response message are set. Matches with the group identification code returned as.

If the group identification code set in the wireless communication unit 2D matches the group identification code returned as the response message, the registration is successful (step ST3).

As described above, both radio communication units 2D
If there is no group identification code in the wireless communication unit 2E, a new group identification code is generated and set in the wireless communication unit 2D and the wireless communication unit 2E.

FIG. 6 shows a process when a group identification code is set in the wireless communication unit 2F and there is no group identification code in the wireless communication unit 2G.

When the group identification code setting switch 3 of the wireless communication unit 2F is pressed, the wireless communication unit 2F
Sends a connection confirmation message to the wireless communication unit 2G (step ST5).

When receiving the connection confirmation message, radio communication unit 2G returns a response message to radio communication unit 2F (step ST14).

Since the group identification code is already stored in the wireless communication unit 2F, the wireless communication unit 2F
Receives the response message, sends the stored group identification code to the wireless communication unit 2G (step ST10).

Since the wireless communication unit 2G does not previously store the group identification code, when receiving the group identification code, the wireless communication unit 2G stores the transmitted group identification code (step ST1).
7), the group identification code is sent as a response message to the wireless communication unit 2F (step ST18).

Upon receiving the response message, the wireless communication unit 2F compares the group identification code set in the wireless communication unit 2G with the group identification code returned as the response message (step ST1).
2).

The wireless communication unit 2G sets the group identification code sent from the wireless communication unit 2F and sends it as a response message. Therefore, the group identification code set in the wireless communication unit 2G and the response message are set. Matches with the group identification code returned as.

If the group identification code set in the wireless communication unit 2G matches the group identification code returned as the response message, the registration is successful (step ST3).

As described above, the group identification code is set in the wireless communication unit 2F, and the wireless communication unit 2F
If G has no group identification code, the group identification code of the wireless communication unit 2F is
Distributed to As a result, the registration processing of the devices belonging to the same group proceeds.

FIG. 7 shows the processing when the group identification code has already been set in the wireless communication unit 2H and the wireless communication unit 2I.

When the group identification code setting switch 3 of the wireless communication unit 2H is pressed, the wireless communication unit 2H
Sends a connection confirmation message to the wireless communication unit 2I (step ST5).

Upon receiving the connection confirmation message, radio communication unit 2H returns a response message to radio communication unit 2I (step ST14).

Since the group identification code is already stored in the wireless communication unit 2H, the wireless communication unit 2H
Receives the response message, sends the stored group identification code to the wireless communication unit 2I (step ST10).

Since the group identification code is already stored in the wireless communication unit 2I, the wireless communication unit 2I
Receives the group identification code, sends the stored group identification code to wireless communication unit 2H as a response message (step ST19).

Upon receiving the response message, radio communication unit 2H compares the group identification code set in radio communication unit 2H with the group identification code returned as the response message (step ST1).
2).

Here, if the same group identification code is initially set in the wireless communication unit 2H and the wireless communication unit 2I, the group identification code set in the wireless communication unit 2H and the group returned as the response message are set. It matches the identification code.

If the group identification code set in the wireless communication unit 2H matches the group identification code returned as the response message, the registration is successful (step ST3).

If different group identification codes are set in the wireless communication unit 2H and the wireless communication unit 2I, the group identification code set in the wireless communication unit 2H does not match the group identification code returned as a response message. .

If the group identification code set in the wireless communication unit 2H does not match the group identification code returned as the response message, the registration fails (step ST7).

As described above, when the group identification codes are already set in the wireless communication units 2H and 2I, the group identification codes stored in the wireless communication units 2H and 2I are compared.
If the group identification codes do not match, the registration process fails to ensure security. In this case,
The processing may be performed after the group identification code set by the clear switch 4 is cleared.

[0076]

According to the present invention, a wireless LAN is formed by connecting a wireless communication adapter to a computer. Each wireless communication adapter includes a memory storing a group identification code and a group identification code setting switch. When two wireless communication adapters in the same group are connected and a group identification code setting switch is pressed, a common group identification code is set in the same group. As described above, the same identification code can be easily set to the same group by a simple switch operation. If the same identification code is easily set in the same group, data communication can be performed only in the same group, and interference and security problems can be improved.

[Brief description of the drawings]

FIG. 1 is a schematic diagram illustrating an example of a computer network system to which the present invention is applied.

FIG. 2 is a schematic diagram used for describing a wireless communication unit to which the present invention is applied.

FIG. 3 is a block diagram illustrating an example of a wireless communication unit to which the present invention is applied;

FIG. 4 is a flowchart used to describe an example of a wireless communication unit to which the present invention is applied.

FIG. 5 is a sequence diagram used for describing an example of a wireless communication unit to which the present invention has been applied.

FIG. 6 is a sequence diagram used for describing an example of a wireless communication unit to which the present invention has been applied.

FIG. 7 is a sequence diagram used for describing an example of a wireless communication unit to which the present invention has been applied.

FIG. 8 is a schematic diagram used for describing a conventional wireless computer network.

[Explanation of symbols]

1A-1C ... computer, 2, 2A-2I ...
Wireless communication unit, 3, 3A to 3C: group identification code setting switch, 16, 16A to 16C: EE
-PROM

Claims (14)

[Claims] 1. A data communication device for transmitting data to another terminal wirelessly and receiving data from the other terminal. An input means for setting an identification code, and data communication is possible only with a specific device. ID code distributing means for distributing an ID code for storing the ID code, and ID code storing means for storing the ID code. When the ID code is set, devices for which data communication is permitted are placed in the same group. When the devices belonging to the same group are connected to each other and an input for setting an identification code is given from the input unit, the identification code does not exist in the identification code storage unit of both devices. In such a case, an identification code is generated by one device, the generated identification code is stored in the identification code storage means of the one device, and the other device Transfer, and the other device stores the transferred identification code in the identification code storage means of the other device. If the identification code already exists in the identification code storage means of one of the devices, Transfers the identification code already stored in the identification code storage means of the one device to the other device, and transfers the transferred identification code in the other device to the identification code storage means of the other device. Data communication, wherein the same identification code is distributed to the devices belonging to the same group, and data communication is enabled only between the devices belonging to the same group. apparatus. 2. The data communication apparatus according to claim 1, wherein the data communication is performed by spread spectrum, and the identification code is made to correspond to a spread code at the time of spread spectrum. 3. The data communication apparatus according to claim 1, wherein the devices belonging to the same group are connected by a cable, and the same identification code is distributed between the devices belonging to the same group. . 4. The data communication apparatus according to claim 1, wherein the same identification code is wirelessly distributed between the devices belonging to the same group. 5. The data communication device according to claim 4, wherein the distribution of the identification code is performed by a wireless output of a lower level than that of normal communication. 6. The data communication device according to claim 1, wherein the same identification code is distributed by optical communication between devices belonging to the same group. 7. The data communication device according to claim 1, wherein the identification code is generated based on a manufacturing serial number of the device. 8. A data communication method for transmitting data to another terminal wirelessly and receiving data from another terminal, wherein devices permitted for data communication belong to the same group and belong to the same group. If the two devices are connected and the identification codes of both devices do not exist, an identification code is generated by one device, the generated identification code is stored in the one device, and the other device is stored. And the other device stores the transferred identification code in the other device. If the identification code already exists in one of the devices, the identification code is already stored in the one device. The transferred identification code is transferred to the other device, and the transferred identification code is stored in the other device in the other device. Data communication method characterized by distributing an identification code, and to a data communication only between devices belonging to the same group is possible. 9. The data communication method according to claim 8, wherein data communication is performed by spread spectrum, and the identification code is made to correspond to a spread code used when the spread spectrum is performed. 10. The data communication method according to claim 8, wherein the devices belonging to the same group are connected by a cable, and the same identification code is distributed between the devices belonging to the same group. . 11. The data communication method according to claim 8, wherein the same identification code is wirelessly distributed between the devices belonging to the same group. 12. The data communication method according to claim 11, wherein the distribution of the identification code is performed by a wireless output of a lower level than that of normal communication. 13. The data communication method according to claim 8, wherein the same identification code is distributed by optical communication between the devices belonging to the same group. 14. The data communication method according to claim 8, wherein the identification code is generated based on a manufacturing serial number of the device.