JPH10257558A - Data communication system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a data communication system having a plug-and-play personal computer to a modem through a radio channel. SOLUTION: This system consists of a master set 1 and slave sets 3 that execute data communication through a radio wave, a modem 2 that modulates data to be transmitted to a public channel and demodulates data received from the public channel is connected to the master set 1 and a personal computer 4 is connected to each of the slave sets 3 so as to enable the data to transmit/ receive. Upon the receipt of a request of modem information from the slave sets 3, the master set 1 acquires the modem information by inquiring of the modem 2, stores the acquired modem information and sends the stored modem information to the slave sets 3. On the other hand, upon the receipt of a request of the modem information from the personal computer 4, the slave sets 3 request the modem information by extending a radio link with the master set 1 and transmits the modem information received from the master set 1 corresponding to the request to the personal computer 4.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a data communication using a wireless device such as a wireless local area network (LAN) device, a cordless data transmission device, a cordless printer buffer device, and a personal handyphone system (PHS) handling data systems. About the system.

[0002]

2. Description of the Related Art Conventionally, a data terminal interface, a wireless data modem, and a remote control function of an operation mode are provided in a master unit and a slave unit, respectively, and a line network controller and a wired data modem are provided in the master unit. There has been a wireless telephone (for example, refer to Japanese Patent Application Laid-Open No. 63-7069) that enables data communication with another data processing device.

Further, there has been a wireless telephone (for example, see Japanese Patent Application Laid-Open No. 22957/1990) in which a modem function is provided together with a connection terminal to a computer so that the computer can be wirelessly connected to a telephone network. Furthermore, a data collection method using a specific low-power wireless communication in which the position of a polling command is specified and detected in a short time (for example, Japanese Patent Laid-Open No.
-85726).

[0004]

However, in the above-described wireless telephone, a complicated process is required for the terminal device to acquire the modem information from the modem and make it usable, and the terminal device uses the wireless telephone. There is a problem that it is not possible to connect to and use the modem immediately via the telephone. SUMMARY OF THE INVENTION The present invention has been made in view of the above point, and has as its first object to enable a terminal device to plug and play a modem via wireless communication.

[0005] Further, in the data collection method using the specified low power radio as described above, since data is collected by polling, the frequency of use of the control channel becomes high, and the radio section for status notification cannot be used effectively. there were. Therefore, a second object of the present invention is to enable a control channel for wireless data communication to be effectively used.

[0006]

SUMMARY OF THE INVENTION In order to achieve the first object, the present invention comprises a master unit and a slave unit for performing wireless data communication, and modulates data transmitted to the master unit to a public line. And a modem for demodulating data received from the public line, and a terminal device such as a personal computer connected to the slave unit so as to be able to transmit and receive data. The master unit has modem information from the slave unit. A means for inquiring of the modem to obtain the modem information when receiving the request, storing the obtained modem information, and transmitting the stored modem information to the slave unit. When a request for modem information is received from the device, a wireless link is established with the master unit to request modem information, and in response to the request, the modem information received from the master unit is transmitted to the terminal. It is provided with a means for transmitting to the location.

[0007] A master unit and a slave unit for performing wireless data communication are connected to a modem for modulating data to be transmitted to the public line and demodulating data received from the public line to the master unit. A data communication system in which a terminal device such as a personal computer is connected to the machine so as to be able to transmit and receive data, and the master machine inquires the modem when the power is turned on, acquires modem information, and stores the acquired modem information. Preferably, there is provided means for creating a broadcast channel defining option bits for wireless channel information broadcast indicating whether or not a modem is connected based on the modem information, and transmitting the broadcast channel to the slave unit.

[0008] Further, the slave unit analyzes option bits of radio channel information broadcast of a broadcast channel received from the master unit, and determines whether a modem is connected to the master unit based on the analysis result. Then, when it is confirmed that the modem is connected by the determination, a wireless link is established with the master unit to request modem information, and in response to the request, the modem information received from the master unit is stored, Preferably, means for transmitting the stored modem information to the terminal device when receiving a request for modem information from the terminal device may be provided.

Also, a master unit and a slave unit for performing wireless data communication are connected to each other, and a modem for modulating data to be transmitted to the public line and demodulating data received from the public line is connected to the master unit. A data communication system in which a terminal device such as a personal computer is connected to the machine so as to be able to transmit and receive data.The master machine inquires the modem at regular intervals to obtain the modem information, and obtains the obtained modem information and the previously obtained modem information. It is preferable to provide a means for comparing the modem information with the modem information to determine whether or not they match, and transmitting the modem information obtained this time to the slave unit when the determination does not match.

[0010] Further, the slave unit receives the modem information transmitted from the master unit, stores the received modem information, and stores the stored modem information when a request for the modem information is received from the terminal device. It is preferable to provide a means for transmitting to the terminal device.

Next, in order to achieve the second object, the present invention comprises a master unit and a slave unit for performing data communication by radio, and modulates data to be transmitted to a public line to the master unit and a public line. A data communication system in which a modem for demodulating data received from the terminal is connected, and a terminal device such as a personal computer is connected to the slave unit so as to be able to transmit and receive data, and a modem initialization command is transmitted from the terminal device to the slave unit. Recognizing the reception, storing the recognized modem initialization command, returning an OK command to the terminal device, recognizing that a dial command has been received following the modem initialization command, and based on the recognition. Means for establishing a wireless link with the master unit, adding the dial command to the modem initialization command, and transmitting the dial command to the master unit. A.

Also, a master unit and a slave unit for performing wireless data communication are connected to the master unit, and a modem for modulating data to be transmitted to the public line and demodulating data received from the public line is connected to the master unit. A data communication system in which a terminal device such as a personal computer is connected to the device so as to be able to transmit and receive data. The slave device recognizes that a FAX modem command has been received from the terminal device, and communicates with the master device based on the recognition. Means for establishing a wireless link and switching from data communication control to FAX communication control may be provided.

Further, a master unit and a slave unit for performing wireless data communication are connected to a modem for modulating data to be transmitted to the public line and demodulating data received from the public line to the master unit. A data communication system in which a terminal device such as a personal computer is connected to a machine so as to be able to transmit and receive data.
An incoming call is detected, and based on the detection, a broadcast channel is defined in which option bits for wireless channel information broadcast indicating a fax incoming call are defined, and the created broadcast channel is transmitted to the slave unit, and the wireless link is transmitted from the slave unit. When the establishment request is received, the wireless link with the above
A means for shifting to X communication processing, wherein the slave receives the broadcast channel transmitted from the master, analyzes the option bits of the radio channel information broadcast of the received broadcast channel, and, based on the analysis result, To determine whether or not a modem is connected to the master unit, to confirm that the modem is connected, and to determine whether or not communication software is running on the terminal device. Preferably, means for transmitting a wireless link establishment request to the master unit when the communication software is running to establish a wireless link with the master unit and shifting to FAX communication processing may be provided.

[0014] Furthermore, a master unit and a slave unit for performing wireless data communication are connected to each other, and a modem for modulating data to be transmitted to the public line and demodulating data received from the public line is connected to the master unit. A data communication system in which a terminal device such as a personal computer is connected to a slave device so that data can be transmitted and received. The master device inquires of the modem to determine whether or not the fax machine is in a usable state, and based on the determination, A broadcast channel is defined which defines an option bit for radio channel information broadcast indicating that the FAX modem in the usable state is connected, and the generated broadcast channel is transmitted to the slave unit, and the wireless link is transmitted from the slave unit. Means for establishing a wireless link with the slave unit when receiving the establishment request and shifting to facsimile communication processing;
When the communication software of the terminal device is activated, the slave device analyzes option bits of the radio channel information broadcast of the broadcast channel received from the master device, and, based on the analysis result, the FAX which can be used by the master device. It is determined whether or not a modem is connected. Based on the determination, it is confirmed that an available fax modem is connected. Based on the confirmation, a wireless link establishment request is transmitted to the master unit. It is preferable to provide a means for establishing a wireless link with the master unit and shifting to FAX communication processing.

According to a first aspect of the present invention, there is provided a data communication system in which a modem for modulating data to be transmitted to a public line and demodulating data received from the public line is connected to a master unit, and a terminal such as a personal computer is connected to the slave unit. Connect the device so that data can be transmitted and received, and when the slave receives a request for modem information from the terminal device, establish a wireless link with the master to request modem information, and the master requests modem information from the slave. Upon receipt, the modem is inquired of the modem, the modem information is acquired and stored, and then the modem information is transmitted to the slave, and the slave receives the modem information transmitted from the master and transmits it to the terminal device.

Therefore, in response to a wireless modem information inquiry request from a terminal device connected to the slave device, the master device can automatically and accurately transmit the modem information of the modem connected to the own device by wireless. Thus, a plug-and-play function can be realized between the terminal device and the modem through wireless communication.

In a data communication system according to a second aspect of the present invention, a modem for modulating data to be transmitted to the public line and demodulating data received from the public line is connected to the master unit, and a personal computer or the like is connected to the slave unit. Wireless communication information indicating whether or not the modem is connected based on the modem information by connecting the terminal device so that data transmission / reception is possible, and inquiring the modem when the power is turned on, acquiring and storing modem information. A broadcast channel defining broadcast option bits is created, and the broadcast channel is transmitted to the slave unit.

Therefore, the master unit can obtain the modem information of the modem connected to the master unit and notify the slave unit of the modem connection every time the power is turned on. Modem information can be provided.

Further, in the data communication system according to a third aspect of the present invention, the slave unit receives the broadcast channel transmitted from the master unit, and analyzes the option bits of the broadcast channel information broadcast of the received broadcast channel, Based on the analysis result, determine whether the modem is connected to the parent machine,
After confirming that the modem is connected based on the judgment, establish a wireless link with the master unit and request modem information,
The modem information transmitted from the master unit in response to the request is received and stored, and the stored modem information is transmitted when a request for modem information is received from the terminal device.

In this way, the slave unit does not need to request the master unit for modem information more than necessary each time an inquiry from the terminal unit is made, and the modem unit quickly transmits the modem information in response to the inquiry from the terminal unit. can do. Therefore, each time the user resets the terminal device, the parent device and the child device do not need to establish a wireless link for acquiring modem information.

In the data communication system according to a fourth aspect of the present invention, a modem for modulating data to be transmitted to the public line and demodulating data received from the public line is connected to the master unit, and a personal computer or the like is connected to the slave unit. The terminal device is connected so as to be able to transmit and receive data, the master unit queries the modem at regular intervals to obtain modem information, and compares the obtained modem information with the previously obtained modem information to determine whether they match. Judgment is made, and if the judgments do not match, the modem information acquired this time is transmitted to the slave unit.

In this way, the master unit automatically updates the slave unit with new modem information even if the modem connected to the master unit is exchanged for a different model or the modem state is changed and the modem information is updated. Can be provided.

Further, in the data communication system according to claim 5 of the present invention, the slave unit receives and stores the modem information transmitted from the master unit, and receives the stored modem information from the terminal device for a request for modem information. When it is sent to the terminal device. Therefore, since the new modem information can be automatically acquired, the slave does not need to make an inquiry to the master as to whether the modem information has been updated, and does not needlessly establish a wireless link with the master.

In a data communication system according to a sixth aspect of the present invention, a modem for modulating data to be transmitted to the public line and demodulating data received from the public line is connected to the master unit, and a personal computer or the like is connected to the slave unit. When the slave unit recognizes that the terminal unit has received the modem initialization command from the terminal unit, the terminal unit stores the modem initialization command, returns an OK command to the terminal unit, and initializes the modem. When it recognizes that a dial command has been received following the command, it establishes a wireless link with the base unit based on the recognition, adds the dial command to the modem initialization command, and sends it to the base unit.

In this way, by establishing a wireless link between the master unit and the slave unit only during communication by the terminal device,
It is not necessary to establish a wireless link every time the communication software on the terminal device is activated, and a control channel for wireless data communication can be effectively used.

Therefore, the termination of the wireless link when transmitting the modem initialization command (AT command) transmitted when the communication software is started from the slave unit to the master unit does not have to be determined by the timer value, and thus the command transmission is performed. Unnecessary transmission time can be prevented from occurring after the timer expires. In addition, the transmission time until the timer expires is saved, and the wireless link itself is not required.

Further, in the data communication system according to a seventh aspect of the present invention, a modem for modulating data to be transmitted to the public line and demodulating data received from the public line is connected to the master unit, and a personal computer or the like is connected to the slave unit. When the terminal recognizes that the terminal has received the FAX modem command from the terminal, the terminal establishes a wireless link with the base based on the recognition and switches from data communication control to FAX communication control. Switch.

As described above, when the terminal device performs the FAX communication, the wireless link between the master unit and the slave unit is immediately established to switch to the FAX communication.
It is not necessary to establish a wireless link every time the X software is started up, a control channel for wireless data communication can be effectively used, and FAX communication can be performed normally.

Therefore, the FAX software of the terminal device sends an AT command for facsimile (AT & F) before the dial command and cannot distinguish between a modem initialization command and a negotiation command. It is possible to prevent the communication from being performed normally by returning OK.

In the data communication system according to the present invention, a modem for modulating data to be transmitted to the public line and demodulating data received from the public line is connected to the master unit, and a personal computer or the like is connected to the slave unit. The base station detects the incoming fax from the modem, and based on the detection, creates a broadcast channel defining an option bit of the radio channel information broadcast indicating the incoming fax, based on the detection. Send to On the other hand, the slave unit receives the broadcast channel transmitted from the master unit, analyzes the option bits of the radio channel information broadcast of the broadcast channel, and determines whether a modem is connected to the master unit based on the analysis result. When it is determined that the modem is connected, it is determined whether or not the communication software is running on the terminal device. When the communication software is running, a wireless link establishment request is transmitted to the master unit. When the master unit receives the wireless link establishment request from the slave unit, the master unit establishes a wireless link with the slave unit and shifts to FAX communication processing. One of the slave units also establishes a wireless link with the master unit. Is established, and the process proceeds to the fax communication process.

Thus, when a fax is received by the modem,
By establishing a wireless link between the master unit and the slave unit only when it is confirmed that the fax communication software of the terminal device is running, it is possible to avoid unnecessary use of the wireless link when a fax cannot be received. Thus, the control channel at the time of wireless data communication can be effectively used.

Therefore, the modem connected to the master unit
When X is received, it is possible to prevent the facsimile from being received because the communication software on the terminal device connected to the slave unit is not ready, thereby preventing an unnecessary wireless link from being generated.

Further, in the data communication system according to the ninth aspect of the present invention, a modem for modulating data to be transmitted to the public line and demodulating data received from the public line is connected to the master unit, and a personal computer or the like is connected to the slave unit. Is connected so that data transmission / reception is possible, and the master unit inquires of the modem to determine whether or not it is an available FAX modem, and indicates that the available FAX modem is connected based on the determination. A broadcast channel defining option bits for radio channel information broadcast is created and transmitted to the slave unit. On the other hand, at the time of starting the communication software of the terminal device, the slave device analyzes the option bits of the radio channel information broadcast of the broadcast channel received from the master device and, based on the analysis result, connects the available FAX modem to the master device. It is determined whether or not the FAX modem is in a usable state based on the determination, and a wireless link establishment request is transmitted to the parent device based on the confirmation. When the master unit receives the wireless link establishment request from the slave unit, the master unit establishes a wireless link with the slave unit and shifts to FAX communication processing. One of the slave units also establishes a wireless link with the master unit. To establish F
The process proceeds to the AX communication process.

In this way, the slave unit can be made to recognize that the modem connected to the master unit is a FAX modem in advance, and the control channel at the time of wireless data communication can be effectively used.

Therefore, it is impossible for the slave unit to know in advance whether the modem connected to the master unit is a FAX modem, and the FAX communication software of the terminal device is activated to establish a wireless link with the master unit and perform FAX communication. It is not necessary to confirm that the wireless communication device is not a modem, and it is possible to prevent an unnecessary wireless link from being generated.

[0036]

Embodiments of the present invention will be specifically described below with reference to the drawings. FIG. 1 is a diagram showing a configuration of a communication system according to an embodiment of the present invention. This communication system employs a system for performing data transmission by a TDMA / TDD digital cordless telephone device, and includes a plurality of master units 1 and slave units 3 that perform wireless data communication with each other. And the slave unit 3 are used in combination. For convenience, only one master unit 1 and two slave units 3 combined therewith are shown in the figure.

The base unit 1 is connected to a modem 2 for modulating data to be transmitted to a telephone line (public line) such as PSTN and demodulating data received from the telephone line via a communication cable such as RS232C. On the other hand, each handset 3 is RS2
A personal computer (hereinafter, referred to as a "personal computer") 4 is connected via a communication cable such as 32C so that data communication is possible.

Wireless data communication is performed between the master unit 1 and each slave unit 3. That is, when an incoming call is received by the facsimile communication or the data communication to the modem 2, the base unit 1 wirelessly transmits the received data such as images and sounds to the sub unit 3 to which the personal computer 4 is connected. Slave device 3 transmits the data received from master device 1 to personal computer 4 connected to itself. The slave 3 wirelessly transmits data received from the personal computer 4 connected to the slave 3 to the master 1, and the master 1 transmits the data to the destination via the telephone line by the modem 2. Then, the plug-and-play function according to the present invention is executed between the master unit 1 and each slave unit 3. Further, the present invention executes a function for effectively utilizing the control channel according to the present invention.

FIG. 2 is a block diagram showing the configuration of the master unit shown in FIG. Base unit 1 includes a CPU, a ROM, and an RA
This is a digital cordless telephone device incorporating a microcomputer made of M or the like, and includes the components shown in FIG.

Then, the data received from the slave unit 3 received by the antenna 11 is received by the radio unit 12, the modulation / demodulation unit 13 demodulates the received data, and the communication control unit 14 performs TDMA baseband processing. Audio codec (AD
The signal is converted into an analog voice signal by a PCM (15) and transmitted to a telephone line (17) by a line interface (I / F) unit (16).

The line I /
A telephone call (voice call) with the telephone line 17 is performed via the F unit 16. Further, various operation information is input from the key input unit 20, and based on the input operation from the key input unit 20, various states are displayed on the display unit 19 and the LED 23 via the man-machine interface (I / F) unit 18. Perform The display unit 19 and the LED 23 also display various operation information during data communication and a notification of an operation state, and also display status information of a connected printer (not shown).

The EEPROM 22 stores ID information. Furthermore, data such as a modem control command (AT command), modem information of a connected modem, a modem initialization command, a dial command, and the like are stored in the RAM in the communication control unit 14. In the case of digital data, the communication control unit 14 performs TDMA baseband processing, and then transmits the RS232C I / F from the serial I / F unit 24.
Connect to the modem via F25.

In the base unit 1, the communication control unit 14 executes various processes related to the plug and play function between the modem 2 connected to the base unit 1 and the personal computer connected to the slave unit 3. In addition, various processes related to the function of effectively utilizing the control channel with the slave 3 are also executed.

FIG. 3 is a block diagram showing the configuration of the slave unit shown in FIG. Slave unit 3 includes a CPU, a ROM, and an RA
This is a digital cordless telephone device incorporating a microcomputer made of M or the like, and includes the components shown in FIG.

The data received from the base unit 1 received by the antenna 31 is received by the radio unit 32, processed by the modem unit 33 to demodulate the received data, and subjected to TDMA baseband processing by the communication control unit 34. Audio codec (AD
The signal is converted into an analog audio signal by the PCM 35 and output as audio by the speaker 36.

At the time of transmission, the sound input from the microphone 37 is transmitted through a path opposite to the above-described sound output.
Further, various operation information is input from the key input unit 40, and various states are displayed on the display unit 39 and the LED 43 via the man-machine interface (I / F) unit 38 based on the input operation from the key input unit 40. Perform

The EEPROM 42 stores ID information. Further, data such as a modem control command (AT command), modem information of a modem connected to the base unit 1, a modem initialization command, a dial command, and the like are stored in the RAM in the communication control unit 34.

Then, the radio section 32 is transmitted via the antenna 31.
The modem information from the master unit 1 received by the modem 1 is demodulated by the modem 33 and stored in the RAM in the communication control unit 34.
The data is transmitted to the personal computer via the RS232C I / F 41 by the / F unit 44.

In the case of digital data, modem data from a personal computer connected to the serial I / F unit 44 is input, sent to the communication control unit 34 via the RS232C / I / F 41, and then the modem information is transmitted. The signal is modulated by the modulation / demodulation unit 33 and transmitted from the antenna 31 via the radio unit 32.

In the slave unit 3, the communication control unit 34 executes various processes related to the plug-and-play function between the personal computer 4 connected to the slave unit 3 and the modem 2 connected to the master unit 1. Also,
Various processes related to the function of effectively utilizing the control channel with the base unit 1 are also executed.

(1) Processing of First Plug-and-Play Function In the first plug-and-play function, the communication control unit 14 of the base unit 1 sends a request for modem information from the slave unit 3 through the wireless unit 12 or the like. When received, the modem 2 is inquired through the serial I / F unit 24 to obtain modem information, the obtained modem information is stored in the RAM in the communication control unit 14, and the stored modem information is stored in the wireless unit 12 The function of a means for transmitting to the slave unit 3 is performed by the above-described method.

When receiving a request for modem information from the personal computer (terminal device) 4 via the serial I / F unit 44, the communication control unit 34 of the slave unit 3 A link is established to request modem information, the modem information transmitted from master unit 1 in response to the request is received, and the received modem information is transmitted to personal computer (terminal device) 4 via serial I / F unit 44. Acts as a means for sending to

FIG. 4 is a diagram showing a modem information acquisition sequence between the master unit 1 and the slave unit 3. When the power is turned on, the personal computer 4 plugs and plays (Plug & Play)
y). Slave unit 3 is a personal computer 4 connected to own unit
When a plug-and-play request is received from the device, a wireless link establishment request is transmitted to the base unit 1. On the other hand, upon receiving the wireless link establishment request from the child device 3, the parent device 1 transmits a reception of the wireless link establishment request to the child device 3. In this way, the handset 3
Establishes a wireless link with the base unit 1.

After establishing a wireless link with master device 1, slave device 3 transmits a request for modem information to master device 1. When receiving the request for the modem information from the slave 3, the master 1 transmits a modem information request acceptance to the slave 3, and inquires of the modem 2 about the modem information by requesting the plug-and-play to acquire the modem information. The modem information is transmitted to the device 3. In this way, master device 1 acquires modem information from modem 2 based on the request from slave device 3 and transmits the modem information to slave device 3.

When the slave unit 3 receives the modem information from the master unit 1, it sends a modem information transmission OK to the master unit 1, sends the modem information to the personal computer 4, and sends a wireless link disconnection request to the master unit 1. I do. On the other hand, upon receiving the wireless link disconnection request from child device 3, master device 1 transmits a reception of the wireless link disconnection request to child device 3 and disconnects the wireless link. In this way,
The slave unit 3 acquires the modem information from the master unit 1 and transmits it to the personal computer 4, and then disconnects the wireless link with the master unit 1.

FIG. 5 is a timing chart of the modem information acquisition control of base unit 1. Base unit 1 simultaneously outputs the RTS signal and DTR signal of the RS232C port to the high level (Hi).
gh), and sets the RTS signal to a low level (Low) at a timing between T1 = 150 ms and T2 = 250 ms to receive modem information from the modem 2.

(2) Processing of the second plug-and-play function In the second plug-and-play function, the communication control unit 14 of the master unit 1 transmits the data to the modem 2 via the serial I / F unit 24 when the power is turned on. The modem information is obtained by inquiring, and the obtained modem information is stored in the RAM in the communication control unit 14,
Based on the stored modem information, a broadcast channel is defined which defines an option bit for radio channel information broadcast indicating whether or not the modem 2 is connected, and the generated broadcast channel is transmitted to the slave unit 3 by the radio unit 12 or the like. Acts as a means for sending to

Further, the communication control unit 34 of the slave unit 3 receives the broadcast channel transmitted from the base unit 1 by the wireless unit 32 or the like, analyzes the option bits of the broadcast channel information broadcast of the received broadcast channel, It is determined whether or not the modem 2 is connected to the base unit 1 based on the analysis result,
Based on the determination, it is confirmed that the modem 2 is connected, and a wireless link is established with the base unit 1 by the wireless unit 32 or the like to request modem information, and the modem information transmitted from the base unit 1 in response to the request. Is received, the received modem information is stored in the RAM in the communication control unit 34, and the stored modem information is transmitted to the serial I / F unit 44 when a request for modem information is received from the personal computer (terminal device) 4. Serves as the means of transmitting via

FIG. 6 is a flowchart showing a modem information acquisition sequence of master unit 1. Master unit 1 performs step 1
When power-on (power-on) is detected in step 2, the process proceeds to step 2 where the modem is queried for modem information (status) to determine whether or not the modem information has been captured.

If the modem information is fetched from the modem in the judgment of step 2, the process proceeds to step 3 to store the modem information in the RAM in the communication control unit, and proceeds to step 4 to notify based on the modem information stored in the RAM. The modem information is included in the channel (BCCH), and an option bit for radio channel information notification indicating that the modem is connected is set (defined), and the process proceeds to step 5 to transmit the BCCH to the slave unit.

If it is determined in step 2 that the modem information cannot be acquired from the modem, the flow advances to step 4 to set an option bit for radio channel information broadcast indicating that the modem is not connected to the broadcast channel (BCCH) (definition). ), And proceeds to step 5 to transmit the BCCH to the slave unit.

FIG. 7 is a diagram showing a configuration of a radio channel information broadcast slot of a broadcast channel (BCCH) in which base unit 1 broadcasts control information to slave unit 3. R, SS, PR, UW, C
It includes BCCH (A) along with I, calling identification code, and CRC.

FIG. 8 is a diagram showing a detailed configuration inside the BCCH. An option bit indicating whether or not a modem is connected is defined in the option area of 2 to 6 octets.

FIG. 9 is a flowchart showing a modem information request sequence of the slave unit 3. Slave unit 3 performs step 1
When the power is turned on in step 1, when the power is turned on, the super frame transmitted from the base unit 1 is constantly monitored. In step 12, it is determined whether or not the broadcast channel (BCCH) in the super frame has been received. Channel (BCC
H) is analyzed, and the routine proceeds to step 14, where it is determined whether or not there is modem information.

If it is determined in step 14 that there is modem information, the flow advances to step 15 to store the modem information in a memory (RAM in the communication control unit). If it is determined in step 14 that the modem information is empty, the process proceeds to step 18 to execute a modem information acquisition process for the parent device, confirm again whether or not the modem is connected, and check the BC transmitted from the parent device.
If there is modem information in the CH, the memory (RA in the communication control unit)
M).

If there is no modem information in the judgment of step 14,
If it is determined that the modem is not connected to the master unit by referring to the BCCH option bits and the list of the option bits registered in the own unit, no information is returned when the modem information is requested from the personal computer. Absent. That is, the request from the personal computer is ignored.

Then, in step 16, it is determined whether or not there has been a request for modem information from the personal computer. If there is no request for modem information, the process returns to step 12, and if there is a request for modem information, the process proceeds to step 17. Transmits the modem information stored in the RAM in the communication control unit to the personal computer.

(3) Processing of Third Plug-and-Play Function In the third plug-and-play function, the communication control unit 14 of the master unit 1 transmits the modem 2 via the serial I / F unit 24 at regular time intervals. To obtain the modem information, and compares the obtained modem information with the previously obtained modem information stored in the RAM in the communication control unit 14 to determine whether or not they match. Means for rewriting the previously obtained modem information stored in the RAM in the communication control unit 14 to the currently obtained modem information when the communication is not performed, and transmitting the currently obtained modem information to the slave unit 3 by the wireless unit 12 or the like. Perform the function of

The communication control unit 34 of the slave unit 3 receives the modem information transmitted from the master unit 1 by the wireless unit 32 or the like, and transmits the received modem information to the RA in the communication control unit 34.
M, and when the modem information request is received from the personal computer (terminal device) 4 via the serial I / F unit 44, the modem information stored in the RAM in the communication control unit 34 of the own device is transmitted to the serial I / F. PC (terminal device) via the unit 44
4 performs the function of the transmitting means.

FIG. 10 is a flowchart showing a modem information acquisition sequence of master unit 1. When power is turned on, master device 1 inquires the modem of modem information in step 21;
The modem information is obtained from the modem, the process proceeds to step 22, the previous modem information stored in the memory (RAM in the communication control unit) is compared with the currently obtained modem information, and the process proceeds to step 23 where the modem information is obtained. It is determined whether they match.

If it is determined in step 23 that they do not match, the flow advances to step 24 to change the BCCH information.
The modem information in the BCCH is rewritten from the previously obtained modem information to the currently obtained modem information and transmitted to the slave unit 3,
Proceed to step 25. If they match in the determination in step 23, the process directly proceeds to step 25. Step 25
Then, it is determined whether or not a predetermined period of time has elapsed, and if it has elapsed, the process proceeds to step 21 to repeat the above processing.

In this way, the base unit 1 inquires of the modem 2 about the modem information when the power is turned on, and compares the modem information stored in the RAM in the communication control unit with the newly obtained modem information. If they match, the modem information is processed as if it did not change. If they do not match, the modem information in the BCCH is rewritten with the modem information acquired this time and transmitted to the slave unit 3. By executing the process of the plug & play function at regular intervals, the latest modem information is always provided to the slave unit 3.

(1) Processing of First Control Channel Effective Utilization Function In this first control channel effective utilization function, the communication control unit 34 of the slave unit 3 transmits a modem from the personal computer 4 via the serial I / F unit 44 to the modem. The communication control unit 3 recognizes that the initialization command has been received and transmits the recognized modem initialization command.
4 and returns an OK command to the personal computer 4 via the serial I / F unit 44, recognizes that a dial command has been received following the modem initialization command from the personal computer 4, and based on the recognition, The wireless unit 32 and the like establish a wireless link with the base unit 1 and add a dial command to the modem initialization command to transmit the modem initialization command to the base unit 1.

FIG. 11 is a flowchart showing a first modem initialization sequence by the slave unit 3. Slave unit 3
At step 31, an AT command is received from the communication software of the personal computer. The process proceeds to step 32 to determine whether or not the command is a dial command. If the command is not a dial command, the process proceeds to step 33 to store it in a memory (RAM in the communication control unit). Then, the flow advances to step 34 to return OK to the personal computer and returns to the first processing.

If it is determined in step 32 that the command is a dial command, the flow advances to step 35 to store the memory (RA in the communication control unit).
It is determined whether or not there is a modem initialization command in M). If there is, the process proceeds to step 36 to add a dial command to the modem initialization command, and proceeds to step 37 to transmit a wireless link establishment request to the parent device. Then, the process proceeds to a step 38, wherein A comprising a modem initialization command and a dial command is executed.
Send a T command.

If it is determined in step 35 that there is no modem initialization command in the memory (RAM in the communication control unit), the flow advances to step 37 to transmit a wireless link establishment request to the master unit. Only the AT command is transmitted.

Then, the process proceeds to a step 39 to judge whether or not an OK command has been returned from the modem via the master unit. If not, the process returns to the step 38 to send an AT command. Proceed to and start communication.

Further, the first modem initialization sequence will be described. The slave 3 receives the modem initialization command (AT command) from the communication software of the personal computer 4 and recognizes that it is not a dial command (ATD), and transmits the received modem initialization command to the RAM in the communication control unit 34. To the PC 4 and OK
Returns a command.

When it is recognized that the AT command received from the personal computer 4 is a dial command, it is checked whether or not the RAM in the communication control unit 34 has a modem initialization command. An AT command in which a dial command is added to a conversion command is created. If there is no AT command, an AT command including only a dial command is created. FIG. 12 shows a format example of an AT command in which a dial command is added to a modem initialization command.

Then, after establishing a wireless link with master device 1, an AT command is sent to master device 1. If the OK command of modem 2 is not returned from master device 1 after sending the AT command, a modem initialization command is again issued. Is sent, and when it returns, communication is started.

(2) Processing of Second Control Channel Effective Utilization Function In this second control channel effective utilization function, the communication control unit 34 of the slave unit 3 sends a fax from the personal computer 4 via the serial I / F unit 44 to the FAX. It recognizes that the modem command has been received, and based on the recognition, establishes a wireless link with the base unit 1 by the wireless unit 12 or the like and performs a function of switching from data communication control to FAX communication control.

FIG. 13 is a flowchart showing a second modem initialization sequence by the slave unit 3. Slave unit 3
At step 41, an AT command is received from the communication software of the personal computer, and the process proceeds to step 42 to determine whether the command is a FAX command. If not, the process proceeds to step 43 to determine whether the command is a dial command. If it is not a command, the process proceeds to step 44 to store it in a memory (RAM in the communication control unit), and proceeds to step 45 to return OK to the personal computer and return to the first process.

If it is determined in step 42 that the command is a FAX command, or if it is determined that the command is a dial command in step 43, the flow advances to step 46 to determine whether or not there is a modem initialization command in the memory (RAM in the communication control unit). For example, proceed to step 47 to add a dial command to the modem initialization command, proceed to step 48 to transmit a wireless link establishment request to the master unit, and proceed to step 49 to set an AT consisting of a modem initialization command and a dial command. Send a command.

If there is no modem initialization command in the memory (RAM in the communication control unit) in step 46, the flow advances to step 48 to transmit a wireless link establishment request to the master unit. Only the AT command is transmitted.

Then, the process proceeds to step 50, where it is determined whether or not an OK command has been returned from the modem via the master unit. If not, the process returns to step 49 to send the AT command. Proceed to and start communication.

Next, the second modem initialization sequence will be described. The slave unit 3 receives the modem initialization command (AT command) from the communication software of the personal computer 4 and, when recognizing that it is a FAX command (AT & F), immediately establishes a wireless link with the master unit 1 and transmits the command. Start an exchange. If the received AT command is not a FAX command, it is determined whether or not the received AT command is a dial command (ATD). If it is recognized that the received AT command is not a dial command (ATD), the received modem initialization command is transmitted to the communication control unit 34. And returns an OK command to the personal computer 4.

Further, when recognizing that the AT command received from the personal computer 4 is a dial command, it checks whether or not the RAM in the communication control unit 34 has a modem initialization command. AT command that adds a dial command to the conversion command,
If there is no AT command, an AT command consisting of only a dial command is created.

Then, after establishing a wireless link with the base unit 1, an AT command is sent to the base unit 1. If the OK command of the modem 2 is not returned from the base unit 1 after sending the AT command, a modem initialization command is again issued. Is sent, and when it returns, communication is started.

(3) Processing of Third Control Channel Effective Utilization Function In the third control channel effective utilization function, the communication control unit 14 of the base unit 1 transmits the data from the modem 2 via the serial I / F unit 24. FAX incoming call is detected, and FA
A broadcast channel defining an option bit of radio channel information broadcast indicating X arrival is created, and the broadcast channel is transmitted to the slave unit 3 by the wireless unit 12 or the like, and a wireless link establishment request is issued from the slave unit 3 by the wireless unit 12 or the like. Upon reception, it functions as means for establishing a wireless link with the handset 3 and shifting to FAX communication processing.

Further, the communication control unit 34 of the slave unit 3 receives the broadcast channel transmitted from the base unit 1 by the wireless unit 32 or the like, analyzes the option bits of the received broadcast channel, and broadcasts the radio channel information. It is determined whether or not the modem 2 is connected to the base unit 1 based on the analysis result,
By the determination, it is confirmed that the modem 2 is connected, and it is determined whether or not the communication software is running on the personal computer 4. 1 to establish a wireless link with the base unit 1 and
It functions as a means for shifting to the AX communication process.

FIG. 14 is a flowchart showing a BCCH option bit creation sequence at the time of facsimile reception of base unit 1 in the third modem initialization sequence. Master device 1 determines in step 61 whether or not the modem connected to itself has a facsimile call. If there is, the process proceeds to step 62 where an option bit indicating the facsimile call is set in BCCH and the process proceeds to step 63. Sends the BCCH to the slave unit.

FIG. 15 is a flowchart showing a response sequence at the time of fax reception of the slave 3 in the third modem initialization sequence. The slave 3 receives the BCCH from the master in step 71, and proceeds to step 72 to determine whether or not there is a modem initialization command in the memory (RAM in the communication control unit). Returning to step 73, if there is, the process proceeds to step 73, where it is determined whether or not there is a fax reception based on the option bit of BCCH.

If it is determined in step 73 that there is no incoming fax, the process returns to the first process. If there is, the process proceeds to step 74 to send a wireless link establishment request to the master unit, and establish a wireless link with the master unit. Proceeding to step 75, FAX communication using the modem of the master unit is executed, and when the facsimile communication ends, the flow proceeds to step 76 to disconnect the wireless link.

Further, the processing of the master unit 1 and the slave unit 3 will be described. Master device 1 detects an incoming fax by monitoring a RING signal from connected modem 2. When it is detected that a fax has arrived, an option bit indicating that a fax has arrived is set in a broadcast channel (BCCH) to be sent to the slave 3, and the fax is sent to the slave 3.

On the other hand, slave 3 always receives and monitors the BCCH transmitted from master 1. Then, when the modem initialization command transmitted when the communication software of the personal computer 4 is started is received, and it is recognized that the communication software of the personal computer 4 is started, the B which is constantly being received is received.
When analyzing the CCH and recognizing that the modem 2 of the base unit 1 has received a facsimile call based on the option bit indicating that the facsimile call has been received, the base station 1 issues a wireless link establishment request to the base unit 1 and A facsimile communication is started via the base unit 1 by establishing a wireless link between the two. When the facsimile communication ends, the wireless link with the base unit 1 is disconnected, and the BCCH monitoring process is continued again.

(4) Processing of Fourth Control Channel Effective Use Function In this fourth control channel effective use function, the communication control unit 14 of the base unit 1 inquires the modem 2 via the serial I / F unit 24. To determine whether or not the FAX modem is in a usable state, and based on the determination, creates a broadcast channel defining radio channel information broadcast option bits indicating that a usable FAX modem is connected. The notification channel is transmitted to the slave unit 3 by the wireless unit 12 or the like,
When a wireless link establishment request is received from the slave unit 3 by the wireless unit 12 or the like, a wireless link with the slave unit 3 is established and F
It functions as a means for shifting to the AX communication process.

Further, when the communication software of the personal computer 4 is started, the communication control unit 34 of the slave unit 3 analyzes the option bits of the broadcast channel information broadcast of the broadcast channel received from the master unit 1 by the wireless unit 32 and the like. Based on the analysis result, it is determined whether or not an available FAX modem is connected to base unit 1. Based on the determination, it is confirmed that an available FAX modem is connected. Based on this, the wireless unit 32 or the like transmits a wireless link establishment request to the base unit 1, establishes a wireless link with the base unit 1, and performs a function of shifting to FAX communication processing.

First, base unit 1 transmits a broadcast channel (BCCH).
The process for setting the option bit in the "?"
FIG. 16 is a flowchart showing a BCCH transmission sequence of base unit 1 in the fourth modem initialization sequence. FIG. 17 is an operation diagram of a modem signal of the modem 2.

As shown in FIG. 16, base unit 1 determines in step 81 whether the CS signal of the modem is high (Hi), and if high, proceeds to step 82, where the DTR signal of the modem is high (Hi). Hi) is determined, and if not high, the process proceeds to step 83 and the command "AT + fcla" is sent to the modem.
ss =? , And proceeds to step 84 to determine whether or not there is a response from the modem.
To determine whether the response is "1" or "2".

If it is determined in step 85 that the response from the modem is "1" or "2", the flow advances to step 86 to set the option bit of the broadcast channel (BCCH) to "1, 1". The BCCH is transmitted to the slave unit. If it is determined in step 85 that the response from the modem is not "1" or "2", the flow advances to step 90 to set the option bit of the broadcast channel (BCCH) to "0, 0".
And the process proceeds to step 87 to transmit the BCCH to the slave unit.

Further, the DT of the modem is determined in step 82.
If the R signal is not high (Hi), and if there is no response from the modem in the determination at step 84, the process proceeds to step 88 to determine whether or not there is a facsimile reception. The option bit of the channel (BCCH) is set to "1, 0", and the routine proceeds to step 87, where the BCCH is transmitted to the slave unit.

If no fax is received in step 88, the flow advances to step 91 to set an option bit of the broadcast channel (BCCH) to "0, 1".
To send the BCCH to the slave unit.

Further, this processing will be described with reference to FIG. When the power of the modem 2 is turned on, the CS signal of the modem 2 becomes high (Hi). Therefore, the base unit 1 detects that the CS signal of the modem 2 has become high (Hi) and confirms that the power of the modem 2 is turned on. Then, the DTR signal of the modem 2 is monitored.

While the modem 2 is communicating, the DTR signal is high (H
i), the master unit 1 detects that the DTR signal of the modem 2 has become high (Hi) and confirms that the modem 2 is communicating.
It is determined whether it is an AX incoming call.

Then, if it is confirmed that the fax is being received based on the CI signal, the FACH is sent to the broadcast channel (BCCH).
An option bit “1, 0” indicating X incoming call is set.
When it is confirmed that the modem 2 is being used instead of receiving a fax, the option bits “0, 1” indicating the modem busy are set to the broadcast channel (BCCH).

Further, when it is confirmed that the modem 2 is not in use by monitoring the DTR signal of the modem 2, the command "A" for asking the modem 2 about the class capability of the FAX modem is provided.
T + fclass =? Is sent.

"1" when the modem 2 is a fax modem
Or, when "2" is returned, master device 1 receives the response of "1" or "2" from modem 2, determines that it is a FAX modem, and indicates FAX modem ready on the broadcast channel (BCCH). Set the option bit "1,1".

When receiving a reply of "ERROR" from modem 2, it determines that the modem is a data modem, and sets an option bit "0,0" indicating data modem ready on the broadcast channel (BCCH). During fax transmission, an option bit “0, 1” indicating modem busy is set. In this way, when the base station 1 sets the BCCH option bit, the base station 1 sends the BCCH to the handset 3.

FIG. 18 is a diagram showing a format example of a broadcast channel (BCCH). The BCCH is an area in which the fifth and sixth bits of the eighth octet each set an option bit indicating the FAX incoming call or the like.

As described above, the status of the option bit indicates that the master 1
Is notified to the slave unit 3. There are “0, 0” indicating data modem ready, “1, 0” indicating incoming fax, “0, 1” indicating modem busy, and “1, 1” indicating fax modem ready.

FIG. 19 is a flowchart showing a process of the modem initialization sequence by the slave unit 3 in the fourth modem initialization sequence. Slave device 3 performs step 101
Receives the BCCH from the parent device, proceeds to step 102, determines whether or not the fax communication software of the personal computer has been activated, returns to the initial processing if not activated, and returns to step 103 if activated. Then, it is determined whether or not the option bit of the BCCH is "1, 1".

If "1, 1", the flow advances to step 104 to execute the modem initialization process shown in FIG.
If it is not "1, 1", the process proceeds to step 105, and even if an AT command is transmitted from the FAX communication software of the personal computer, the AT command is ignored and the operation of establishing a wireless link with the master unit is not performed. In this way, the handset 3
Can monitor the status of the modem 2 connected to the base unit 1 by monitoring the option bits of the BCCH received from the base unit 1.

[0113]

As described above, according to the data communication system of the first to fifth aspects of the present invention, the terminal device can plug and play the modem through the radio. Further, according to the data communication system of claims 6 to 9 of the present invention, it is possible to effectively utilize a control channel at the time of wireless data communication.

[Brief description of the drawings]

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

FIG. 2 is a block diagram showing a configuration of a master unit shown in FIG.

FIG. 3 is a block diagram showing a configuration of a slave unit shown in FIG.

FIG. 4 is a diagram showing a modem information acquisition sequence between a master unit 1 and a slave unit 3.

FIG. 5 is a timing chart of the modem information acquisition control of the base unit 1.

FIG. 6 is a flowchart showing another modem information acquisition sequence of base unit 1.

FIG. 7 is a diagram showing a configuration of a radio channel information broadcast slot of a broadcast channel (BCCH) in which a base unit 1 broadcasts control information to a slave unit 3;

FIG. 8 is a diagram showing a detailed configuration inside the BCCH.

FIG. 9 is a flowchart showing a modem information request sequence of the slave unit 3.

FIG. 10 is a flowchart showing yet another modem information acquisition sequence of the base unit 1.

FIG. 11 is a flowchart showing a first modem initialization sequence by the slave 3;

FIG. 12 shows a format example of an AT command in which a dial command is added to a modem initialization command.

FIG. 13 is a flowchart showing a second modem initialization sequence by the slave 3;

FIG. 14 is a flowchart showing a BCCH option bit creation sequence at the time of facsimile reception of master device 1 in a third modem initialization sequence.

FIG. 15 is a flowchart showing a response sequence at the time of facsimile reception of the slave unit 3 in the third modem initialization sequence.

FIG. 16 is a flowchart showing a BCCH transmission sequence of the base unit 1 in a fourth modem initialization sequence.

FIG. 17 is an operation diagram of a modem signal of the modem 2.

FIG. 18 is a diagram illustrating a format example of a broadcast channel (BCCH).

FIG. 19 is a flowchart showing a process of a modem initialization sequence by the slave unit 3 in a fourth modem initialization sequence.

[Explanation of symbols]

 1: master unit 2: modem 3: slave unit 4: personal computer 11, 31: antenna 12, 32: wireless unit 13, 33: modulation and demodulation unit 14, 34: communication control unit 15, 35: voice codec unit 16: line I / F section 17: telephone line 18, 38: man-machine I / F section 19, 39: display section 20, 40: key input section 21: handset 22, 42: EEPROM 23, 43: LED 24, 44: serial I / F Part 25, 41: RS232C I / F 36: Speaker 37: Microphone

Claims (9)

[Claims] A modem for performing data modulation to be transmitted to a public line and demodulating data received from the public line to the master, and comprising: A data communication system in which a terminal device such as a personal computer is connected to the device so as to be able to transmit and receive data, and the master device obtains modem information by inquiring of the modem when receiving a request for modem information from the slave device.
Means for storing the obtained modem information and transmitting the stored modem information to the slave unit, wherein the slave unit establishes a wireless link with the master unit when receiving a request for modem information from the terminal device; A data communication system comprising means for requesting modem information and transmitting the modem information received from the master unit to the terminal device in response to the request. 2. A master unit and a slave unit for performing wireless data communication, and a modem for modulating data to be transmitted to a public line and demodulating data received from the public line is connected to the master unit. A data communication system in which a terminal device such as a personal computer is connected to the device so as to be able to transmit and receive data.The master device obtains modem information by inquiring of the modem when the power is turned on, stores the obtained modem information, Means for creating a broadcast channel defining option bits for radio channel information broadcast indicating whether or not a modem is connected based on the modem information, and transmitting the broadcast channel to the slave unit. Data communication system. 3. The data communication system according to claim 2, wherein the slave unit analyzes option bits of a radio channel information broadcast of a broadcast channel received from the master unit, and transmits the option bit to the master unit based on the analysis result. It is determined whether or not a modem is connected, and when it is confirmed that the modem is connected, a wireless link is established with the master unit to request modem information, and the master is requested in response to the request. A data communication system for storing modem information received from a terminal, and transmitting the stored modem information to the terminal device when a request for modem information is received from the terminal device. 4. A master unit and a slave unit for performing wireless data communication, and a modem for modulating data to be transmitted to a public line and demodulating data received from the public line is connected to the master unit. A data communication system in which a terminal device such as a personal computer is connected to the device so as to be able to transmit and receive data.The master device inquires the modem at regular time intervals to obtain modem information, and obtains the modem information and the previously obtained modem information. A data communication system comprising means for comparing modem information to determine whether or not they match, and transmitting the modem information acquired this time to the slave unit when the determination does not match. 5. The data communication system according to claim 4, wherein the slave unit receives modem information transmitted from the master unit, stores the received modem information, and requests the terminal device for modem information. A data communication system, comprising: means for transmitting the stored modem information to the terminal device when receiving the data. 6. A master unit for performing wireless data communication and a slave unit, and a modem for modulating data to be transmitted to a public line and demodulating data received from the public line is connected to the master unit. A data communication system in which a terminal device such as a personal computer is connected to the device so as to be able to transmit and receive data. The slave device recognizes that a modem initialization command has been received from the terminal device, and transmits the recognized modem initialization command to the slave device. It stores and returns an OK command to the terminal device, recognizes that a dial command has been received following the modem initialization command, establishes a wireless link with the master device based on the recognition, and initializes the modem. A data communication system comprising means for adding the dial command to a command and sending the command to the master unit. 7. A master unit and a slave unit for performing wireless data communication, and a modem for modulating data transmitted to a public line and demodulating data received from the public line is connected to the master unit. A data communication system in which a terminal device such as a personal computer is connected to the device so as to be able to transmit and receive data. The slave device recognizes that a FAX modem command has been received from the terminal device, and, based on the recognition, recognizes that A data communication system comprising means for establishing a wireless link and switching from data communication control to FAX communication control. 8. A master unit and a slave unit that perform wireless data communication, and a modem that modulates data transmitted to a public line and demodulates data received from the public line is connected to the master unit. A data communication system in which a terminal device such as a personal computer is connected to a device so as to be able to transmit and receive data. The master device detects a FAX call from the modem and, based on the detection, transmits a radio channel information notification indicating the FAX call. Create a broadcast channel with option bits defined,
Means for transmitting the created notification channel to the slave unit, establishing a wireless link with the slave unit when receiving a wireless link establishment request from the slave unit, and shifting to a facsimile communication process; The slave unit receives a broadcast channel transmitted from the master unit, analyzes an option bit of radio channel information broadcast of the received broadcast channel, and a modem is connected to the master unit based on the analysis result. To determine whether or not the modem is connected, and determine whether or not communication software is running on the terminal device. A data communication system comprising means for transmitting a wireless link establishment request to the master unit, establishing a wireless link with the master unit, and shifting to facsimile communication processing. 9. A modem comprising a master unit and a slave unit for performing wireless data communication, and a modem for modulating data to be transmitted to a public line and demodulating data received from the public line is connected to the master unit. A data communication system in which a terminal device such as a personal computer is connected to the machine so as to be able to transmit and receive data. A broadcast channel is defined which defines an option bit of radio channel information broadcast indicating that a facsimile modem in an enabled state is connected, the generated broadcast channel is transmitted to the slave, and a wireless link is established from the slave. Means for establishing a wireless link with the slave unit when receiving the request and shifting to facsimile communication processing; At the time of starting the software, an option bit of a radio channel information broadcast of a broadcast channel received from the master unit is analyzed, and it is determined whether or not a usable FAX modem is connected to the master unit based on the analysis result. Then, based on the determination, confirms that a fax modem in an available state is connected, and transmits a wireless link establishment request to the master based on the confirmation to establish a wireless link with the master. A data communication system comprising means for establishing and shifting to facsimile communication processing.