JPH0964878A - Communication equipment - Google Patents

Abstract

PROBLEM TO BE SOLVED: To monitor a communication state and an operating state of a terminal equipment in the case of radio communication between radio communication terminal equipments synchronously with each other. SOLUTION: The system for the communication equipment is made up of a master equipment and a single or plural terminal equipments 2, and the master equipment 1 is made up of a synchronization matching control section 12 sending a synchronizing signal periodically to the terminal equipment 2 via a transmission reception section 11 making communication, a reply control section 13 receiving a reply signal from the terminal equipment 2 with respect to the synchronizing signal, a terminal equipment identification section 14 identifying the terminal equipment from the received reply signal and a terminal equipment state storage section 15 storing a state of the reply signal corresponding to the identified terminal equipment 2. Thus, the operating state of the terminal equipment is monitored depending on the state of the reply signal with respect to the synchronizing signal and it is stored.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a communication device such as a home automation system and a home information system, which comprises a main device and a single or plural terminal devices.
It is the most suitable for confirming communication between the terminal device and the main device.

[0002]

2. Description of the Related Art Conventionally, a communication device of this type is disclosed in, for example, Japanese Patent Laid-Open No. 62-1345 in a home automation device.
As described in Japanese Patent Publication, the control device corresponding to the main device and the terminal device communicate with each other, and the function of determining the communication state (disconnection of the line, etc.) between the terminal device and the terminal device is determined by the content and presence of the response. It was A wireless home automation device also incorporates a similar confirmation method, for example, Japanese Patent Application Laid-Open No. Hei 3
As shown in Japanese Patent Laid-Open No. 165644, polling communication is performed between a master station and a slave station, and the communication state has been confirmed by response signals that are sequentially responded.

[0003]

By the way, in these communication devices, the power supply to the wireless device is always performed, each device is always in the receiving state, and waits for the signal from the main station. However, with the widespread use of home automation, it was necessary to drive it with a battery because it was impossible to carry out power supply work and it was necessary to control relocated equipment. Therefore, there is a need for a communication device that can prevent battery consumption as much as possible and that can detect battery consumption and wireless communication line anomalies at an early stage.

In the present invention, attention is paid to power saving, which is a problem peculiar to batteries, and an attempt is made to solve these problems by providing a method of diagnosing the communication status of a connected terminal device while performing a synchronous communication system. To do.

[0005]

In order to solve these problems, the communication device of the present invention comprises a main device and one or a plurality of terminal devices. Further, the main device includes a transmission / reception unit for performing communication, a synchronization control unit that periodically transmits a synchronization signal to the terminal device via the transmission / reception unit at a predetermined timing, and the transmission / reception unit. A response control unit that receives a response signal from the terminal device via the synchronization signal, a terminal identification unit that identifies the terminal device from the received response signal, and a response signal corresponding to the identified terminal device. A terminal state storage unit that stores a state, wherein the terminal device receives and transmits a transmission / reception unit through the communication unit, and a communication timing in the transmission / reception unit that receives a synchronization signal from the main device. And a synchronization response control unit for transmitting a response signal in response to the synchronization signal received via the receiving unit.

Further, the terminal device further includes a priority storage unit for storing the priority of the terminal device and a synchronization received via the reception unit when the priority storage unit stores the priority. And a synchronous response control unit that transmits a response signal to the signal.

Further, the main device further has a group designating unit for adding information for designating a group to the synchronization signal, and the terminal device further comprises a group storage unit for storing a group to which the terminal device belongs. And a synchronization response control unit that transmits a response signal via the reception unit when the received synchronization signal specifies a group stored in the group storage unit.

Further, the main device further includes a group designation changing section for periodically changing the group designation contents.

Further, the main device further comprises a retransmission control unit for confirming the received response signal and retransmitting the synchronization signal when a signal indicating reception failure is included.

[0010]

According to the present invention, according to the above-mentioned configuration, the main unit and each terminal device are periodically connected to the terminal device via the transmission / reception unit at a predetermined timing by the synchronization control unit via the transmission / reception unit. The terminal device controls the communication timing in the transmitter / receiver unit according to the synchronization signal received via the transmitter / receiver unit, and also transmits the response signal, and the response control unit of the main unit transmits / receives the signal. When this response signal is received via the section, the terminal identification section identifies the terminal device, the terminal state storage section stores the state of the response signal corresponding to the identified terminal apparatus, and the communication state with each terminal apparatus. Can be confirmed.

Further, the response control unit of the terminal device is a priority storage unit that stores the priority of the terminal device for the received synchronization signal. Acting to send a response signal to the received synchronization signal, the terminal state storage unit of the main device stores the state of the response signal corresponding to the terminal device having a high priority setting for returning the response signal, and stores these states. The communication state with the terminal device can be confirmed.

Further, the group designation unit of the main device adds information for designating a group to the synchronization signal, and the response control unit of the terminal device stores the group to which the terminal device belongs in the group storage unit and receives the received information. When the synchronization signal designates a group stored in the group storage unit, it operates to transmit a response signal to this synchronization signal, and the terminal state storage unit of the main device responds to the transmission of the synchronization signal by It is possible to store the state of the response signal of the returned terminal device designated by the group and confirm the communication state with each terminal device.

Further, the group designation changing unit of the main unit periodically changes the group designation contents, and the group designation unit adds the information for designating the periodically changed group, and the response control unit of the terminal unit The group storage unit stores the group to which the terminal device belongs, and when the received synchronization signal specifies the group stored in the group storage unit, transmits a response signal to the synchronization signal. In response to the transmission of the synchronization signal, the terminal state storage unit of the main device stores the state of the response signal of the returned terminal device of the designated group, and can confirm the communication state with each terminal device.

The retransmission control unit of the main device confirms the received response signal and retransmits the synchronization signal when a signal indicating reception failure is included, and the group designation unit retransmits the synchronization signal. At the time of, it acts so as not to specify the group, and in this case, the terminal device does not return the response signal because the group is not specified.

Further, the retransmission control unit of the main device confirms the received response signal, and retransmits the synchronization signal when a signal indicating no response or poor reception is included, and the group designation unit , If the synchronization signal is retransmitted due to the reception of a signal indicating poor reception, the group designation is not performed, and if the synchronization signal is retransmitted because there is no response from the terminal device of the designated group, the same as the previous time It acts to specify the group, and in this case the terminal device does not send back a response signal in the case of poor reception because no group is specified.

[0016]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A first embodiment of the present invention will be described below with reference to FIG. FIG. 1 is a block diagram showing a system configuration when the communication device of the present invention is applied to an information board of home automation. 1 is a main device (information board), 2 is a terminal device,
3 is a terminal device. FIG. 2 is a block diagram showing the configurations of the main device 1 and the terminal device 2, 11 is a transmission / reception unit, 12 is a synchronization control unit, 13 is a response control unit, 14 is a terminal identification unit, 15 is a terminal state storage unit, Reference numeral 16 is an information display unit, 17 is an abnormality display unit, 21 is a transmission / reception unit, 22 is a synchronization control unit, and 23.
Is a synchronous response control unit, and 24 is a data detection unit.

The main unit 1 and the terminal unit 2 wirelessly communicate with each other via the respective transmitting / receiving units 11 or 21. The terminal device 2 detects a change in the operating state of the terminal device 3 with the data detection unit 24, and when the change is detected, transmits data to the main device 1 via the transmission / reception unit 21. The main device 1 is a transmission / reception unit 1
When this signal is received via 1, the terminal identification unit 14 identifies the terminal device and displays the operating state on the information display unit 16. Here, the wireless communication intermittently performs synchronous communication for power saving and collision prevention, and the main device 1 causes the synchronization control unit 12 to generate synchronous communication timing and to transmit via the transmission / reception unit 11 at every cycle T. And transmits a synchronization signal to the terminal device 2. On the other hand, the terminal device 2 generates the synchronous communication timing by the synchronization control unit 22, waits for a signal from the main device 1 and transmits the detected data, and corrects the deviation of the timer and changes the timing. When the synchronization signal is received from the main device 1, the synchronization communication timing is reset with the content of the received synchronization signal, and the synchronization response control unit 23 then sends a response signal to the main device 1 via the transmission / reception unit 21. (ACK) is returned.

In the main unit 1, this response signal is sent to the response control unit 1
3 is received via the transmission / reception unit 11, and the terminal identification unit 14
Identifies the terminal device and informs the terminal state storage unit 15. The terminal state storage unit 15 stores the normal reception of the response signal at this timing in the terminal device 2. by the way,
If the wireless line between the main device 1 and the terminal device 2 cannot be communicated at a certain timing due to noise or the like, the response signal from the terminal device 2 is not returned to the synchronization signal from the main device 1 at that timing. Therefore, the terminal state storage unit 15 stores the inability to receive the response signal from the terminal device 2 at this timing. The anomaly notification unit 17 displays the current communication status from the latest stored content, the incommunicable period from the earliest response signal unreceivable timing, and anomaly the communication line. As a result, the user can check the detection data performed during the abnormal communication period in the operating state of the terminal device 3 or know the operating state of the terminal device 2.

A second embodiment of the present invention will be described with reference to FIGS. 1 and 3. FIG. 3 is a block diagram showing the configurations of the main unit 1 and the terminal unit 2. Items common to the first embodiment are as follows. Common numbers are attached. Reference numeral 25 is a priority storage unit.

The detection of the operating state of the terminal device 3 and the synchronization with the transmission to the main unit and the radio transmission / reception are the same as in the first embodiment. Of the terminal devices 2a, 2b and 2c, 2a and 2 to which a device for detecting an emergency is connected as the terminal device 3
If c is prioritized by the priority storage unit 25, when the main device 1 transmits a synchronization signal, the terminal device 2
The a, 2b, and 2c receive this, and the respective synchronization control units 22 reset the synchronization timing. Here, the synchronization response control unit 23 of the terminal device 2b does not return the response signal because the priority storage unit 25 has set it as not prioritized. On the other hand, the synchronization response control unit 23 of the terminal devices 2a and 2c transmits the response signal via the transmission / reception unit 21 because the priority storage unit 25 sets the priority. The main device 1 receives the response signal from the terminal devices 2a, 2c, and the terminal state storage unit 15 normally receives the response signal at this timing corresponding to the terminal devices 2a, 2c as in the first embodiment. Memorize If the terminal device 2c is broken here, the response signal from the terminal device 2c is not returned to the synchronization signal from the main device 1 thereafter. Therefore, the terminal state storage unit 15 stores the inability to receive the response signal from the terminal device 2c at this timing. The abnormality notification unit 17 displays the current communication status from the latest stored content, the communication disabled period from the oldest response signal unreceivable timing, and displays the communication line abnormality. In this way, only the terminal device that has been set with priority returns the response, and by storing the communication status of these, it is possible to monitor only the communication status of the particularly necessary device and to send and receive only the necessary response signal. The processing is easy because the line is not congested and the processing time is not extended.

A third embodiment of the present invention will be described with reference to FIGS. 1 and 4. FIG. 4 is a block diagram showing the configurations of the main device 1 and the terminal device 2. Items common to the first embodiment are as follows. Common numbers are attached. Reference numeral 18 is a group designation unit, and 26 is a group storage unit.

The detection of the operating state of the terminal device 3 and the synchronization of the transmission to the main unit and the radio transmission / reception are the same as in the first embodiment. Now, the group designation unit 18 of the main device 1 designates the group A, and among the terminal devices 2a, 2b, 2c, the devices 2a and 2 to which the device for detecting an emergency is connected as the terminal device 3 are connected.
If c is stored as group A and terminal device 2b is stored as group B in the respective group storage units 26, when the main device 1 adds the designation of group A and transmits the synchronization signal, the terminal devices 2a, 2b. , 2c receive this, and each synchronization control unit 22 resets the synchronization timing. Here, the synchronization response control unit 23 of the terminal device 2b detects that the designated group added to the synchronization signal is the group A, and compares it with the content stored in the group storage unit 26. Since the terminal device 2b is in the group B, they do not match each other and do not return the response signal. On the other hand, since the terminal devices 2a and 2c are in the group A, they coincide with each other and transmit a response signal via the transmission / reception unit 21. Similarly, the main device 1 receives the response signal from the terminal devices 2a and 2c, and the terminal state storage unit 15 responds to the terminal devices 2a and 2c in the same manner as in the first embodiment. Memorize normal reception of.

As described above, the types of the connected terminal devices are divided into groups, the group is designated from the main unit, and the operation is confirmed by the response signal.
Since setting and specification can be done easily and no response signal is received when no response signal is not needed,
It is possible to monitor only the communication status of necessary equipment,
Since only the necessary response signals are sent and received, the congestion of the line and the extension of the processing time are eliminated, and the processing can be simplified.

A fourth embodiment of the present invention will be described with reference to FIGS. 1 and 5. FIG. 5 is a block diagram showing the configurations of the main device 1 and the terminal device 2. Items common to the fourth embodiment are as follows. Common numbers are attached. Reference numeral 19 is a group designation change unit.

The detection of the operating state of the terminal device 3, transmission to the main unit, transmission / reception of synchronization, and storage of the operating state are the third.
This is the same as the embodiment. Now, the group designation changing unit 19 of the main device 1 alternately changes the group designation to A, B, A, B, .... Therefore, the communication status with the terminal devices 2a and 2c in the group A is confirmed at a certain timing, and the communication status with the terminal device 2b in the group B is confirmed at another timing.

The terminal devices connected in this way are divided into groups, and the operation is confirmed by the response signal while the group designation from the main unit is changed at any time. Since it can be divided into times and can be performed without increasing the confirmation work once, the processing can be simplified without line congestion and processing time extension. Further, when the signal is unnecessary, the communication can be confirmed as often as necessary by not specifying it.

A fifth embodiment of the present invention will be described with reference to FIGS. 1 and 6. FIG. 6 is a block diagram showing the configurations of the main unit 1 and the terminal unit 2. Items common to the fourth embodiment are as follows. Common numbers are attached. 110 is a retransmission control unit.

The detection of the operating state of the terminal equipment 3, transmission to the main unit, transmission / reception of synchronization, and storage of the operating state are the third.
This is the same as the embodiment. Now, in response to the synchronization signal transmitted by the main device 1 by designating the group A, the terminal device 2a in the group A normally receives and returns an ACK response signal, and the terminal device 2c is added with the synchronization signal. Although the group designation information is received, a part of the data is erroneous and the NAK response signal is returned. As a result, the main device 1 is provided with the terminal device 2
Since the response signals are sent back to both a and 2c, the fact that they are operating normally is stored in the terminal state storage unit 15. On the other hand, the retransmission control unit 110 requests the synchronization control unit 12 for retransmission because the response signal from the terminal device 2c is a NAK response signal. Since the group designation unit 18 does not designate the group at this time, there is no response from the terminal device 2 to this retransmission signal. Therefore, at the time of retransmission, the response signal allows the response from the terminal device whose operating state has been confirmed to be omitted, smooth synchronization can be performed, and line congestion and current consumption increase due to the transmission and reception of unnecessary response signals. And so on.

A sixth embodiment of the present invention will be described with reference to FIGS. 1 and 6. The detection of the operation state of the terminal device 3, transmission / reception of synchronization with the main device, storage of the operation state, and operation upon reception of the NAK response are the same as in the sixth embodiment. Now, with respect to the synchronization signal transmitted by the main device 1 specifying the group A, the terminal devices 2a and 2c in the group A normally receive and send back the ACK response signal. It is assumed that the main device 1 cannot receive the response signal from the terminal device 2c among the response signals. The retransmission control unit 110 of the main device 1 uses the terminal devices 2a and 2c belonging to the group A.
However, since the response signal from the terminal device 2c is not returned, the synchronization control unit 12
Request to resend. At this time, the group designating unit 18 designates the group A again and normally receives the response signal from the terminal devices 2a and 2b.

As described above, when there is no response signal, the same group is designated again and the data is retransmitted. Therefore, even if the response signal cannot be received, the operation state can be correctly confirmed by the response signal to the retransmitted synchronization signal. You can

[0031]

As is apparent from the above description, the communication device of the present invention has the following effects.

The response control section of the main unit receives the response signal to the synchronization signal transmitted from the main unit to each terminal unit via the transmission / reception unit, and the terminal identification unit identifies the terminal unit from this response signal. Since the terminal state storage unit stores the state of the response signal corresponding to the identified terminal device, it is possible to periodically check the communication state with each terminal device, and use the synchronization signal to perform special communication. Since this is not performed, there is an effect that communication can be confirmed without causing an increase in current.

In the second configuration, the response control unit of the terminal device stores the priority of the received synchronization signal in the priority storage unit that stores the priority of the terminal device. To send a response signal to the synchronization signal received via the receiving unit, and the terminal state storage unit of the main unit returns the response signal to the state of the response signal corresponding to the terminal device with a high priority setting. Since the communication status is stored, it is possible to check the communication status with respect to a terminal device with a high degree of necessity and a high priority, and no extra processing or work is required.
Since unnecessary response signals are not transmitted and received, there is a further power saving effect.

In the third configuration, the group designating unit of the main device adds information for designating a group to the synchronization signal, and the response control unit of the terminal device has the group storage unit in which the group to which the terminal device belongs. When the received synchronization signal designates a group stored in the group storage unit, it operates to send a response signal in response to this synchronization signal, and the terminal state storage unit of the main device synchronizes Since the status of the response signal of the terminal device specified by the group that is returned for the signal transmission is stored, it is possible to check the communication status for the group of terminal devices that have a high necessity and have a high priority. Therefore, extra processing and work become unnecessary, and unnecessary response signals are not transmitted or received, so that there is a further power saving effect. Also, since the group is set in advance, to change the group to check communication,
Since it is only necessary to change the setting content of the group designation unit of the main device, and it is not necessary to change the setting of the terminal device, there is an effect that the work is simplified.

Further, in the fourth configuration, the group designation changing unit of the main device periodically changes the group designation contents, adds the group designation unit information for designating the periodically changed groups, and The response control unit of the device responds to the synchronization signal when the group storage unit stores the group to which the terminal device belongs and the received synchronization signal specifies the group stored in the group storage unit. Sends a response signal, and the terminal status storage unit of the main device stores the status of the response signal of the terminal device designated by the group that is returned in response to the transmission of the synchronization signal. Since the synchronization signal is used and no special communication is performed, the communication can be confirmed without an increase in current. In addition, since communication confirmation of a large number of terminal devices is performed for each group, there is an effect that one process can be easily performed.

In the fifth configuration, the retransmission control unit of the main device confirms the received response signal, retransmits the synchronization signal when the signal indicating the reception failure is included, and specifies the group. Since the unit does not specify the group at the time of this retransmission, it does not return a response signal to the retransmitted synchronization signal, and there is a further power saving effect.

In the sixth configuration, the retransmission control unit of the main device confirms the received response signal and retransmits the synchronization signal when a signal indicating no response or poor reception is included, The group designating unit does not perform group designation when performing synchronization signal retransmission because a signal indicating poor reception is received, and when performing synchronization signal retransmission because there is no response from the terminal device of the designated group. Specifies the same group as the previous time, and if there is no response signal, communication confirmation by the response signal to the resend signal can be performed, and if there is a response signal, the response signal can be eliminated and the reliability of communication confirmation can be improved. There is an effect of improvement and power saving.

[Brief description of drawings]

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

FIG. 2 is a block diagram showing a communication device according to the first embodiment of the present invention.

FIG. 3 is a block diagram showing a communication device according to a second embodiment of the present invention.

FIG. 4 is a block diagram showing a communication device according to a third embodiment of the present invention.

FIG. 5 is a block diagram showing a communication device according to a fourth embodiment of the present invention.

FIG. 6 is a block diagram showing a communication device according to fifth and sixth embodiments of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Main device (information board) 2 Terminal device 3 Terminal device 3a Fire alarm 3b Electric lock 3c Gas leak detector 11 Transmitter / receiver unit 12 Synchronization control unit 13 Response control unit 14 Terminal identification unit 15 Terminal state storage unit 16 Information display unit 17 Abnormality Display Section 18 Group Designation Section 19 Group Designation Modification Section 110 Retransmission Control Section 21 Transmission / Reception Section 22 Synchronization Control Section 23 Synchronization Response Control Section 24 Data Detection Section 25 Priority Storage Section 26 Group Storage Section

 ─────────────────────────────────────────────────── ─── Continuation of front page (72) Inventor Yoshio Horiike 1006 Kadoma, Kadoma City, Osaka Prefecture Matsushita Electric Industrial Co., Ltd. (72) Takayuki Suematsu 1006 Kadoma, Kadoma City, Osaka Matsushita Electric Industrial Co., Ltd.

Claims (6)

[Claims] 1. A main device and a single or a plurality of terminal devices, wherein the main device includes a transmitting / receiving unit for performing communication.
A synchronization control unit that periodically sends a synchronization signal to the terminal device via the transmission / reception unit at a predetermined timing, and a response signal from the terminal device to the synchronization signal via the transmission / reception unit. A response control unit, a terminal identification unit that identifies a terminal device from the received response signal, and a terminal state storage unit that stores the state of the response signal corresponding to the identified terminal device, The terminal device includes a transmission / reception unit for performing communication, a synchronization control unit that receives a synchronization signal from the main device received via the communication unit and controls communication timing in the transmission / reception unit, and the reception unit. And a synchronization response control unit that transmits a response signal to the received synchronization signal. 2. A main device and a single or a plurality of terminal devices, said main device comprising a transmitter / receiver for communication.
A synchronization control unit that periodically sends a synchronization signal to the terminal device via the transmission / reception unit at a predetermined timing, and a response signal from the terminal device to the synchronization signal via the transmission / reception unit. A response control unit, a terminal identification unit that identifies a terminal device from the received response signal, and a terminal state storage unit that stores the state of the response signal corresponding to the identified terminal device, The terminal device has a transmission / reception unit, a synchronization control unit that receives a synchronization signal from the main device received via the communication unit and controls communication timing in the transmission / reception unit, and a priority of the terminal device. And a synchronization response control unit that transmits a response signal to the synchronization signal received through the reception unit when the priority storage unit stores the priority. That communication device. 3. A main device and a single or a plurality of terminal devices, said main device comprising a transmitter / receiver for communication.
A synchronization control unit that periodically transmits a synchronization signal toward the terminal device via the transmission / reception unit at a predetermined timing, and a group designation unit that adds information for designating a group to the synchronization signal, A response control unit that receives a response signal from the terminal device to the synchronization signal via the transmission / reception unit, a terminal identification unit that identifies the terminal device from the received response signal, and a terminal identification unit that corresponds to the identified terminal device. A terminal state storage unit that stores the state of the response signal, and the terminal device receives and transmits the transmission / reception unit for performing communication and the synchronization signal from the main device received via the communication unit. A synchronization control unit that controls communication timing in the unit, a group storage unit that stores a group to which the terminal device belongs, and a received synchronization signal are stored in the group storage unit. Communication device and a synchronization response control unit which transmits a response signal through the receiver if you specify the group. 4. A main device and a single or a plurality of terminal devices, said main device comprising a transmitter / receiver unit for communication.
A synchronization control unit that periodically transmits a synchronization signal toward the terminal device via the transmission / reception unit at a predetermined timing, and a group designation unit that adds information for designating a group to the synchronization signal, A group designation changing unit that periodically changes the group designation content, a response control unit that receives a response signal from the terminal device to the synchronization signal via the transmission / reception unit, and a terminal device from the received response signal. It has a terminal identification unit for identifying, and a terminal state storage unit for storing the state of the response signal corresponding to the identified terminal device, and the terminal device includes a transmission / reception unit for performing communication, and the communication unit. And a group for storing a group to which the terminal device belongs, which receives a synchronization signal from the main device via the synchronization control unit and controls the communication timing in the transmission / reception unit. Communication apparatus having a 憶部, a synchronization response control unit the synchronization signal received transmits a response signal through the receiver if you specify a group stored in the group storage unit. 5. A main device and a single or a plurality of terminal devices, said main device comprising a transmitting / receiving section for performing communication.
A synchronization control unit that periodically transmits a synchronization signal toward the terminal device via the transmission / reception unit at a predetermined timing, and a group designation unit that adds information for designating a group to the synchronization signal, A response control unit that receives a response signal from the terminal device to the synchronization signal via the transmission / reception unit, a terminal identification unit that identifies the terminal device from the received response signal, and a terminal identification unit that corresponds to the identified terminal device. And a terminal state storage unit that stores the state of the response signal, and a retransmission control that confirms the received response signal and retransmits the synchronization signal when a signal indicating reception failure is included. The device includes a transmitting / receiving unit for performing communication, a synchronization control unit that receives a synchronization signal from the main device received via the communication unit and controls communication timing in the transmitting / receiving unit, and the terminal. A group storage unit that stores a group to which the device belongs, and a synchronization response control unit that transmits a response signal via the reception unit when the received synchronization signal specifies a group stored in the group storage unit. And a group designation unit of the main device does not designate a group when the retransmission control unit retransmits a synchronization signal. 6. A main device and a single or a plurality of terminal devices, the main device including a transmitter / receiver for communication.
A synchronization control unit that periodically transmits a synchronization signal toward the terminal device via the transmission / reception unit at a predetermined timing, and a group designation unit that adds information for designating a group to the synchronization signal, A response control unit that receives a response signal from the terminal device to the synchronization signal via the transmission / reception unit, a terminal identification unit that identifies the terminal device from the received response signal, and a terminal identification unit that corresponds to the identified terminal device. A terminal state storage unit that stores the state of the response signal and a retransmission control unit that confirms the received response signal and retransmits the synchronization signal when a signal indicating no response or poor reception is included. However, the terminal device has a transmitting / receiving unit for performing communication, and a synchronization for receiving a synchronization signal from the main device received via the communication unit and controlling communication timing in the transmitting / receiving unit. Control unit, a group storage unit that stores a group to which the terminal device belongs, and a response signal is transmitted via the reception unit when the received synchronization signal specifies a group stored in the group storage unit And a synchronization response control unit, wherein the group designation unit of the main device does not perform group designation when performing synchronization signal retransmission because a signal indicating reception failure is received by the retransmission control unit,
A communication device, wherein when the synchronization signal is retransmitted because there is no response from the terminal device of the specified group, the same group as the previous time is specified.