JP6281584B2 - Communications system - Google Patents

Description

  The present invention relates to a communication system, and more particularly, to a communication system that can be suitably used when performing, for example, specific low power wireless communication.

  Patent Document 1 discloses an example of a control system in which a physical state is transmitted from a slave unit including sensors such as temperature and illuminance.

Specifically, in this control system, a sensor group arranged in an artificial environment such as a house or a natural environment converts one or a plurality of types of physical quantities (such as temperature and illuminance) into an electrical signal, and a sensor ID, Sensor information to which additional information such as a synchronization signal for establishing synchronization and transmitter ID is added is transmitted to the portable terminal using an internal transmitter.
Paragraph (0022) of Japanese Patent Laid-Open No. 2004-356785

  However, in the invention disclosed in Patent Document 1, when transmitting information such as temperature from a group of sensors serving as slave units to a portable terminal serving as a master unit using an internal transmitter, Additional information such as machine ID is used. In order to use these additional information, it is necessary to store the information in a nonvolatile memory or the like provided in the sensor group. Further, in order to operate the sensor group alone, the sensor group needs to incorporate a power source such as a battery.

  Then, when the sensor group is activated, such as when the communication module is woken up to transmit information such as temperature, or the nonvolatile memory is accessed, the current consumption of the sensor group increases. A drop occurs in the output voltage. Generally, a battery has a power supply capability that decreases under a low temperature environment, and a voltage drop associated with an output current increases as the temperature decreases.

  In particular, when trying to reduce the size of a sensor group, a button type battery is typically considered as a battery to be adopted. However, a button type battery has a voltage drop in a low temperature environment as compared with other batteries. It is remarkable. For this reason, even if the apparent battery voltage appears to be sufficient, due to this voltage drop, information such as temperature cannot be normally communicated, or load information can be written to or read from the nonvolatile memory. In some cases, the communication with the mobile terminal may be hindered due to failure.

  Therefore, an object of the present invention is to provide a communication system that does not hinder communication even in a low temperature environment.

In order to solve the above problems, the present invention provides:
A communication system for transmitting a sensing result by a temperature sensor provided in a slave unit to the master unit by radio waves and transmitting a command including the transmission condition from the master unit to the slave unit,
The slave unit includes a battery that supplies power to the means for transmitting the sensing result, and a non-volatile memory that stores conditions included in the command,
The master unit includes control means for controlling not to transmit the command when the ambient temperature indicated by the sensing result is equal to or lower than a predetermined temperature.
It is a communication system.

The command is
A command for deleting information necessary for pairing, which is executed when the pairing between the parent device and the child device is canceled;
A command for instructing the frequency of the radio wave for transmitting the sensing result;
A command for instructing an interval for transmitting the sensing result;
At least one of the following. This is because all of these commands are necessary for realizing appropriate communication.

  Further, the predetermined temperature can be set to 10 ° C. or less, for example. Although the battery differs depending on the type, it is generally considered that the battery has good performance when it is 10 ° C to 25 ° C. Therefore, here, the command is not transmitted when the temperature is 10 ° C. or lower. However, the command may not be transmitted when the temperature is 5 ° C. or lower or 0 ° C. or lower.

  The control means may further perform control so that the command is not transmitted when the voltage of the battery is equal to or lower than a predetermined threshold. Even in such a case, the sensing result is not erroneously transmitted to the base unit.

  The battery may be a button type battery. This contributes to miniaturization of the slave unit.

The master unit is connected to a plurality of slave units, and has means for transmitting an instruction to switch the predetermined frequency to the slave units by the radio wave,
As a result of transmitting the instruction, when a response signal from any one of the slave units cannot be received within a predetermined time, switching between the slave units other than the slave unit that cannot receive the response signal is instructed. Communication can also be performed using radio waves of a frequency. If it carries out like this, it will become possible to change a communication channel, when the deterioration of a communication state is detected.

BEST MODE FOR CARRYING OUT THE INVENTION

Hereinafter, each embodiment of the present invention will be described with reference to the drawings.
(Overview)
In the communication system of each embodiment, an access point that is a parent device and an endpoint that is a plurality of child devices are wirelessly connected. Various sensors such as a temperature sensor can be connected to the end point.

In each embodiment, when, for example, a temperature sensor is connected to an end point, the ambient temperature is measured at regular intervals by the temperature sensor, and the temperature data is transmitted from the end point to the access point. . By installing endpoints, for example, in each room of a house or outdoors,
A monitoring system that can grasp the temperature of each installation location can be constructed.

  Further, the access point and the end point are not limited to this, but communication is performed using a specific low-power radio frequency for power saving. Normally, when this type of communication is performed, a plurality of channels having frequencies different from each other by about several MHz may be prepared so that desired communication can be realized even when a situation such as deterioration of the communication state occurs. Many. When the communication state deteriorates, the frequency can be changed actively.

  In each embodiment, all the endpoints and all the temperature sensors are set to a sleep state at normal times for power saving. Then, the active state is established by waking up at a predetermined interval, and at that time, temperature data is transmitted from the end point to the access point.

  When the access point receives temperature data from one of the endpoints, it returns an ACK to the endpoint. At that time, the access point returns an ACK with a frequency change request and information indicating the changed frequency added. Like to do. Thereby, the change of the frequency set in the end point is realized. Further, the access point makes a change process for the frequency set in the own device after making a frequency change request to all the end points.

  According to this method, when all the endpoints are operating normally, first, the frequencies set for all the endpoints are changed. After that, since the frequency set in the access point is changed, it is possible to avoid a situation in which an end point whose frequency is not changed occurs.

  By the way, according to the above method, if any failure occurs in the wireless line connecting any endpoint and the access point, or if any battery runs out or a device failure occurs in any endpoint, the endpoint Alternatively, it is impossible to transmit a request for changing the frequency set for the endpoint until the wireless line is restored. As a result, since the frequency set in the access point is not changed after all, in the worst case, desired communication cannot be performed between the access point and the end point.

  The communication system of each embodiment takes measures against this point. Hereinafter, the configuration and operation of the communication system of each embodiment will be described.

<Embodiment 1>
In the present embodiment, a method for avoiding a situation in which an endpoint whose frequency is not changed occurs when a failure occurs in a wireless line connecting any endpoint to an access point will be described.

(Configuration explanation)
FIG. 1 is a block diagram showing a schematic configuration of a communication system according to the first embodiment of the present invention. FIG. 1 shows a host device 100, an access point 200, end points 300A to 300D, and wireless lines 400A to 400D, which will be described below.

  The host device 100 is connected to the access point 200 by wire or wireless. The operation of the host device 100 may be realized by hardware or may be realized by software. Here, the host device 100 employs hardware such as a personal computer, for example. In this case, radio wave intensity acquisition means 110 and comparison means 120, which will be described later, can be realized by cooperation between a CPU built in the personal computer and an application program stored in the memory.

  The host device 100 normally determines the transmission timing of temperature data from the end points 300A and 300B and the frequency (channel) of radio waves for communication between the access point 200 and the end points 300A and 300B. A pairing execution request command for executing pairing with the endpoints 300A to 300D is generated, the pairing execution request command is output to the access point 200, or the endpoint 300A output from the access point 200 The temperature data transmitted from ~ 300D is input.

  The host device 100 generates a frequency change request command for changing the frequency of radio waves for communication between the access point 200 and the end points 300A to 300D when the radio wave condition is poor, or the frequency change request command. Is output to the access point 200, or a stop request command for interrupting the frequency change process is output to the access point 200 when a frequency change completion notification is not input from the access point 200 within a predetermined period.

  For this reason, the host device 100 includes a radio wave intensity acquisition unit 110 that acquires the radio wave intensity of communication between the access point 200 and the end points 300A to 300D from the access point 200, and a radio wave intensity acquired by the radio wave intensity acquisition unit 110. Comparing means 120 for comparing whether or not is equal to or less than a predetermined threshold value. In addition, in the description related to the radio wave intensity in the following description, the received radio wave intensity at the frequency used for communication is relatively relative due to the influence of external noise in a frequency band very close to the frequency (channel) used for communication at a certain point in time. In the case of a decrease, the “reduction in radio field strength” is also included.

  The access point 200 is connected to the host device 100 by a wired connection or the like, and is selectively connected to a plurality of end points 300A to 300D through wireless lines 400A to 400D, respectively. It is.

  The access point 200 normally receives temperature data transmitted from the endpoints 300A to 300D and outputs the temperature data to the host device 100 or requests corresponding to various commands output from the host device 100 to the endpoints 300A to 300D. Or send to.

  When the radio wave condition is poor, the access point 200 inputs a frequency change request command or an interrupt request command output from the host device 100, and sends a frequency change request corresponding to these commands to the end points 300A to 300D. This is what we do.

  The access point 200 includes a microcontroller 210 that performs various controls, an RF module 220 that communicates with the end points 300A to 300D, and a pair between the end points 300A to 300D even when the power of the own device is off. And a non-volatile memory 230 such as a flash memory for holding ring information.

  Note that the RF module 220 may have the same configuration as RF modules 320A to 320D described later, or may have a different configuration. The RF module 220 or the like includes an antenna, a matching circuit, a low-pass filter, a surface acoustic wave filter, a balanced / unbalanced conversion circuit, and the like as is well known. The RF module 220 includes an integrated circuit for confirming whether or not a communication error has occurred every time communication of various commands, which will be described later, or communication for data transmission is performed. If the communication cannot be normally terminated due to the influence of extraneous noise or the like, it can be determined that a communication error has occurred and can be notified to the host device 100.

  Moreover, the non-volatile memory 230 may have a configuration similar to that of the non-volatile memories 330A to 330D described later, or may have a different configuration. The pairing information stored in the non-volatile memory 230 or the like is information including the transmission timing and frequency (channel) determined by the higher-level device 100.

  The end points 300A to 300D are slave units that are wirelessly connected to the access point 200 through the radio lines 400A to 400D, respectively. FIG. 1 shows four endpoints 300A to 300D, but these numbers are merely examples, and for example, in the present embodiment, a maximum of 32 endpoints can be connected. ing.

  The end points 300 </ b> A to 300 </ b> D are temperature sensors 310 </ b> A to 310 </ b> D that measure the ambient temperature with a battery such as a button-type battery as a power source, and the temperature data measured by the temperature sensors 310 </ b> A to 310 </ b> D RF modules 320A to 320D and non-volatile memories 330A to 330D such as a flash memory that holds pairing information with the access point 200 even when the power of the own device is off.

  The temperature sensors 310A to 310D are not necessarily built in the end points 300A to 300D, and may be externally connected to the end points 300A to 300D. The temperature sensors 310A to 310D are merely examples of sensors that can be mounted on the endpoints 300A to 300D. Therefore, instead of or in combination with this, various sensors such as an illuminance sensor, a humidity sensor, a magnetic field sensor, a noise sensor, and a rotation sensor can be used.

  For example, the radio lines 400A to 400D have a frequency near 920 MHz in order to perform specific low-power radio. In the present embodiment, for example, a total of 14 channels of ch0 to ch13 are prepared as the above-described frequencies, and the center frequencies are set from 922.5 MHz to 927.7 MHz at intervals of 0.4 MHz.

  However, it is not essential that the frequency employed in the radio lines 400A to 400D be in the vicinity of 920 MHz, and a radio line other than the specific low-power radio can be used. Further, when the frequency employed in the wireless lines 400A to 400D is around 920 MHz, the above-described center frequency itself and the interval between them are also examples, and the present invention is not limited thereto.

  Since the communication method of the wireless lines 400A to 400D is a specific low power wireless, a simplex method and a broadcast communication method are adopted. In this case, the antenna power is 0.01 W or less, and the allowable value of the occupied frequency bandwidth is 200 kHz or less. However, it should be noted that the present invention can be applied even when these systems are changed due to a future change in the standard of specific low-power radio.

(Description of operation)
2 to 4 are a series of sequence diagrams showing the operation of the communication system shown in FIG. For ease of understanding, FIG. 2 shows a sequence in the case where the target of pairing with the access point 200 is the end points 300A and 300B.

  First, the higher-level device 100 determines pairing information such as the transmission timing and frequency (channel) described above. At the same time, a pairing execution request command including information indicating that the endpoints 300A and 300B are pairing execution targets and pairing information is generated (step S1).

  Subsequently, the host device 100 outputs the pairing execution request command generated by the execution of step S <b> 1 to the access point 200. Here, as shown in steps S5 and S7 described later, the pairing information shows an example in which the transmission timing is “5 minutes” and the frequency (channel) is “ch0” (step S2). .

  On the other hand, when the pairing execution request command is input, the access point 200 stores the pairing information included in the pairing execution request command in the nonvolatile memory 230. At the same time, an ACK indicating that a pairing execution request command has been input is output to the host device 100 (step S3).

  On the other hand, when there is a key interrupt while the power is on, the end point 300A transmits a pairing request to the access point 200 through the RF module 320A, the radio line 400A, and the RF module 220 (step S4).

  On the other hand, the access point 200 includes the pairing information included in the pairing execution request command received by the execution of step S2 in the ACK indicating that the pairing request has been received, and transmits it to the end point 300A. (Step S5).

  In the present embodiment, the pairing information is included in the ACK transmitted from the access point 200 in step S5, but this is not essential. Therefore, the pairing information may be transmitted from the access point 200 to the end point 300A separately from the ACK.

  Similarly, processing similar to steps S4 and S5 is executed between the end point 300B and the access point 200 (steps S6 and S7).

  Note that even if a pairing request is transmitted from an endpoint other than the endpoints 300A and 300B, the access point 200 does not transmit an ACK to the endpoint because the endpoint is not a pairing target. Therefore, the pairing process between the endpoints other than the endpoints 300A and 300B is not executed.

  When Steps S4 to S7 are executed, pairing information with the access point 200 is stored in the nonvolatile memories 330A to 330D, and pairing between the access point 200 and the end points 300A and 300B is completed. The access point 200 outputs a pairing completion notification indicating this to the higher-level device 100 (step S8).

  Thereafter, as a normal operation, in this example, the temperature data is measured by the temperature sensor 310A at intervals of 5 minutes according to the transmission timing in the pairing information. Then, the measurement result is transmitted from the end point 300A to the access point 200 through the wireless line 400A at intervals of 5 minutes (step S9).

  When receiving the temperature data transmitted from the end point 300A, the access point 200 transmits an ACK indicating that to the end point 300A (step S10).

  Here, the ACK transmitted from the access point 200 shown in step S10 does not include pairing information. This is because the pairing information used when transmitting ACK (step S5) from the access point 200 to the end point 300A before that is not changed. However, pairing information may also be included in the ACK shown in step S10. This also applies to the case of ACK in steps S13, S38, and S41 described below.

  Further, when the access point 200 receives the temperature data transmitted from the end point 300A, the access point 200 outputs the temperature data to the upper level apparatus 100 together with information indicating that the transmission source is the end point 300A (step S11).

  Similarly, processing similar to steps S9 to S11 is executed among the end point 300B, the access point 200, and the higher-level device 100 (steps S12 to S14).

  On the other hand, the host device 100 is not specifically shown in FIG. 2 for the purpose of confirming the quality of the radio wave condition, but the access point 200 and the end point 300A are regularly or irregularly transmitted by the radio wave intensity acquisition unit 110. , 300B is acquired. Then, it is confirmed by the comparison means 120 whether or not the radio wave intensity has become a predetermined threshold value or less. Further, the host device 100 confirms whether or not a communication error has occurred based on the communication error occurrence notification from the RF module 220 described above.

  Then, if it is confirmed that the radio wave intensity is equal to or less than a predetermined threshold value, or the occurrence of a communication error is confirmed, for example, in the same manner as in step S1, the access point 200 and the end points 300A and 300B Decide to change the frequency of radio waves for communication between them. Then, a frequency change request command for executing this is generated.

  Note that, as described above, the frequency change request command typically causes a decrease in radio wave intensity during communication between the access point 200 and one of the end points 300A and 300B, or a communication error. However, the command is for changing the frequency of the radio wave of communication between them in order to maintain desired communication between them. However, this command can also be generated regardless of the above-mentioned decrease in radio field intensity or occurrence of a communication error.

  Subsequently, the host device 100 outputs this frequency change request command to the access point 200. Here, as shown in steps S18 and S21, an example in which the frequency (channel) to be changed is “ch5” is shown. (Step S15). Further, when the frequency change request command is input, the access point 200 outputs an ACK indicating this to the higher-level device 100 (step S16).

  After that, as in steps S9 to S14, the end points 300A and 300B, the access point 200, and the host device 100 exchange ACKs including temperature data and information on the frequency to be changed. As a result, the non-volatile memories 330 </ b> A to 330 </ b> D store the changed frequency of the radio wave for communication with the access point 200 (steps S <b> 17 to S <b> 22).

  Thereafter, the access point 200 has completed the frequency change request processing for all the paired endpoints 300A and 300B, and therefore, information indicating the frequency (channel) in the nonvolatile memory 230 is changed from “ch0” to “ch5”. The frequency change process of the own machine is performed (step S23). Then, a frequency change completion notification is output to the host device 100 (step S24).

  After that, it is assumed that the frequency needs to be changed for some reason. In such a case, the higher-level device 100 inputs / outputs a frequency change request command and an ACK to / from the access point 200 in the same manner as in steps S15 and S16 (steps S25 and S26).

  Next, in the example illustrated in FIG. 2 and the like, when the temperature data is transmitted from the end point 300A (step S27), the access point 200 indicates that the frequency to be changed is “ch8”. An ACK including information is transmitted to the endpoint 300A (step S28). And the information which shows that the transmission source of the temperature data is the end point 300A is output with respect to the high-order apparatus 100 (step S29).

  On the other hand, at this timing, for example, if any failure occurs in the wireless line 400B connecting the access point 200 and the end point 300B, the temperature data is transmitted from the end point 300B (step S30). Cannot receive. Therefore, although the end point 300B retries the temperature data transmission process several times (step S31), if the failure is not recovered at that time, the temperature data is not received by the access point 200.

  In such a case, the higher-level device 100 grasps that the temperature data from the end point 300B is not output from the access point 200 within the predetermined predetermined time, based on the relationship between the current time and “transmission timing”. it can. Therefore, at that time, an interruption request command is output in order to interrupt the frequency change process currently requested to be executed (step S32).

  When the access point 200 receives the interrupt request command output from the higher-level device 100, the access point 200 outputs an ACK indicating that to the higher-level device 100 (step S33).

  Thereafter, the access point 200, for example, the endpoint 300A, with respect to the endpoint that has already transmitted an ACK including information that the frequency to be changed is “ch8”, for example, A frequency change request is transmitted so as to change to the frequency set before transmission of the frequency change request command shown in step S25, which is the basis for transmission of ACK, that is, “ch5” (step S34).

  When receiving the frequency change request transmitted from the access point 200, the endpoint 300A transmits an ACK to that effect to the access point 200 (step S35).

  Then, the access point 200 outputs an interruption completion notification indicating that the frequency change interruption process has been completed to the higher-level device 100 (step S36).

  At this time, the frequency (channel) set in the access point 200 is maintained while being changed to “ch5” in step S23. That is, since the transmission of the temperature data from the end point 300B (step S30) is not completed, the ACK as shown in step S28 is not transmitted to the end point 300B. Therefore, the frequency (channel) set in the access point 200 is not changed even if the frequency change request command shown in step S25 is transmitted.

  Thereafter, similarly to steps S9 to S11, as normal operation, temperature data is transmitted from the endpoint 300A to the access point 200 at intervals of 5 minutes (step S37), and the access point 200 to the endpoint 300A. Then, ACK is transmitted (step S38), and the temperature data from the end point 300A is output from the access point 200 to the host device 100 (step S39).

  Subsequently, for example, when a failure that has occurred in the wireless line 400B connecting the access point 200 and the end point 300B is recovered, the end point 300B is operated at intervals of 5 minutes as normal operations as in steps S12 to S14. Temperature data is transmitted from the access point 200 to the access point 200 (step S40), ACK is transmitted from the access point 200 to the end point 300B (step S41), and the end point is transmitted from the access point 200 to the host device 100. Temperature data from the point 300B is output (step S42).

  According to the communication system of the present embodiment, since the frequency change can be interrupted by using the interruption request command, it is possible to avoid a situation in which desired communication with the access point 200 and the endpoint 300A is not performed for a while. it can. This is very effective if the communication interval between the access point 200 and the end point 300A is long, since it takes a lot of time (for example, 30 minutes) to complete the frequency change normally. It is a correspondence.

<Embodiment 2>
In the present embodiment, a communication system suitable for a case where a battery runs out or a device failure occurs at any endpoint will be described. For example, when a battery runs out or an equipment failure occurs in the end point 300B, communication with the end point 300B cannot be continued until such a situation is avoided. It is preferable to continue the communication.

  FIG. 5 is a sequence diagram relating to a case where the battery serving as the power source of the endpoint 300B according to Embodiment 2 of the present invention is exhausted or the endpoint 300B itself fails, and corresponds to FIG. In FIG. 5, the same processes as those shown in FIG. 4 are denoted by the same reference numerals, and the processes shown in FIGS. 2 to 3 are similarly performed in the second embodiment. The configuration of the communication system according to the present embodiment may be the same as that described in the first embodiment.

  Here, in FIG. 4, transmission and retry of temperature data are performed in steps S30 and S31. However, when the end point 300B runs out of battery or the end point 300B itself fails (step S30 '), the end point 300B cannot transmit temperature data to the access point 200 in the first place.

  In this case, as in the first embodiment, the host device 100 receives the temperature data to be transmitted from the end point 300B from the access point 200 within a predetermined predetermined time in relation to the current time and “transmission timing”. Since it can be grasped that it has not been output, an interruption request command is output (step S32), and the access point 200 outputs an ACK indicating the input of the interruption request command to the host device 100 (step S33).

  Thereafter, as in the first embodiment, a frequency change request is transmitted from the access point 200 to the end point 300A so as to change the frequency to “ch5” that was set before the transmission of the frequency change request command. (Step S34) An ACK indicating that the frequency change request has been received is transmitted from the end point 300A to the access point 200 (Step S35), and the frequency change interruption process is performed from the access point 200 to the higher-level device 100. An interruption completion notification indicating that has been completed is output (step S36).

  Thereafter, as in the first embodiment, as a normal operation, temperature data is transmitted from the endpoint 300A to the access point 200 at intervals of 5 minutes (step S37), and the access point 200 to the endpoint 300A. ACK is transmitted (step S38), and temperature data from the end point 300A is output from the access point 200 to the host device 100 (step S39).

  If the temperature data to be transmitted from the end point 300B is not output from the access point 200 to the host device 100 after a predetermined time has elapsed, the host device 100 stores the data in the nonvolatile memory 230 at the access point 200. You may output the pairing clear request | requirement of deleting the pairing information regarding the stored endpoint 300B.

  In this way, a desired frequency change process is executed for an endpoint that is continuing communication with the access point 200 including the endpoint 300A (here, an example in which only the endpoint 300A exists) is shown. be able to.

(Other embodiments)
1. Processing after Output of Interrupt Request Command The method described in the first embodiment is based on the endpoint 300B that has recovered from a communication failure even if the radio field strength during communication is somewhat reduced due to external noise or the like. This is a method suitable for achieving smooth temperature data acquisition. However, steps S34 to S42 surrounded by a broken line can be variously changed according to the purpose of the communication system.

  For example, there may be a case where it is desired to continue the communication with the end point 300B even if the relative radio wave intensity is lowered during the communication with the end point 300A. In such a case, for example, the communication between the access point 200 and the end point 300A uses “ch8” which is the frequency to be changed, and the communication between the access point 200 and the end point 300B is the original frequency “ ch5 "can also be used.

  In order to realize this, “ch8” is used for the end point 300A and “ch5” is used for the end point 300B in place of the processing of steps S34 and S35. What is necessary is just to perform a "frequency change process." Note that the processing after step S36 may be the same as in FIG.

  As an example, first, based on the “transmission timing” and the current time, the channel is switched to “ch8” in a time zone in which temperature data is transmitted from the endpoint 300A. Secondly, the frequency of the access point 200 is changed in a time division manner such as switching to “ch5” in the time zone in which the temperature data is transmitted from the end point 300B. Alternatively, the access point 200 may be of a type that can perform multi-frequency communication.

2. Processing in the case where the power source of the endpoints 300A to 300D is a button type battery or the like. It is known that when the ambient temperature of the battery is low, a voltage drop occurs, especially in the button type battery. Then, in the end points 300A to 300D that use a button type battery or the like as a power source, a situation in which a scheduled operation cannot be performed properly may occur.

  If the scheduled operation is simply the transmission of temperature data to the access point 200, there will be no serious problem with the communication system. This is because the end points 300 </ b> A to 300 </ b> D can also transmit the temperature data to the access point 200 by executing the transmission retry of the temperature data.

  On the other hand, the communication system described in the first embodiment appropriately changes, for example, the frequency of radio waves for communication between the access point 200 and the end points 300A to 300D or the transmission timing of temperature data. To be able to. When these processes are performed, information in the nonvolatile memories 330A to 330D is rewritten.

  Then, when the voltage drop of a battery such as a button-type battery occurs due to the low ambient temperature at the rewriting timing, the rewriting may not be performed successfully. As an example, this is a case where the above-mentioned frequency needs to be rewritten but is not rewritten.

  In this case, the frequency to be set by the radio wave for communication between the end point and the access point 200 is different. If it does so, it will become impossible to communicate between both machines after that.

  In this embodiment, in order to avoid this, when each temperature data transmitted from the end points 300A to 300D is lower than a predetermined threshold (for example, 10 ° C.), the access point 200 and the end points 300A to 300D In order to continue communication between the two, the frequency change request is limited.

Table 1 is a list of names and outlines of signals (commands) that are restricted from being transmitted from the access point 200 to the endpoints 300A to 300D.

Table 1 shows
(1) A command for requesting a change in the frequency of radio waves for communication between the access point 200 and the end points 300A to 300D, referred to as a “frequency change request command”;
(2) A command for requesting a change in the timing of communication between the access point 200 and the end points 300A to 300D, referred to as a “transmission timing change request command”;
(3) A command called “interrupt request command” for requesting to interrupt the change of the radio wave frequency of communication between the access point 200 and the end points 300A to 300D;
(4) When releasing the pairing between the access point 200 and at least one of the end points 300A to 300D, which is referred to as a “pairing clear request command”, the pairing information between the at least the end point A command to request deletion,
Is shown.

  In the present embodiment, in order to limit signal (command) transmission from the access point 200 to the end points 300A to 300D, first, the host device 100 determines whether the temperature data is lower than a predetermined threshold. Then, as a result of the determination, when the temperature data is lower than a predetermined threshold, a command for requesting transmission of the signal is not output to the access point 200.

  To illustrate, in this case, the “frequency change request command” shown in step S15 of FIG. 3 or step S25 of FIG. 4 is not output. Further, it is possible not to output the “interrupt request command” shown in step S32 of FIG.

  In addition, since the signal (command) transmission from the access point 200 to the end points 300 </ b> A to 300 </ b> D is not limited to the above case, for example, the determination is first performed by the access point 200. Even if any of the commands listed in Table 1 is output from the host device 100, a signal corresponding to the command can be prevented from being transmitted to the endpoints 300A to 300D.

  For example, in this case, information indicating the frequency after the change is not included in the ACK shown in steps S18 and S21 in FIG. 3 or step S28 in FIG. Another example is not to output the “frequency change request” shown in step S34 of FIG.

3. Change / Suspension Subject and Target Part of the operations executed by the host device 100 can be realized by the access point 200. More specifically, for example, the access point 200 compares the radio wave intensity that can be used to generate the interruption request command with a predetermined threshold value, and when the radio wave intensity is equal to or lower than the predetermined threshold value, FIG. ACKs in steps S18 and S21 may be transmitted. In this way, steps S32, S33, and S36 can be omitted.

  Further, in each of the above-described embodiments, the case where the “frequency change request command” is output from the higher-level device 100 to the access point 200 has been described as an example. However, the target to be changed by the command is “frequency”. For example, “transmission timing” may be used. Moreover, it can also be set as both of these.

It is a block diagram which shows the typical structure of the communication system of embodiment of this invention. FIG. 2 is a series of sequence diagrams illustrating an operation of the communication system illustrated in FIG. 1. FIG. 2 is a series of sequence diagrams illustrating an operation of the communication system illustrated in FIG. 1. FIG. 2 is a series of sequence diagrams illustrating an operation of the communication system illustrated in FIG. 1. It is a sequence diagram which concerns on the time of the battery running out which is the power supply of the endpoint 300B which concerns on Embodiment 2 of this invention, or failure of the endpoint 300B itself.

DESCRIPTION OF SYMBOLS 100 Host apparatus 110 Radio wave intensity acquisition means 120 Comparison means 200 Access point 210 Microcontroller 220 RF module 230 Non-volatile memory 300A-300D Endpoint 310A-310D Temperature sensor 320A-320D RF module 330A-330D Non-volatile memory 400A-400D Wireless line

Claims (6)

A communication system for transmitting a sensing result by a temperature sensor provided in a slave unit to the master unit by radio waves and transmitting a command including the transmission condition from the master unit to the slave unit,
The slave unit includes a battery that supplies power to the means for transmitting the sensing result, and a non-volatile memory that stores conditions included in the command,
The master unit includes control means for controlling not to transmit the command when the ambient temperature indicated by the sensing result is equal to or lower than a predetermined temperature.
Communications system. The command is
A command for deleting information necessary for pairing, which is executed when the pairing between the parent device and the child device is canceled;
A command for instructing the frequency of the radio wave for transmitting the sensing result;
A command for instructing an interval for transmitting the sensing result;
The communication system according to claim 1, comprising at least one of the following.    The communication system according to claim 1, wherein the predetermined temperature is 10 ° C. or less. It said control means further the voltage of the battery is controlled so as not to perform transmission of the command if below a predetermined threshold value, the communication system according to claim 1, wherein.    The communication system according to claim 1, wherein the battery is a button-type battery. The master unit is connected to a plurality of slave units, and has means for transmitting an instruction to switch the predetermined frequency to the slave units by the radio wave,
As a result of transmitting the instruction, when a response signal from any one of the slave units cannot be received within a predetermined time, switching between the slave units other than the slave unit that cannot receive the response signal is instructed. The communication system according to claim 1, wherein communication is performed using radio waves of a frequency.

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