JP7291391B2 - Wireless communication system and slave station control program - Google Patents

Description

The present invention relates to a radio communication system and a slave station control program. More specifically, the present invention relates to a wireless communication system and a slave station control program for wirelessly transmitting measurement data from a slave station to a master station.

LPWA (Low Power Wide Area) is a general term for wireless communication technology standards that can keep communication terminal power consumption low while ensuring a wide communication area of several kilometers to several tens of kilometers. It is intended for communication equipment that requires long-term operation with a small amount of power. In a wireless communication system using this LPWA, a communication terminal that can be flexibly installed using a dry battery or the like without using an electric wire is used to supply power to the communication terminal. As a result, for example, smart metering (remote automatic meter reading) of electricity, water, etc., equipment monitoring such as failures in plants, etc., are applied to an extremely wide range.

When two or more child stations are employed in the above LPWA, it is necessary to prevent overlapping of transmission timings between these child stations. Here, in LPWA, a communication system with polling calls and an event-driven communication system are mainly adopted. This overlap does not occur in those communication systems that use polling calls. However, in the case of a communication system that uses polling calls, it is necessary to keep the receiver of the slave station constantly energized in order to receive the command signal from the master station, which increases the power consumption of the slave station. be. In addition, in a communication system that performs polling calls, inquiry communication from the master station to the slave station and response communication from the slave station to the master station are required, resulting in a problem of long communication times.

Patent Literature 1 discloses a wireless communication system including one or more child stations and a parent station that receives data transmitted from these child stations. This system is an event-driven communication system. A wireless communication system using LPWA often adopts an event-driven communication system disclosed in Patent Document 1. This is because, in the event-driven communication system, the power consumption of the slave station can be suppressed because the receiver of the slave station does not need to be energized all the time. In addition, this eliminates the time required for inquiry communication from the master station to the slave station, thereby shortening the communication time. In Patent Literature 1, which discloses this event-driven communication system, each slave station is provided with an antenna for receiving a radio-controlled clock in order to prevent overlapping of transmission timings between slave stations.

JP-A-2007-36342

However, since the wireless communication system described in Patent Document 1 is equipped with an antenna for receiving a radio-controlled clock, it is necessary to supply electricity to this antenna, and this part consumes power. be. Due to this power consumption, depending on the timing of data transmission, there is a problem that it is necessary to replace the dry cell etc. in about a few days, and it is necessary to set the timing of data transmission to several tens of minutes. .

SUMMARY OF THE INVENTION It is therefore an object of the present invention to provide a wireless communication system capable of minimizing power consumption in slave stations and increasing the number of times of communication within a certain period of time.

A wireless communication system according to a first invention includes two or more slave stations and a master station that receives data transmitted from the two or more slave stations, and the two or more slave stations the child station control units for controlling the child stations, the child station control units transmitting data to the parent station at predetermined periodic intervals, the child station control units comprising the child station control units When it is determined that the first data and the second data following the first data could not be transmitted from the child station controlled by the child station control unit, the third data after the second data from the child station controlled by the child station control unit It is characterized by delaying the timing of data transmission after the data by a predetermined delay time.
A wireless communication system according to a second aspect of the invention is the wireless communication system according to the first aspect, wherein the child station control unit controls transmission of data from the two or more child stations based on ID numbers assigned to the two or more child stations. They are characterized by being performed at different timings.
A wireless communication system according to a third aspect of the invention is the wireless communication system according to the second aspect, wherein the slave station control unit controls the slave station clocks provided in the two or more slave stations by the IDs assigned to the two or more slave stations, respectively. The transmission of data from the two or more slave stations is performed at different timings by delaying them based on the numbers.
A wireless communication system according to a fourth aspect of the invention is the wireless communication system according to any one of the first aspect to the third aspect, wherein a transmission rate between the two or more slave stations and the master station is 50 bps or more and 2000 bps or less,
The number of the two or more child stations is 4 or more and 24 or less.
A slave station control program according to a fifth aspect of the present invention is a slave station control program for a wireless communication system including two or more slave stations and a master station that receives data transmitted from the two or more slave stations. and transmitting data to the parent station at predetermined regular intervals to the child station controllers respectively provided in the two or more child stations, from the two or more child stations to the parent station, When the slave station control unit determines that the first data and the second data subsequent to the first data could not be transmitted from the slave station controlled by the slave station control unit, the slave station controlled by the slave station control unit and transmitting the third data after the second data with a predetermined delay time.
A child station control program according to a sixth aspect of the invention is the child station control program in the fifth aspect of the invention, which causes the child station control unit to transmit data from the two or more child stations to the parent station by IDs assigned to the two or more child stations, respectively. It is characterized by delaying each based on the number.
A slave station control program according to a seventh aspect of the invention is the slave station control program according to the sixth aspect, wherein the slave station control unit controls the slave station clocks provided in the two or more slave stations by ID numbers assigned to the two or more slave stations, respectively. The data transmission from the two or more slave stations to the master station is delayed by delaying each based on the following.

According to the first invention, when the child station control section determines that the transmission of the first data and the second data from the child station controlled by the child station control section has failed, the subsequent data transmission of the third and subsequent data is performed. By delaying the timing by a predetermined delay period for transmission, even if the timing of transmission with other slave stations overlaps with the first data, etc., the transmission with other slave stations from the third data after that is delayed. Timing can be shifted, and transmission timings of slave stations can be prevented from overlapping with a simple configuration in an event-driven communication system. That is, with this configuration, the number of data retransmissions can be suppressed, power consumption in the slave station can be suppressed, and although it is a flexible system that uses dry batteries as a power supply, it is not necessary to replace the power supply of the slave station such as the dry battery. The frequency of maintenance work can be reduced. In addition, since the communication system is an event-driven communication system, the time required for inquiry communication from the master station to the slave station is eliminated, and the number of times of communication within a certain period of time can be increased.
According to the second aspect of the invention, the slave station control unit transmits data from the slave station at different timings based on the ID numbers assigned to the slave stations. Transmission timings from the slave stations can be shifted, and users of the wireless communication system can acquire data from all the slave stations at an early stage when the system is started up.
According to the third invention, by delaying the slave station clock and transmitting data at different timings, it is possible to share the software for transmission used in the slave station controllers.
According to the fourth invention, since the transmission rate between the slave station and the master station is 50 bps or more and 2000 bps or less, a wireless communication system using so-called LPWA can be constructed, so that a wide communication area can be secured and the slave station A system that consumes less power can be constructed. Also, by setting the number of child stations to be 4 or more and 24 or less, the size of the system can be optimized from the viewpoint of the number of master stations and the number of terminals per unit.
According to the fifth invention, when the slave station control program causes the slave station control unit to transmit data to the master station at predetermined periodic intervals, it is determined that the first data and the second data could not be transmitted. Then, by delaying the transmission timing of the third and subsequent data by the delay period, the radio communication system implementing this child station control program can prevent the transmission of the first data and the like to other child stations. Even if the timings overlap, the timing of transmission with other child stations can be shifted from the subsequent third data, and the transmission timings of the child stations can be prevented from overlapping with a simple configuration in an event-driven communication system. . In other words, the wireless communication system can reduce the power consumption of slave stations, and is a flexible system using dry batteries as a power source, while reducing the frequency of maintenance work such as replacing the dry batteries. can do.
According to the sixth invention, the slave station control program causes the slave station control unit to delay transmission of data from the slave station to the master station based on the ID number assigned to the slave station. A wireless communication system that implements a control program can shift the timing of transmission from each slave station when starting up a slave station, and the user of the wireless communication system can acquire data early at the time of system start-up. .
According to the seventh invention, the slave station control program delays the slave station clock provided in the slave station based on the ID number assigned to the slave station, thereby preventing data transmission from the slave station. , are delayed respectively, so that software for transmission used in the slave station controllers can be shared.

FIG. 3 is an explanatory diagram of the communication status of the wireless communication system according to the first embodiment of the present invention; (A) is a communication state when all transmissions from four slave stations are received by the master station. (B) shows the communication situation when the transmission timings of one of the four child stations overlap with that of the other child station. (C) shows the communication state when the transmission timing of one of the redundant slave stations is delayed from the state of (B). 1 is a block configuration diagram of a radio communication system according to a first embodiment of the present invention; FIG. FIG. 4 is an operation flow diagram of the wireless communication system according to the first embodiment of the present invention;

Next, embodiments of the present invention will be described with reference to the drawings. However, the embodiment shown below exemplifies a radio communication system and a slave station control program for embodying the technical idea of the present invention. not specific to Note that the sizes and positional relationships of members shown in each drawing may be exaggerated for clarity of explanation.

A wireless communication system 10 according to the present invention includes two or more slave stations 21 and a master station 11 that receives data transmitted from the two or more slave stations 21. each has a slave station controller 22 that controls two or more slave stations 21 . These slave station controllers 22 transmit data to the master station 11 at predetermined periodic intervals T1, and the slave station controllers 22 transmit data from the slave stations 21 controlled by the slave station controllers 22 to the master station 11. When it is determined that the first data and the second data following the first data could not be transmitted, the timing of data transmission from the slave station 21 controlled by the slave station control unit 22 after the second data is set. , is transmitted with a delay of a predetermined delay time T3. Hereinafter, after explaining the configuration of the wireless communication system 10, the operation flow of the wireless communication system 10 according to the configuration will be explained, and the communication situation according to the operation flow will be explained.

(Configuration of wireless communication system 10)
FIG. 2 shows a block configuration diagram of the radio communication system 10 according to the first embodiment of the present invention. In this embodiment, the radio communication system 10 includes one parent station 11 and four child stations 21 . FIG. 2 shows the details of only one of the four child stations 21 . Note that the number of slave stations 21 is not particularly limited to four, and there is no problem if the number is two or more. There is no upper limit on the number of slave stations. However, considering that as the number of slave stations 21 increases, the number of contacts provided in the signal output section 13 of the master station 11 increases and the body of the master station 11 becomes unnecessarily large, the number of slave stations 21 is It is preferably 4 or more and 24 or less. Thus, by setting the number of slave stations to 4 or more and 24 or less, the size of the system can be optimized from the viewpoint of the number of master stations and the number of terminals per unit.

In this embodiment, the master station 11 includes a master station control unit 12, a signal output unit 13, a master station communication module 14, a master station storage unit 15, and a GPS receiver 16. ing. The master station control unit 12 is electrically connected to these other elements provided in the master station 11 and controls them. The configuration of the master station 11 is not limited to this configuration, and other elements may be added or elements such as the master station storage unit 15 may be omitted. Although not shown in the drawing, the power of the master station 11 is supplied by an electric wire. In addition, the master station control unit 12 may be provided with a master station clock.

The signal output unit 13 is connected to an external device 17 such as a PC or PLC provided separately from the master station 11 . The parent station control unit 12 outputs the data sent from the slave station 21 to the external device 17 through the signal output unit 13 .

The master station communication module 14 is connected to the slave station communication module 24 provided in the slave station 21 by wireless communication. Preferably, so-called LPWA is used for this wireless communication. Specifically, it is preferable that the transmission rate is 50 bps or more and 2000 bps or less.

A wireless communication system 10 using a so-called LPWA that secures a wide communication area and suppresses the power consumption of the slave station 21 by setting the transmission rate between the slave station 21 and the master station 11 to 50 bps or more and 2000 bps or less. can build.

The master station storage unit 15 may store a master station control program for controlling the master station control unit 12 . In some cases, data transmitted from the child station 21 is temporarily stored in the master station storage unit 15 before being transmitted to the external device 17 .

The GPS receiver 16 receives time information from the GPS in accordance with the location information of the GPS receiver 16 . Then, the master station control unit 12 associates the time information from the GPS receiver 16 with the data transmitted from the slave station 21 .

In this embodiment, each slave station 21 is configured including a slave station control section 22 , a signal input section 23 , a slave station communication module 24 , and a slave station storage section 25 . The slave station controller 22 is electrically connected to these elements provided in the slave station 21 and controls them. The configuration of the child station 21 is not limited to this configuration, and other elements may be added or elements such as the child station storage unit 25 may be omitted. Also, all of the plurality of child stations 21 do not need to have the same configuration. Although not shown in the drawing, the slave station 21 is provided with a power supply for operating the slave station 21. FIG. In addition, the slave station control unit 22 may be provided with a slave station clock.

The signal input section 23 is connected to a sensor 26 provided separately from the slave station 21 . The slave station control unit 22 transmits the data obtained here to the master station 11 through the slave station communication module 24 . The signal input unit 23 can acquire data of analog current, analog voltage, and digital signals.

The child station storage unit 25 may store a child station control program for controlling the child station control unit 22 . In some cases, data acquired by the signal input unit 23 is temporarily stored in the slave station storage unit 25 before being transmitted from the slave station communication module 24 .

The wireless communication system 10 according to this embodiment is an event-driven communication system in which the master station 11 does not make a polling call to the slave station 21 . In other words, the child station 21 does not need to be continuously energized for the polling call from the master station 11 . This event-driven communication system does not mean a communication system in which the master station 11 does not send data to the slave station 21 at all. , the fact that the data transmitted from the child station 21 has been received is transmitted.

(Operation flow of wireless communication system 10)
FIG. 3 shows an operation flow diagram of the wireless communication system 10 according to the first embodiment of the present invention. 3, the operation flow in the master station 11 is shown on the left side, and the operation flow in the slave station 21 is shown on the right side. Although the wireless communication system 10 according to the present embodiment has two or more child stations 21, only one operation flow of the child station 21 is shown in FIG. 3 in order to facilitate understanding of the operation flow. For each step of the operation flow, for example, step 01 is described as S01.

In S01, master station initial processing is performed in the master station 11 . In this master station initial processing, the user of the wireless communication system 10 first turns on the power of the master station 11 . When the master station 11 is powered on, the master station control unit 12 reads the master station control program stored in the master station storage unit 15 . Then, the master station control unit 12 initializes the master station communication module 14 to enable reception of transmission data from the slave station 21 .

In S02, the master station 11 performs GPS time synchronization processing. That is, the master station controller 12 acquires time data from the GPS by the GPS receiver 16 provided in the master station 11, and converts the master station clock provided in the master station controller 12 to the time data. Synchronize.

In S<b>03 , in the master station 11 , the master station controller 12 determines whether or not there is a request for time data from any of the slave stations 21 . This time data request is confirmed by the master station control unit 12 through the master station communication module 14 . When the master station control unit 12 determines that there is a request for time data, the master station control unit 12 proceeds to S04. When the master station control unit 12 determines that there is no time data request, the master station control unit 12 proceeds to S05.

In S04, in the master station 11, the master station controller 12 transmits the time data in the master station clock of the master station controller 12 to the slave station 21 that has requested the time.

In S<b>05 , in the master station 11 , the master station controller 12 determines whether data has been transmitted from any of the child stations 21 . The transmission of this data is confirmed by the master station controller 12 through the master station communication module 14 . If the master station control unit 12 determines that data has been received, the master station control unit 12 proceeds to S06. When the master station control unit 12 determines that no data has been received, the master station control unit 12 returns to the step before S02.

In S06, in the master station 11, the master station controller 12 notifies the slave station 21 that has transmitted the data that the data has been received. At this time, when the timing of transmission from one slave station 21 overlaps with the timing of transmission from another slave station 21, data is received by the slave station 21 that received the data first, and in S06 , the fact that the data has been received is transmitted, but the data is not received for the child station 21 that received the data later, and the fact that the data has been received is not transmitted in S06.

In S<b>07 , in the master station 11 , the master station control unit 12 stores the transmitted data in the master station storage unit 15 . In S08, in the master station 11, the master station controller 12 confirms whether or not there is a communication error. This communication error is detected by the master station 11 as an error when data does not arrive from one slave station 21 within a predetermined time. For example, when one of the slave stations 21 fails and data from the slave station 21 is not transmitted, the master station 11 determines that an error has occurred. After S08, the parent station control unit 12 returns to before S02 and repeats this flow.

Next, the operational flow of the slave station 21 will be described. At this time, the operation flow will be described using FIG. 1 together with FIG. FIG. 1 is an explanatory diagram of the communication status of a wireless communication system 10 according to this embodiment. Specifically, it is a diagram showing a transmission state from the child station 21 when there are four child stations 21. FIG. FIG. 1(A) shows a communication situation when transmissions from four child stations 21 are all received by the master station 11 . FIG. 1(B) shows a communication situation when the transmission timings of one of the four child stations 21 and the other child station 21 overlap. Specifically, the transmission timing overlaps between the slave station 21 with the ID number 2 and the slave station 21 with the ID number 3, and the overlap is indicated by a symbol C. FIG. FIG. 1(C) shows the communication state when the transmission timing of one of the redundant slave stations 21 is delayed from the state of FIG. 1(B).

In S<b>11 , slave station initial processing is performed in the slave station 21 . In this child station initial processing, the user of the wireless communication system 10 turns on the power of the child station 21 . At this time, it is preferable that the process of turning on the power of the child station 21 is performed after the process of turning on the power of the master station 11 . When the slave station 21 is powered on, the slave station control section 22 reads the slave station control program stored in the slave station storage section 25 . Further, the child station control unit 22 acquires information such as an ID number set in the child station 21 by the user. Then, the slave station control unit 22 initializes the slave station communication module 24 and enables the slave station control unit 22 to transmit data through the slave station communication module 24 .

In S12, the slave station 21 performs time synchronization processing of the slave station 21. FIG. That is, the child station control unit 22 transmits to the master station 11 a request to transmit the current time. Upon receiving this request, the master station 11 transmits the time data of the master station clock in the master station controller 12 to the slave station 21 . Based on the sent time data, the slave station control unit 22 synchronizes the time of the slave station clock provided in the slave station control unit 22 with the time data.

In S13, in the child station 21, the child station controller 22 reads the internal time. In S12, the slave station clock in the slave station controller 22 is synchronized with the time data of the master station clock, and the slave station controller 22 reads the time based on this time data.

In S14, the slave station controller 22 of the slave station 21 determines whether or not it is time to transmit. Here, transmission timing will be described in detail with reference to FIG.

Each diagram in FIG. 1 shows four child stations 21 and the state of data transmission of the child stations 21 . In FIG. 1, the X axis is the time axis (time elapses from left to right on the page of FIG. 1), and the Y axis is the ID number assigned to the slave station 21 . The hatched rectangular portion represents the timing at which the child station 21 having the ID number transmits the data, that is, the data transmission time.

As shown in FIG. 1(A), the slave station 21 with ID number 0 transmits data using a transmission time T2 at predetermined regular intervals T1. The slave station 21 with the ID number 1 has the same periodic period T1 and the length of the transmission time T2 as those of the slave station 21 with the ID number 0. is getting late too. In this way, the child station control unit 22 of the child station 21 changes the length from the time when the periodic cycle T1 starts to the time when the transmission time T2 starts according to the ID number. Then, for example, the slave station controller 22 of the slave station 21 with the ID number 1 determines that the time when the transmission time T2 of the slave station 21 with the ID number 1 starts is earlier than the time when the transmission time T2 of the slave station 21 with the ID number 0 ends. is also slowed down. Similarly, the slave station controllers 22 with ID numbers 2 and 3 control the length of time from the start of the periodic cycle T1 to the start of the transmission time T2. Then, as shown in FIG. 1(A), the transmission timings of the child stations 21 are arranged so as not to overlap each other.

That is, as shown in FIG. 1A, each child station control unit 22 of each child station 21 controls transmission of data from each child station 21 based on the ID number assigned to each child station 21. The transmission timings of the child stations 21 are set so as not to overlap with each other. By doing so, the master station 11 can receive transmission data from all slave stations 21 . Since the ID number is assigned to each slave station 21 in S11, the timing of transmission from each slave station 21 can be shifted when the slave station 21 is started up. Data from all slave stations 21 can be acquired early at startup.

The slave station control unit 22 transmits data from the slave station 21 at different timings based on the ID number assigned to the slave station 21, so that when the slave station 21 is started up, each slave station 21 Therefore, the user of the wireless communication system 10 can acquire data from all the slave stations 21 at an early stage when the system is started up.

As a method for shifting the transmission timing of each slave station 21 as described above, in this embodiment, the slave station control unit 22 assigns the slave station clock provided to the slave station 21 to the slave station 21. By delaying each transmission based on the ID number, transmission of data from the child station 21 is performed at different timings.

By delaying the slave station clock and transmitting data at different timings, the software for transmission used in the slave station controller 22 can be shared.

The length of the periodic cycle T1 can be arbitrarily determined by the user of the wireless communication system 10, for example, by changing the numerical value in the slave station control program of the slave station 21 or by changing the switch of the skeleton of the slave station 21. It is possible to change by doing. The length of the regular period T1 does not need to be the same for all slave stations 21, but must be an integral multiple of a predetermined period. For example, if the predetermined cycle is 10 seconds, the regular cycle T1 of each child station 21 is selected from numerical values of 10 seconds, 20 seconds, and 30 seconds. The periodic period T1 is preferably 20 seconds or less, more preferably 10 seconds or less, when data changes relatively frequently, such as in factory equipment. In addition, it is preferable to set the time to 20 seconds or more when the displacement of the data is relatively small, such as a natural phenomenon.

When the number of slave stations 21 is 4 or more and 24 or less, and the periodical period T1 is 5 seconds or more and 60 seconds or less, it is possible to monitor the operating state of equipment that requires urgent response and monitor the temperature with a relatively large time margin. It can be applied to a wide range of applications and the size of the system can be optimized.

The length of the transmission time T2 is determined by the size of the data transmitted from the slave station 21 to the master station 11 and the transmission speed between the slave station 21 and the master station 11. FIG. For example, when sending measurement data together with time data at a transmission speed of around 980 bps, the length of the transmission time T2 is around 1 second.

For example, the length from the start of the periodic cycle T1 to the start of the transmission time T2 of the slave station 21 with the ID number 1 is 1.2 times or more the length of the transmission time T2 of the slave station 21 with the ID number 0. 2.0 times or less is preferable.

In S14, the slave station control unit 22 of the slave station 21 determines whether the current time is the timing to start data transmission calculated according to the ID number assigned to the slave station 21 . If the slave station controller 22 determines that the timing is not right, the slave station controller 22 returns to before S13. When the slave station control unit 22 determines that it is the timing, the slave station control unit 22 proceeds to S15.

In S<b>15 , in the child station 21 , the child station control section 22 acquires measurement data from the signal input section 23 connected to the sensor 26 . Then, in S<b>16 , in the child station 21 , the child station controller 22 transmits the acquired data from the child station communication module 24 to the master station 11 .

In S17, in the child station 21, the child station controller 22 confirms whether the data transmitted in S16 has been received by the master station 11 or not. This point will be described in detail with reference to FIG.

In an event-driven communication system that does not perform polling calls, when signals are transmitted from a plurality of slave stations 21 and the transmission timings overlap, data transmitted later is not received by the master station 11 . For example, if the environments in which the slave stations 21 are arranged are different, the slave station clock provided in the slave station control unit 22 is delayed or advanced by a unit of one second per day. In FIG. 1B, the transmission time T2 from the slave station 21 with the ID number 2 and the transmission time T2 from the slave station 21 with the ID number 3 overlap, and an overlap C exists. In this case, the transmission data of the slave station 21 with the ID number 2, which has been transmitted earlier, is received by the master station 11, but the transmission data of the slave station 21 with the ID number 3, which is transmitted later, is received by the master station 11. not received by

It should be noted that FIG. 1 is not a diagram of "data transmission timing" but a diagram of "data transmission timing". That is, in FIG. 1(B), transmission data may not be transmitted from the slave station 21 with the ID number 3 in some cases. For example, although not shown in FIG. 3, each slave station 21 enters the radio wave reception mode for an extremely short time before transmission, and checks whether or not the other slave stations 21 are emitting radio waves. When it is detected that the radio wave is emitted from another slave station 21, the slave station 21 does not transmit the radio wave and does not transmit the radio wave. At this time, the transmission data of the slave station 21 is not received by the master station 11 .

In S18, when the slave station controller 22 of the slave station 21 determines that there is a transmission from the master station 11, it returns to the step before S13. If the slave station control unit 22 determines that there is no transmission from the master station 11 indicating that it has been received, it proceeds to S19.

In S19, the slave station controller 22 in the slave station 21 performs a delay process of delaying the data to be sent next by a predetermined delay time T3. This point will be described in detail with reference to FIG.

As described in S17, when duplication C occurs as shown in FIG. When such duplication C occurs, in S18, the child station control unit 22 determines that data transmission from the child station 21 has not succeeded. FIG. 1C shows that the leftmost data transmission of ID number 3 is not received by the master station 11 . It also indicates that the next data transmission will not be received by the master station 11 either. Then, for the third data from the left, in S19, the slave station control unit 22 with ID number 3 delays the transmission time T2 by a predetermined delay time T3. In FIG. 1C, the data of ID number 3 in T1, which is the first from the left, corresponds to the "first data" described in the claims, and the ID number in T1, which is the second from the left. The data of ID number 3 corresponds to the "second data" described in the claims, and the data of the ID number 3 in the third T1 from the left corresponds to the "third data" of the claims. However, FIG. 1(C) is a part of time-series data extracted, and data is continuously transmitted to the left and right sides of FIG. 1(C).

In this embodiment, as shown in FIG. 1(C), the child station control unit 22 determines that the data transmission of the child station 21 has failed two times in succession. When the child station control unit 22 determines that the child station 21 transmits data next time, the child station control unit 22 delays the transmission time T2 by a predetermined delay time T3. Note that it is preferable to delay the transmission time T2 when the duplication C occurs twice in succession. If it is 1 degree, it may be sporadic when an obstacle is crossed or an interfering radio wave is present. Also, if it is assumed that it is three times or more in succession, the recovery of communication becomes slow.

Although the length of the delay time T3 is not particularly limited, it is determined in advance in consideration of the periodic period T1, the transmission time T2, and the like. Also, FIG. 1(C) shows the case where the slave station control unit 22 determines that the duplication C has occurred twice, but other cases are also conceivable. For example, it is possible for the slave station control unit 22 to perform delay processing when it is determined that the overlap C has occurred once, or when it is determined that it has occurred three times in succession.

When the slave station control unit 22 determines that the transmission of the first data and the second data has failed, the transmission timing of the third data and subsequent data is delayed by a predetermined delay time T3. Even if the transmission timing of the first data etc. overlaps with the other child station 21, the timing of transmission with the other child station 21 can be shifted from the third data after that, which is simple in the event-driven communication system. With such a configuration, the transmission timings of the child stations 21 can be prevented from overlapping. That is, with this configuration, the number of data retransmissions can be suppressed, power consumption in the slave station 21 can be suppressed, and although the system is flexible with a dry battery as a power supply, the power supply of the slave station 21 such as a dry battery can be reduced. The frequency of replacement maintenance work can be reduced. In addition, since it is an event-driven communication system, the time required for inquiry communication from the master station 11 to the slave station 21 is eliminated, and the number of times of communication within a certain period of time can be increased.

(Child station control program of child station 21 configuring wireless communication system 10)
The slave station control program of the slave station 21 constituting the wireless communication system 10 according to the present embodiment is read from the slave station storage unit 25 to the slave station control unit 22 in S11. This slave station control program can implement the flow from S11 to S19 described above.

This slave station control program is used to transmit data to the master station 11 at predetermined regular intervals T1 to the slave station control unit 22 provided in the slave station 21. From the slave station 21 to the master station 11, When the child station control unit 22 determines that the first data could not be transmitted, the transmission of the second data after the first data is delayed by a predetermined delay time T3 and transmitted.

When the slave station control program transmits data to the master station 11 every predetermined periodic cycle T1, and the slave station control unit 22 determines that the first data could not be transmitted, By delaying the transmission of the second data after the first data by the delay time T3, the wireless communication system 10 executing this slave station control program can transmit the first data to the other slave station 21. Even if the timing of the second data overlaps, the timing of transmission with another slave station 21 can be shifted from the subsequent second data, and the timing of transmission of the slave station 21 does not overlap with a simple configuration in the event-driven communication system. can be done. That is, the wireless communication system 10 can suppress power consumption in the slave station 21, and can reduce the frequency of maintenance work for replacing the dry battery while being a flexible system using a dry battery as a power source. can be system.

The slave station control program causes the slave station control unit 22 to delay transmission of data from the slave station 21 to the master station 11 based on the ID number assigned to the slave station 21 .

As a result, the wireless communication system 10 executing this slave station control program can shift the timing of transmission from each slave station 21 when starting up the slave station 21, and the user of the wireless communication system 10 can Data can be acquired early when the system is started up.

In addition, the slave station control program causes the slave station control unit 22 to delay the slave station clock provided in the slave station 21 based on the ID number assigned to the slave station 21, thereby allowing the slave station 21 to control the parent station clock. The transmission of data to station 11 is delayed respectively.

As a result, it is possible to standardize software for transmission used in the child station control unit 22 .

REFERENCE SIGNS LIST 10 wireless communication system 11 master station 21 slave station 22 slave station control unit T1 periodic cycle T3 delay time

Claims (7)

comprising two or more slave stations and a master station that receives data transmitted from the two or more slave stations,
each of the two or more child stations includes a child station control unit that controls the two or more child stations;
The slave station control unit transmits data to the master station at predetermined periodic intervals,
When the child station control unit determines that the child station controlled by the child station control unit cannot continuously transmit the first data and the second data following the first data,
Delaying the timing of data transmission from the slave station controlled by the slave station control unit for the third data after the second data by a predetermined delay time and transmitting the data;
A wireless communication system characterized by: The slave station control unit
transmission of data from the two or more slave stations;
performed at different timings based on the ID numbers assigned to the two or more slave stations;
The wireless communication system according to claim 1, characterized by: The slave station control unit
a slave station clock provided in each of the two or more slave stations,
By delaying each based on the ID number assigned to each of the two or more child stations,
transmitting data from the two or more slave stations at different timings;
3. The radio communication system according to claim 2, characterized by: a transmission rate between the two or more slave stations and the master station is 50 bps or more and 2000 bps or less;
The number of the two or more slave stations is 4 or more and 24 or less.
4. The wireless communication system according to any one of claims 1 to 3, characterized by: A slave station control program for a wireless communication system including two or more slave stations and a master station that receives data transmitted from the slave stations,
In the child station control unit provided in each of the two or more child stations,
When transmitting data to the master station at regular intervals determined in advance,
When the slave station controller determines that the first data and the second data following the first data cannot be transmitted from the two or more slave stations to the master station from the slave station controlled by the slave station controller,
delaying the timing of data transmission from the slave station controlled by the slave station control unit by a predetermined delay time for the transmission of the third data after the second data;
A slave station control program characterized by: In the slave station control unit,
transmission of data from the two or more slave stations to the master station;
each delaying based on the ID number assigned to each of the two or more child stations;
6. The slave station control program according to claim 5, characterized by: a slave station clock provided in the two or more slave stations in the slave station control unit;
By delaying each based on the ID number assigned to each of the two or more child stations,
respectively delaying the transmission of data from the two or more child stations to the master station;
7. The slave station control program according to claim 6, characterized by:

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