JP2006343983A - Fire alarm system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To surely avoid collision even if information is transferred between a receiving device and fire sensors at a high frequency. <P>SOLUTION: A super frame SF comprises a collection of a plurality of frames F1-F30 comprising a time slot B in a downward direction (receiving device 1 to fire sensors 10) and a plurality of time slots D1-D99 in an upward direction (fire sensors 10 to receiving device 1). The time slots D1-D99 of the frames F1-F30 in the upward direction are individually allocated to the respective fire sensors 10. Thus even if the frequency of periodic message exchanges (exchanges of return request messages and response messages) is relatively high, the collision between wireless signals sent from the fire sensors 10 can be surely avoided. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a fire alarm system having a plurality of fire detectors for detecting a fire and a receiving device for performing wireless communication using a radio wave as a medium between the fire detectors.

  2. Description of the Related Art Conventionally, various fire alarm systems have been provided that include a plurality of fire detectors that detect a fire and a receiver that receives a fire detection signal transmitted from the fire detector that detects a fire in a wired manner. On the other hand, wireless communication between the fire detector and the receiving device should be performed due to the advantage that the wiring between the fire detector and the receiving device is not required when newly installed in an existing facility. A fire alarm system has been proposed (see Patent Document 1).

  On the other hand, in any of the wired or wireless communication systems, in order to confirm that a plurality of fire detectors are operating normally, a transmission request message is periodically sent from the receiving device to each fire detector. And a response message indicating the operating state of each fire detector is returned to the receiving device, and based on the response message, it is determined whether or not a failure such as a dead battery has occurred in the fire detector.

Here, in order to improve the reliability of the fire alarm system, it is necessary to exchange the periodic transmission request message and the response message as described above as frequently as possible. For example, in the EN standard (European unified standard), a standard (EN54-25) that obligates the exchange of messages at a rate of once every 300 seconds is planned.
Japanese Patent No. 3029716

  By the way, periodic message exchanges are frequently performed as described above, and the more the number of fire detectors included in the system, the higher the probability that a collision will occur due to overlapping transmission timings of the fire detectors. Therefore, it is necessary to avoid such a collision. Therefore, in the thing of patent document 1, while the carrier used for radio | wireless communication is detected, the carrier sense system which transmits a radio signal when a carrier is not detected without transmitting a radio signal is detected. It has been adopted.

  However, in the carrier sense system, since a certain time is required for switching between transmission / reception of radio circuits, collision cannot be completely avoided. In addition, in a wireless fire alarm system, a frequency assigned to a radio station that does not require a license is generally used, but in some countries, a severe limitation is imposed on transmission time duty. For example, in the European Union, the transmission time duty must be less than 0.1% at the Alarm frequency used in the fire alarm system.

  On the other hand, as a collision avoidance method other than the carrier sense method, a polling method in which a transmission request is made from a receiving device to a plurality of fire detectors in a predetermined order, and a plurality of fire detectors circulate transmission rights (tokens). Token ring method (registered trademark), fire detector periodically sends a response message, and the receiving device sends back an acknowledgment (ACK) to the fire detector that received the response message, and the fire detector receives it. An automatic retransmission (ARQ) method that repeats transmission of a response message until a reception confirmation is returned from the device has been proposed. In the polling method and the ARQ method, the transmission frequency of the reply request message in the receiving device is the product of the transmission frequency of the fire detector and the number of fire detectors, so that the transmission frequency increases in proportion to the number of fire detectors. Become. For example, in the above-mentioned EN standard (EN54-25), the transmission interval is 300 seconds, the transmission time is 100 milliseconds, and the transmission time duty limit is less than 0.1%, so that one receiver and system can be configured. The number of fire detectors will be less than 30. In the token ring system, if even one fire detector fails, the token may disappear and all the fire detectors may not be able to transmit.

  The present invention has been made in view of the above circumstances, and its purpose is to provide a fire notification that can reliably avoid a collision even when the frequency of information exchange between the receiving device and the fire detector is high. To provide a system.

  In order to achieve the above object, the invention of claim 1 includes a plurality of fire detectors for detecting a fire, and a receiver for performing wireless communication using radio waves as a medium between the fire detectors. The sensor detects a fire by detecting temperature changes and smoke generated by a fire, a wireless transmission / reception unit that transmits and receives radio signals to and from the receiver, and at least the detection unit detects a fire. A wireless transmission / reception unit for controlling the wireless transmission / reception unit to transmit the fire detection information by a wireless signal, and the reception device transmits / receives a wireless signal to / from the fire detector, and a wireless transmission / reception unit And a control unit that obtains fire detection information from a radio signal received by the radio transmission / reception unit, and the control unit of the reception device and the fire detector includes one downstream time slot from the reception device to the fire detector. And each fire feeling Sending and receiving various information including fire detection information in a superframe consisting of a fixed number of frames consisting of a plurality of upstream time slots from the fire detector assigned to each device to the receiver. Features.

  According to a second aspect of the present invention, in the first aspect of the present invention, the control unit of the receiving device causes the wireless transmission / reception unit to transmit a synchronization signal in a downlink time slot in one frame included in the superframe, and the fire detector The control unit determines a timing at which an uplink time slot assigned to the own device starts based on a time point when the wireless transmission / reception unit receives the synchronization signal.

  According to a third aspect of the present invention, in the second aspect of the present invention, the control unit of the receiving device sends a transmission request message for requesting a predetermined response to all fire detectors in the same downlink time slot as the synchronization signal. When a transmission request message is received, the control unit of the fire detector periodically transmits from the wireless transmission / reception unit, and the upstream unit assigned in the same frame as the frame including the downlink time slot that received the transmission request message. In the direction time slot, a predetermined response message indicating the operation state of the device is returned to the wireless transmission / reception unit.

  According to a fourth aspect of the present invention, in the third aspect of the present invention, the control unit of the receiving device performs the next in the same superframe for the fire detector assigned to the upstream time slot in which the response message could not be received. The wireless transmission / reception unit transmits a transmission request message only to the fire detector in the downlink time slot of the frame, and the fire detector control unit transmits the downlink time slot in the frame next to the frame that transmitted the previous response message. When the transmission request message suitable for the device is received, the wireless transmission / reception unit returns the response message again.

  The invention according to claim 5 is the invention according to claim 2, wherein the control unit of the fire detector sends the fire detection information to the wireless transmission / reception unit at the next assigned uplink time slot when the fire is detected by the detection unit. It is characterized by transmitting.

  According to a sixth aspect of the present invention, in the fifth aspect of the present invention, when the control unit of the receiving device receives the fire detection information, a confirmation message is sent to the wireless transmission / reception unit for the source fire detector in the downlink time slot. The fire detector control unit that has transmitted the fire detection information causes the wireless transmission / reception unit to transmit the fire detection information every time in the uplink time slot assigned to itself in each frame until the confirmation message is received. It is characterized by.

  According to a seventh aspect of the present invention, in the second aspect of the invention, a unique address is assigned to a plurality of fire detectors, and a code assigned to a lower order of the address is an upstream time slot assigned to the own equipment in a frame. It corresponds to the code | symbol which shows the position of one to one.

  The invention according to claim 8 is the invention according to claim 7, wherein the control unit of the fire detector is assigned to a higher rank of its own address when transmitting the fire detection information and the response message to the receiving device. Only the code is transmitted to the radio transmission / reception unit in an uplink time slot assigned to the own device.

  The invention according to claim 9 is the invention according to claim 2, wherein the control unit of the fire detector has a timer synchronized with the synchronization signal, and the start timing of the downlink time slot estimated from the time measured by the timer and the radio signal An error with respect to the reception timing is calculated, and the start timing of the downlink time slot in the next frame is corrected based on the error.

  According to the first aspect of the present invention, information is transmitted from the receiving device in the downlink time slot, and information is transmitted from the fire detector in the individually assigned uplink time slot. Even when the frequency of information exchange with the fire detector is high, collisions can be reliably avoided.

  According to the invention of claim 2, each fire detector can determine the timing of the upstream time slot assigned to the fire detector based on the synchronization signal transmitted from the receiving device. Since it is only necessary to perform the receiving operation only in the time period expected to be transmitted, wasteful power consumption can be reduced.

  According to the third aspect of the present invention, it is possible to cause all the fire detectors to return a response message without increasing the frequency of sending a periodic reply request message in the receiving device.

  According to the invention of claim 4, even if the reply request message cannot be received by the fire detector due to the influence of noise, interference waves, etc., the reply message is sent back to the fire detector again to ensure periodic message exchange. Can be done.

  According to the fifth aspect of the present invention, the fire detection information transmitted from the fire detector is reliably transmitted to the receiving device without colliding with the periodically exchanged message or the fire detection information transmitted from another fire detector. Can be sent.

  According to the sixth aspect of the present invention, even when the fire detection information cannot be received by the receiving device due to the influence of noise or interference wave, the fire detection information is transmitted again to the fire detector and is reliably received by the receiving device. be able to.

  According to the invention of claim 7, it is not necessary to set up time slot allocation information other than the unique address for the fire detector.

  According to the invention of claim 8, the transmission time of the radio signal from the fire detector to the receiving device can be shortened, and the power consumption in the fire detector can be reduced.

  According to the ninth aspect of the present invention, the error of the start timing of the time slot that has occurred between the receiving device and the fire detector in the previous frame can be corrected in the next frame.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

FIG. 2 is a system configuration diagram of this embodiment, and a fire alarm system is configured by one receiving device 1 and a plurality of fire detectors 10. In the following, when the fire detectors 10 are shown individually, they are indicated as fire detectors 10 ₁ , 10 ₂ ,..., 10 _n, and when they are shown collectively, they are indicated as fire detectors 10.

  The fire detector 10 is installed on the ceiling of a facility, for example, and as shown in FIG. 3A, a detection unit 11 that detects a fire by detecting a temperature change and smoke generated by a fire. And a radio transmission / reception unit 12 for transmitting / receiving a radio signal using a radio wave as a medium to / from the receiving apparatus 1 by modulating / demodulating a data format to be described later to a carrier wave of a prescribed frequency, For transmitting and receiving wireless signals, a control unit 13 for transmitting information and response messages by wireless signals, a sensing unit 11 using a battery as a power source, a wireless transmission / reception unit 12, and a battery power unit 14 for creating an operating power source for the control unit 13 An antenna 15 and a switch 16 that opens and closes a power feeding path from the power supply unit 14 to the wireless transmission / reception unit 12 under the control of the control unit 13 are provided. The control unit 13 includes a microcomputer and a nonvolatile memory such as an EEPROM as main components, and executes various processes described later by executing a program stored in the nonvolatile memory. Each fire detector 10 is given a unique address at the time of manufacture or construction and is stored in the nonvolatile memory of the control unit 13.

  On the other hand, the receiving device 1 is installed in, for example, a management room of a facility. As shown in FIG. 3B, the receiving device 1 modifies and demodulates a data format, which will be described later, to a carrier wave of a prescribed frequency. A wireless transmission / reception unit 2 for transmitting / receiving a radio signal using radio waves as a medium, an operation switch 3a for performing various settings, and a display device (for example, a liquid crystal display) 3b for performing a fire alarm and various displays In addition, a display operation unit 3 including a speaker 3c that sounds an alarm sound, an alarm message, and the like, a control unit 4 that controls the wireless transmission / reception unit 2 and the display operation unit 3, a wireless transmission / reception unit 2, and a display operation unit 3 from a commercial power source. A power supply unit 5 that creates an operating power supply for the control unit 4 and an antenna 6 for transmitting and receiving radio signals are provided. The control unit 4 includes a microcomputer and a nonvolatile memory such as an EEPROM as main components, and executes various processes described later by executing a program stored in the nonvolatile memory. A unique address different from that of the fire detector 10 is also given to the receiving device 1 at the time of manufacture or construction, and is stored in the nonvolatile memory of the control unit 4.

  Here, a frequency that does not require a license is used for wireless communication between the receiving device 1 and the fire detector 10. For example, radio characteristics conforming to low power security and specific low power radio standards in Japan, FCC Regulations Part 15 SubpartC in the US, and Short Range Device standards in Europe must be satisfied.

  A data format of data exchanged between the receiving device 1 and the fire detector 10 is shown in FIG. This data format consists of a 32-bit preamble (bit synchronization pattern) PR in which 1 and 0 alternate, a 16-bit unique word (frame synchronization pattern) UW consisting of a prescribed bit string, and a 32-bit allocated to the fire alarm system. A unique ID (system ID) SysID, an 8-bit unique ID (sensor ID) NodeID assigned to each fire detector 10, a 16-bit message Msg, and a 16-bit error detection code CRC Is done. That is, the unique address of the fire detector 10 is the system ID + sensor ID, and the unique address of the receiving device 1 is the system ID.

  When the receiving device 1 transmits a message specifying a specific fire detector 10, the detector ID of the fire detector 10 is specified as the sensor ID of the data format, and all the fire detectors 10 are specified. When broadcasting a message, it is only necessary to specify “0 (zero)” for the sensor ID of the data format. Further, when the fire sensor 10 sends a reply to the receiving device 1, the sensor ID of its own device may be set to the sensor ID of the data format and transmitted.

  On the other hand, in the fire detector 10 and the receiving device 1 that have received the wireless signal, the wireless transmission / reception units 12 and 2 amplify the reception signal, demodulate the data format, and output to the control units 13 and 4. The control units 13 and 4 sample the data demodulated by the radio transmission / reception units 12 and 2 at a digital input port provided in the microcomputer, extract the bit timing during reception of the preamble PR, and then successively 16 bits. The unique word is detected by shifting the received bits for one minute at a time until it matches the specified unique word. Furthermore, the control units 13 and 4 collate the received system ID and sensor ID with the unique address stored in the nonvolatile memory, and accept the message Msg when they match and no bit error is detected. .

  By the way, in this embodiment, the radio | wireless communication between the receiver 1 and the some fire detector 10 is performed by a time division multiple access (TDMA) system. That is, as shown in FIG. 5, the time slot B in one downstream direction (receiver 1 → fire detector 10) and the time in a plurality (99 in the illustrated example) upstream (fire detector 10 → receiver 1). A plurality of (30 in the illustrated example) frames F1 to F30 including slots D1 to D99 are collected to form a super frame SF, and the upstream time slots D1 to D99 in the frames F1 to F30 are assigned to each fire detector 10. By assigning them individually, the frequency of periodic message exchange (reply request message and response message exchange) is relatively high, for example, even once in 300 seconds in the above EN standard. The collision between the radio signals transmitted from the fire detector 10 can be reliably avoided. The time slots B and Di (i = 1 to 99) in the down direction and the up direction have a period of 100 milliseconds, and the breakdown is 50 milliseconds in the above data format. The wireless transmission / reception unit of the receiver 1 and the fire detector 10 20 milliseconds are assigned to the time (startup time) until the transmission is possible at a stable carrier frequency after starting 2 and 12, and 15 milliseconds are assigned to the guard time. The guard time is a free time for absorbing a timing difference caused by an error between the operation clock frequencies of the fire detector 10 and the receiver 1 (the operation clock frequency of the microcomputer configuring the control units 13 and 4). Further, the allocation of the upstream time slots D1 to D99 to each fire detector 10 is set by, for example, a dip switch provided in the fire detector 10, or stored in advance in the nonvolatile memory of the control unit 13 in the manufacturing process. Alternatively, it may be performed by a method such as assigning to each fire detector 10 in order from the receiving device 1 using wireless communication at the time of installation and storing in the nonvolatile memory of the control unit 13.

  Next, the operation of this embodiment will be described. First, a reply request message is periodically transmitted from the receiving device 1 to all the fire detectors 10, and a response message returned from each fire detector 10 is received by the receiving device 1. The operation for confirming whether the device 10 is operating normally will be described with reference to the time chart of FIG. 1 and the flowchart of FIG.

  When the power is turned on, the control unit 4 of the receiving apparatus 1 sets the sensor ID of the data format to “0” in the downstream time slot B of the first frame F1 of the super frame SF, and sends a reply request message as the message Msg. Is sent to all the fire detectors 10. On the other hand, in the fire detector 10, immediately after the power is turned on, the control unit 13 closes the switch 16 to supply power to the wireless transmission / reception unit 12, and is in a continuous reception state until a synchronization signal (reply request message) is received. (Steps S1 and S2 in FIG. 6). If the reply request message can be received, the control unit 13 of the fire detector 10 opens the switch 16, cuts off the power supply to the wireless transmission / reception unit 12 and stops continuous reception (step S 3 in FIG. 6), and then built in the microcomputer. The started first timer, second timer, and third timer are started (step S4 in FIG. 6). The first timer is the time from the end of the downlink time slot B in the first frame F1 to the end of the superframe SF (for example, each of the frames F1 to F30 is 10 seconds, the superframe SF is 300 seconds, If the time slot in each of the downstream and upstream directions is 100 milliseconds, 300−0.1 = 299.9 seconds) is counted. In addition, the second timer is configured so that the upstream time slot Di (i = 1 to 99) individually assigned to each fire detector 10 from the time when the downstream time slot B ends in each frame Fk (k = 1 to 30). ) Is counted (for example, 0.1 × (number of upstream time slot Di i−1)). Further, the third timer is a time (for example, 10−0.1 = 9.9) from the time when the downlink time slot B ends in each frame Fk (k = 1 to 30) to the time when the frame Fk ends. Seconds).

  The control unit 13 of each fire detector 10 can determine the start time point of the upstream time slot Di assigned to itself by the end of the counting of the second timer, and the assigned upstream time slot. A response message to the reply request message of the receiving apparatus 1 is transmitted from the wireless transmission / reception unit 12 by Di, and then a fourth timer built in the microcomputer is started (steps S5 and S6 in FIG. 6). The fourth timer is a time from the end time of the uplink time slot Di assigned to itself in a certain frame Fk to the start time of the uplink time slot Di assigned to itself in the next frame Fk + 1 (for example, 10−0.1 = 9.9 seconds).

  On the other hand, the control unit 4 of the receiving device 1 receives a response message returned from each fire detector 10 in the upstream time slots D1 to D99 in the first frame F1 that has transmitted the reply request message. The content of the response message is the presence or absence of an abnormality in the fire detector 10 (for example, the battery voltage drops below a threshold value or the malfunction of the sensing unit 11), and the fire detector returns an abnormal response message. The control unit 4 of the receiving device 1 displays ten sensor IDs on the display operation unit 3 to notify the system administrator. In addition, when the response message from all the fire detectors 10 included in the system is received, the control unit 4 of the receiving device 1 designates “0” for the sensor ID of the data format and sends a reception completion message to the message Msg. As a result, broadcast transmission is performed to all the fire detectors 10 in the downstream time slot B of the second frame F2.

  When the third timer expires, the control unit 13 of the fire detector 10 closes the switch 16 and operates the wireless transmission / reception unit 12 to receive the downlink time slot B in the second frame F2, and the third timer The timer is started again (steps S7 and S8 in FIG. 6). At this time, if the response messages from all the fire detectors 10 are normally received by the receiving device 1, the reception completion message should be received in the downlink time slot B in the second frame F2. Therefore, when the control unit 13 of the fire detector 10 receives the reception completion message (step S9 in FIG. 6), the switch 16 is opened until the first timer expires to stop the operation of the wireless transmission / reception unit 12 (FIG. 6). 6, when the first timer expires and the next super frame SF is started, the switch 16 is closed again to operate the wireless transmission / reception unit 12 to set the downlink time slot B in the first frame F1. (Step S11 in FIG. 6), the first to third timers are started and the above-described processing is repeated for each superframe.

By the way, even if the fire detector 10 is normal, there may occur a case where the reception device 1 cannot receive a response message from the fire detector 10 due to the influence of external noise, interference waves, or the like. For example, if one return signal T of the fire detector 10 ₃ of the three fire detectors 10 _1, 10 _2, 10 ₃ as shown in FIG. 1 can not be received by the receiving apparatus 1, received The control unit 4 of the apparatus 1 designates the sensor ID of the fire sensor 10 ₃ to which the upstream time slot D3 in which the response message could not be received is assigned instead of the reception completion message as the sensor ID of the data format. In addition, an individual reply request message is transmitted as a data format message Msg in the downlink time slot B of the second frame F2.

On the other hand, in the control unit 13 of the fire detectors 10 ₁ and 10 ₂ that has received the response message normally, the detector ID of the data format transmitted in the downstream time slot B of the second frame F2 is detected by itself. The reply request message is not accepted because it does not match the device ID (step S12 in FIG. 6), and the switch 16 is opened until the third timer expires, and the wireless transmission / reception unit 12 is stopped. On the other hand, the control unit 13 of the fire detector 10 ₃ in which the response message has not been normally received has detected that the detector ID of the data format transmitted in the downstream time slot B of the second frame F2 is its own device. When the response request message is received because it matches the device ID (step S12 in FIG. 6) and the fourth timer ends, that is, the upstream time allocated in the second frame F2 as shown in FIG. The response message is transmitted again in slot D3 (steps S13 and S6 in FIG. 6). In addition, when there are a plurality of fire detectors 10 that could not receive the response message in the first frame F1, the control unit 4 of the receiving device 1 specified each detector ID in the second and subsequent frames F2 and F3. Reply request messages are sequentially transmitted, and transmission of individual reply request messages is repeated until response messages of all the fire detectors 10 can be received. In this case, until the reception completion message is received in the downlink time slot B, the control unit 13 of the fire detector 10 continues to receive the downlink time slot B of each frame Fk, and after receiving the reception completion message, In the frame, the switch 16 is opened to stop the wireless transmission / reception unit 12.

  Here, when the frames F1 to F30 are each 10 seconds, the superframe SF is 300 seconds, and the time slot in each of the downstream and upstream directions is 100 milliseconds, the response message to the reply request message is all normal in the first frame F1. If it can be received at the same time, the receiving apparatus 1 transmits a reply request message in the downlink time slot B of the first frame F1 and a reception completion message in the downlink time slot B of the second frame F2 in the super frame SF of 300 seconds. Therefore, the transmission time duty is 0.1 seconds × 2/300 seconds × 100≈0.067%, and the transmission time duty limit value (= 0) in the alarm frequency used in the fire alarm system in the European Union Less than 1%).

  Next, the operation when a fire is detected by any of the fire detectors 10 will be described with reference to the flowchart of FIG. 7 and the time chart of FIG. The following process performed by the control unit 13 of the fire detector 10 when a fire is detected is an interrupt process (subroutine) for the above-described process (main routine shown in the flowchart of FIG. 6) that is always repeated.

  The control unit 13 of the fire detector 10 determines whether the second timer is counting when the detection unit 11 detects a fire (step S1 in FIG. 7). In other words, if the second timer is counting, the uplink time slot Di assigned in the frame Fk has not yet passed, so the uplink direction assigned to the own device when the second timer ends. The fire detection information is transmitted as a message Msg to the receiving device 1 through the time slot Di, and the fourth timer is started after the transmission (steps S2 and S3 in FIG. 7). In addition, if the second timer is not counting, the uplink time slot Di assigned in the frame Fk has already passed, so the control unit 13 of the fire detector 10 That is, the fire detection information is transmitted as the message Msg to the receiving device 1 by the uplink time slot Di assigned in the next frame Fk + 1, and the fourth timer is started after transmission (steps S7 and S3 in FIG. 7).

  The control unit 4 of the receiving device 1 that has received the fire detection information from the fire detector 10 specifies the detector ID of the fire detector 10 that is the transmission source of the fire detection information, and completes reception indicating that the fire detection information has been received. The message is transmitted as a message Msg in the downlink time slot B in the frame Fk + 1 (or Fk + 2) next to the frame Fk (or Fk + 1) that has received the fire detection information.

  The control unit 13 of the fire detector 10 that has transmitted the fire detection information closes the switch 16 when the third timer expires and operates the wireless transmission / reception unit 12 to operate the downlink time slot in the next frame Fk + 1 (or Fk + 2). B is received and the third timer is started again (steps S4 and S5 in FIG. 7). Furthermore, if the control unit 13 receives a reception completion message from the receiving device 1 in the downlink time slot B, the control unit 13 returns to the main routine (the flowchart in FIG. 6) without retransmitting the fire detection information. However, since the reception completion message is not transmitted from the reception device 1 unless the reception device 1 can receive the fire detection information from the fire detector 10 due to the influence of external noise or interference waves, the control unit 13 displays the reception completion message. If not received, the fire detection information is retransmitted at the end of the fourth timer, that is, in the upstream time slot Di assigned in the next frame Fk + 2 (or Fk + 3) (steps S6 and S8 in FIG. 7). Until the reception completion message is received from the reception device 1, the fire detection information is retransmitted repeatedly to reliably notify the reception device 1 of the occurrence of the fire.

For example, when having detected a fire in a frame F1 fire detector 10 _2, 10 ₃ is the head of two of the three sets of the fire detector 10 _1, 10 _2, 10 ₃ as shown in FIG. 8, fire sends fire information in the uplink direction time slot D2 assigned in the fire detector 10 ₂ in the next frame F2 of the uplink time slot D2 assigned to the own vessels has already elapsed at the time of the sensing, transmitting the fire information in the uplink time slot D3 of the uplink time slot D2 of at the time of sensing the fire allocated to the own vessel is allocated in the fire detector 10 ₃ in the frame F1 is not yet expired. On the other hand, the receiving apparatus 1 transmits the reception completion message to the fire detector 10 ₃ in the downlink time slot B in the second frame F2, the fire detector 10 ₂ in downlink time slot B in the third frame F3 A reception completion message is transmitted to.

  As described above, the fire detector 10 that has detected a fire in the sensing unit 11 transmits the fire detection information to the receiving device 1 in the frame Fk + 1 next to the frame Fk at the time of detecting the fire at the latest. The fire detection information can be transmitted to the receiving apparatus 1 within 10 seconds of the frame period from the first frame, and the standard value (within 10 seconds from detection) of the European EN standard (EN54-25) can be satisfied.

  By the way, in this embodiment, the upstream time slot having the same slot number as the sensor ID that determines the unique address is assigned to each fire sensor 10. For example, in each fire sensor 10, a sensor ID that matches the slot number is stored in the nonvolatile memory, and the control unit 13 assigns the same slot number as the sensor ID stored in the nonvolatile memory. What is necessary is just to set to the upstream time slot Di, and the trouble which sets or sets separately the sensor ID and the slot number of the allocated upstream time slot in a non-volatile memory can be saved.

  Further, in the receiving device 1, since the upstream time slot having the same slot number as the sensor ID that determines the unique address is assigned to each fire detector 10, when a message is received in the upstream time slot Di, The fire detector 10 that is the source of the message can be immediately known from the slot number i of the upstream time slot Di. Therefore, the sensor ID can be omitted from the data format shown in FIG. 4, the message transmission time can be shortened, and the current consumption of the fire sensor 10 can be reduced.

  As shown in FIG. 5, in this embodiment, a guard time of 15 milliseconds is provided before and after one time slot B, Di. On the other hand, the control unit 13 of the fire detector 10 detects the synchronization signal (reply request message) transmitted from the receiving device 1 and then starts the first timer to start the next superframe SF (at the beginning) (The start timing of the downlink time slot B in the frame F1), but the error between the operation clock of the microcomputer constituting the control unit 13 and the operation clock of the microcomputer constituting the control unit 4 of the receiving device 1 Therefore, an error may occur in the time length of the super frame SF counted by the first timer. Since the guard time is 15 milliseconds, only a relative error of 15 milliseconds ÷ 299.9 seconds = 50 ppm is acceptable. In other words, the absolute error allowed for the microcomputer constituting the fire detector 10 and the control units 13 and 4 of the receiver 1 is ± 25 ppm, even if the clock of the microcomputer is created using a crystal oscillator. In order to satisfy the absolute error, the cost is considerably increased.

  Therefore, the control unit 13 of the fire detector 10 obtains an error between the start timing of the super frame SF estimated by the count of the first timer and the timing at which the synchronization signal is actually received from the receiving device 1 to obtain the next super frame. If the error is corrected by estimating the SF start timing, the estimation error of the super frame SF caused by the microcomputer operating clock as described above can be suppressed, and the tolerance for the microcomputer operating clock can be relaxed. There is an advantage that the cost can be reduced.

  In the present embodiment, when a fire is detected by the fire detector 10, it is displayed on the display operation unit 3 of the receiving device 1 to notify the system administrator. For example, a plurality of receiving devices 1 are provided. Is connected to the central monitoring board by wire, and the fire detection information received by the receiving device 1 is relayed to the central monitoring board by wired communication, and necessary countermeasures are taken in the central monitoring board (for example, issuing a fire alarm or reporting to the fire department) Etc.).

It is a time chart for demonstrating the operation | movement of the periodic message exchange of embodiment of this invention. It is a system block diagram same as the above. (A) is a block diagram of a fire detector in the same as above, (b) is a block diagram of a receiving device. It is explanatory drawing of the data format in the same as the above. It is a block diagram of the super frame in the same as the above. It is a flowchart for demonstrating the operation | movement of the periodic message exchange same as the above. It is a flowchart for demonstrating the operation | movement at the time of the fire detection in the same as the above. It is a time chart for demonstrating the operation | movement at the time of the fire detection same as the above.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Receiver 10 Fire detector 11 Sensor 12 Wireless transmitter / receiver 13 Controller

Claims (9)

A plurality of fire detectors for detecting a fire, and a receiver for performing wireless communication using radio waves as a medium between the fire detectors;
A fire detector is a sensor that detects fire by detecting temperature changes and smoke generated by a fire, a wireless transmitter / receiver that transmits and receives radio signals to and from the receiver, and at least the detector detects a fire. A control unit that controls the wireless transmission / reception unit to transmit fire detection information by a wireless signal when sensed,
The receiving device includes a wireless transmission / reception unit that transmits / receives a wireless signal to / from the fire detector, and a control unit that controls the wireless transmission / reception unit and obtains fire detection information from the wireless signal received by the wireless transmission / reception unit,
The control unit of the receiving device and the fire detector includes one downstream time slot from the receiving device to the fire detector, and a plurality of upstream ports from the fire detector to the receiving device assigned to each fire detector. A fire alarm system that transmits and receives various information including fire detection information in a super frame in which a predetermined number of frames composed of time slots are collected. The control unit of the reception device causes the wireless transmission / reception unit to transmit a synchronization signal in a downlink time slot in one frame included in the superframe,
2. The fire alarm according to claim 1, wherein the control unit of the fire detector determines a timing at which an upstream time slot assigned to the self-device starts when a synchronization signal is received by the wireless transmission / reception unit. system. The control unit of the reception device periodically transmits a transmission request message for requesting a predetermined response from all radio detectors from the wireless transmission / reception unit in the same downlink time slot as the synchronization signal,
When the control unit of the fire detector receives the transmission request message, the control unit of the fire detector operates in the uplink time slot assigned in the same frame as the frame including the downlink time slot that received the transmission request message. The fire alarm system according to claim 2, wherein a predetermined response message indicating the above is returned to the wireless transmission / reception unit. The control unit of the receiving device applies only to the fire detector in the downstream time slot of the next frame in the same superframe for the fire detector assigned to the upstream time slot for which the response message could not be received. To send a transmission request message to the wireless transceiver
The control unit of the fire detector causes the wireless transmission / reception unit to return a response message again when a transmission request message for the device is received in the downlink time slot in the frame next to the frame in which the previous response message was transmitted. The fire alarm system according to claim 3.   3. The fire alarm according to claim 2, wherein the control unit of the fire detector causes the wireless transceiver to transmit fire detection information in the next assigned uplink time slot when the fire is detected by the detection unit. system. When receiving the fire detection information, the control unit of the receiving device causes the wireless transmitter / receiver to transmit a confirmation message to the source fire detector in the downlink time slot,
The control unit of the fire detector that has transmitted the fire detection information causes the wireless transmission / reception unit to transmit the fire detection information every time in the uplink time slot assigned to the device in each frame until the confirmation message is received. The fire alarm system according to claim 5.   A unique address is assigned to a plurality of fire detectors, and a code assigned to the lower part of the address corresponds to a code indicating the position of the upstream time slot assigned to the fire detector in the frame on a one-to-one basis. The fire alarm system according to claim 2.   When transmitting fire detection information and response messages to the receiving device, the control unit of the fire detector uses only the code assigned to the higher rank of its own address in the uplink time slot assigned to its own device. 8. The fire alarm system according to claim 7, wherein the fire alarm system is transmitted to a radio transceiver unit.   The control unit of the fire detector has a timer synchronized with the synchronization signal, obtains an error between the start timing of the downlink time slot estimated from the time measured by the timer and the reception timing of the radio signal, and based on the error. The fire alarm system according to claim 2, wherein the start timing of the downlink time slot in the next frame is corrected.

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