JP2018093485A - Communication device and system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To perform radio signal transmission between a control board and a car without degrading safety.SOLUTION: A communication device installed in a car is communicably connected to a plurality of radio devices installed in an elevator path. The communication device selectively performs broadcast communication and unicast communication with a communication destination radio device among the radio devices, using a first frequency and a second frequency different from the first frequency. At the unicast communication with the communication destination radio device, if the acquisition of response confirmation from the radio device in the first frequency fails, the communication device changes a time slot for the unicast communication in the first frequency to a time slot for the broadcast communication, in regard to a communication frame which includes a plurality of time slots.SELECTED DRAWING: Figure 1

Description

  Embodiments described herein relate generally to a communication device and a system.

  Generally, an elevator is provided with a device for controlling the entire elevator, called a control panel.

  The control panel drives the hoisting machine to control the raising / lowering operation of the car in the hoistway and, for example, a control signal for controlling opening / closing of the car door landing on a predetermined landing is given to the car. To transmit.

  On the other hand, a control signal called a car call that is output in response to an operation on a destination floor button provided in the car is transmitted from the car to the control panel. In addition to the control signal, a regulation signal indicating the opening / closing state of the car door is transmitted from the car to the control panel in order to monitor whether the car is running open.

  Such signal transmission between the control panel and the car is performed by wire via a transmission cable called a tail cord that connects the control panel and the car.

JP-A-2015-199581

  However, when the up-and-down stroke in which the car travels is a long distance, it is necessary to lengthen the tail cord described above.

  When the tail cord is lengthened in this way, the weight of the tail cord increases. Since the tail cord is connected to the car, it is necessary to increase the capacity of the hoist for moving the car up and down as the weight of the tail cord increases.

  For this reason, a mechanism has been devised in which signal transmission between the control panel and the car is performed wirelessly without using a tail cord.

  However, in the case of wireless signal transmission, signal transmission may not be stable depending on the environment. If stable signal transmission cannot be performed, there is a possibility that the transmission of the above-mentioned regulatory signal may be interrupted, which leads to a disadvantage that safety is lowered.

  The problem to be solved by the present invention is to provide a communication apparatus and system capable of realizing wireless signal transmission between a control panel and a car without deteriorating safety.

  The communication device according to the embodiment is connected to a plurality of wireless devices so as to be able to perform wireless communication. The communication apparatus uses a first frequency and a second frequency different from the first frequency to selectively perform broadcast communication and unicast communication with a communication destination wireless apparatus among the wireless apparatuses. When a response confirmation cannot be obtained from the wireless device at any of the frequencies during unicast communication between the communication means and the communication destination wireless device, the communication frame includes a plurality of time slots. First changing means for changing a communication time slot to a broadcast communication time slot.

FIG. 1 is a diagram illustrating a schematic configuration example of an elevator system including a communication device according to the first embodiment. FIG. 2 is a diagram illustrating an example of a data structure of a communication destination selection table regarding the communication apparatus according to the embodiment. FIG. 3 is a block diagram illustrating a functional configuration example of the communication apparatus according to the embodiment. FIG. 4 is a diagram for explaining communication frames in the communication apparatus according to the embodiment. FIG. 5 is a flowchart showing an example of a procedure of wireless communication processing executed by the communication apparatus according to the embodiment. FIG. 6 is a diagram for supplementarily explaining the flowchart of FIG. FIG. 7 is another diagram for supplementarily explaining the flowchart of FIG. FIG. 8 is still another diagram for supplementarily explaining the flowchart of FIG. FIG. 9 is a diagram for explaining the advantages of the communication apparatus according to the embodiment. FIG. 10 is a flowchart illustrating an example of a procedure of wireless communication processing executed by the communication device according to the second embodiment.

Hereinafter, embodiments will be described with reference to the drawings.
In the following, a case where IEEE 802.11 is used as a wireless communication method will be described as an example, but other wireless communication methods may be used.

<First Embodiment>
FIG. 1 is a diagram illustrating a schematic configuration example of an elevator system including a communication device according to the first embodiment. In the elevator system shown in FIG. 1, a control panel (hereinafter referred to as “elevator control device”) 11 that controls the entire elevator is provided in the upper machine room. A car 12 and a counterweight 13 are provided in the hoistway and are supported by guide rails (not shown) so as to be able to move up and down.

  A car 12 is connected to one end of the main rope 14, and a counterweight 13 is connected to the other end of the main rope 14. The main rope 14 is wound around a main sheave 16 a attached to the rotating shaft of the hoisting machine 15. Reference numeral 16b denotes a deflecting sheave. The hoisting machine 15 is installed in the upper machine room together with the elevator control device 11. When the hoisting machine 15 is driven by a drive instruction from the elevator control device 11, the car 12 moves up and down together with the counterweight 13 via the main rope 14.

  Although not shown in FIG. 1, a car control device is provided at the top of the car 12. The car control device performs opening / closing control of the car door of the car 12 landing on the landing, driving control of the lighting equipment, air conditioning control, and the like in accordance with an instruction from the elevator control device 11.

  A car operation panel 17 that is operated by passengers is provided in the car 12. The car operation panel 17 is provided with a destination floor button 17a corresponding to each floor, a door opening / closing button 17b for controlling the door opening / closing of the car door, and the like. The destination floor button 17a is a button for registering a passenger's destination floor (destination floor). When the destination floor button 17a is operated (pressed) by the passenger, a control signal (hereinafter referred to as “car call”) indicating the destination floor operated by the passenger is output.

  A hall call button 18 is provided at the hall on each floor where the car 12 is landed. The hall call button 18 is a button for registering the position of the hall where the passenger gets on the car 12. When the hall call button 18 is operated (pressed) by a passenger at a predetermined hall, the hall information indicating the floor where the hall call button 18 is installed and the control indicating the destination direction (up or down) A signal (hereinafter referred to as “call hall”) is output.

  Here, as shown in FIG. 1, in the elevator system according to the present embodiment, various types of wireless communication are used instead of wired communication using a tail cord that connects the elevator controller 11 and the car 12. Send and receive signals. For this reason, the car 12 is provided with a communication device 21 that functions as an access point (AP) compliant with IEEE 802.11, as shown in FIG. A plurality of wireless devices 22 functioning as IEEE 802.11 compliant stations (STAs) are provided in the hoistway. In addition, the some radio | wireless apparatus 22 is connected with the elevator control apparatus 11 with the wire as shown in FIG. Further, as shown in FIG. 1, each of the plurality of wireless devices 22 may be connected to each adjacent wireless device 22 by wire.

  Although FIG. 1 illustrates the case where the communication device 21 is provided on both the top and bottom of the car 12, the communication device 21 is provided only on either the top or the bottom of the car 12. May be. In addition, FIG. 1 illustrates a case where a plurality of wireless devices 22 are provided on each floor in addition to the top (top gap) and bottom (pit) of the hoistway. Two or more predetermined floors may be provided. However, considering the redundancy of the communication path, it is preferable that the plurality of wireless devices 22 be arranged so that the communication device 21 that moves together with the car 12 can always communicate with two or more wireless devices 22.

  The communication device 21 considers the redundancy of the communication path and uses each first radio and each radio installed in the hoistway using a second frequency that is a frequency different from the first frequency. The device 22 is connected to be communicable. Which wireless device 22 the communication device 21 is communicably connected to is determined based on, for example, a communication destination selection table shown in FIG. The communication destination selection table shown in FIG. 2 is a table in which the current position of the car 12 is associated with one or more wireless devices 22 near the current position. That is, the communication device 21 that moves together with the car 12 is communicably connected to one or more wireless devices 22 that are located near the current position of the car 12. In addition, when the movement plan which shows how the car 12 moves is decided, the communication apparatus 21 which moves with the car 12 is one or more radio | wireless apparatuses 22 near a movement destination according to the said movement plan. You may connect so that communication is possible. According to this, for example, even after the car 12 has just passed the vicinity of the wireless device 22 closest to the current position, the communication device 21 communicates with the wireless device 22 that moves away as the car 12 moves. It is not possible to connect, but according to a predetermined movement plan, since it is communicably connected to the wireless device 22 located in the vicinity of the next destination, a wireless communication link with the wireless device 22 can be established more reliably. Can be established.

  Here, the case where the communication destination of the communication device 21 is one or more wireless devices 22 near the current position of the car 12 has been described. However, for example, the communication destination of the communication device 21 is the current position of the car 12. It may be one or more wireless devices 22 having good radio field strength and low bit error rate (BER) and packet error rate (PER).

  Here, the function of the communication device 21 will be described with reference to FIG. Although detailed description is omitted here, the functional configuration of the wireless device 22 is the same as that of the communication device 21.

  As shown in FIG. 3, the communication device 21 includes a control unit 21a and a communication unit 21b. The communication destination selection table shown in FIG. 2 is stored in advance in a memory (not shown). The control unit 21 a controls various operations of the communication device 21. The communication unit 21b communicates with a plurality of wireless devices 22 provided in the hoistway, and has a function of selectively performing unicast communication (UC: Unicast) and broadcast communication (BC: Broadcast). Specifically, the communication unit 21b transmits a control signal to each wireless device 22 by unicast communication and receives a response confirmation (ACK response). In addition, the communication unit 21b transmits a legal signal, which will be described later, to each wireless device 22 by broadcast communication. Furthermore, the communication part 21b receives the control signal transmitted by unicast communication from each radio | wireless apparatus 22, and transmits a response confirmation.

  Although the communication unit 21b selectively performs unicast communication and broadcast communication here, the communication unit 21b may perform multicast communication (MC: Multicast) instead of broadcast communication. Further, the communication unit 21b selectively performs various types of communication, so that it is not necessary to provide a dedicated communication device for each type of communication, and the cost for installing the communication device can be reduced.

  The control signal is a signal for controlling various operations of the elevator, and examples of the control signal transmitted from the communication device 21 to each wireless device 22 include the car call described above. The control signal transmitted from each wireless device 22 to the communication device 21 includes, for example, a signal for feeding back the hall call to the car 12, a signal indicating the current position (movement status) of the car 12, Examples thereof include a signal for controlling the moving speed of the car 12, a signal for instructing opening / closing of the car door 12, and the like.

  Note that since the control signal is a signal with a response confirmation as described above, the control signal transmission source device determines that the transmission destination device correctly sends the control signal according to whether or not the response confirmation is obtained. Whether or not it has been received can be confirmed.

  The regulation signal is a signal indicating the door open / closed state of the car door, and is used to determine whether the car 12 is running open. Since the regulation signal is a signal without a response confirmation unlike the control signal, the communication device 21 that is the transmission source of the regulation signal determines whether the wireless device 22 that is the transmission destination has received the regulation signal normally. Can not be confirmed.

  When a wireless communication link is established with the communication destination wireless device 22 determined based on the communication destination selection table, the communication unit 21b transmits a control signal by unicast communication and receives a response confirmation for each communication frame. To do. Or a regulation signal is transmitted by broadcast communication. Furthermore, the control signal from each radio | wireless apparatus 22 is received by unicast communication, and a response confirmation is transmitted. The communication frame indicates a predetermined communication time defined for transmitting and receiving signals and includes a plurality of time slots. The time slot indicates a time allocated for performing unicast communication. Alternatively, the time allocated for performing broadcast communication is indicated.

  In the present embodiment, as shown in FIG. 4, the first frequency is 2.4 GHz, the second frequency is 5.2 GHz, and three time slots are included in every communication frame (for example, 4 ms). A description will be given assuming that this is the case. However, frequencies other than the above-described frequencies may be used as the first and second frequencies. Further, the number of time slots included in one communication frame is not limited to the above numerical values.

  Note that the control unit 21a and the communication unit 21b may cause a processing device such as a CPU (Computer Processing Unit) (not shown) to execute a program stored in a memory (not shown), that is, may be realized by software or an IC ( It may be realized by hardware such as (Integrated Circuit), or may be realized by using software and hardware together.

Next, an example of a procedure of wireless communication processing executed by the communication device 21 configured as described above will be described with reference to the flowchart of FIG. However, a description will be given on the assumption that a wireless communication link with the communication destination wireless device 22 has already been established.
First, the communication device 21 selectively performs unicast communication and broadcast communication according to the assigned time slot for each communication frame using the first and second frequencies. More specifically, the communication device 21 transmits a control signal to the wireless device 22 that is a communication destination by unicast communication, and receives a response confirmation in response thereto. Alternatively, a control signal is received from the wireless device 22 that is the communication destination by unicast communication, and a response confirmation is transmitted. Alternatively, a regulation signal is transmitted to the wireless device 22 as a communication destination by broadcast communication (step S1).

  For example, as shown in FIG. 6, the number of time slots included in one communication frame is three, and these time slots are allocated in time series in the order of broadcast communication, broadcast communication, and unicast communication. The communication device 21 first transmits a regulation signal to the wireless device 22 of the communication destination by broadcast communication using the first and second frequencies. Subsequently, similarly, a regulation signal is transmitted to the wireless device 22 of the communication destination by broadcast communication. Thereafter, a control signal is transmitted to the communication destination wireless device 22 by unicast communication, and a response confirmation is received for the control signal, and a control signal is received from the communication destination wireless device 22 and a response confirmation is transmitted. .

  Subsequently, the communication device 21 confirms whether or not a response confirmation for the control signal transmitted during the unicast communication is received at the first frequency (step S2). If a response confirmation is received from the wireless device 22 that is the communication destination (YES in step S2), the process returns to step S1, and the same process is executed after the next communication frame.

  On the other hand, when the response confirmation from the communication destination wireless device 22 has not been received (NO in step S2), the communication device 21 performs unicast communication at the first frequency after the next communication frame. Stop (stop) (step S3), and assign a time slot assigned for performing unicast communication to broadcast communication (step S4).

  Specifically, as shown in FIG. 7, a time slot assigned for performing unicast communication at the first frequency is set as a time slot for performing broadcast communication. That is, at the first frequency, all three time slots included in one communication frame are time slots for performing broadcast communication. On the other hand, since the assignment is not changed at the second frequency, the time slots included in one communication frame remain arranged in time series in the order of broadcast communication, broadcast communication, and unicast communication.

  Next, in the next communication frame in the second frequency, the communication device 21 is based on the control signal indicating the movement status of the car 12 transmitted from the wireless device 22 as the communication destination by unicast communication. It is determined whether or not is moving (step S5). Note that, at the first frequency, the communication device 21 transmits a regulation signal to the communication destination wireless device 22 by broadcast communication in all time slots as described above.

  Here, the control signal indicating the movement status of the car 12 is obtained from the wireless device 22 of the communication destination. For example, when the car 12 is provided with a device for grasping the movement status of the car 12, The control signal may be obtained from the device.

  If it is determined in step S5 that the car 12 is moving (YES in step S5), the communication device 21 executes the process in step S5 again after the next communication frame. That is, the communication device 21 transmits a regulation signal by broadcast communication in all time slots in the first frequency, and performs wireless communication processing in the order of broadcast communication, broadcast communication, and unicast communication in the second frequency. Then, based on the control signal indicating the movement status of the car 12 received during unicast communication, the process of step S5 is executed again.

  On the other hand, if it is determined in step S5 that the car 12 is not moving (NO in step S5), the communication device 21 stops the car 12 in the same communication frame at the second frequency. A control signal indicating that the wireless communication device 22 is transmitted to the wireless device 22 of the communication destination by unicast communication (step S6). When the elevator control device 11 receives an input of a control signal indicating that the car 12 is stopped via the wireless device 22, the elevator control device 11 instructs to try unicast communication according to the input of the control signal. Outputs a communication trial instruction. The communication trial instruction is transmitted to the communication device 21 via the wireless device 22.

  Here, the elevator control device 11 outputs a communication trial instruction when the car 12 is stopped. For example, the elevator control device 11 counts the number of communication errors during a predetermined period at the first frequency. The communication trial instruction may be output when is smaller than a predetermined threshold.

  When the communication device 21 receives a communication trial instruction by unicast communication at the second frequency, the communication device 21 performs unicast communication by using the time slot in which the allocation is changed in the next communication frame at the first frequency. A process of transmitting a control signal to the wireless device 22 of the communication destination is tried (step S7).

  Specifically, as shown in FIG. 8, the control signal is trial-transmitted to the wireless device 22 of the communication destination by unicast communication using the time slot in which the allocation change is performed at the first frequency. That is, at the first frequency, three time slots included in one communication frame are arranged in time series in the order of broadcast communication, broadcast communication, and provisional unicast communication.

  Note that the control signal that is trial-transmitted to the communication target radio apparatus 22 at the first frequency may be a control signal similar to the control signal transmitted at the second frequency, or for trial transmission. It may be a prepared control signal.

  In addition, here, the communication device 21 executes the process of step S7 described above when receiving a communication trial instruction from the elevator control device 11, but the communication device 21 is not limited to this, and the communication device 21 performs the above step. After the process of S6, the above-described process of step S7 may be spontaneously executed without receiving a communication trial instruction from the elevator control device 11.

  Thereafter, the communication device 21 confirms whether or not a response confirmation for the control signal trial-transmitted during the unicast communication is received at the first frequency (step S8). If the response confirmation from the wireless device 22 of the communication destination has not been received (NO in step S8), the communication device 21 executes the process of step S5 even after the next communication frame.

  On the other hand, when the response confirmation from the communication destination wireless device 22 has been received (YES in step S8), the communication device 21 reassigns the time slot whose assignment has been changed at the first frequency to the unicast communication. (Step S9), the process returns to Step S1, and the same process is executed after the next communication frame.

  In the wireless communication process described above, attention is paid to the presence or absence of a communication error at the first frequency. However, wireless communication that pays attention to the presence or absence of a communication error at the second frequency by exchanging the first frequency and the second frequency. Communication processing may be executed. Furthermore, the above-described wireless communication process may be executed by changing the frequency of interest at every predetermined time. That is, initially, wireless communication processing focusing on the presence or absence of communication errors at the first frequency is executed, and after a predetermined time has elapsed, wireless communication processing focusing on the presence or absence of communication errors at the second frequency is executed. The above-described wireless communication processing may be executed by alternately exchanging the frequency of interest.

According to the first embodiment described above, the following effects can be obtained.
In general, door-opening traveling is an event that should be avoided from the viewpoint of safety, and a regulatory signal used to determine whether or not door-opening traveling is required to be always input to the elevator control device 11. . On the other hand, the communication device 21 according to the present embodiment uses the response confirmation at the time of unicast communication, changes the time slot allocated to the unicast communication to the broadcast communication at the frequency with the communication error, It has a function of transmitting only the regulation signal to the wireless device 22 of the communication destination. According to this, even if a communication error occurs at random (suddenly), the regulatory signal can be transmitted in all the time slots included in one communication frame, so that the regulatory signal to the elevator control device 11 can be transmitted. Can reduce the possibility of interruption of input.

  Specifically, as shown in FIG. 9, after changing the assignment of the third time slot from unicast communication to broadcast communication among the three time slots included in one communication frame, the first and second Even if a communication error occurs continuously in the time slot, the regulation signal can be transmitted to the elevator control device 11 in the third time slot, so that the input of the regulation signal to the elevator control device 11 may be interrupted. Can be lowered.

<Second Embodiment>
Next, a second embodiment will be described. In the second embodiment, not only the time slot allocation is changed using response confirmation during unicast communication, but also the time slot allocation is changed in accordance with an instruction from the elevator controller 11. explain.

  Below, the function of the elevator control apparatus 11 is demonstrated first. It is assumed that the elevator control device 11 stores in advance a communication schedule of the communication device 21, that is, allocation information indicating allocation of time slots included in one communication frame in a memory (not shown).

  The elevator control device 11 refers to the allocation information stored in advance, and at each of the first and second frequencies, the regulations transmitted from the communication device 21 by broadcast communication according to the communication schedule indicated by the allocation information. It is determined whether or not a signal input is accepted.

  For example, as shown in FIG. 6, the number of time slots included in one communication frame is three, and these time slots are assigned in time series in the order of broadcast communication, broadcast communication, and unicast communication. In this case, the elevator control device 11 determines whether or not the input of the regulation signal is received twice for each of the first and second frequencies for each communication frame. As a result of the above determination, when the input of the regulation signal is received twice, it is judged that the regulation signal is transmitted according to the communication schedule and there is no communication error. On the other hand, when the input of the regulation signal is not received twice, the regulation signal is not transmitted according to the communication schedule, and it is determined that there is a communication error.

  Here, the elevator control device 11 determines that there is a communication error when the input of the regulation signal is not received twice, but, for example, when the input of the regulation signal is not continuous for a certain period, or It may be determined that there is a communication error when the number of times no legal signal is input during a certain period is greater than a preset threshold.

  The elevator control device 11 performs broadcast communication for a time slot assigned to perform unicast communication among a plurality of time slots included in one communication frame with respect to a frequency determined to have a communication error. A function of outputting an allocation change instruction for instructing the communication device 21 to set a time slot for the communication. The assignment change instruction is transmitted to the communication device 21 via the wireless device 22.

  Here, with reference to the flowchart of FIG. 10, an example of a procedure of wireless communication processing executed by the communication device 21 in the elevator system including the elevator control device 11 having the above function will be described. In addition, the same code | symbol is attached | subjected about the process same as the process already demonstrated in the flowchart of FIG. 5, and the detailed description shall be abbreviate | omitted here.

  When the processing of steps S1 and S2 is executed and the response confirmation from the wireless device 22 of the communication destination is received in the processing of step S2 (YES in step S2), the communication device 21 It is determined whether an assignment change instruction transmitted from the wireless device 22 of the communication destination has been received (step S10). If it is determined that an allocation change instruction has not been received (NO in step S10), the process returns to step S1, and the same process is executed after the next communication frame.

  On the other hand, if it is determined that an allocation change instruction has been received (YES in step S10), the process proceeds to step S3. That is, after the next communication frame, the communication device 21 stops (stops) the unicast communication at the first frequency (step S3), and broadcasts the time slot allocated for the unicast communication. Assigned to communication (step S4).

  Henceforth, as already demonstrated, the process of step S5-S9 is performed in order.

  According to the second embodiment described above, the communication device 21 broadcasts the time slot assigned to the unicast communication in response to an assignment change instruction from the elevator control device 11 in addition to the response confirmation during the unicast communication. A function of changing to communication and transmitting only a regulation signal to the wireless device 22 of the communication destination is further provided. According to this, the possibility that the input of the regulation signal to the elevator control device 11 is interrupted can be further reduced.

  According to at least one embodiment described above, it is possible to provide a communication device and an elevator system that can realize wireless signal transmission between a control panel and a car without reducing safety.

  In addition, although some embodiment of this invention was described, these embodiment is shown as an example and is not intending limiting the range of invention. These novel embodiments can be implemented in various other forms, and various omissions, replacements, and changes can be made without departing from the scope of the invention. These embodiments and modifications thereof are included in the scope and gist of the invention, and are included in the invention described in the claims and the equivalents thereof.

  DESCRIPTION OF SYMBOLS 11 ... Control panel, elevator control device, 12 ... Ride car, 13 ... Counterweight, 14 ... Main rope, 15 ... Hoisting machine, 16a ... Main sheave, 16b ... Warp sheave, 17 ... Car operation panel, 17a ... Destination floor Button, 17b ... Door open / close button, 18 ... Hall call button, 21 ... Communication device, 22 ... Wireless device.

Claims (10)

A communication device connected to a plurality of wireless devices so as to be capable of wireless communication,
Communication means for selectively performing broadcast communication and unicast communication with a communication destination wireless device among the wireless devices using a first frequency and a second frequency different from the first frequency; ,
When a response confirmation cannot be obtained from the radio device at any of the frequencies during unicast communication with the communication destination radio device, a time slot for unicast communication is set for a communication frame including a plurality of time slots. And a first changing means for changing to a time slot for broadcast communication.   2. The communication apparatus according to claim 1, further comprising trial means for attempting unicast communication with the communication destination wireless apparatus using a frequency for which the response confirmation cannot be obtained. The trial means includes
When a communication trial instruction is received during unicast communication with the communication destination wireless device using a frequency different from the frequency for which the response confirmation cannot be obtained, the response confirmation cannot be obtained according to the communication trial instruction. 3. The communication apparatus according to claim 2, wherein unicast communication with the communication destination wireless apparatus is attempted using a determined frequency. The trial means includes
3. The communication apparatus according to claim 2, wherein when the communication apparatus is stopped, unicast communication with the communication destination wireless apparatus is attempted using a frequency for which the response confirmation cannot be obtained.   When a response confirmation is obtained from the wireless device of the communication destination during the attempted unicast communication, a second time slot that is changed for the broadcast communication is changed again to the time slot for the unicast communication. The communication apparatus according to claim 2, further comprising a changing unit. The communication means includes
The communication device according to claim 1, wherein one or more wireless devices located in the vicinity of the communication device are selected as the wireless devices of the communication destination. The communication means includes
2. The communication apparatus according to claim 1, wherein one or more wireless apparatuses having good radio field strength and low bit error rate and packet error rate are selected as the wireless apparatuses of the communication destination. The first changing means includes
2. The time slot for unicast communication is changed to the time slot for broadcast communication when a change instruction is transmitted from the wireless device of the communication destination and the change instruction is received. Communication equipment. The change instruction is
The communication apparatus according to claim 8, wherein the communication apparatus is output when the communication destination wireless apparatus fails to obtain a legal signal transmitted by the broadcast communication a predetermined number of times. A communication device;
A plurality of wireless devices connected so as to be capable of wireless communication with the communication device,
The communication device
Communication means for selectively performing broadcast communication and unicast communication with a communication destination wireless device among the wireless devices using a first frequency and a second frequency different from the first frequency; ,
When a response confirmation cannot be obtained from the radio device at any of the frequencies during unicast communication with the communication destination radio device, a time slot for unicast communication is set for a communication frame including a plurality of time slots. And a first changing means for changing to a time slot for broadcast communication.

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