JP2014099677A - Communication system and terminal apparatus - Google Patents

Abstract

Provided are a communication system and a terminal device capable of controlling communication timing and communication order even when the number of terminal devices increases.
A first terminal 201 receives an operation input from a user on a display panel 7 and transmits a primary request from a primary request unit 251 to a transmission unit 1 (S31). The transmission unit 1 that has received the primary request transmits a secondary request for requesting the measurement result of the measurement unit 6 according to the primary request in the secondary request unit 151 to the second terminal 202 by the superimposed signal (S32). The second terminal 202 that has received the secondary request from the transmission unit 1 transmits the measurement result of the measurement unit 6 from the primary response unit 252 to the transmission unit 1 as a primary response to the transmission unit 1 (solid line in S33). At this time, the first terminal 201 directly receives the primary response sent from the second terminal 202 on the communication line 10 without using the transmission unit 1 via the superimposition communication unit 22 (broken line in S33).
[Selection] Figure 1

Description

  The present invention relates to a communication system including a parent device connected to a communication line and a plurality of terminal devices connected to the communication line and communicating with the parent device, and a terminal device used in the communication system.

  Conventionally, a communication system in which a transmission unit (base unit) and a plurality of communication terminals (slave units) are connected to a transmission line and performs communication between each communication terminal and the transmission unit has been widely used. As an example of this type of communication system, the transmission unit periodically monitors the state of the communication terminal, and when there is a change in the state of the communication terminal, the transmission unit performs other processing so as to perform processing corresponding to the state change. There are systems that send signals to communication terminals (see, for example, Patent Documents 1 to 3).

  However, the communication system configured as described above is originally a system used for on / off control of lighting fixtures and the like, and has a low communication speed, and is not suitable for transmission of information having a relatively large amount of data such as an analog amount. .

  Therefore, a communication system including a communication terminal that performs communication using a transmission signal transmitted from a transmission unit and a superimposition terminal that performs communication at higher speed using a superimposed signal superimposed on the transmission signal has been proposed. (For example, refer to Patent Document 4). In the system described in Patent Document 4, a communication terminal (“first communication terminal” in Patent Document 4) and a superimposing terminal (“second communication terminal” in Patent Document 4) share a communication line (transmission path). This can be easily realized by adding superposition terminals to the existing communication system. In Patent Document 4, communication terminals communicate with each other via a transmission unit (master unit), and overlapping terminals directly communicate with each other via peer-to-peer (P2P) without passing through a transmission unit.

Japanese Patent No. 1180690 Japanese Patent No. 1195362 Japanese Patent No. 1144477 JP 2009-225328 A

  By the way, in the communication system described in Patent Document 4, since the superimposed terminals directly communicate with each other, when the number of superimposed terminals increases and each superimposed terminal communicates freely, the communication timing and the communication order are controlled. Not. Therefore, the superimposition terminal may have a long waiting time for avoiding a collision between the superimposition signals or may not be able to communicate.

  The present invention has been made in view of the above reasons, and an object of the present invention is to provide a communication system and a terminal device that can control communication timing and communication order even when the number of terminal devices increases.

  The communication system of the present invention is a communication system comprising a master unit connected to a communication line, and a first terminal and a second terminal connected to the communication line and communicating with the master unit, wherein the first terminal is A primary request unit that transmits a primary request to the base unit, and the base unit includes a secondary request unit that transmits a secondary request to the second terminal when the primary request is received; When receiving the secondary request, the terminal includes a primary response unit that directly transmits a primary response to the first terminal without passing through the parent device.

  In this communication system, when the secondary request unit receives the primary request, the secondary request unit determines whether or not a predetermined condition is satisfied with respect to communication between the first terminal that is the transmission source of the primary request and the second terminal. It is preferable that the second request is transmitted based on the determination result.

  In this communication system, it is more preferable that the first terminal and the second terminal are configured to communicate in synchronization with a synchronization signal transmitted from the master unit to the communication line.

  In this communication system, the base unit is a transmission unit that repeatedly transmits a transmission signal as the synchronization signal to the communication line, and the first terminal and the second terminal are superimposed on the transmission signal. It is more desirable that it is a superposition terminal that communicates using a signal.

  In this communication system, the transmission signal is divided into a plurality of sections in the time axis direction, and the base unit communicates a part of the plurality of sections with the first terminal using the superimposed signal. It is more desirable that the communication is performed in a time division manner by allocating to a first period in which communication is performed and a second period in which communication with the second terminal is performed using the superimposed signal.

  In this communication system, it is more desirable that the second terminal is configured to limit a period for receiving the superimposed signal to a section allocated as the second period.

  In this communication system, it is more preferable that the transmission signal section is allocated in the first period so that the time taken for one frame of the transmission signal is longer than that in the second period.

  In this communication system, the transmission signal includes an interrupt band for detecting an interrupt signal, and a reply band that is a time slot for receiving return data. When the interrupt signal is detected, the reply band is secured to receive the return data from the transmission source of the interrupt signal, and the primary request unit is secured by transmitting the interrupt signal. More preferably, the primary request is transmitted in the reply band.

  In this communication system, it is more preferable that the primary request unit is configured to transmit the interrupt signal using the superimposed signal.

  In this communication system, the transmission signal detects a transmission band for transmitting data, a reply band that is a time slot for receiving a return signal, an interrupt band for detecting an interrupt signal, and a short circuit. And a superimposable band capable of superimposing the superposed signal in a section excluding the transmission band, the reply band, the interrupt band, and the short-circuit detection band in the transmission signal. Is more preferably assigned as the first period and the second period.

  In this communication system, it is more preferable that the base unit has a processing unit that receives the primary response transmitted from the primary response unit to the first terminal and executes a predetermined process.

  In this communication system, the primary request unit transmits the primary request to the base unit as a trigger for acquiring acquired data from the second terminal, and the primary response unit responds to the content of the secondary request. More preferably, the acquired data is configured to be transmitted to the first terminal as the primary response.

  In the terminal device according to the present invention, a base unit that repeatedly transmits a transmission signal to a communication line and a plurality of terminal devices that communicate using a superimposed signal superimposed on the transmission signal so as to be synchronized with the transmission signal When used as the terminal device in a communication system connected to a line, a primary request unit that transmits a primary request to the master unit, and a secondary request that is transmitted when the master unit receives the primary request, And a primary response unit that directly transmits a primary response to a partner terminal device without going through the base unit.

  In the present invention, the first terminal has a primary request unit that transmits a primary request to the base unit, and the base unit has a secondary request unit that transmits a secondary request to the second terminal when receiving the primary request. When the second terminal receives the secondary request, the second terminal has a primary response unit that directly transmits the primary response to the first terminal without going through the parent device. Therefore, even if the number of terminal devices increases, there is an advantage that communication timing and communication order can be controlled.

1 is a block diagram illustrating a schematic configuration of a communication system according to a first embodiment. 1 is a system configuration diagram of a communication system according to a basic configuration. It is a block diagram which shows schematic structure of the communication system which concerns on basic composition. It is explanatory drawing of operation | movement of the communication system which concerns on a basic structure. It is explanatory drawing of operation | movement of the communication system which concerns on a basic structure. FIG. 6 is an explanatory diagram of an operation of the communication system according to the first embodiment. 6 is an explanatory diagram of an operation of a communication system according to Embodiment 2. FIG.

(Basic configuration)
The communication system having this basic configuration includes, for example, a transmission unit 1 connected to a two-wire communication line 10, a superimposing terminal 2, and a communication terminal 3, as shown in FIG. In this communication system, basically, the communication terminal 3 performs communication using a transmission signal (a signal of the first protocol) transmitted through the communication line 10, and the superimposing terminal 2 superimposes a superposed signal (first signal superposed on the transmission signal). (2 protocol signals).

  FIG. 2 shows an example in which the communication system is applied to a lighting system for controlling the lighting fixture 4 in an office building or the like. In the example of FIG. 2, one transmission unit 1 is provided in each area (for example, floor), and a plurality of communication terminals 3 and superposition terminals 2 are connected to the communication line 10 connected to each transmission unit 1. .

  Further, the transmission unit 1 is connected to an energy saving controller (not shown) which is a higher-level device. The energy-saving controller is provided for each area (for example, floor), and performs overall monitoring control on an air conditioner (not shown) as well as an illumination system to which the communication system is applied. The energy saving controllers in a plurality of areas are connected to a personal computer (not shown) having a browser function via a network such as the Internet or a LAN, and can be monitored from the personal computer.

  In the communication system of this basic configuration, the transmission unit 1 has a function of communicating with each communication terminal 3 using a transmission signal and a function of communicating with each superposition terminal 2 using a superimposition signal. Therefore, the communication terminals 3 can communicate with each other when the transmission unit 1 is interposed therebetween, and the superposition terminals 2 can also communicate with each other when the transmission unit 1 is interposed therebetween.

  The plurality of communication terminals 3 are connected in parallel to the transmission unit 1 via the communication line 10. The transmission unit 1 and the communication terminal 3 are time-division multiplex transmission systems (hereinafter referred to as “basic systems”) in which data transmission from the transmission unit 1 to the communication terminal 3 and data transmission from the communication terminal 3 to the transmission unit 1 are performed in a time division manner. ”). In the following, first, a schematic configuration of the basic system will be described.

  In the basic system, the communication terminal 3 has a monitoring terminal for monitoring a monitoring input of a switch (not shown) such as a wall switch and a relay (not shown), and a load (here, the lighting fixture 4) is turned on / off. It is classified into two types, that is, a control terminal that performs control and the like. In this basic configuration, a case where a plurality of monitoring communication terminals 3 and a plurality of control communication terminals 3 are connected to the same communication line 10 will be described as an example. Here, the communication terminal 3 stores its own individually assigned address in each memory (not shown). Note that the monitoring communication terminal 3 is not limited to a switch, and may be configured to monitor a monitoring input automatically generated by a sensor such as a human sensor or a brightness sensor.

  As shown in FIG. 3, the transmission unit 1 includes a transmission communication unit 11 that transmits a transmission signal to the communication line 10, a transmission unit 12 that transmits data to the communication terminal 3, and a reception unit that receives data from the communication terminal 3. 13, a storage unit 14, and a control unit 15. In this basic configuration, the transmission unit 1 further includes a superimposition communication unit 16 that performs communication using a superimposition signal so that communication can be performed not only with the communication terminal 3 but also with the superimposition terminal 2. The control unit 15 controls operations of the transmission communication unit 11, the transmission unit 12, the reception unit 13, and the superimposition communication unit 16. In this basic configuration, the transmission unit 1 has a microcomputer (microcomputer) as a main configuration, and implements the functions of each unit by executing a program stored in the storage unit 14. In addition, illustration of the communication terminal 3 is abbreviate | omitted in FIG.

  The transmission unit 1 stores a control table in which the monitoring communication terminal 3 and the control communication terminal 3 are associated with each other by an address in the storage unit 14. However, for example, when the monitoring communication terminal 3 has a plurality of circuit switches, all the switches of the communication terminal 3 correspond to the terminal address unique to the communication terminal 3, and the only one actually operated The switch cannot be specified.

  Therefore, in the monitoring communication terminal 3, a load number is assigned to each switch so that the only actually operated switch can be identified, and an address with the load number added after the terminal address of the communication terminal 3 is assigned. Used as an address (identifier) unique to the switch. Similarly, a load number is assigned to each relay in the control communication terminal 3, and an address in which the load number is added after the terminal address of the communication terminal 3 is set as an address (identifier) unique to the relay. In the control table, the switch-specific address and the relay-specific address are associated one-to-one or one-to-many.

  Next, the operation of the basic system will be described.

  As shown in FIG. 4, the transmission unit 1 repeatedly transmits to the communication line 10 a time-division transmission signal having a voltage waveform in a format divided into a plurality of sections in the time axis direction. That is, the transmission signal is composed of seven sections: a spare interrupt band 101, a spare band 102, a transmission band 103, a reply band 104, an interrupt band 105, a short-circuit detection band 106, and a pause band 107. This is a time-division multiplexed signal with multiple poles (± 24V).

  The spare interrupt band 101 is a period for detecting the presence or absence of a secondary interrupt, the spare band 102 is a period set according to the interrupt band 105 and the short-circuit detection band 106, and the transmission band 103 is connected to the communication terminal 3. This is a period for transmitting data. The reply band 104 is a time slot for receiving return data from the communication terminal 3, the interrupt band 105 is a period for detecting the presence or absence of an interrupt signal, which will be described later, and the short circuit detection band 106 is for detecting a short circuit. Is the period. The idle zone 107 is a period for when processing is not in time.

  When an interrupt signal is detected in the interrupt band 105, the transmission unit 1 communicates with the communication terminal 3 that generated the interrupt signal in the first transmission band 103 and the reply band 104 thereafter. Therefore, in this basic configuration, each period starting from the interrupt band 105 and ending in the reply band 104 in the transmission signal is defined as one frame (F1, F2,...). However, since the spare interrupt band 101 and the spare band 102 are originally sections set as start pulses and the interrupt band 105 and the short-circuit detection band 106 are end pulses, the spare interrupt band 101 to the short-circuit detection band 106 are set. The period up to may be one frame. In this case, the pause zone 107 is an interval between frames of the transmission signal.

  The transmission unit 1 always transmits a transmission signal whose mode data is the normal mode, and constantly polls the communication terminal 3 sequentially by changing the address data included in the transmission band 103 of this transmission signal cyclically. Do. At the time of constant polling, the communication terminal 3 whose address data included in the transmission band 103 matches its own address receives the data included in this transmission band 103, and then the first reply band (of the same frame) At 104, the return data is transmitted to the transmission unit 1. Here, the communication terminal 3 transmits the return data by a current mode signal (a signal transmitted by short-circuiting the communication line 10 via an appropriate low impedance) synchronized with the transmission signal return band 104. Note that power for the internal circuit of the communication terminal 3 is supplied by rectifying and stabilizing a transmission signal transmitted via the communication line 10.

  On the other hand, when the monitoring communication terminal 3 detects the monitoring input, it generates an interrupt signal in synchronization with the interrupt band 105 of the transmission signal. The operation of the basic system when an interrupt signal is generated in the monitoring communication terminal 3 in the communication system of FIG. 2 will be described below with reference to FIG.

  When the transmission unit 1 detects an interruption signal generated in the monitoring communication terminal 3 in the interruption band 105 of the first frame F1 of the transmission signal (S11 in FIG. 4), it is included in the transmission band 103 of the transmission signal. Switch mode data from normal mode to interrupt polling mode. In the interrupt polling mode, the transmission unit 1 uses the transmission unit 12 to transmit the return request data composed of the upper bits of the address in the transmission band 103 of the transmission signal (S12), and cyclically sets the address (upper bits). Perform address search while changing. If the address (upper bit) in the return request data matches the upper bit of its own address, the communication terminal 3 that has generated the interrupt signal lowers its address in the reply band 104 of the first frame F1. The bits are transmitted as return data to the transmission unit 1 (S13). As a result, the transmission unit 1 receives the address of the communication terminal 3 that generated the interrupt signal in the first frame F1 at the reception unit 13 as return data.

  When the transmission unit 1 obtains the address of the communication terminal 3 that has generated the interrupt signal, the transmission request data is sent from the transmission unit 12 to the communication terminal 3 by designating the address in the transmission band 103 of the second frame F2. Is transmitted (S14). When the communication terminal 3 receives the return request data including its own address, in response to this, the monitoring data including the load number of the switch corresponding to the monitoring input and the on / off status in the reply band 104 of the second frame F2 Is transmitted to the transmission unit 1 as return data (S15).

  When the transmission unit 1 receives the return data including the monitoring data at the receiving unit 13, the transmission unit 1 transmits the monitoring data to the control communication terminal 3 corresponding to the monitoring data on the control table in the transmission band 103 of the third frame F3. Control data is transmitted (S16). Thereby, the communication terminal 3 which received the control data controls the lighting fixture 4 on and off according to the control data.

  As described above, in the basic system, the communication terminals 3 (the monitoring terminal and the control terminal) communicate with each other via the transmission unit 1 in accordance with the polling / selecting protocol (first protocol). Become.

  By the way, in the communication system which concerns on this basic structure, the superimposition terminal 2 which is a terminal device communicates using the superimposition signal superimposed on a transmission signal, sharing the communication line 10 with the said basic system.

  As illustrated in FIG. 3, the superimposing terminal 2 includes a memory 21, a superimposing communication unit 22 that performs communication using the superimposing signal (terminal side), and a transmission communication unit 23 that can receive at least a transmission signal (terminal side). The interface unit 24 and the (terminal side) control unit 25 are provided. The interface unit 24 is connected to a measurement unit 6 and the like which will be described later. The control unit 25 controls operations of the superimposition communication unit 22, the transmission communication unit 23, and the interface unit 24. In this basic configuration, the superimposing terminal 2 has a microcomputer (microcomputer) as a main configuration, and implements the functions of each unit by executing a program stored in the memory 21.

  Here, the superimposed signal is a signal having a sufficiently high frequency compared to the transmission signal, and the amount of data that can be transmitted per frame (of the transmission signal) is sufficiently large. For this reason, the communication using the superimposed signal can increase the communication speed compared to the communication using the transmission signal, and is suitable for transmitting information having a relatively large amount of data such as an analog amount. Therefore, in this basic configuration, the superposition terminal 2 transmits the measurement results of the measurement unit (multi-circuit energy monitor) 6 that measures voltage, current, power, and the like.

  Specifically, the plurality of superposition terminals 2 are connected to a monitoring terminal connected to the measurement unit 6 and a display panel (floor integration panel) 7 that displays the measurement result of the measurement unit 6. It is classified as a terminal. The display panel 7 displays the measurement result of the measurement unit 6 in various formats such as a table and a graph. Hereinafter, the superimposing terminal 2 for display will be described as the first terminal 201, and the superimposing terminal 2 for monitoring will be described as the second terminal 202.

  In this basic configuration, it is assumed that a plurality of first terminals 201 and a plurality of second terminals 202 are connected to the same communication line 10. However, at least a plurality of second terminals 202 may be provided, and only one first terminal 201 may be provided. Here, the first terminal 201 is integrated with the display panel 7 by being housed in a common housing with the display panel 7. However, the first terminal 201 is not limited to this configuration, and is a separate housing from the display panel 7. The display panel 7 may be connected to the interface unit 24. Conversely, the second terminal 202 is separate from the measurement unit 6, but is not limited to this configuration and may be integrated with the measurement unit 6.

  According to the above configuration, the second terminal 202 transmits the measurement result of the measurement unit 6 to the first terminal 201, for example, periodically using the superimposed signal, and causes the display panel 7 to display the measurement result of the measurement unit 6. Can do. Further, the display panel 7 has a touch panel display (not shown), and is configured to display information desired by the user by receiving an operation input from the user. Therefore, the first terminal 201 issues a request in response to a user operation input to the display panel 7 and causes the display panel 7 to display the measurement result of the measurement unit 6 acquired from the second terminal 202 as a response to this request. Can do.

  Here, the superimposing terminal 2 stores its own address individually assigned in advance in each memory 21. However, the address areas that can be set are distinguished between the communication terminal 3 and the superimposing terminal 2. In the following, addresses “1” to “128” can be used for the entire communication system, of which “1” to “64” are address areas of the communication terminal 3, and “65” to “128” are superimposed terminals. Description will be made on the assumption that the address area is assigned as the second address area.

  As for the superposition terminal 2, when a plurality of sensors and loads are connected to one superposition terminal 2, a unique address is not assigned to the superposition terminal 2, but a unique address for each sensor or load. Is assigned. That is, for example, a total of four addresses such as “65”, “66”, “67”, and “68” are assigned to the superimposing terminal 2 to which four sensors (such as the measurement unit 6) are connected. Become.

  Further, the superimposing terminal 2 of this basic configuration is configured to be capable of bidirectional communication using the transmission signal with the transmission unit 1 by the transmission communication unit 23 as with the communication terminal 3. That is, the superimposition terminal 2 can communicate with the transmission unit 1 by a transmission signal as well as communication using the superimposition signal.

  The superimposing terminal 2 has a function of monitoring a transmission signal used in the basic system and analyzing a data transmission state (hereinafter referred to as “state”) of the transmission signal. Here, the superimposing terminal 2 monitors the transmission signal by the transmission communication unit 23. The superimposing terminal 2 determines whether or not it is in a superimposable band suitable for superimposition of the superimposing signal from the analysis result of the state, and the superimposing communication unit 22 superimposes the superimposing signal on the transmission signal at the timing determined as the superimposable band. Is superimposed. That is, the superposition terminal 2 is configured to communicate in synchronization with a transmission signal transmitted from the transmission unit 1 serving as a master unit to the communication line 10. Therefore, the transmission unit 1 does not need to send out a synchronization signal only for synchronization in communication using the superimposed signal by using the transmission signal as a synchronization signal.

  In this basic configuration, the superimposing terminal 2 uses the spare interrupt band 101, the spare band 102, and the pause band 107 in the transmission signal as superimposable bands in principle for superimposing the superimposed signal. In other words, the spare interrupt band 101, the spare band 102, and the idle band 107 do not affect the communication of the first protocol even if the superimposed signal is superimposed, and the superimposed signal is not easily affected by the transmission signal.

  Furthermore, the superimposing terminal 2 is configured to generate an interrupt signal in synchronization with the transmission signal interrupt band 105 in the same manner as the communication terminal 3, and can also superimpose the reply band 104 secured by the interrupt signal. It can be used for superimposition of a superimposition signal as a band. That is, since the superimposition terminal 2 can also perform communication using the transmission signal in the transmission communication unit 23, by generating the interrupt signal using the transmission signal in synchronization with the interrupt band 105, The reply band 104 (in the same frame) can be secured for communication between itself and the transmission unit 1. The superimposition terminal 2 can avoid interference between the return data transmitted from the communication terminal 3 to the transmission unit 1 and the superimposition signal in the reply band 104 by using the reply band 104 secured in this way as a superimposable band. .

  As with the other superimposable bands, the reply band 104 does not affect the communication of the first protocol even if the superimposed signal is superimposed, and the superimposed signal is not easily affected by the transmission signal. Moreover, the reply band 104 has a longer time during which the voltage of the transmission signal is kept constant, and the ratio of the transmission signal to one frame is larger than that of the spare interrupt band 101, the spare band 102, and the pause band 107. It is suitable for superposition of superposition signals. As a specific example, if the time width of the reply band 104 is about 6.5 ms, and the superimposing terminal 2 can transmit 350-bit data in one reply band 104 by a superimposition signal, When the frame period of the transmission signal is about 15 ms, the transmission speed is about 23 kbps.

  In other sections (the transmission band 103, the interrupt band 105, and the short-circuit detection band 106), the time during which the transmission signal is stable at a high level or a low level is relatively short. It is easy to affect communication. Moreover, when a superimposition signal is superimposed on the said other area, a superimposition signal will also be easily received by the signal (interrupt signal and transmission data) transmitted / received between the transmission unit 1 and the communication terminal 3. FIG. Therefore, in this basic configuration, the sections other than the spare interrupt band 101, the spare band 102, the pause band 107, and the reply band 104 are sections that are not used for superimposition of the superimposed signal (hereinafter referred to as “non-superimposed band”). .

  The superimposition communication unit 22 functions as a data transmission unit that transmits data by a superimposition signal and a data reception unit that receives data transmitted by the superimposition signal. The superimposition communication unit 22 is configured to transmit a superimposition signal only when it is determined as a superimposable band from the state analysis result. In this way, the superimposing terminal 2 superimposes the superimposition signal only on the superimposable band in synchronization with the transmission signal, so that interference between the communication of the first protocol and the communication of the second protocol using the common communication line 10 occurs. To avoid.

  Note that the rising and falling periods of the transmission signal are also not suitable for superimposing the superimposed signal due to the influence of harmonic noise or the influence of a transient response accompanying the signal voltage inversion. Therefore, the superimposing terminal 2 determines that a predetermined avoidance time (for example, 300 μs) after the switching (rise) of the sections among the preliminary interrupt band 101, the standby band 102, the pause band 107, and the reply band 104 is a non-superimposable band. to decide.

  As with the communication terminal 3, the power supply to the superimposing terminal 2 is performed by a system (centralized power supply system) that is supplied by rectifying and stabilizing a transmission signal transmitted from the transmission unit 1 via the communication line 10. The However, the power supply to the superposition terminal 2 is not limited to this configuration, and may be performed by a method (local power supply method) that is supplied by rectifying and stabilizing the commercial power supply.

  By the way, in the communication system according to the basic configuration, the transmission unit 1 has a master right that is an authority for functioning as a master unit (master node) that directly communicates with the superposition terminal 2 using the superposition signal. Therefore, when transmitting data between the first terminal 201 and the second terminal 202, the transmission unit 1 acquires data from the first terminal 201 using the superimposed signal by the superimposed communication unit 16, and transmits this data to the second terminal. It transmits to 202 using a superimposition signal. In other words, in a normal time when the transmission unit 1 functions as a parent device, the superposition terminals 2 that are terminal devices do not communicate directly with each other but communicate with each other via the transmission unit 1.

  As a specific configuration for that purpose, as shown in FIG. 3, the first terminal 201 has a primary request unit 251, the second terminal 202 has a primary response unit 252, and the transmission unit 1 that is a parent device has two units. It has a next request unit 151 and a secondary response unit 152. Here, since the terminal devices having the same configuration are used for the first terminal 201 and the second terminal 202, a primary request unit 251 and a primary response unit are provided for each of the first terminal 201 and the second terminal 202. Both 252 are provided. However, when different terminal devices are used for the first terminal 201 and the second terminal 202, the first terminal 201 is not provided with the primary response unit 252 but the primary request unit 251 is provided, and the second terminal 202 is provided with the primary request unit 251. The primary response unit 252 may be provided without the request unit 251.

  The primary request unit 251 is provided in the control unit 25 and has a function of transmitting a primary request to the transmission unit 1 that is a master unit. Here, the primary request represents the type of data requested to be transmitted to the second terminal 202, for example, which measurement unit 6 the measurement result is requested.

  The secondary request unit 151 is provided in the control unit 15 of the transmission unit 1 and has a function of transmitting a secondary request to the second terminal 202 when receiving a primary request from the first terminal 201. Here, the secondary request reflects the content of the primary request and indicates the type of data requested to be transmitted to the second terminal 202, for example, the measurement result of which measurement unit 6 is requested. .

  The primary response unit 252 is provided in the control unit 25 and has a function of transmitting a primary response to the transmission unit 1 that is a master unit when receiving a secondary request from the transmission unit 1. Here, the primary response is a response to the secondary request, and includes data requested from the first terminal 201, for example, the measurement result of the measurement unit 6.

  The secondary response unit 152 is provided in the control unit 15 of the transmission unit 1 and has a function of transmitting a secondary response to the first terminal 201 when receiving a primary response from the second terminal 202. Here, the secondary response reflects the content of the primary response and includes data requested from the first terminal 201, for example, the measurement result of the measurement unit 6.

  In this basic configuration, the above-described primary request, secondary request, primary response, and secondary response are all transmitted using a superimposed signal. That is, the primary request unit 251 transmits a primary request from the superimposed communication unit 22, and the secondary request unit 151 receives a primary request and transmits a secondary request at the superimposed communication unit 16. The primary response unit 252 receives a secondary request and transmits a primary response in the superimposed communication unit 22, and the secondary response unit 152 receives a primary response and transmits a secondary response in the superimposed communication unit 16.

  Hereinafter, the operation of the communication system according to the basic configuration will be described with reference to FIGS. 3 and 5. Here, the first terminal 201 receives an operation input from the user with respect to the display panel 7, and obtains the measurement result (for example, instantaneous value of power consumption) of the measurement unit 6 at this time (in real time) from the second terminal 202. The operation at the time of doing will be described as an example.

  The first terminal 201 receives an operation input from the user on the display panel 7 and generates an interrupt signal in synchronization with the interrupt band 105 of the transmission signal (S11 in FIG. 5). The transmission unit 1 that has detected the interrupt signal transmits the return request data by the transmission signal in the first transmission band 103 thereafter (S12 in FIG. 5). The first terminal 201 that has generated the interrupt signal transmits a primary request to the transmission unit 1 using the superimposed signal in the first reply band 104 thereafter (S21 in FIGS. 3 and 5).

  The transmission unit 1 that has received the primary request is a secondary request for requesting the measurement result of the measurement unit 6 in accordance with the primary request in synchronization with the subsequent first idle band 107, spare interrupt band 101, and spare band 102. Is transmitted to the second terminal 202 by the superimposed signal (S22 in FIGS. 3 and 5). The second terminal 202 that has received the secondary request from the transmission unit 1 synchronizes with the subsequent first idle band 107, spare interrupt band 101, and spare band 102, and uses the measurement result of the measurement unit 6 as a primary response. It transmits to the transmission unit 1 by a superimposition signal (S23 of FIG. 3). When the transmission unit 1 receives the primary response (measurement result) from the second terminal 202, the transmission unit 1 sends the measurement result to the secondary response in synchronization with the first pause band 107, the backup interrupt band 101, and the backup band 102 thereafter. Is transmitted (transferred) to the first terminal 201 by the superimposed signal (S24 in FIG. 3).

  In this way, the first terminal 201 can obtain the measurement result of the measurement unit 6 from the second terminal 202 via the transmission unit 1 that is the parent device. At that time, the four-step communication of S21 to S24 as described above is performed between the transmission unit 1 and the superimposing terminal (first terminal 201 and second terminal 202) 2. That is, the primary request from the first terminal 201 to the transmission unit 1, the secondary request from the transmission unit 1 to the second terminal 202, the primary response from the second terminal 202 to the transmission unit 1, the transmission unit 1 to the first terminal 201 A four-step communication of a secondary response to

  As described above, in the communication system according to the present basic configuration, the superimposition terminals 2 communicate with each other via the transmission unit 1 as a master unit, so that a plurality of superimposition terminals 2 communicate with each other at the same time. Can avoid interference. That is, according to this basic configuration, the superimposition terminal 2 that does not have the master right cannot communicate freely using the superimposition signal, but can communicate with the transmission unit 1 that is the only parent device in the communication system. Only direct communication is possible. In other words, since the transmission unit 1 having the master right controls communication using the superimposed signal in the communication system, the superimposed terminal 2 does not perform communication using the superimposed signal without permission. Therefore, the communication system of the present embodiment can avoid occurrence of collision between superimposed signals due to data transmission simultaneously by a plurality of overlapping terminals 2 in the same superimposable band.

  Furthermore, in this basic configuration, the transmission unit 1 accumulates data acquired from one superimposing terminal (second terminal 202) 2 in the storage unit 14, and a plurality of superimposing terminals (first terminal 201) 2 Can also be transferred. Therefore, for example, when the transmission unit 1 shares data acquired from the second terminal 202 (measurement result of the measurement unit 6) among the plurality of first terminals 201, the first terminal 201 communicates with the second terminal 202, respectively. Communication traffic can be reduced as compared with the case of doing so. For example, when there are a plurality of second terminals 202 and the transmission unit 1 groups the plurality of second terminals 202, the first terminal 201 can request data by designating a group. Data can be requested to a plurality of second terminals 202 at once. That is, when data is exchanged between the one-to-many superposition terminals 2, the communication system can reduce communication traffic by causing the transmission unit 1 to function as a master unit.

(Embodiment 1)
In the communication system according to the present embodiment, the primary response unit 252 of the superimposing terminal (second terminal 202) 2 directly transmits the primary response to the first terminal 201 without going through the transmission unit 1 that is the master unit. This is different from the communication system according to the basic configuration. Hereinafter, the same reference numerals are assigned to configurations similar to the basic configuration, and description thereof will be omitted as appropriate.

  That is, in this embodiment, the transmission unit 1 as a base unit does not need to receive a primary response from the second terminal 202 and transmit a secondary response to the first terminal 201. Therefore, transmission is performed as shown in FIG. The secondary response unit 152 (see FIG. 3) is omitted from the control unit 15 of the unit 1.

  More specifically, the first terminal 201 is configured to directly receive the primary response transmitted from the primary response unit 252 of the second terminal 202 to the transmission unit 1 that is the base unit without passing through the transmission unit 1. ing. That is, the first terminal 201 waits in a state of receiving the superimposed signal transmitted from the second terminal 202 for a predetermined time after transmitting the primary request from the primary request unit 251, whereby the second terminal 202. Directly receive the primary response sent from.

  For this reason, the first terminal 201 receives the secondary request from the transmission unit 1 as a response to the secondary request, and then enters the first idle band 107, the standby interrupt band 101, and the standby band 102 as a response to the secondary request. When the primary response is transmitted in synchronism with the superimposed signal, the primary response is directly received. In other words, when the transmission unit 1 serving as a master (master unit) and the second terminal 202 serving as a slave communicate with each other, a superimposed signal (primary response) exchanged between the two is a different slave. The first terminal 201 will receive it.

  In the present embodiment, when the secondary request unit 151 of the transmission unit 1 receives the primary request, the secondary request unit 151 determines whether or not a predetermined condition is satisfied with respect to communication between the first terminal 201 and the second terminal 202 that are the transmission source of the primary request. Whether or not to transmit the secondary request based on the determination result is determined. As the predetermined condition here, for example, the first terminal 201 that is the transmission source of the primary request is registered as a member of the communication system, and the transmission unit 1 is not communicating with the other superposition terminal 2 when the primary request is received. There are things. The transmission unit 1 transmits a secondary request when these predetermined conditions are satisfied, and does not transmit a secondary request when the conditions are not satisfied. Therefore, for example, the transmission unit 1 is configured to periodically acquire the measurement result of the measurement unit 6 from the second terminal 202, and the primary request from the first terminal 201 during the periodic communication with the second terminal 202. However, the secondary request is not transmitted because the condition is not satisfied.

  By the way, the transmission unit 1 divides in a time axis direction a first period in which communication with the first terminal 201 is performed using the superimposed signal and a second period in which communication with the second terminal 202 is performed using the superimposed signal. The time-division communication is performed. That is, the transmission unit 1 periodically transmits a synchronization signal (synchronization pulse) such as a beacon, and the first terminal 201 and the second terminal 202 perform time-division communication in synchronization with the synchronization signal. Therefore, communication is not performed between the transmission unit 1 and the second terminal 202 in the first period in which communication is performed between the transmission unit 1 and the first terminal 201, and conversely, the transmission unit 1 in the second period is not performed. There is no communication between the first terminals 201. Therefore, interference between the superimposed signal used for communication between the transmission unit 1 and the first terminal 201 and the superimposed signal used for communication between the transmission unit 1 and the second terminal 202 can be avoided.

  In this embodiment, the transmission signal transmitted from the transmission unit 1 to the communication line 10 is used as a synchronization signal, and a part of the transmission signal divided into a plurality of sections in the time axis direction is the first section. It is divided into a period and a second period. In this embodiment, since the transmission signal is used for superimposition of the superimposition signal, the spare interrupt band 101, the spare band 102, the pause band 107, and the reply band 104, so these sections are the first period and the second period. Sorted by period.

  Here, in the first period, a section of the transmission signal is allocated so that the time taken for one frame of the transmission signal is longer than that in the second period. More specifically, as shown in FIG. 6, the reply band 104 that can take a relatively long superimposable band is the first period T1, the remaining spare interrupt band 101, the spare band 102, and the rest band 107 are the second. The sections are distributed so as to be the period T2. Therefore, when transmitting the primary request, the primary request unit 251 is configured to first secure the reply band 104 by transmitting an interrupt signal and transmit the primary request to the secured reply band 104. In short, the primary request unit 251 secures the subsequent reply band 104 (of the same frame) for transmission of the primary request by generating an interrupt signal using the transmission signal in synchronization with the interrupt band 105. To do.

  In this way, the transmission unit 1 distributes the transmission signal section into the first period and the second period, thereby using the first terminal 201 and the second terminal 202 without using a synchronization signal (synchronization pulse) such as a beacon. And time-sharing communication. In addition, since a relatively long section (reply band 104) of the transmission signal superimposable band is allocated to communication between the transmission unit 1 and the first terminal 201, the first terminal 201 has a relatively large amount of information as a primary request. A lot of data can be sent together. The reply band 104 is a time slot for receiving return data transmitted from the communication terminal 3 in the first place, but the primary request unit 251 uses the reply band 104 secured by the interrupt signal for transmission of the primary request. Thereby, the communication system can avoid the interference between the return data from the communication terminal 3 and the superimposed signal (primary request) in the reply band 104.

  The primary request unit 251 may be configured to transmit an interrupt signal using a superimposed signal. In this case, the superimposed communication unit 22 generates an interrupt signal in the transmission signal interrupt band 105. To do. As a result, the first terminal 201 transmits not only an interrupt element for interrupting in the interrupt band 105 but also information other than the interrupt element such as an address and priority information as an interrupt signal together with the interrupt element. Communication efficiency can be improved.

  Here, when receiving the secondary request from the transmission unit 1, the second terminal 202 performs tunneling that allows all data to pass through the measurement unit 6 without reading the content of the secondary request. For this reason, the second terminal 202 cannot output data to the measurement unit 6 in the order in which it is transmitted from the transmission unit 1 when it receives data from the first terminal 201 due to a secondary request. There is. Therefore, the second terminal 202 is configured to limit the period for receiving the superimposed signal to the section allocated as the second period.

  Thereby, the second terminal 202 can limit the data received by the superimposed signal to the data (secondary request) from the transmission unit 1, and may receive the data from the first terminal 201 by mistake. Absent. Therefore, the second terminal 202 can output data to the measurement unit 6 in the order in which it is transmitted from the transmission unit 1.

  The operation of the communication system according to the present embodiment will be described below with reference to FIG. Here, the first terminal 201 receives an operation input from the user with respect to the display panel 7, and obtains the measurement result (for example, instantaneous value of power consumption) of the measurement unit 6 at this time (in real time) from the second terminal 202. The operation at the time of doing will be described as an example.

  The first terminal 201 receives an operation input from the user with respect to the display panel 7, generates an interrupt signal, and transmits a primary request to the transmission unit 1 using the superimposed signal in the first reply band 104 thereafter (S31). ). The transmission unit 1 that has received the primary request is a secondary request for requesting the measurement result of the measurement unit 6 in accordance with the primary request in synchronization with the subsequent first idle band 107, spare interrupt band 101, and spare band 102. Is transmitted to the second terminal 202 by the superimposed signal (S32). The second terminal 202 that has received the secondary request from the transmission unit 1 synchronizes with the subsequent first idle band 107, spare interrupt band 101, and spare band 102, and uses the measurement result of the measurement unit 6 as a primary response. It transmits to the transmission unit 1 by a superimposition signal (solid line of S33).

  At this time, the first terminal 201 directly receives the primary response (measurement result) sent from the second terminal 202 onto the communication line 10 without passing through the transmission unit 1 at the superimposition communication unit 22 (S33). Dashed line). In short, the first terminal 201 receives the primary response transmitted as a response to the secondary request by the second terminal 202 at the same time as the transmission unit 1. In addition, since the secondary response unit 152 (see FIG. 3) is omitted, the transmission unit 1 transmits a secondary response to the first terminal 201 even if the primary response from the second terminal 202 is received. Never do.

  In this way, the first terminal 201 can acquire the measurement result of the measurement unit 6 from the second terminal 202. At this time, the three-step communication of S31 to S33 as described above is performed between the transmission unit 1 and the superimposing terminal (first terminal 201 and second terminal 202) 2. That is, three steps of a primary request from the first terminal 201 to the transmission unit 1, a secondary request from the transmission unit 1 to the second terminal 202, and a primary response from the second terminal 202 to the transmission unit 1 and the first terminal 201. Communication occurs. Therefore, according to the configuration of the present embodiment, the transmission unit 1 and the superimposing terminal (the first terminal 201 and the first terminal 201) are compared with the basic configuration in which communication of four steps of the primary request, the secondary request, the primary response, and the secondary response occurs. The number of communications performed with the two terminals 202) 2 is reduced, and the communication time is shortened.

  According to the configuration of the present embodiment described above, since the superimposing terminals 2 communicate with each other via the transmission unit 1 serving as a parent device when a request is made from the first terminal 201 to the second terminal 202, a plurality of superimposing terminals. Interference between superimposed signals due to simultaneous communication of the two can be avoided. That is, according to the present embodiment, the superimposition terminal 2 that does not have the master right cannot communicate freely using the superimposition signal, but can communicate with the transmission unit 1 that is the only parent device in the communication system. Only direct communication is possible. In other words, since the transmission unit 1 having the master right controls communication using the superimposed signal in the communication system, the superimposed terminal 2 does not perform communication using the superimposed signal without permission. Therefore, the communication system of the present embodiment can avoid occurrence of collision between superimposed signals due to data transmission simultaneously by a plurality of overlapping terminals 2 in the same superimposable band.

  In other words, since the transmission unit 1 organizes traffic for communication between the superimposing terminals 2, the communication timing and the communication order can be controlled even if the number of terminal devices increases. That is, in this embodiment, since the transmission unit 1 performs traffic control of communication, it is possible to avoid a problem that the waiting time becomes extremely long or communication cannot be performed by the superimposing terminal 2.

  If the first terminal 201 makes a request to the second terminal 202 directly without going through the transmission unit 1, the first terminal 201 is in the middle of the transmission unit 1 communicating with the second terminal 202. In some cases, the superimposed signal is transmitted by interruption, and in this case, interference between the superimposed signals occurs. On the other hand, in the present embodiment, the first terminal 201 makes a request to the second terminal 202 via the transmission unit 1. Further, when receiving the primary request, the secondary request unit 151 of the transmission unit 1 determines whether or not a predetermined condition is satisfied with respect to communication between the first terminal 201 and the second terminal 202 that are the transmission source of the primary request, It is determined whether or not to transmit the secondary request based on the determination result. Therefore, even if the first terminal 201 interrupts and transmits a superimposed signal while the transmission unit 1 is communicating with the second terminal 202, the transmission unit 1 does not transmit a secondary request to the second terminal 202. Interference between superimposed signals can be avoided.

  Moreover, in the communication system according to the present embodiment, since the primary response unit 252 directly transmits the primary response to the first terminal 201, the superimposing terminals 2 are transmission units when responding from the second terminal 202 to the first terminal 201. It is possible to communicate directly without going through 1 and suppress an increase in communication traffic. That is, this communication system can reduce the number of communication between the transmission unit 1 and the superimposing terminals (first terminal 201 and second terminal 202) 2 and shorten the communication time compared to the communication system according to the basic configuration. The communication speed between the superimposing terminals 2 can be increased.

  In short, according to the communication system of this embodiment, there is an advantage that interference between (superimposed) signals can be avoided and the communication speed between the superimposed terminals 2 can be increased.

  By the way, in the present embodiment, as shown in FIG. 1, the transmission unit 1 that is a master unit receives a primary response transmitted from the primary response unit 252 to the first terminal 201 and executes a predetermined process. The control unit 15 has a unit 153. The predetermined processing here is, for example, processing for accumulating data acquired from the second terminal 202 as a primary response in the storage unit 14, processing for obtaining statistics of data acquired from the second terminal 202, or the like.

  Thereby, the communication system of the present embodiment reduces the number of communication between the transmission unit 1 and the superposition terminals (first terminal 201 and second terminal 202) 2 from the second terminal 202 by the transmission unit 1. It is possible to execute predetermined processing upon receiving the data. For example, as described in the basic configuration, the transmission unit 1 accumulates data acquired from one superposition terminal (second terminal 202) 2 in the storage unit 14, and a plurality of superposition terminals (first terminal 201). ) 2 can also be transferred.

  Further, in the present embodiment, the primary request unit 251 transmits a primary request to the transmission unit 1 serving as a parent device as a trigger for acquiring acquisition data from the second terminal 202, and the primary response unit 252 Acquired data corresponding to the content is transmitted to the first terminal 201 as a primary response. In short, communication between the first terminal 201 and the second terminal 202 is performed in order for the first terminal 201 to acquire data (such as a measurement result of the measurement unit 6) from the second terminal 202. Therefore, for example, the second terminal 202 periodically notifies the transmission unit 1 of the measurement result (such as the amount of power) of the measurement unit 6 at normal times, and when the primary request is transmitted from the first terminal 201, at that time The measurement result of the measurement unit 6 can be notified to the first terminal 201.

  However, in the communication system of the present embodiment, not only the first terminal 201 acquires data from the second terminal 202 in this way, but also connected to the second terminal 202 according to a command from the first terminal 201, for example. It is also possible to control a device (not shown). In this case, the first terminal 201 transmits a device control command as a primary request, and the second terminal 202 transmits a device control result as a primary response.

(Embodiment 2)
The communication system according to the present embodiment is used to superimpose a superimposition signal in that the transmission signal is a section excluding the transmission band 103, the reply band 104, the interrupt band 105, and the short-circuit detection band 106 in the first embodiment. It is different from the communication system. Hereinafter, the same configurations as those of the first embodiment are denoted by common reference numerals, and description thereof will be omitted as appropriate.

  That is, in the present embodiment, the superimposable band of the spare interrupt band 101, the spare band 102, and the pause band 107 includes the first period used for communication between the first terminal 201 and the transmission unit 1, and the second terminal 201-. They are distributed to the second period used for communication between the transmission units 1. Specifically, as shown in FIG. 7, the sections are allocated such that the spare band 102 is in the first period T1, and the idle band 107 and the spare interrupt band 101 are in the second period T2.

  According to the configuration of the present embodiment, communication between the transmission unit 1 and the superimposed terminal (first terminal 201 and second terminal 202) 2 by the superimposed signal does not use the return band 104, so There is an advantage that communication between the transmission units 1 is hardly affected. When communication using the superimposition signal is performed in the reply band 104, the reply band 104 is reserved for the superimposition signal. Therefore, the communication terminal 3 cannot transmit return data using the reply band 104, and data using the transmission signal Transmission may be delayed. On the other hand, in the present embodiment, since the return band 104 is not used for communication using the superimposed signal, it is difficult for data transmission using the transmission signal to be delayed.

  Other configurations and functions are the same as those of the first embodiment.

1 Transmission unit (base unit)
151 Secondary request unit 153 Processing unit 2 Superimposition terminal (terminal device)
201 1st terminal 202 2nd terminal 251 Primary request part 252 Primary response part 6 Measurement unit 7 Display panel 10 Communication line

Claims (13)

A communication system comprising a master unit connected to a communication line, and a first terminal and a second terminal connected to the communication line and communicating with the master unit,
The first terminal has a primary request unit that transmits a primary request to the master unit;
The master unit has a secondary request unit that transmits a secondary request to the second terminal when the primary request is received;
When the second terminal receives the secondary request, the second terminal includes a primary response unit that directly transmits a primary response to the first terminal without passing through the base unit. When the secondary request unit receives the primary request, the secondary request unit determines whether or not a predetermined condition is satisfied with respect to communication between the first terminal that is the transmission source of the primary request and the second terminal. The communication system according to claim 1, wherein the communication system is configured to determine whether to transmit the secondary request based on the communication request. The said 1st terminal and the said 2nd terminal are comprised so that it may synchronize and synchronize with the synchronizing signal sent to the said communication line from the said main | base station. Communications system. The master unit is a transmission unit that repeatedly transmits a transmission signal as the synchronization signal to the communication line,
The communication system according to claim 3, wherein the first terminal and the second terminal are superimposing terminals that communicate using a superimposition signal superimposed on the transmission signal. The transmission signal is divided into a plurality of sections in the time axis direction,
The base unit communicates a part of the plurality of sections with a first period in which communication with the first terminal is performed using the superimposed signal and communication with the second terminal using the superimposed signal. 5. The communication system according to claim 4, wherein the communication system is configured to perform communication in a time-sharing manner in two periods. The communication system according to claim 5, wherein the second terminal is configured to limit a period for receiving the superimposed signal to a section allocated as the second period. The section of the transmission signal is allocated in the first period so that the time occupied in one frame of the transmission signal is longer than that in the second period. Communications system. The transmission signal includes an interrupt band for detecting an interrupt signal and a reply band that is a time slot for receiving return data,
When the base unit detects the interrupt signal in the interrupt band, it secures the reply band to receive the return data from the transmission source of the interrupt signal,
The communication system according to claim 7, wherein the primary request unit is configured to transmit the primary request to the reply band secured by transmitting the interrupt signal. The communication system according to claim 8, wherein the primary request unit is configured to transmit the interrupt signal using the superimposed signal. The transmission signal includes a transmission band for transmitting data, a return band that is a time slot for receiving a return signal, an interrupt band for detecting an interrupt signal, and a short-circuit detection band for detecting a short circuit. And
Among the transmission signals, a superimposable band in which the superimposition signal can be superimposed is a section excluding the transmission band, the reply band, the interrupt band, and the short-circuit detection band as the first period and the second period. It is allocated. The communication system of any one of Claims 5-7 characterized by the above-mentioned. The base unit includes a processing unit that receives the primary response transmitted from the primary response unit to the first terminal and executes a predetermined process. The communication system according to 1. The primary request unit transmits the primary request to the master as a trigger for acquiring acquisition data from the second terminal,
The said primary response part is comprised so that the said acquisition data according to the content of the said secondary request | requirement may be transmitted to the said 1st terminal as the said primary response. The any one of Claims 1-11 characterized by the above-mentioned. The communication system according to item. A communication system in which a base unit that repeatedly transmits a transmission signal to a communication line and a plurality of terminal devices that communicate using a superimposed signal that is superimposed on the transmission signal so as to be synchronized with the transmission signal are connected to the communication line Used as the terminal device,
A primary request unit that transmits a primary request to the master unit;
A primary response unit that directly transmits a primary response to a partner terminal device without passing through the master unit when receiving a secondary request transmitted when the master unit receives the primary request. Terminal device.

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