JP2011239024A - Communication unit, communication system, display unit and display system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To allow a unit ID to be set simply and surely.SOLUTION: When a communication unit 40 serves as a master at one end of a daisy-chain connection, a processing unit 201 performs a processing of outputting an ID setting permission signal 254 to a signal port 250R or 250L, whichever a slave communication unit 40 is connected to, and a processing of broadcasting an ID for slave via a communication circuit 210. When the communication unit 40 serves as a slave, the processing unit 201 performs a processing of setting the acquired ID for slave to its own ID, and in conjunction with ID setting, a processing of outputting the above signal 254 to a signal port which is a different signal port than the signal port 250R or 250L, whichever the above signal 254 has been input, subject to a condition that an ID of the communication unit 40 is not set and the above signal 254 and the ID for slave are acquired.

Description

  The present invention relates to a communication unit, a communication system, a display unit, and a display system.

  Generally, in a communication system, an ID is assigned to each communication unit in order to identify each communication unit. Conventionally, ID assignment has been performed by manually setting a dip switch.

  In addition, a system operation method is known in which one communication unit is operated as a master in a communication system. A communication unit to be operated as a master is selected by assigning an ID determined in advance according to specifications. Therefore, the master can be selected by setting the dip switch.

JP-A-8-37538

  However, setting the dip switches one by one is cumbersome. Further, when changing the connection mode of the communication unit, the dip switch must be reset, and complicated manual work must be performed each time. For this reason, a setting error such as an ID overlap setting may occur. In addition, the work cost increases.

  Also, depending on the position of the dip switch and the installation environment of the communication unit, it may be difficult to set the dip switch and to check the setting contents after the communication unit is installed at a predetermined location.

  In addition, the use of a dip switch contributes to an increase in component costs.

  An object of this invention is to provide the communication unit which can set ID easily and reliably.

  It is another object of the present invention to provide a highly convenient communication unit for selecting a master.

  Another object of the present invention is to provide a communication system, a display unit, and a display system by adopting a communication unit that achieves the above object.

  The communication unit according to the first aspect of the present invention is one of a plurality of communication units constituting a communication system, and the remaining communication units excluding the communication unit among the plurality of communication units. The communication system is configured to be capable of broadcasting to the remaining communication units in the communication system, and includes a communication circuit, a processing unit connected to the communication circuit, and the processing unit and the outside of the unit. A first signal port and a second signal port, which are used for daisy chain connection with the remaining communication units and used for input / output of a predetermined signal between the communication units, and the communication unit is one of the daisy chain connections. When operating as a master at the end, the processing unit sets the ID of the communication unit to a master ID assigned in advance. And execution of the ID setting process as the predetermined signal to the signal port connected to the remaining communication unit operating as a slave among the first signal port and the second signal port. A process of outputting an ID setting permission signal for permitting the communication and a process of broadcasting the slave ID to the remaining communication units via the communication circuit, and when the communication unit operates as a slave, The processor is configured to acquire the slave on condition that the ID of the communication unit is not set, the ID setting permission signal is acquired, and the slave ID is acquired. A process for setting the ID for the communication unit to the ID of the communication unit, and the setting of the ID of the communication unit, Serial to the signal port of a different person than the signal port the ID setting permission signal is input among the second signal port, as the predetermined signal, and a process for outputting the ID setting permission signal.

  The communication unit according to the second aspect is the communication unit according to the first aspect, wherein the communication circuit includes a transmission / reception circuit connected to the processing unit and intra-unit communication connected to the transmission / reception circuit. A bus line and a first communication connector and a second communication connector that are connected to the intra-unit communication bus line and are used for the daisy chain connection with the remaining communication units.

  The communication unit according to the third aspect is the communication unit according to the second aspect, wherein it is determined whether or not a connector serving as the other party is connected to the first communication connector, and the determination result is A first connection determination unit configured to output to the processing unit, and whether or not a counterpart connector is connected to the second communication connector, and the determination result is output to the processing unit And a second connection determination unit, wherein the processing unit assigns the communication unit to the master and the slave according to the determination result by the first connection determination unit and the second connection determination unit. A master / slave determination process, wherein the master / slave determination process includes a first connection state in which the connector serving as the counterpart is connected only to the first communication connector; Or, when a second connection state in which the connector as the counterpart is connected only to the second communication connector is detected, based on a master selection condition imposed to be selected as the master, And a process of determining a communication unit as either the master or the slave.

  The communication unit according to the fourth aspect is one of a plurality of communication units constituting a communication system, and communication with the remaining communication units excluding the communication unit among the plurality of communication units. The communication system includes a communication circuit provided in a manner capable of broadcasting to the remaining communication units, and a processing unit connected to the communication circuit, and the communication circuit includes the processing A transmission / reception circuit connected to the communication unit, an intra-unit communication bus line connected to the transmission / reception circuit, an intra-unit communication bus line, and the daisy chain connection to the remaining communication units. A first communication connector and a second communication connector, the communication unit being a counterpart to the first communication connector Whether or not a connector as a counterpart is connected to the first connection determination unit configured to determine whether or not a connector is connected and to output the determination result to the processing unit and the second communication connector A second connection determination unit configured to determine whether or not and output the determination result to the processing unit, wherein the processing unit includes the first connection determination unit and the second connection determination unit In accordance with the determination result, a master / slave determination process is performed to determine the communication unit as either the master or the slave, and the master / slave determination process is performed only on the first communication connector with the counterpart. When the first connection state in which the connector is connected or the second connection state in which the connector as the counterpart is connected only to the second communication connector is detected, Based on the master selection condition imposed in order to be selected as static includes a process of determining the communication unit to one of the said master-slave.

  The communication unit according to the fifth aspect is the communication unit according to the third or fourth aspect, wherein the master selection condition is supplied by data expressed in a format readable by the processing unit. .

  The communication unit according to the sixth aspect is a communication unit according to any one of the third to fifth aspects, and the data related to the master selection condition is supplied from an external storage medium.

  Further, the communication unit according to the seventh aspect is the communication unit according to the sixth aspect, and the processing unit, when the external storage medium is attached to the communication unit, the external storage medium If the external storage medium is not attached to the communication unit, the data relating to the master selection condition is obtained from another communication in which the external storage medium is attached. Obtained from the unit via the communication circuit.

  The communication unit according to the eighth aspect is the communication unit according to the third or fourth aspect, and the master selection condition is that the communication unit in the state where an external storage medium is mounted is selected as the master. The content is to be done.

  The communication unit according to a ninth aspect is the communication unit according to the third or fourth aspect, further comprising a master selection switch connected to the processing unit, wherein the master selection condition is the master selection condition The content is that a communication unit whose switch is in a predetermined state is selected as the master.

  The communication unit according to a tenth aspect is a communication unit according to any one of the first to ninth aspects, wherein the processing unit is prepared for each communication unit and the ID is associated in advance. The process for obtaining the individual data being transmitted and the individual data for the remaining communication units excluding the communication unit are transmitted to the corresponding communication unit among the remaining communication units via the communication circuit. Process.

  The communication unit according to the eleventh aspect is the communication unit according to the tenth aspect, wherein the individual data is stored in the same external storage medium together with the data related to the master selection condition according to the sixth aspect. Supplied.

  The communication unit according to a twelfth aspect is the communication unit according to any one of the third to eleventh aspects, further comprising a termination circuit for terminating the intra-unit communication bus line. In the master / slave determination process, when the first connection state or the second connection state is detected and the communication unit is determined to be the slave, the termination circuit is operated to operate the intra-unit communication bus. Performs line termination processing.

  A communication unit according to a thirteenth aspect is a communication unit according to any one of the third aspect and the fifth to twelfth aspects quoting the third aspect, and the communication unit is the above-mentioned communication unit. When operating as a slave, the processing unit transmits a response message indicating that the setting of the ID is completed to the master via the communication circuit in accordance with the setting of the ID of the communication unit. If the communication unit is the last-stage slave, the processing unit further includes in the response message that the setting of the ID has been completed up to the last-stage slave.

  The communication unit according to the fourteenth aspect is the communication unit according to the thirteenth aspect, and when the communication unit operates as the master, the processing unit receives the response message from the slave. The slave ID broadcast having the same content is repeated.

  A communication system according to the fifteenth aspect includes a communication unit according to any one of the first to third aspects and the fifth to fourteenth aspects that cite the first to third aspects. A plurality of communication units each configured and daisy chain connected in a form in which the first signal port of one communication unit and the second signal port of another communication unit are connected to each other are provided. .

  In addition, the communication system according to the sixteenth aspect is configured by a communication unit according to any one of the fourth aspect and the fifth to fourteenth aspects quoting the fourth aspect, A plurality of communication units that are daisy chain connected in a form in which the first communication connector of one communication unit and the second communication connector of another communication unit are connected.

  A display unit according to a seventeenth aspect includes a communication unit according to any one of the first to fourteenth aspects and a display unit connected to the communication unit, wherein the display unit is Data received by the communication unit is provided so as to be displayed.

  Further, a display system according to an eighteenth aspect includes the communication system according to the fifteenth or sixteenth aspect, and a plurality of display units respectively connected to the plurality of communication units constituting the communication system, Each of the plurality of display units is provided so as to be able to display data received by the communication unit to which the display unit is connected.

  According to the first aspect, the master ID value is assigned in advance, and the slave ID value is determined by the master. For this reason, the ID of each communication unit is centrally managed in the master. Therefore, setting errors such as duplicate registration of IDs can be prevented.

  According to the first aspect, the ID setting permission signal is sequentially transmitted between the plurality of communication units under the control of each communication unit. For this reason, ID can be provided automatically and without omission.

  As described above, according to the first aspect, it is possible to easily and reliably assign an ID as compared with the case where manual setting of the dip switch is required for each communication unit. In addition, since the setting operation of the dip switch is unnecessary, it is possible to reduce the part cost and the work cost.

  These effects can also be obtained in the above-described other modes that cite the first mode.

  According to the second aspect, it is possible to provide a configuration example capable of broadcasting to the remaining communication units in the communication system by wired communication.

  According to the third aspect, the communication unit located at one end in the daisy chain connection can be automatically set as the master.

  At this time, which of the communication units located at both ends of the daisy chain connection is set as the master is defined by the contents of the master selection condition. For this reason, the more convenient communication unit can be set or changed to the master according to the installation environment of the communication system.

  Thus, according to the said 3rd aspect, a highly convenient communication unit can be provided about the setting of a master.

  According to the fourth aspect, the same effect as in the third aspect can be obtained, and the effect can also be obtained in the other aspect in which the fourth aspect is cited.

  According to the fifth aspect, since the master selection condition is realized by software, it is easy to change the contents.

  According to the sixth aspect, the master selection condition can be easily changed by rewriting the master selection condition data in the external storage medium or by replacing the external storage medium.

  According to the seventh aspect, the master selection condition data can be acquired regardless of which communication unit is installed in the communication system. For this reason, it is only necessary to attach the external storage medium to a convenient communication unit according to the installation environment of the communication system, which is convenient.

  According to the eighth aspect, the master can be set only by mounting the external storage medium. At this time, it is easy to attach the external storage medium to a convenient unit in accordance with the installation environment of the communication system among the communication units at both ends.

  According to the ninth aspect, it is convenient to set the master selection switch to a predetermined state only for the communication unit at both ends that is desired to be set as the master.

  Here, the state of the master selection switch of the communication unit not located at both ends does not affect the master / slave determination process. This is because the determination as to whether or not the master selection condition is satisfied is executed only in the communication units at both ends. For this reason, it is not necessary to operate a master selection switch about all the communication units in a communication system. For this reason, even if the master selection switch is adopted, the complicated work is not significantly increased.

  According to the tenth aspect, for example, unlike the case where one piece of data is supplied in units of a plurality of units, it is not necessary for the processing unit to perform data division processing. That is, the processing load on the processing unit can be reduced. Therefore, high performance of the processing unit can be avoided, and cost reduction can be achieved.

  According to the eleventh aspect, if one external storage medium is attached, both master selection condition data and individual data can be supplied, which is convenient. Further, it is not necessary to distinguish and manage the external storage medium for master selection condition data and the external storage medium for individual data.

  According to the twelfth aspect, unnecessary signal reflection is prevented in the communication unit at the final stage of the daisy chain connection, and good communication can be performed.

  According to the thirteenth aspect, the master processing unit can grasp the progress of the slave ID setting process, contributing to reliable ID assignment.

  Further, according to the thirteenth aspect, the processing unit receives the response message including the fact that the ID setting is completed up to the slave at the final stage, so that the number of slave IDs transmitted so far is It is possible to know the number of slaves connected in a chain. According to this, for example, it is possible for the processing unit to confirm whether or not the planned number of slaves are connected, which contributes to the reliable construction of the communication system.

  According to the fourteenth aspect, it contributes to reliable ID assignment.

  According to the fifteenth aspect, the same effect as in the first aspect and the like can be obtained.

  According to the sixteenth aspect, the same effect as in the fourth aspect can be obtained.

  According to the seventeenth aspect, the same effect as in the first aspect and the like can be obtained.

  According to the eighteenth aspect, the same effect as in the fifteenth or sixteenth aspect can be obtained.

1 is a block diagram outlining a display system according to a first embodiment of the present invention. It is a block diagram which outlines the display unit which concerns on 1st Embodiment. 1 is a block diagram outlining a display system according to a first embodiment. 4 is a flowchart outlining an ID setting process and a master / slave determination process according to the first embodiment. 4 is a flowchart outlining a slave ID setting process according to the first embodiment. It is a flowchart which outlines the data delivery process which concerns on 1st Embodiment. It is a block diagram which outlines the 1st example of the communication system which concerns on 2nd Embodiment. It is a block diagram which outlines the 2nd example of the communication system which concerns on 2nd Embodiment. It is a block diagram which outlines the display unit which concerns on 4th Embodiment. It is a figure which outlines the 1st example of the display system which concerns on 7th Embodiment. It is a figure which outlines the 2nd example of the display system which concerns on 7th Embodiment.

<First Embodiment>
<Display system>
FIG. 1 shows a block diagram outlining the display system 10 according to the first embodiment. The display system 10 illustrated in FIG. 1 includes three display units 20, and these display units 20 are daisy chain connected. However, the number of display units 20 included in the display system 10 is not limited to the example of FIG.

  In order to distinguish the three display units 20 connected in a daisy chain, reference numeral 20R is used for the rightmost display unit 20 in the arrangement illustrated in FIG. 20L will be used respectively.

  Here, in order to simplify the description, an example in which each display unit 20 has the same configuration is given. In the example of FIG. 1, each display unit 20 includes a display unit 30 and a communication unit 40 connected to the display unit 30.

  When distinguishing the three communication units 40 in the display system 10, the reference numeral 40R is used for the communication unit 40 of the display unit 20R, and the reference numerals 40M and 40L are used for the communication units 40 of the display units 20M and 20L. To. The communication units 40R, 40M, and 40L are daisy chain-connected in this order, thereby configuring the daisy chain connection of the display units 20R, 20M, and 20L.

  According to such a configuration, the display unit 20 has a communication function realized by the communication unit 40, and can display various data received by the communication function on the display unit 30.

  Here, when the configuration responsible for communication between the display units 20 in the display system 10 is referred to as a “communication system 50”, the communication system 50 is configured to include three communication units 40R, 40M, and 40L connected in a daisy chain. The

  Each communication unit 40 is assigned a unit ID (hereinafter also abbreviated as “ID”) for identifying each other. Here, in order to simplify the description, the ID of the communication unit 40 is also adopted as the ID of the display unit 20.

  Specifically, in the example of FIG. 1, when the ID of the rightmost communication unit 40R is # 0, the ID of the rightmost display unit 20R having the communication unit 40R is also # 0. Similarly, FIG. 1 illustrates a case where the ID of the central communication unit 40M and the display unit 20M is # 1, and the ID of the left communication unit 40L and the display unit 20L is # 2.

  In this case, in the daisy chain connection (in other words, in the mode of following the daisy chain connection), IDs are assigned so that the ID values are in ascending order from the side closest to the right end units 40R and 20R. However, as long as information that can identify the units 40 and 20 from each other is assigned, another ID provision rule may be adopted.

  Further, FIG. 1 illustrates a case where the rightmost communication unit 40R is a master communication unit and the rightmost display unit 20R is a master display unit. In this case, the central units 40M and 20M and the leftmost units 40L and 20L are slaves. However, as will be apparent from the description below, the leftmost units 40L and 20L can be selected as masters. That is, in the systems 50 and 10, one of the units 40 and 20 connected in the daisy chain operates as a master.

  In the daisy chain connection form, the side closer to the master is expressed as the front side or the higher side, and the side far from the master is expressed as the rear side or the lower side.

  FIG. 2 shows a block diagram outlining a configuration example of the display unit 20. Note that the positions of the various elements in FIG. 2 do not limit the actual arrangement positions.

<Display section>
In the example of FIG. 2, the display unit 30 includes a liquid crystal display module (hereinafter also referred to as “LCD module”) 101, a backlight driver 102, and a connector 103.

  The LCD module 101 includes a liquid crystal panel, a drive circuit, a backlight device, and the like, and is configured to be able to perform display on the liquid crystal panel. The backlight driver 102 controls the backlight device. The connector 103 connects the backlight driver 102 and the communication unit 40 to the LCD module 101. Note that the display unit 30 may be configured by an LCD module of a type that does not use a backlight (so-called reflection type) or a display device other than liquid crystal.

<Communication unit>
In the example of FIG. 2, the communication unit 40 includes a processing unit 201, a storage unit 202, an interface (hereinafter also referred to as “I / F”) 203, an oscillator 204, a power supply circuit 205, A power connector 206R and a second power connector 206L are included. 2 does not limit the arrangement positions of the various elements as described above, but in order to make the explanation easy to understand, the first power connector 206R will be referred to as a “right power connector 206R” below. The two power supply connector 206L may be referred to as a “left power supply connector 206L”.

  The processing unit 201 performs various processes in the communication unit 40. The processing unit 201 is connected to the connector 103 of the display unit 30 and performs various processes on the display unit 30. The processing unit 201 can include, for example, a microcomputer (in other words, a microprocessor). In this case, the microcomputer performs various processing by executing processing steps (in other words, processing procedures) described in a program stored in the storage unit 202 in advance.

  According to such a configuration, the microcomputer functions as various units corresponding to one or a plurality of processing steps, or various functions corresponding to one or a plurality of processing steps are realized by the microcomputer. Note that some or all of the various means or functions implemented by the microcomputer can be implemented by hardware. Further, the number of microcomputers included in the processing unit 201 may be one or plural.

  The storage unit 202 includes, for example, one or more of a ROM (Read Only Memory), a RAM (Random Access Memory), and a rewritable nonvolatile memory (such as an EPROM (Erasable Programmable ROM)). In addition to storing the program executed by the processing unit 201 as described above, the storage unit 202 stores various types of data and provides a work area for executing the program. The storage unit 202 is provided so that the processing unit 201 can access it.

  2 illustrates a form in which various elements such as the storage unit 202 are directly connected to the processing unit 201. For example, various elements such as the storage unit 202 and the processing unit 201 are connected to each other with a bus structure. You may connect by.

  The I / F 203 is a device for mounting the external storage medium 60 on the communication unit 40 and is connected to the processing unit 201. As a result, the processing unit 201 can access the external storage medium 60 via the I / F 203. Note that the number of I / Fs 203 may be one or plural.

  In FIG. 2, the external storage medium 60 is illustrated by a two-dot chain line for the sake of explanation. An SD card is exemplified as the external storage medium 60. For example, a semiconductor storage medium other than the SD card, a magnetic storage medium, an optical storage medium, or the like can be used as the external storage medium 60.

  The oscillator 204 generates a clock signal used by the processing unit 201 and supplies the clock signal to the processing unit 201.

  The power supply circuit 205 generates various voltages used in the communication unit 40 and supplies them to predetermined locations. In FIG. 2, the detailed illustration of the voltage supply path is omitted in order to avoid complication of the drawing. Here, it is assumed that the power supply circuit 205 generates not only the voltage for the communication unit 40 but also the voltage for the display unit 30.

  In the example of FIG. 2, the right power supply connector 206 </ b> R is a power input connector for supplying power to the power supply circuit 205 from the outside of the display unit 20. Thus, the power supply circuit 205 is driven by the external power input via the right power supply connector 206R to generate the various voltages.

  The left power connector 206L is connected to the right power connector 206R. In the example of FIG. 2, the left power connector 206L is a power output side connector for outputting the power input via the right power connector 206R to the outside of the display unit 20. By adopting the power output side connector 206L, it is possible to supply power to a plurality of display units 20 from a single external power source.

  Specifically, when the left power connector 206L of one display unit 20 and the right power connector 206R of the other display unit 20 are connected, a plurality of display units 20 are daisy chain connected. Good. According to this, by supplying power from the external power source to the leftmost display unit 20L, power is supplied to the plurality of display units 20 connected in a daisy chain. Note that the daisy chain connection by the power supply connectors 206R and 206L may be a form in which a cable is interposed, or may be a form in which the display units 20 are directly connected to each other.

  In contrast to the example of FIG. 2, the left power connector 206L can be used as the power input side, and the right power connector 206R can be used as the power output side.

<Communication circuit>
The communication unit 40 further includes a communication circuit 210 responsible for communication with other communication units 40. The communication circuit 210 includes a transmission / reception circuit 211, an intra-unit communication bus line 212, a first communication connector 220R, a second communication connector 220L, and a termination circuit 230. 2 does not limit the arrangement positions of the various elements as described above, but in order to make the explanation easier to understand, the first communication connector 220R will be referred to as a “right communication connector 220R” below. The two communication connector 220L may be referred to as a “left communication connector 220L”.

  The transmission / reception circuit 211 is connected to the processing unit 201 and the intra-unit communication bus line 212. The transmission / reception circuit 211 is configured in accordance with a predetermined communication specification (for example, RS-485). The transmission / reception circuit 211 acquires transmission data from the processing unit 201, converts the transmission data into an electrical signal in accordance with the predetermined communication specification, and outputs the electrical signal to the communication bus line 212. Further, the transmission / reception circuit 211 converts the signal received from the communication bus line 212 into data in a format that can be processed by the processing unit 201 in accordance with the predetermined communication specification, and outputs the obtained reception data to the processing unit 201. .

  The communication connectors 220 </ b> R and 220 </ b> L are connectors used for daisy chain connection with other communication units 40, in other words, for daisy chain connection with other display units 20. In the example of FIG. 2, the communication connector 220 </ b> R has three terminals 221, 222, and 223, and the terminal 221 is connected to the intra-unit communication bus line 212. The same applies to the communication connector 220R.

  Specifically, a plurality of communication units 40 are daisy-chain connected by connecting the left communication connector 220L of one communication unit 40 and the right communication connector 220R of the other communication unit 40. Is possible. According to this, the intra-unit communication bus line 212 of each communication unit 40 is connected in series, and a shared communication bus line extending over the plurality of communication units 40 is configured. In this case, since the transmission / reception circuit 211 of each communication unit 40 is connected to the communication bus line in a bus type, each communication unit 40 can execute broadcasting to the remaining communication units 40.

  Note that the daisy chain connection by the communication connectors 220R and 220L may be a form in which a cable is interposed, or may be a form in which the communication units 40 are directly connected.

  The termination circuit 230 is a circuit for terminating the intra-unit communication bus line 212, and includes a termination resistor 231 and a switch 232 in the example of FIG. The termination resistor 231 is connected to the intra-unit communication bus line 212 via the switch 232. When the switch 232 is controlled to be closed by the processing unit 201, the termination resistor 231 is connected to the bus line 212. Note that the switch 232 can be configured by various elements and circuits having a switching function.

<Connection determination unit>
The communication unit 40 further includes a first connection determination unit 240R and a second connection determination unit 240L. The first connection determination unit 240R is provided for the right-side communication connector 220R, determines whether or not a connector as a counterpart is connected to the connector 220R, and outputs a signal 244R related to the determination result to the processing unit 201. Output to. On the other hand, the second connection determination unit 240L is provided for the left communication connector 220L, operates in the same manner as the first connection determination unit 240R, and outputs a determination result signal 244L to the processing unit 201.

  As described above, FIG. 2 does not limit the arrangement positions of various elements. However, in order to make the explanation easy to understand, the first connection determination unit 240R is hereinafter referred to as a “right connection determination unit 240R”. The two connection determination unit 240L may be referred to as a “left side connection determination unit 240L”. In addition, the signals 244R and 244L related to the determination result may be referred to as a “right connection determination signal 244R” and a “left connection determination signal 244L”, respectively.

  Here, the connector that is the counterpart of the right communication connector 220 </ b> R is the left communication connector 220 </ b> L of the other communication unit 40. In other words, the connector that is the counterpart of the left communication connector 220 </ b> L is the right communication connector 220 </ b> R of the other communication unit 40.

  The right connection determination unit 240R includes wirings 241 and 242 and a resistor 243 in the example of FIG. The wiring 241 connects the terminal 222 of the communication connector 220R and the processing unit 201. The wiring 241 connects the terminal 223 of the communication connector 220R and a predetermined point that provides a ground potential. The resistor 243 is a so-called pull-up resistor, and is connected between a predetermined point that applies the potential Vcc and the wiring 241. Here, the ground potential and the potential Vcc correspond to a low level (hereinafter also referred to as “L level”) and a high level (hereinafter also referred to as “H level”) of a digital signal that can be processed by the processing unit 201, respectively. Shall.

  In the example of FIG. 2, the left connection determination unit 240L is configured in the same manner as the right connection determination unit 240R.

  Note that the arrangement of the terminals 222 and 223 differs between the communication connectors 220R and 220L. Specifically, the communication connector 220R is connected so that the terminal 222 is connected to the terminal 223 of the communication connector as the counterpart, in other words, the terminal 223 is connected to the terminal 222 of the communication connector as the counterpart. , 220L is defined.

  According to this configuration example, in a state where the right communication connector 220R is not connected to the left communication connector 220L of the other communication unit 40, the right connection determination signal 244R is at the H level. In contrast, when the right communication connector 220R is connected to the left communication connector 220L of the other communication unit 40, the terminal 222 of the right communication connector 220R is connected to the left communication connector 220L of the other communication unit 40. The terminal 223 is grounded. For this reason, the right side connection determination signal 244R becomes L level.

  Similarly, in a state where the left communication connector 220L is not connected to the right communication connector 220R of the other communication unit 40, the left connection determination signal 244L is at the H level. In contrast, when the left communication connector 220L is connected to the right communication connector 220R of the other communication unit 40, the left connection determination signal 244L is at the L level.

  Therefore, the processing unit 201 determines that the counterpart connector 220L is connected only to the right communication connector 220R from the level of the connection determination signals 244R and 244L (hereinafter “first connection state” or “right connection state”). May be detected).

  Further, the processing unit 201 determines from the level of the connection determination signals 244R and 244L that the other connector 220R is connected only to the left communication connector 220L (hereinafter referred to as “second connection state” or “left connection state”). May be detected).

  Further, the processing unit 201 is in a state in which the other connectors 220L and 220R are connected to the connectors 220R and 220L from the level of the connection determination signals 244R and 244L (hereinafter “third connection state” or “both side connection state”). May be detected).

  Further, the processing unit 201 determines that the connectors 220L and 220R as the other party are not connected to either of the connectors 220R and 220L (hereinafter “fourth connection state” or “not connected”) from the level of the connection determination signals 244R and 244L. It may be referred to as a “state”.

  In addition, although the connection discrimination | determination part 240R, 240L illustrates the structure which electrically discriminate | determines the connection state of the communication connectors 220R, 220L as mentioned above, the mechanical or optical discrimination method is used as the connection discrimination part 240R, It is also possible to employ 240L.

<Signal port>
The communication unit 40 further includes a first signal port 250R and a second signal port 250L. Here, a case where the signal ports 250R and 250L are configured by connectors 251R and 251L as illustrated in FIG. 2 is illustrated.

  As described above, FIG. 2 does not limit the arrangement positions of the various elements. However, in order to make the explanation easier to understand, the first signal port 250R and the second signal port 250L are hereinafter referred to as “right signal port 250R”. And “left side signal port 250L”. Further, the connectors 251R and 251L may be referred to as “right signal connector 251R” and “left signal connector 251L”, respectively.

  The right signal connector 251R includes an input terminal (in other words, an input port) 252 for the processing unit 201 to receive the predetermined signal 254 from the outside of the unit, and an output for the processing unit 201 to transmit the predetermined signal 254 to the outside of the unit. Terminal (in other words, output port) 253. Similarly, the right signal connector 251L also has terminals 252 and 253. That is, the signal ports 250R and 250L are used for input / output of the predetermined signal 254.

  As will be apparent from the description below, the predetermined signal 254 is a signal that permits the communication unit 40 operating as a slave to execute a process of setting its own ID (hereinafter also referred to as an “ID setting permission signal”). It is.

  The signal ports 250R and 250L are used for daisy chain connection with other communication units 40, in other words, for daisy chain connection with other display units 20. Specifically, a plurality of communication units 40 are daisy-chain connected by connecting the left signal connector 251L of one communication unit 40 and the right signal connector 251R of the other communication unit 40. Is possible.

  Note that the daisy chain connection by the signal connectors 251R and 251L may be a form in which a cable is interposed, or may be a form in which the communication units 40 are directly connected.

  Here, the arrangement of the terminals 252 and 253 differs between the signal connectors 251R and 251L. Specifically, the signal connector 251R is connected so that the terminal 252 is connected to the terminal 253 of the signal connector as the counterpart, in other words, the terminal 253 is connected to the terminal 252 of the communication connector as the counterpart. , 251L terminal arrangement is defined.

<Connector>
The right three connectors 206R, 220R, and 251R can be combined into one or two connectors. According to this, the burden of unit connection work can be reduced by reducing the number of connectors. Similarly, the left three connectors 206L, 220L, and 251L can be combined into one or two connectors.

<ID setting process>
3 and 4 are diagrams for explaining the ID setting process in each communication unit 40. FIG. FIG. 3 is a block diagram outlining the communication system 50 and corresponds to FIG. In FIG. 3, the configuration of each communication unit 40 is illustrated more simply than in FIG. 2. FIG. 3 illustrates a case where the external storage medium 60 is connected to the I / F 203 of the rightmost communication unit 40R. FIG. 4 is a flowchart outlining the ID setting process ST10 in the communication unit 40.

  The ID setting process ST10 illustrated in FIG. 4 is roughly divided into a master / slave determination process ST20 and a slave ID allocation process ST40. After the communication system 50 is activated, each communication unit 40 first executes a master / slave determination process ST20.

<Master / slave decision processing>
In summary, the master / slave determination process ST20 is a process of determining the communication unit 40 as either a master communication unit or a slave communication unit according to the connection determination results 244R and 244L by the connection determination units 240R and 240L. is there.

  In the example of FIG. 4, in step ST21, it is determined whether or not another communication unit 40 is connected to both the communication connectors 220R and 220L, in other words, whether or not the communication unit 40 is in a both-side connection state. Is done. Specifically, the processing unit 201 determines whether both the right determination signal 244R and the left determination signal 244L are at the L level.

  Here, in the communication system 50, the communication unit 40 at one end among the units 40 connected in a daisy chain operates as a master. For this reason, the communication unit 40 in which the other communication units 40 are connected to both sides (corresponding to the central communication unit 40M in the example of FIG. 3) operates as a slave.

  Accordingly, when determining that both of the connection determination signals 244R and 244L are at the L level, the processing unit 201 executes the slave ID allocation process ST40. The process ST40 will be described in detail later.

  On the other hand, when the processing unit 201 determines that at least one of the connection determination signals 244R and 244L is at the L level, in other words, the processing unit 201 has another communication unit 40 on at least one side of the communication unit 40. When it determines with not being connected, the process part 201 performs step ST22.

  In step ST22, it is determined whether or not the other communication unit 40 is connected to only one of the communication connectors 220R and 220L. Specifically, the processing unit 201 determines whether only one of the connection determination signals 244R and 244L is at the L level.

  As a result of the determination in step ST22, if it is determined that the other communication unit 40 is connected to only one of the communication connectors 220R and 220L, the processing unit 201 determines that the communication unit 40 satisfies the master selection condition in step ST23. Determine if you are satisfied.

  The master selection condition is a condition imposed to be selected as a master communication unit. Here, a case where the master selection condition is given by the data 300 expressed in a format that can be decoded by the processing unit 201 is illustrated. In addition, the master selection condition data 300 defines that the communication unit 40 in a state where another communication unit 40 is connected only to the left communication connector 220L (that is, the left connection state) is selected as a master. The case where it is done is illustrated. The same purpose can be defined in various expressions.

  The master selection condition data 300 is stored in the external storage medium 60 and supplied to the communication system 50.

  According to this example, the rightmost communication unit 40R to which the external storage medium 60 is connected reads the master selection condition data 300 from the external storage medium 60 and uses the data 300. The communication unit 40R on the right end broadcasts the read master selection condition data 300 via the transmission / reception circuit 211. Thereby, the leftmost communication unit 40M can acquire the master selection condition data 300. In addition, since it is not necessary to specify the ID of the communication unit 40 of the transmission destination in the broadcast, in other words, since it is transmitted to all communication units, the broadcast unit is executed even if the ID of each communication unit 40 is not set. Is possible.

  The acquisition of the master selection condition data 300 may be completed before the execution of step ST23. For example, the reading process and the distribution process of the master selection condition data 300 are executed before step ST21.

  When it is determined in step ST23 that the communication unit 40 satisfies the master selection condition, the processing unit 201 assigns the ID of the communication unit 40 to a predetermined ID (here, assigned to the master communication unit) in step ST24. Is stored in the storage unit 202. As a result, the master ID is set in the communication unit 40, and the communication unit 40 thereafter operates as the master communication unit.

  After step ST24, the processing unit 201 executes slave ID allocation processing ST40.

  On the other hand, when it is determined in step ST23 that the master selection condition is not satisfied, the communication unit 40 operates as a slave communication unit.

  Here, the communication unit 40 determined as the slave through the above steps ST22 and ST23 is located at the final stage (in other words, the end) of the daisy chain connection. In view of this point, when it is determined in step ST23 that the master selection condition is not satisfied, the processing unit 201 activates the termination circuit 230 (see FIG. 2) in step ST25 to terminate the intra-unit communication bus line 212. . As a result, the shared communication bus line across the communication units 40R, 40M, and 40L is terminated. As a result, unnecessary signal reflection in the final-stage communication unit 40 can be prevented and good communication can be performed.

  After step ST25, the processing unit 201 executes slave ID allocation processing ST40.

  More specifically, when the master selection condition is such that the communication unit 40 in the left connection state is selected as the master as exemplified above, the rightmost communication unit 40R is determined as the master through the determination step ST23. Is done. On the other hand, the leftmost communication unit 40L is determined as a slave through the determination step ST23.

  If it is determined as a result of the determination in step ST22 that no other communication unit 40 is connected to any of the communication connectors 220R and 220L, the communication unit 40 is in a state of being used alone. Here, it is assumed that the single communication unit 40 operates as a master.

  Specifically, when it is determined in step ST22 that both of the connection determination signals 244R and 244L are at the H level, the processing unit 201 thereafter sets the ID of the communication unit 40 as the master ID (# 0) and the ID is stored in the storage unit 202. In the case of single use, since it is not necessary to execute the slave ID allocation process ST40, the processing unit 201 ends the ID setting process ST10 after step ST26.

  Note that steps ST21 and ST22 can be executed in the reverse order.

  Further, by using the master selection condition that the communication unit 40 in the right connection state is selected as the master, the leftmost communication unit 40L can be made the master.

<Slave ID allocation process>
The slave ID allocation process ST40 (see FIG. 4) will be described in detail with reference to the flowchart of FIG. In FIG. 5, for easy understanding, ID setting instruction processing STST50 in the master communication unit 40 (here, the communication unit 40R) and ID setting processing ST70 in the slave communication unit 40 (here, the communication units 40M and 40L). Is also written.

  In the example of FIG. 5, the slave communication unit 40 first determines in step ST71 whether or not the ID of the communication unit 40 is not set. For example, a flag for indicating whether or not an ID is set is prepared in the processing unit 201 or the storage unit 202 in advance, and the processing unit 201 determines the state of the flag, thereby executing step ST71. Is possible.

  When it is determined in step ST71 that the ID has been set, the slave communication unit 40 ends its own ID setting process ST70.

  On the other hand, if it is determined in step ST71 that the ID is not set, the slave communication unit 40 waits until the ID setting permission signal 254 is input to either of the signal ports 250R and 250L in step ST72. To do. Specifically, the processing unit 201 of the slave communication unit 40 stands by until one of the input ports 252 of the signal ports 250R and 250L becomes H level.

  On the other hand, in step ST51, the master communication unit 40R outputs the ID setting permission signal 254 to the left signal port 250L. Specifically, the processing unit 201 of the master communication unit 40R sets the output port 253 of the signal port 250L to the H level. In this example, the ID setting permission signal 254 is output only to the left signal port 250L to which the slave communication unit 40 is connected, but the ID setting permission signal 254 is output to both the signal ports 250R and 250L. It doesn't matter.

  The ID setting permission signal 254 output from the master communication unit 40R is transmitted to the input port 252 of the right signal port 250R of the central communication unit 40M, which is the next stage unit of the master communication unit 40R (dashed line in FIG. 5). (See arrow A51). The central communication unit 40M exits the standby state in step ST72 by the input of the ID setting permission signal 254, and waits until the slave ID 260 (see FIG. 3) is received in step ST73.

  By the way, the central communication unit 40M does not transmit the ID permission signal 254 to the leftmost slave communication unit 40L, which is a subsequent unit, until its own ID is set. Specifically, the processing unit 201 of the central communication unit 40M holds the output of the left signal port 250L at the L level. For this reason, the slave communication unit 40L at the left end maintains an input standby state for the ID setting permission signal 254 (step ST72).

  In step ST52, the master communication unit 40R broadcasts the slave ID 260. Specifically, the processing unit 201 of the master communication unit 40R generates a packet for transmitting the slave ID 260 and transmits the packet via the transmission / reception circuit 211 (in other words, via the communication circuit 210). Broadcast to the units 40M and 40R (see broken line arrow A52 in FIG. 5). Here, since it is not necessary to specify the ID of the transmission destination communication unit 40 for the broadcast, the slave communication units 40M and 40L can receive the packet of the slave ID 260 even when the ID of the slave communication units 40M and 40L is not set. .

  Here, as an example of the slave ID 260, an initial value is set to # 1, and a value obtained by sequentially increasing the initial value by +1 (so-called increment) is employed.

  The central communication unit 40M receives the slave ID 260 via the transmission / reception circuit 211 (in other words, via the communication circuit 210), thereby leaving the reception standby state at step ST73 and executing the next step ST74. .

  The slave communication unit 40L at the left end also receives the slave ID 260, but the received slave ID 260 is not used in the unit 40L because the unit 40L is not yet in a standby state for receiving the slave ID 260.

  In step ST74, the central communication unit 40M sets the received slave ID 260 as its own ID. Specifically, the processing unit 201 stores the received slave ID 260 in the storage unit 202 and changes the flag to a state in which the ID has been set.

  Here, considering that the ID setting step ST74 is executed after the steps ST71 to ST73, the step ST74 includes (a) that the slave ID is not set, and (b) the ID setting permission signal 254. Is executed, and (c) the slave ID 260 is acquired.

  Thereafter, in step ST75, the central communication unit 40M outputs the ID setting permission signal 254 to the opposite side of the right signal port 250R to which the ID setting permission signal 254 is input, that is, to the left signal port 250L. Specifically, the processing unit 201 of the central communication unit 40M sets the output port 253 of the left signal port 250L to the H level. As a result, the ID setting permission signal 254 is transmitted to the slave communication unit 40L at the left end (see the broken line arrow A75 in FIG. 5).

  In step ST76, the central communication unit 40M determines whether or not it is the last-stage slave. By the way, this determination has already been performed by steps ST21 to ST23 (see FIG. 4) of the master / slave determination process ST20. For this reason, step ST76 can be easily performed by managing the determination result at that time, for example, with a flag. Specifically, the processing unit 201 may determine the state of the flag.

  Since the central communication unit 40M is not the last-stage slave, the central communication unit 40M transmits a response message 261 (see FIG. 3) indicating that the setting of the ID of the unit 40M is completed in step ST77. Specifically, the processing unit 201 generates a packet of the response message 261 and transmits the packet via the transmission / reception circuit 211 (in other words, via the communication circuit 210) (a broken line arrow A77 in FIG. 5). reference). Such transmission may be broadcast without designating a transmission destination, or may be unicast with the transmission destination designated in the master communication unit 40R.

  By executing step ST77, the ID setting process ST70 in the central communication unit 40M ends.

  On the other hand, the processing unit 201 of the master communication unit 40R determines whether or not the response message 261 has been received within a predetermined time in step ST53.

  If the response message 261 is not received within the predetermined time, the processing unit 201 of the master communication unit 40R returns to step ST52 and broadcasts the slave ID 260 having the same content as the previous time.

  On the other hand, when the response message 261 is received within the predetermined time, the processing unit 201 of the master communication unit 40R includes the fact that the ID of the response message 261 has been set up to the last slave in step ST54. It is determined whether or not. Since the central communication unit 40M is not the last-stage slave, when the response message 261 is received from the central communication unit 40M, the processing unit 201 of the master communication unit 40R next executes step ST55.

  In step ST55, the processing unit 201 of the master communication unit 40R increments the value of the slave ID 260. Thereafter, the processing unit 201 returns to step ST52 and broadcasts the incremented slave ID 260.

  Here, the leftmost communication unit 40L is in a standby state for receiving the slave ID 260 by acquiring the ID setting permission signal 254 from the central communication unit 40M (step ST73). Therefore, the new slave ID 260 is received by the leftmost communication unit 40L.

  In step ST74, the leftmost communication unit 40L sets the received slave ID 260 as its own ID.

  According to the example of FIG. 5, the left end communication unit 40L also executes step ST75. However, since the left end communication unit 40L is located at the final stage, the step ST75 can be omitted. It is.

  Thereafter, the leftmost communication unit 40L executes step ST78 through step ST76. Specifically, since the leftmost communication unit 40L is positioned at the final stage, the leftmost communication unit 40L sets the ID for its slave in the step ST78, and sets the ID up to the final slave. A response message 261 indicating that is completed is transmitted. Specifically, the processing unit 201 generates a packet of the response message 261 and transmits the packet via the transmission / reception circuit 211 (in other words, via the communication circuit 210) (a broken line arrow A78 in FIG. 5). reference). Such transmission may be broadcast without designating a transmission destination, or may be unicast with the transmission destination designated in the master communication unit 40R.

  By executing step ST78, the ID setting process ST70 in the leftmost communication unit 40L ends.

  On the other hand, the master communication unit 40R also performs step ST53 for the response message 261 from the leftmost communication unit 40L. If the response message 261 is not received within a predetermined time, the process returns to step ST52.

  On the other hand, when the response message 261 from the leftmost communication unit 40L is received within a predetermined time, the master communication unit 40R indicates that the ID setting is completed in the response message 261 up to the slave at the final stage in step ST54. It is discriminated that it is included, and the process is terminated.

  Steps ST71 to ST73 can be executed in any order. Steps ST74 and ST75 can also be executed in the reverse order.

<Data distribution>
According to the example of FIG. 3, the data 310 for each communication unit 40 is stored in the external storage medium 60 and supplied to the communication system 50. Here, as the data 310, content data to be displayed on each display unit 20 is illustrated.

  In the example of FIG. 3, the content data 310 for the display units 20R, 20M, and 20L is individually prepared in advance. In order to distinguish between them, reference numeral 310R is used for the content data 310 for the display unit 20R, and similarly reference numerals 310M and 310L are used for the content data 310 for the display units 20M and 20L.

  The content data 310R, 310M, 310L is, for example, divided image data obtained by dividing one image in accordance with the arrangement of the display units 20R, 20M, 20L. According to this, the one image is displayed using the display units 20R, 20M, and 20L integrally. In other words, the display units 30 of each display unit 20 are assembled to form one display unit. The content data 310 may be data other than the divided image data.

  FIG. 6 shows a flowchart outlining the content data 310 distribution process ST90. FIG. 6 also shows the process ST110 in the communication unit 40 that receives the distributed content data 310 (here, the central and leftmost communication units 40M and 40L).

  According to the example of FIG. 6, in step ST91, the content data 310 in the external storage medium 60 is processed by the processing unit 201 of the communication unit 40 (here, the rightmost communication unit 40R) to which the external storage medium 60 is connected. Read out.

  In step ST92, the processing unit 201 of the communication unit 40R determines whether or not the read content data 310 is the content data 310R for the display unit 20R in which the communication unit 40R is provided.

  Here, each content data 310R, 310M, 310L is associated in advance with the ID of the corresponding display unit 20 (that is, the ID of the communication unit 40) as information on which display unit 20 the data is for. Therefore, the processing unit 201 can execute step ST92 by determining the ID given to the content data 310.

  When the read data 310 is the content data 310R for the display unit 20R, the processing unit 201 of the communication unit 40R controls the display unit 30 (see FIG. 1) to display the content data 310R in step ST93.

  On the other hand, if the read data 310 is not the content data 310R for the display unit 20R, the communication unit 40R sends the read content data 310 to the corresponding communication unit 40 (and thus the corresponding display unit) in step ST94. 20) to send. Specifically, the processing unit 201 of the communication unit 40R generates a packet of the content data 310 using the ID assigned to the read content data 310 as a transmission destination, and transmits the packet via the transmission / reception circuit 211 (in other words, Then, it is unicast (via the communication circuit 210) (see broken line arrow A94 in FIG. 6).

  The transmitted content data 310 is received by the communication unit 40 on the receiving side (step ST111) and used for display (step ST112).

  In the communication unit 40R that is the data distribution source, after step ST93 and ST94, the processing unit 201 confirms whether or not the data 310 to be read remains in step ST95. Then, the processing unit 201 returns to step ST91 if data to be read remains, and ends processing ST90 if the reading is completed.

  In addition, although the case where the content data 310 is read one by one was illustrated above, the steps ST92 to ST94 can be executed after all the content data 310 is read.

<Overview of the first embodiment>
According to the first embodiment, the master ID value is assigned in advance, and the slave ID value is determined in the master communication unit 40. For this reason, the ID of each communication unit 40 is centrally managed in the master. Therefore, setting errors such as duplicate registration of IDs can be prevented.

  Further, under the control of each communication unit 40, the ID setting permission signal 254 is transmitted in order between the communication units 40R, 40M, and 40L. For this reason, ID can be provided automatically and without omission.

  As described above, according to the first embodiment, it is possible to easily and reliably assign an ID as compared with the case where manual setting of the dip switch is required for each communication unit. In addition, since the setting operation of the dip switch is unnecessary, it is possible to reduce the part cost and the work cost.

  In addition, since the response message 261 is employed in the slave ID allocation process (see FIG. 5), the master processing unit 201 can grasp the progress of the process, contributing to reliable ID assignment.

  In addition, by adopting a response message 261 that indicates that ID setting has been completed up to the last slave, the master processing unit 201 can know the number of slaves from the number of slave IDs 260 transmitted so far. It is. According to this, for example, the processing unit 201 can check whether or not a predetermined number of slaves are connected, which contributes to the reliable construction of the communication system 50.

  If the response message 261 is not received, the slave ID 260 having the same value is broadcast again, which contributes to reliable ID assignment.

  According to the first embodiment, the communication unit 40 located at one end in the daisy chain connection can be automatically set as the master.

  At this time, which of the communication units 40R and 40L positioned at both ends of the daisy chain connection is set as the master is defined by the contents of the master selection condition. For this reason, according to the installation environment etc. of the systems 50 and 10, the convenient unit 40 and 20 can be set or changed to a master.

  Thus, according to the first embodiment, high convenience can be obtained for the setting of the master.

  Also, the master selection condition is given in software by data 300 in a format that can be decoded by the processing unit 201. For this reason, it is easy to change the contents.

  The master selection condition data 300 is stored in the external storage medium 60. For this reason, the master selection condition can be easily changed by rewriting the master selection condition data 300 in the external storage medium 60 or by replacing the external storage medium 60.

  In addition, the communication unit 40 to which the external storage medium 60 is attached acquires the master selection condition data 300 from the external storage medium 60, and the communication unit 40 that is not so uses the communication function to acquire the master selection condition data from the other communication units 40. Data 300 is acquired. That is, the master selection condition data 300 can be acquired regardless of which communication unit 40 the external storage medium 60 is attached to. For this reason, it is only necessary to attach an external storage medium to the convenient units 40 and 20 according to the installation environment of the systems 50 and 10 (for example, to the units 40 and 20 at positions where the installation work is easy).

  The content data 310 is supplied in a state prepared in advance for each display unit 20. For this reason, for example, when one image is displayed by using the display units 20R, 20M, and 20L integrally, the processing unit 201 does not need to perform division processing of the entire image data. That is, the processing load on the processing unit 201 can be reduced. Therefore, high performance of the processing unit 201 can be avoided, and cost reduction can be achieved.

  In the system described in Patent Document 1, the master LAN device has a unique configuration different from that of the slave LAN device. That is, the master is fixed in advance in the system. Therefore, although it corresponds to the master / slave determination process ST20, it is not performed. In the system described in Patent Document 1, the slave LAN device keeps the subsequent device disconnected until its own ID setting is completed. For this reason, broadcast communication cannot be used until IDs are set for all devices.

Second Embodiment
In the first embodiment, the case where the external storage medium 60 that holds the master selection condition data 300 is connected to the rightmost communication unit 40R that is a master candidate is illustrated (see FIG. 3). Moreover, the leftmost communication unit 40L, which is another master candidate, illustrated a case where the master selection condition data 300 is acquired using the communication function.

  On the other hand, as illustrated in FIG. 7, it is possible to connect the external storage medium 60 that holds the master selection condition data 300 to the central communication unit 40M that is a slave. In this case, when the central communication unit 40M broadcasts the master selection condition data 300, the communication units 40R and 40L at both ends can acquire the master selection condition data 300.

  In the example of FIG. 7, since the content data 310 is stored in the external storage medium 60 together with the master selection condition data 300, the content data 310 is distributed from the central communication unit 40M to the communication units 40R and 40L at both ends. .

  On the other hand, as illustrated in FIG. 8, the master selection condition data 300 and the content data 310 are stored in separate external storage media 61 and 62, and these external storage media 61 and 62 are stored in separate communication units 40. It is also possible to connect. The connection destinations of the external storage media 61 and 62 are not limited to the example of FIG.

  Here, when the data 300 and 310 are stored in the same external storage medium 60, both data 300 and 310 can be supplied simply by mounting one external storage medium 60. Further, it is not necessary to distinguish and manage the external storage medium 61 for the master selection condition data 300 and the external storage medium 62 for the content data 310, which is also convenient in this respect.

  Further, the external storage medium 60 may be connected to all the communication units 40. According to this, the distribution process of the master selection condition data 300 and the content data 310 becomes unnecessary. However, according to the embodiment in which the external storage medium 60 is connected to one communication unit 40, the amount of connection work of the external storage medium 60 is small, which is convenient.

<Third Embodiment>
In 1st and 2nd embodiment, the case where master selection conditions took the format of data was illustrated.

  On the other hand, the master selection condition can be defined such that the communication unit 40 in the state where the external storage medium is connected is selected as the master. In this case, in step ST23 (see FIG. 4) for determining whether or not the master selection condition is satisfied, the processing unit 201 determines whether or not an external storage medium is connected to the I / F 203. . For example, the determination in step ST23 can be performed by the processing unit 201 attempting to access an external storage medium. Alternatively, when the I / F 203 detects the connection of the external storage medium, a signal indicating that may be output from the I / F 203 to the processing unit 201.

  Here, the external storage medium according to the third embodiment does not need to have the master selection condition data 300. For this reason, for example, the external storage medium 62 (see FIG. 8) for the content data 310 can be used.

  According to the third embodiment, a master can be set only by mounting an external storage medium. At this time, of the communication units 40R and 40L at both ends, an external storage medium is used in a convenient manner according to the installation environment of the systems 50 and 10 (for example, the units 40 and 20 at positions where the installation work is easy). All you need to do is install it.

<Fourth embodiment>
In the fourth embodiment, an example in which the master selection condition is supplied by another method different from the above will be described. FIG. 9 shows a block diagram outlining the display system 21 according to the fourth embodiment. The display system 21 has a configuration in which the communication unit 40 in the display system 20 is changed to a communication unit 41. The communication unit 41 according to the fourth embodiment has a configuration in which a master selection switch 270 is added to the communication unit 40.

  The master selection switch 270 can be configured by various switch parts such as a dip switch. The master selection switch 270 is connected to the processing unit 201, whereby the processing unit 201 can acquire the setting state of the master selection switch 270.

  In the communication unit 41 having such a configuration, the master selection condition is that the communication unit 40 in which the master selection switch 270 is in a predetermined state is selected as the master. In this case, in step ST23 (see FIG. 4) for determining whether or not the master selection condition is satisfied, the processing unit 201 determines whether or not the state of the master selection switch 270 is in the predetermined state.

  Therefore, the system administrator only needs to set the master selection switch 270 to the above-mentioned predetermined state for only one of the communication units 40R and 40L at both ends that is desired to be selected as the master, which is convenient.

  Here, the state of the master selection switch 270 of the communication unit 40M not located at both ends does not affect the master / slave determination process ST20 (see FIG. 4). This is because the above-described step ST23 for determining whether or not the master selection condition is satisfied is executed only in the communication units 40R and 40L at both ends. For this reason, it is not necessary to operate the master selection switch 270 for all the communication units 40. For this reason, even if the master selection switch 270 is adopted, the complicated work is not significantly increased.

<Fifth Embodiment>
In the first embodiment, the combination of the master / slave determination process ST20 and the slave ID allocation process ST40 is exemplified.

  However, the master / slave determination process ST20 can be combined with a slave ID allocation process different from the process ST40. Similarly, the slave ID allocation process ST40 can be combined with a master / slave determination process different from the process ST20.

<Sixth Embodiment>
The first embodiment exemplifies a configuration in which broadcast communication is possible when the transmission / reception circuit 211 of each communication unit 40 is wired by a bus-type structure (see FIGS. 2 and 3).

  On the other hand, broadcast communication between the communication units 40 is also possible by wireless communication. Specifically, instead of the transmission / reception circuit 211, a transmission / reception circuit configured to be capable of wireless communication may be employed. Also in this example, each communication unit 40 is daisy chain connected via the signal ports 250R and 250L.

  Note that when wireless communication is employed, the communication connectors 220R and 220L are not necessary, and the connection determination units 240R and 240L cannot be provided. For this reason, the master / slave determination process ST20 cannot be employed.

  Further, in the above, communication by electricity or radio wave has been illustrated, but for example, optical communication can also be used. It is also possible to use an optical signal for transmitting the ID setting permission signal 254 between units.

<Seventh embodiment>
In the display system 10 illustrated in the first embodiment, three display units 20 are arranged in a straight line (see FIG. 1). However, the number and arrangement of the display units 20 are not limited to this example. Therefore, another example will be described in the seventh embodiment.

  FIG. 10 shows a schematic diagram of a display system 11 according to the seventh embodiment. In the example of FIG. 10, 36 display units 20 are arranged in a matrix of 4 rows and 9 columns. The display unit 20 at the right end of the first row is the master (# 0), the display unit 20 at the left end of the fourth row is the last stage, and these display units 20 are daisy chain connected. Note that illustration of daisy chain connections in each row is omitted.

  In the example of FIG. 10, the display unit 20 at the rear stage (in other words, the display unit 20 having a larger ID value) is arranged in the left direction in each row. In this case, the leftmost display unit 20 (# 8) in the first row is connected to the rightmost display unit 20 (# 9) in the second row via the cable 401, and the leftmost display unit in the second row. 20 (# 17) is connected to the rightmost display unit 20 (# 18) of the third row via the cable 402, and the leftmost display unit 20 (# 26) of the third row is connected to the third row via the cable 403. It is connected to the display unit 20 (# 27) at the right end of the fourth row. The cables 401 to 403 are cables for daisy chain connecting the communication connectors 220R and 220L (see FIG. 3), and the cables for daisy chain connecting the signal connectors 250R and 250L are not shown.

  In the example of FIG. 10, the first power supply 500 is connected to the display unit 20 # 0 via the power supply cable 501, and the display unit 20 # 8 is connected to the display unit # 17 via the power supply cable 502. 20 is connected. As a result, power is supplied to the display units 20 of # 0 to # 17 by the first power supply 500.

  On the other hand, the second power supply 510 is connected to the # 18 display unit 20 via the power supply cable 511, and the # 26 display unit 20 is connected to the # 35 display unit 20 via the power supply cable 512. . Thus, power is supplied to the display units 20 of # 18 to # 35 by the second power source 510.

  In addition, you may supply electric power to all the display units 20 with one power supply. Three or more power supplies may be employed.

  Here, in the arrangement form of FIG. 10, the display unit 20 in the foremost stage in each row (in other words, the display unit 20 with the smallest ID) is located on the same side (here, the right end).

  On the other hand, as illustrated in FIG. 11, it is possible to employ an arrangement form in which the display unit 20 in the foremost stage in each row is positioned on the opposite side between two adjacent rows. In addition, illustration of the power supply form is abbreviate | omitted in FIG. According to the arrangement form of FIG. 11, the cables 401 to 403 connecting the display units 20 in adjacent rows can be short. For this reason, for example, it is possible to facilitate the arrangement work, facilitate the distinction of the cables, and the like.

  For example, the display system 11 can be installed on a display shelf of a store to constitute an electronic POP (Point Of Purchase). More specifically, the display units 20 may be attached to the front surface of the shelf board with each row in the arrangement form of FIGS. 10 and 11 corresponding to the shelf board of each stage of the display shelf. For example, sales promotion is expected by displaying an advertisement video or the like of the displayed product on the display system 11.

  The display system 11 can also be used as a large screen display device by arranging the display units 20 in close proximity, for example.

<Modification>
Note that the above-described various configurations, processes, and the like can be appropriately combined as long as they do not contradict each other.

10, 11 Display system 20, 21 Display unit 40, 40L, 40M, 40R, 41 Communication unit 50 Communication system 60-62 External storage medium 201 Processing unit 210 Communication circuit 211 Transmission / reception circuit 212 In-unit communication bus line 220L, 220R For communication Connector 230 Termination circuit 240L, 240R Connection determination unit 244L, 244R Connection determination signal 250L, 250R Signal port 260 Slave ID
261 Response message 270 Master selection switch 300 Master selection condition data 310, 310L, 310M, 310R Content data

Claims (18)

One of a plurality of communication units constituting a communication system,
A communication circuit configured to be able to communicate with the remaining communication units other than the communication unit among the plurality of communication units, and provided in the communication system so as to be able to broadcast to the remaining communication units;
A processing unit connected to the communication circuit;
A first signal port and a second signal port, which are used for input / output of a predetermined signal between the processing unit and the outside of the unit, and are used for daisy chain connection with the remaining communication unit;
When the communication unit operates as a master at one end of the daisy chain connection, the processing unit
A process of setting the ID of the communication unit to a master ID assigned in advance;
To permit execution of the ID setting process as the predetermined signal to the signal port connected to the remaining communication unit operating as a slave among the first signal port and the second signal port A process of outputting the ID setting permission signal of
Broadcasting the slave ID to the remaining communication units via the communication circuit,
When the communication unit operates as a slave, the processing unit
On the condition that the ID of the communication unit is not set, the ID setting permission signal is acquired, and the slave ID is acquired, the acquired slave ID is used for the communication. Processing to set the ID of the unit;
In accordance with the setting of the ID of the communication unit, the predetermined signal is sent to a signal port different from the signal port to which the ID setting permission signal is input, of the first signal port and the second signal port. A communication unit that performs processing for outputting the ID setting permission signal. The communication unit according to claim 1,
The communication circuit includes:
A transmission / reception circuit connected to the processing unit;
An intra-unit communication bus line connected to the transceiver circuit;
A communication unit that is connected to the intra-unit communication bus line and includes a first communication connector and a second communication connector that are used for the daisy chain connection with the remaining communication units. The communication unit according to claim 2,
A first connection determination unit configured to determine whether or not a counterpart connector is connected to the first communication connector, and to output a determination result to the processing unit;
A second connection determination unit configured to determine whether or not a connector serving as a counterpart is connected to the second communication connector, and to output a determination result to the processing unit;
The processing unit performs a master / slave determination process for determining the communication unit as either the master or the slave according to the determination result by the first connection determination unit and the second connection determination unit,
The master / slave determination process includes:
A first connection state in which the counterpart connector is connected only to the first communication connector or a second connection state in which the counterpart connector is connected only to the second communication connector is detected. A communication unit including a process of determining the communication unit as one of the master and the slave based on a master selection condition imposed to be selected as the master. One of a plurality of communication units constituting a communication system,
A communication circuit configured to be able to communicate with the remaining communication units other than the communication unit among the plurality of communication units, and provided in the communication system so as to be able to broadcast to the remaining communication units;
A processing unit connected to the communication circuit,
The communication circuit includes:
A transmission / reception circuit connected to the processing unit;
An intra-unit communication bus line connected to the transceiver circuit;
A first communication connector and a second communication connector that are connected to the intra-unit communication bus line and are used for the daisy chain connection with the remaining communication units;
The communication unit is
A first connection determination unit configured to determine whether or not a counterpart connector is connected to the first communication connector, and to output a determination result to the processing unit;
A second connection determination unit configured to determine whether or not a connector serving as a counterpart is connected to the second communication connector, and to output a determination result to the processing unit;
The processing unit performs a master / slave determination process for determining the communication unit as either the master or the slave according to the determination result by the first connection determination unit and the second connection determination unit,
The master / slave determination process includes:
A first connection state in which the counterpart connector is connected only to the first communication connector or a second connection state in which the counterpart connector is connected only to the second communication connector is detected. A communication unit including a process of determining the communication unit as one of the master and the slave based on a master selection condition imposed to be selected as the master. The communication unit according to claim 3 or 4,
The master selection condition is a communication unit supplied by data expressed in a format readable by the processing unit. The communication unit according to any one of claims 3 to 5,
The communication unit, wherein the data related to the master selection condition is supplied from an external storage medium. The communication unit according to claim 6,
The processor is
When the external storage medium is attached to the communication unit, the data regarding the master selection condition is acquired from the external storage medium,
When the external storage medium is not attached to the communication unit, the data related to the master selection condition is acquired from the other communication unit to which the external storage medium is attached via the communication circuit.
communication unit. The communication unit according to claim 3 or 4,
The master selection condition is a communication unit in which a communication unit in a state where an external storage medium is mounted is selected as the master. The communication unit according to claim 3 or 4,
A master selection switch connected to the processing unit;
The master selection condition is a communication unit in which a communication unit in which the master selection switch is in a predetermined state is selected as the master. The communication unit according to any one of claims 1 to 9,
The processor is
Processing for acquiring individual data prepared for each communication unit and associated with the ID in advance;
A communication unit that performs processing for transmitting the individual data for the remaining communication units excluding the communication unit to a corresponding communication unit among the remaining communication units via the communication circuit. The communication unit according to claim 10, wherein
The communication unit, wherein the individual data is stored and supplied in the same external storage medium together with the data related to the master selection condition according to claim 6. The communication unit according to any one of claims 3 to 11,
A termination circuit for terminating the intra-unit communication bus line;
The master / slave determination process includes:
When the first connection state or the second connection state is detected and the communication unit is determined to be the slave, the termination circuit is operated to terminate the intra-unit communication bus line.
communication unit. A communication unit according to any one of claims 3 and 12 quoting claim 3 and claim 3.
When the communication unit operates as the slave, the processing unit sends a response message indicating that the setting of the ID is completed via the communication circuit along with the setting of the ID of the communication unit. Process to send to
When the communication unit is a final stage slave, the processing unit further includes in the response message that the setting of the ID is completed up to the final stage slave.
communication unit. The communication unit according to claim 13, wherein
When the communication unit operates as the master, the processing unit repeats broadcasting the slave ID having the same contents until receiving the response message from the slave.   A communication unit according to any one of claims 1 to 3 and claims 5 to 14 quoting the claims 1 to 3, respectively, and the first signal port of one communication unit; A communication system comprising a plurality of communication units that are daisy-chain connected in a form in which the second signal port of another communication unit is connected.   A communication unit according to claim 4 and any one of claims 5 to 14 quoting the claim 4, respectively, and the first communication connector of one communication unit and the other communication unit. A communication system comprising a plurality of communication units that are daisy chain connected in a form in which the second communication connector of the communication unit is connected. A communication unit according to any one of claims 1 to 14,
A display unit connected to the communication unit,
A display unit, wherein the display unit is provided so as to be able to display data received by the communication unit. A communication system according to claim 15 or 16,
A plurality of display units respectively connected to the plurality of communication units constituting the communication system;
A display system in which each of the plurality of display units is provided so as to be able to display data received by a communication unit to which the display unit is connected.

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