Communication system, infrastructure system using the same, building automation system, and factory automation system

Abstract

To provide a communication system, or the like, connected in multi-drop configured to reduce investigation time for a unique address allocated to a terminal device.SOLUTION: In a central unit of a communication system, a specifying unit which specifies a unique address allocated to each terminal includes: a creation unit which creates a symbol group map; a determination unit which determines, when a command packet including information for returning a response packet including the unique address is transmitted to a terminal device for which a designated symbol group included in the map and the unique address allocated to the device are identical with each other, whether the number of terminal devices to return the response packet is 0, 1 or more; a control unit which issues an instruction, based on a result of the determination, to select a symbol group to be designated in a command packet to be transmitted next or to input information for a list; and an input unit which inputs, when acquiring the unique address allocated to the terminal device, the unique address in association with information indicating the terminal device that is a transmission source, in the list.SELECTED DRAWING: Figure 3

Description

Technical Field

[0001] The present invention relates to a communication system, an infrastructure system using the same, a building automation system, and a factory automation system, and particularly to a multi-drop connected communication system, an infrastructure system using the same, a building automation system, and a factory automation system.

Background Art

[0002] Patent Document 1 discloses an electronic wiring system by automatic communication by the present applicant. In this electronic wiring system, an ICized central device having a shared memory is provided on the control center side, and an ICized terminal device having an input / output port and a transmission / reception circuit is connected to each control target (device) side. The central device and each terminal device are connected in a multi-drop manner through a digital communication line (communication cable), and data exchange of command packets and response packets is performed at high speed in a full-duplex manner via the shared memory without a protocol by a program. According to this electronic wiring system, wiring between a control center having a microprocessor and a number of distributed control targets without a microprocessor is possible with a simple configuration, easy development and maintenance, low cost, and high-speed data communication.

[0003] In such a communication system in which, for example, one central device and ten terminal devices (hereinafter, these are distinguished and denoted as terminal device 1, terminal device 2,..., terminal device 10) are multi-drop connected through a communication cable, for the purpose of enabling the central device to identify the communication destination, unique local addresses such as local addresses 1 to 10 are set for each of all the terminal devices 1 to 10.

[0004] In addition, in this type of communication system, for example, the terminal device 1 is equipped with a temperature sensor, the terminal device 2 is equipped with a humidity sensor, the terminal device 3 is equipped with a temperature regulator, and the terminal device 4 is equipped with a humidity regulator. There is a usage pattern in which each of these is controlled as a control target that is a device.

[0005] In this case, for example, the central device generates a command packet including an instruction such as "Cause the humidity sensor to measure the current humidity and return a response packet including the measurement result of the humidity", and transmits it to the terminal device 2 through the communication cable. In response, the terminal device 2 causes the humidity sensor to measure the humidity according to the instruction included in the command packet, generates a response packet including the measurement result of the humidity, and returns it to the central device through the communication cable.

[0006] Then, for example, when the central device determines that the humidity measurement result included in the response packet returned from the terminal device 2 is equal to or greater than a predetermined threshold, it generates a command packet including an instruction such as "Output a dehumidification command to the humidity regulator and return a response packet including information indicating that the output has been completed", and transmits it to the terminal device 4 through the communication cable. In response, the terminal device 4 outputs a dehumidification command to the humidity regulator according to the instruction included in the command packet, generates a response packet including information indicating that the output has been completed, and returns it to the central device through the communication cable.

[0007] When performing such communication, the central device can use the already set local addresses 2 and 4 for each of the terminal devices 2 and 4 as the destinations of the command packets to be transmitted. That is, since the local address can identify the destination terminal device, it can also be used as the destination of the command packet.

[0008] By the way, generally, in many cases, the designer of the communication system plans the assignment of local addresses to be set for each terminal device and creates a list thereof. Then, the installer of the communication system sets the local addresses for each terminal device according to the list.

[0009] [Patent Document 1] Japanese Patent Laid-Open No. 9-326808 [Disclosure of the Invention] [Problems to be Solved by the Invention]

[0010] However, according to the conventional method, since the designer of the communication system has planned it himself / herself, it is almost impossible to misassign the local address set for each terminal device. On the other hand, since the installer of the communication system may not be able to fully grasp the plan intended by the designer of the communication system, there is a possibility of setting an incorrect local address. If an incorrect local address is used as the destination, of course, the communication system cannot operate correctly.

[0011] For example, if an incorrect local address 2 is set for terminal device 1 which should originally have local address 1 set, and the correct local address 2 is set for terminal device 2 which should originally have local address 2 set, as a result, local address 2 will be set redundantly for terminal devices 1 and 2.

[0012] In this state, when the central device transmits a command packet including local address 2 as the destination, both terminal devices 1 and 2 will return a response packet corresponding to the command packet.

[0013] Normally, response packets returned from terminal devices 1 and 2 almost simultaneously collide with each other in the communication cable, and at least one of them is damaged. In that case, those response packets are either (1) both damaged and cannot be received by the central device, or (2) one of them (for example, the response packet returned from terminal device 1) can be received by the central device, but the other (for example, the response packet returned from terminal device 2) cannot be received by the central device. Therefore, although the local address 2 is actually incorrectly duplicated for terminal devices 1 and 2, the central device cannot detect this situation.

[0014] Also, if an incorrect local address 2 is set for terminal device 1 which should originally have local address 1, and an incorrect local address 1 is set for terminal device 2 which should originally have local address 2, as a result, local addresses 2 and 1 will be set for terminal devices 1 and 2 in the wrong order.

[0015] In this state, even if the central device sends a command packet including local address 2 as the destination in order to determine the necessity of dehumidification, terminal device 1 will measure the current temperature with the temperature sensor and return a response packet including the measurement result. In this case, the central device cannot perform correct humidity adjustment control.

[0016] Furthermore, although local addresses 1 to 10 should be set for terminal devices 1 to 10 respectively, it is also possible that local address 11 is incorrectly set for terminal device 10. Then, even if the central device intends to send a command packet to terminal device 10, since the incorrect local address 11 is set for terminal device 10, terminal device 10 cannot process according to the instructions of that command packet, let alone return a corresponding response packet to the central device.

[0017] Thus, when a system installer sets a local address, a human error of setting an incorrect local address may inevitably occur. Therefore, instead of using the local address set by the system installer to avoid such a situation, there is an idea of using a unique address such as a MAC (Media Access Control) address assigned to the terminal device at the time of manufacture as the destination.

[0018] However, even in that case, if the system installer or the like investigates all the unique addresses assigned to the terminal devices and sets them in the central device, a human error may occur during the investigation in this case as well. Therefore, it is impossible to completely eliminate the situation where communication becomes impossible due to a human error.

[0019] To avoid this, it is also conceivable that the central device investigates the unique addresses assigned to the terminal devices without human intervention. However, generally, a MAC address uses a large number of digits such as 8 digits in hexadecimal considering the total number of devices manufactured in the lifetime of the device (in fact, in many cases, it is 12 digits or more in hexadecimal). Therefore, the number of unique addresses is 16 8 to the power of 16 (≈ 4.3 billion). If all the unique addresses of all the terminal devices are investigated one by one, it would take an enormous amount of time and is not practical.

[0020] Incidentally, if this type of investigation is to be carried out, for example, a command packet including an instruction to the effect that "a terminal device whose unique address assigned to the own device is '00000000' shall return a response packet" is transmitted, and then, "a terminal device whose... is '00000001' shall...", "a terminal device whose... is '00000002' shall...",... "a terminal device whose... is 'FFFFFFFF' shall..." are sequentially transmitted about 4.3 billion command packets. Assuming that 1 ms is allocated as the period required for transmitting each command packet and 1 ms is allocated as the period required for returning the response packet, the investigation time will be [2 ms × 4.3 billion times = about 100 days]. This investigation time is not affected by the number of terminal devices connected to the communication cable.

[0021] Therefore, an object of the present invention is to devise a method for investigating the unique address assigned to a terminal device that is performed without human intervention and to shorten the investigation time.

Means for Solving the Problem

[0022] In order to solve the above problems, the present invention is a communication system in which a central device (for example, "central device 200" in FIG. 1) and a plurality of terminal devices (for example, "terminal devices 300A to 300D" in FIG. 1) are multi-drop connected through a communication cable (for example, "communication cable 100" in FIG. 1), The central device is, When the unique address assigned to each of the plurality of terminal devices is any one of n symbol groups consisting of m digits in an n -ary number (where n and m are both integers), the n symbol groups are arranged in ascending order in a first layer (for example, "first layer" in FIG. 4), and the n / n m symbol groups arranged in ascending order in the p -th layer (p is each integer from 1 to m) are grouped into n groups of (m - p) -digit symbol groups that match in (m - (p - 1)) -digit symbols excluding any one of the following symbols in the symbol groups arranged in ascending order in the p -th layer, and n m with the different one digit being an arbitrary symbol, m / n (P-1) symbol groups are grouped into n groups of (m - p) -digit symbol groups that match in (m - (p - 1)) -digit symbols excluding any one of the following symbols in the symbol groups arranged in ascending order in the p -th layer, and n m / n pA creating unit (e.g., "creating unit 242" in FIG. 3) that creates a tree-like hierarchical symbol group map in which individual symbol groups are arranged in ascending order to the (p + 1)-th layer higher than the p-th layer (e.g., the symbol group map of "first layer" to "fourth layer" shown in FIG. 4). A generating unit (e.g., "generating unit 220" in FIG. 2) that generates a command packet including an instruction to the effect that "a terminal device in which the specified symbol group is the same as the unique address assigned to the own device shall return a response packet including the unique address" among the symbol groups (e.g., "0XXX" in the "fourth layer" of FIG. 4) arranged in ascending order in the symbol group map created by the creating unit. A discriminating unit (e.g., "discriminating unit 244" in FIG. 3) that discriminates whether the number of terminal devices that have returned a response packet through the communication cable in response to the command packet when the command packet generated by the generating unit is transmitted through the communication cable is "plural", "1", or "0". A control unit (e.g., "control unit 246" in FIG. 3) that selects the smallest symbol group (e.g., "00XX" in FIG. 4) in the next lower layer (e.g., "third layer" in FIG. 4) of the layer (e.g., "fourth layer" in FIG. 4) to which the symbol group (e.g., "0XXX" in FIG. 4) specified by the most recently transmitted command packet belongs when the number of terminal devices discriminated by the discriminating unit is "plural" (e.g., when the discrimination step J1 in cycle C1 in FIG. 5 is "plural"), and selects the largest symbol group (e.g., "11XX" in the "third layer" of FIG. 4) that has not been the subject of investigation in the same or higher layer (e.g., "third layer" or "fourth layer" in FIG. 4) as the layer (e.g., "third layer" in FIG. 4) to which the symbol group (e.g., "10XX" in FIG. 4) specified by the most recently transmitted command packet belongs when the number of terminal devices discriminated by the discriminating unit is not "plural" (e.g., when the discrimination step J5 in cycle C5 in FIG. 5 is "0"). When the number of terminal devices determined by the determination unit is "1" (for example, when the determination step J2 of cycle C2 in FIG. 5 is "1"), an input unit (for example, "input unit 248" in FIG. 3) that associates the unique address included in the response packet (for example, "0001" in cycle C2 of FIG. 5) with information indicating the source of the response packet (for example, terminal device 300A in FIG. 5) and inputs them into a list. Comprising.

[0023] Note that the central device may also include an acquisition unit that acquires the setting information of each of the plurality of terminal devices. As an example of acquiring the setting information, a command packet including an instruction to the effect of "return a response packet including the setting information of the own device" is generated, with each unique address input into the list by the input unit as the destination, and these command packets are sequentially transmitted to each of the plurality of terminal devices. The setting information included in the response packets sequentially returned from the plurality of terminal devices may be input into the list in association with the unique address assigned to the terminal device that is the source of each response packet.

[0024] Also, it may include a setting unit that sets a unique local address or setting information for each of the plurality of terminal devices. Since the local address can also be used as the destination of the command packet, a unique local address or the like set for each of the plurality of terminal devices is associated with the corresponding unique address and input into the list. Using each unique address input into the list as the destination and specifying the corresponding local address or the like, a command packet including an instruction to the effect of "since the local address will be used as the destination of future command packets, update the destination setting" is generated and sequentially transmitted to the corresponding terminal device. This is also a method.

[0025] Furthermore, a detection unit for detecting that another terminal device is connected to the communication cable can also be provided. When information to be set in another terminal device detected by the detection unit is input in the list, the information can also be set in the other terminal device.

[0026] Furthermore, the infrastructure system, building automation system, and factory automation system of the present invention include the above communication system.

Brief Description of Drawings

[0027]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Figure 8

Figure 9

Description of Reference Numerals

[0028] 100 Communication cable 200, 200A to 200D Central device 210 Communication Unit 220 Generation Unit 230 Processing Unit 240 Identification Unit 242 Creation Unit 244 Discrimination Unit 246 Control Unit 248 Input Unit 300, 300A to 300D Terminal Devices 310 Communication Unit 320 Generation Unit 330 Processing Unit 340 Setting Unit 400 Device 1000 Tunnel 2000 Vehicle 3000 Embodiment of the Invention of Commercial Facilities

[0029] Hereinafter, embodiments of the present invention will be described with reference to the drawings.

[0030] <Explanation of the Outline of the Communication System of the Embodiment of the Present Invention> The communication system of the embodiment of the present invention is a communication system that is completely different from the so-called Ethernet in which computers are connected to each other one-to-one via LAN cables and communicate according to the TCP / IP protocol. Therefore, first, the outline of the communication system of the embodiment of the present invention will be described.

[0031] The communication system of the embodiment of the present invention is configured by multi-drop connecting N central devices and M terminal devices to a communication cable. Here, N and M are 1 or more, including the case where N = M. However, typically, a 1:M (M is 2 or more) connection is often adopted. Therefore, the communication system of the embodiment of the present invention has a significant difference in configuration from Ethernet, which can only make 1:1 connections.

[0032] Here, in a multi-drop system, since there are usually multiple terminal devices, it is necessary to control the period during which each terminal device can return a response packet. Otherwise, multiple terminal devices will return response packets almost simultaneously, and the response packets will collide with each other on the communication cable, causing at least one of the response packets to be damaged and the central device to be unable to receive the desired data.

[0033] As a method for controlling the period during which a response packet can be returned, (1) This is a commonly adopted method. Under the leadership of the central device, the transmission time of the response packet is sequentially instructed to all terminal devices. (2) This is the method mainly described in this specification. The communication time schedule of the command packet and the response packet is assigned in advance to the central device and all terminal devices. (3) A combination of the methods (1) and (2) above. These can be roughly classified into three types.

[0034] FIG. 1 is a schematic explanatory diagram of a communication system according to an embodiment of the present invention. In FIG. 1, for easy understanding, as typically shown in Japanese Patent Application Laid-Open No. 9-326808 (Patent Document 1), which is incorporated herein by reference, a state of "1:4 connection" in which one central device 200 and four terminal devices 300A to 300D are multi-drop connected through a communication cable 100 is shown. Hereinafter, when the terminal devices 300A to 300D are not distinguished and are collectively referred to, they are referred to as the terminal device 300 including the case where they are collectively referred to.

[0035] The communication system shown in FIG. 1 can adopt either a full-duplex communication method or a half-duplex communication method. In either of these methods, generally speaking, the order of transmission and reception of the command packet and the response packet between the central device 200 and the terminal device 300 is the same. That is, when viewed as a whole communication system, regardless of which of these methods is adopted, through the communication cable 100, (1) The central device 200 transmits a command packet to the terminal device 300A, and the terminal device 300A returns a response packet to the central device 200. (2) The central device 200 transmits a command packet to the terminal device 300B, and the terminal device 300B returns a response packet to the central device 200. (3) The central device 200 transmits a command packet to the terminal device 300C, and the terminal device 300C returns a response packet to the central device 200. (4) The central device 200 transmits a command packet to the terminal device 300D, and the terminal device 300D returns a response packet to the central device 200.

[0036] To describe it in more detail, first, in the case of the half-duplex communication method, through the communication cable 100, (1-1) The central device 200 transmits a command packet intended for the terminal device 300A. (1-2) The terminal device 300A returns a response packet to the central device 200. (2-1) The central device 200 transmits a command packet intended for the terminal device 300B. (2-2) The terminal device 300B returns a response packet to the central device 200. (3-1) The central device 200 transmits a command packet intended for the terminal device 300C. (3-2) The terminal device 300C returns a response packet to the central device 200. (4-1) The central device 200 transmits a command packet intended for the terminal device 300D. (4-2) The terminal device 300D returns a response packet to the central device 200.

[0037] In this case, the terminal device 300 usually receives all the command packets and response packets transmitted through the communication cable 100. That is, for example, the terminal device 300A receives both the packets transmitted from the central device 200 and those transmitted from other terminal devices 300B to 300D, as long as there are no device failures or communication abnormalities.

[0038] Therefore, among all the packets once received by each terminal device 300, only the command packets transmitted at the timing when the command packets destined for the own device are transmitted are taken in, and the processing is performed according to the instructions included in the command packets, while the packets transmitted at other timings are discarded.

[0039] For example, the terminal device 300C temporarily receives the command packet transmitted from the central device 200 during the above period (1-1). However, since the period (1-1) is the allocation period when the command packet destined for the terminal device 300A is transmitted and not the allocation period when the command packet destined for the own device is transmitted, the command packet transmitted from the central device 200 during the above period (1-1) is discarded.

[0040] In this embodiment, the period required for one cycle of the periods (1-1) to (4-2) is fixed. This period is referred to as the "fixed period of one cycle" in this specification. The fixed period of one cycle is typically set as appropriate by the designer of the communication system. When a command packet is transmitted from the central device 200 to the terminal device 300A, for example, in the first cycle, the response packet from the terminal device 300A to the central device 200 is also returned in the same first cycle. The above is the explanation of the half-duplex communication method.

[0041] On the other hand, in the case of the full-duplex communication method, a downstream line through which the command packet transmitted from the central device 200 to the terminal device 300 is transmitted and an upstream line through which the returned response packet from the terminal device 300 to the central device 200 is transmitted are provided separately.

[0042] Therefore, for example, the same period is assigned to the period (2-1) of the fourth cycle and the period (1-2) of the fourth cycle, the same period is assigned to the period (3-1) of the fourth cycle and the period (2-2) of the fourth cycle, the same period is assigned to the period (4-1) of the fourth cycle and the period (3-2) of the fourth cycle, and the same period is assigned to the period (1-1) of the fifth cycle and the period (4-2) of the fourth cycle, so that data communication can be performed simultaneously in both directions.

[0043] That is, in the case of the full-duplex communication system, for example, when the central device 200 transmits a command packet to the terminal device 300B, the terminal device 300A can simultaneously transmit a response packet to the central device 200. Therefore, the length of a certain period of one cycle in the case of the full-duplex communication system is about half of the length of a certain period of one cycle in the case of the half-duplex communication system with the same system configuration.

[0044] Here, in order to perform necessary communication between the central device 200 and the terminal device 300, information indicating the destination is included in the header of the command packet, and the terminal device 300 can refer to the header of the received command packet and capture it when it determines that it is addressed to itself.

[0045] Typically, in addition, all of the above-mentioned periods (1-1) to (4-2) are unified to, for example, 1 ms, and the central device 200 transmits the command packet · only during the period (1-1) to the terminal device 300A, · only during the period (2-1) to the terminal device 300B, · only during the period (3-1) to the terminal device 300C, · only during the period (4-1) to the terminal device 300D, Also, the response packet to the central device 200 is returned · only during the period (1-2) to the terminal device 300A, · It can only be performed on the terminal device 300B during the period (2-2), · It can only be performed on the terminal device 300C during the period (3-2), · It can only be performed on the terminal device 300D during the period (4-2), In this way, a time schedule in which each period is fixedly assigned, and a timing means for synchronizing the progress of the time schedule, can also be provided in the central device 200 and the terminal device 300.

[0046] When time division is performed in this way, the period (1-1) is a dedicated period for the central device 200 to transmit a command packet to the terminal device 300A and a dedicated period for the terminal device 300A to capture the command packet, the period (2-1) is a dedicated period for the central device 200 to transmit a command packet to the terminal device at 300B and a dedicated period for the terminal device 300B to capture the command packet, …, the period (4-1) is a dedicated period for the central device 200 to transmit a command packet to the terminal device 300D and a dedicated period for the terminal device 300D to capture the command packet.

[0047] In this way, the terminal device 300 can capture the command packet transmitted during the dedicated period assigned to itself and discard the command packet transmitted outside the dedicated period assigned to itself.

[0048] Note that the lengths of each of the periods (1-1) to (4-2) do not necessarily have to match each other, but it should be noted that the central device 200 and the terminal device 300 must ensure the minimum length required for reliable packet transmission and reception.

[0049] Also, it should be noted that the communication system according to the embodiment of the present invention may act as a terminal device 300 under certain conditions of the central device 200, and conversely, may act as the central device 200 under certain conditions of the terminal device 300.

[0050] <Description of the overall configuration of the communication system> Returning to FIG. 1 again. The central device 200 transmits a command packet including various instructions regarding a device (not shown) connected to the terminal device 300 to the terminal device 300 through the communication cable 100. Further, the terminal device 300 executes processing regarding the device connected to its own device in accordance with the instructions included in the command packet transmitted from the central device 200, and returns a response packet including information and data regarding the processing result to the central device 200 through the communication cable 100.

[0051] Examples of the device here include various sensors including the temperature sensor and humidity sensor described above, as well as various devices such as lamps, motors, and solenoids. In these examples, the central device 200 may transmit a command packet including an instruction to obtain and return the sensing results by various sensors to the terminal device 300, or may transmit a command packet including an instruction to change the light amount of the lamp, the rotation speed of the motor, or the opening / closing switching of the solenoid.

[0052] Furthermore, as another example of the various sensors in the case of this embodiment, examples suitable for the building automation field include fire detection sensors installed in factories, buildings, etc., examples suitable for the infrastructure field include fall prevention sensors for tracks installed on the platforms of railway stations, and examples suitable for the factory automation field include operation stop sensors for machinery and equipment installed in factories, etc.

[0053] Here, when applying a general communication system with multi-drop connection to a fire alarm system, a person skilled in the art would consider placing a fire detection sensor that outputs fire detection information when a fire is detected and a terminal device 300C connected thereto inside the factory, and placing a fire alarm that alarms when input indicates that a fire has occurred and a terminal device 300D connected thereto in the office.

[0054] Then, (1) Transmitting a command packet including an instruction "When the fire detection sensor outputs fire detection information, return a response packet including this" toward the terminal device 300C, (2) When a response packet including the fact that fire detection information has been output from the terminal device 300C is returned, transmitting a command packet "Output an alarm command to the fire alarm and return a response packet including information indicating that the output has been completed" toward the terminal device 300D, By using a control program that causes the central device 200 to execute the above, when a fire occurs in the factory, it is possible to notify a communication system administrator or the like in the office away from the factory of this fact.

[0055] <Explanation of the configurations of the central device 200 and the terminal device 300> FIG. 2 is a block diagram showing a schematic configuration of the central device 200 and the terminal device 300 shown in FIG. 1. FIG. 2A shows the configuration of the central device 200, and FIG. 2B shows the configuration of the terminal device 300.

[0056] The central device 200 shown in FIG. 2A is a communication unit 210 that performs packet communication with the terminal device 300 through the communication cable 100, a generation unit 220 that generates a command packet transmitted by the communication unit 210, a processing unit 230 that executes processing according to the information included in the payload of the response packet received by the communication unit 210, It includes a specifying unit 240 that specifies a unique address such as a MAC address assigned to each of the terminal devices 300, for example, during manufacturing.

[0057] The configuration of the terminal device 300 shown in FIG. 2B A communication unit 310 that performs packet communication with the central device 200 through the communication cable 100, A generation unit 320 that generates a response packet returned by the communication unit 310, A processing unit 330 that executes processing according to information included in the payload of a command packet addressed to its own device received by the communication unit 310, A setting unit 340 that performs settings according to information included in the payload of a command packet received by the communication unit 310.

[0058] Also, for example, some of the communication unit 210, generation unit 220, processing unit 230, and specifying unit 240 in the central device 200 can be unitized, can be configured with general-purpose hardware such as a CPU and memory, or can be configured with a dedicated LSI like a state machine. This also applies to the terminal device 300.

[0059] Also, for example, each function of the communication unit 210, generation unit 220, processing unit 230, and specifying unit 240 in the central device 200 or some of the operations for realizing the function may be borne by other parts mutually. That is, for example, the specifying unit 240 includes each part described below with reference to FIG. 3, but for some of the processing performed by the specifying unit 240, the processing unit 230 may bear it. This also applies to the terminal device 300.

[0060] FIG. 3 is a block diagram showing a schematic configuration of the specifying unit 240 shown in FIG. 2. The specifying unit 240 shown in FIG. 3 A creation unit 242 that creates a symbol group map as shown in FIG. 4 described later, When the communication unit 210 transmits a command packet including information to the effect that a terminal device in which a specified symbol group among the symbol groups arranged in the symbol group map created by the creation unit 242 and the unique address assigned to the own device are the same shall return a response packet including the unique address, a determination unit 244 that determines whether the number of terminal devices 300 that return the corresponding response packet is "0", "1", or "a plurality", a control unit 246 that executes various controls including selecting a symbol group specified in the next command packet to be transmitted based on the determination result by the determination unit 244 or instructing information input to the following list, and an input unit 248 that, when the unique address assigned to the terminal device 300 can be acquired, inputs it to a list in association with the information indicating the terminal device 300 that is the transmission source thereof.

[0061] Here, if the terminal device 300 returns a response packet, the state of the communication cable 100 that transmits it changes. Therefore, the determination unit 244, for example, determines whether there is a change in the state of the communication cable 100 within a certain period of one cycle, and if there is no change in the state, it can be determined that the number of terminal devices 300 that have returned the response packet is "0". On the other hand, if there is a change in the state, it can be determined that the number of terminal devices 300 that return the response packet is "1" or "a plurality".

[0062] Next, if the communication unit 210 can receive the response packet, the determination unit 244 can determine that the number of terminal devices 300 that have returned the response packet is "1", and if the communication unit 210 cannot receive the response packet, the determination unit 244 can determine that the number of terminal devices 300 that have returned the response packet is "a plurality".

[0063] Note that the fact that the response packet can be received means that no error is detected as a result of the communication unit 210 performing an error test on the response packet using a known method such as parity, checksum, CRC, Hamming code, BCH code, etc.

[0064] In this way, by performing the above presence determination and the above error check, the determination unit 244 can determine whether the number of terminal devices 300 that have returned response packets is "0", "1", or "a plurality". Then, depending on whether the number of terminal devices 300 that have returned response packets, as determined by the determination unit 244, is "a plurality", the control unit 246 selects a symbol group specified by the next command packet to be transmitted. This will be described in detail with reference to FIG. 4.

[0065] Further, when the control unit 246 determines that the number of terminal devices 300 that have returned response packets is "1" by the determination unit 244, the control unit 246 instructs the input unit 248 to input, in a list, the information indicating the terminal device 300 that has returned the response packet in association with the unique address assigned thereto.

[0066] FIG. 4 is an explanatory diagram of a symbol group map created by the creation unit 242 shown in FIG. 3. It should be noted that the symbol group map created by the creation unit 242 is not limited to the form shown in FIG. 4, and for example, it may be in other forms with the same concept.

[0067] In the example shown in FIG. 4, out of a total of 16 symbol groups "0000" to "1111" represented by "4 - digit binary numbers", for example, "0001", "0100", "1110", and "1111" surrounded by thick frames are assumed to be the unique addresses assigned to terminal devices 300A to 300D respectively. Note that the symbol group refers to a single one within each frame in the example of FIG. 4. Therefore, for example, the symbol group "0000" is composed of 4 symbols "0".

[0068] First, the meaning of the symbol group map shown in FIG. 4 will be outlined. In the present embodiment, for example, it is positioned as "first layer", "second layer", "third layer", and "fourth layer" from the bottom to the top of FIG. 4.

[0069] In the "first layer", all 16 symbol groups represented by "4 - digit binary numbers", namely the symbol groups "0000" to "1111", are arranged in ascending order. In the "second layer" which is above the "first layer", a total of 8 symbol groups, namely "000X", "001X", "010X",..., "111X", are arranged in ascending order. In the "third layer" which is above the "second layer", a total of 4 symbol groups, namely "00XX", "01XX", "10XX", "11XX", are arranged in ascending order. In the "fourth layer" which is above the "third layer", a total of 2 symbol groups, namely "0XXX" and "1XXX", are arranged in ascending order. The rules for arranging symbol groups in ascending order in the second to fourth layers are as follows.

[0070] For example, looking at the consecutive symbol groups "0000" and "0001" among the symbol groups "000" to "1111" arranged in ascending order in the "first layer", although the symbols in the first digit (units place) are different between "0" and "1", the symbols in the other second to fourth digits (tens to thousands place) are all the same, which is "000". Symbol groups like "000X" to "111X" where the first digit is represented by an arbitrary symbol "X" are arranged in ascending order in the upper second layer.

[0071] Similarly, looking at the consecutive symbol groups "000X" and "001X" among the symbol groups "000X" to "111X" arranged in ascending order in the "second layer", although the symbols in the second digit (tens place) are different between "0" and "1", the symbols in the other third to fourth digits (hundreds to thousands place) are all the same, which is "00". Symbol groups like "00XX" to "11XX" where the second digit is represented by an arbitrary symbol "X" are arranged in ascending order in the upper third layer.

[0072] Similarly, looking at the consecutive symbol groups "00XX" and "01XX" among the symbol groups "00XX" to "11XX" arranged in ascending order in the "third layer", although the symbols in the third digit (hundreds place) are different between "0" and "1", the symbols in the other fourth digit (thousands place) are all the same, which is "0". Symbol groups like "0XXX" to "1XXX" where the third digit is represented by an arbitrary symbol "X" are arranged in ascending order in the upper fourth layer.

[0073] Generalizing the symbol groups arranged in the symbol group map shown in FIG. 4 without limiting them to the symbol groups of "4-bit binary numbers", when the unique address assigned to each of the plurality of terminal devices 300 is any of the n symbol groups consisting of m digits in base n (where both n and m are integers), m if it is any of the n symbol groups, (n and m are both integers), m arrange the n symbol groups in ascending order in the first layer, and for the p-th layer (p is each integer from 1 to m), arrange the n m / n (P-1) symbol groups arranged in ascending order in the p-th layer. Exclude any of the following symbols, and group n symbol groups in which (m - p) digits of the (m - (p - 1)) digits match into one set, and use the different 1 digit as an arbitrary symbol. Then, the n m / n p symbol groups can be defined as a tree-like hierarchical structure arranged in ascending order from the p-th layer to the (p + 1)-th layer.

[0074] Since the symbol group map generalized in this way is somewhat complex in terms of expression, its components are divided as follows. Specific numerical values are substituted into the respective variables of n, m, and p, and it is verified that the descriptions of each component match the content of FIG. 4. [[ID=2l]]A: When the unique address assigned to each of the plurality of terminal devices 300A to 300D is any of the n symbol groups consisting of m digits in base n (where both n and m are integers), m if it is any of the n symbol groups, (n and m are both integers), B: n m Arrange the n symbol groups in ascending order in the first layer, C-1: For the p-th layer (p is each integer from 1 to m), arrange the n m / n (P-1) symbol groups arranged in ascending order, C-2: Exclude any of the following symbols from the symbol groups arranged in ascending order in the p-th layer, and group n symbol groups in which (m - p) digits of the (m - (p - 1)) digits match into one set, C-3: Use the different 1 digit as an arbitrary symbol, and arrange the n m / n p symbol groups in ascending order from the p-th layer to the upper (p + 1)-th layer, D: A tree-like hierarchical structure.

[0075] <Regarding Component A> Component A defines the variables "n" and "m" included in the description of the generalized symbol group map. In the case of the symbol group map shown in FIG. 4, since the unique address assigned to each of the terminal devices 300A to 300D is "any one of 16 symbol groups consisting of 4-digit binary numbers", "n = 2" and "m = 4".

[0076] <Regarding Component B> Component B is defined as "arranging n m symbol groups in ascending order in the first layer". Substituting "n = 2" and "m = 4", it becomes "arranging 16 symbol groups in ascending order in the first layer". In FIG. 4, a total of 16 symbol groups from symbol group "0000" to symbol group "1111" are arranged in ascending order in the first layer. Therefore, Component B conforms to the content of FIG. 4.

[0077] <Regarding the entire Component C> Component C is further divided into Components C-1 to C-3. Since it is defined as "arranging in ascending order in the p-th layer (p is each integer from 1 to m)", for example, when looking at the second layer, "p = 1". First, substitute "n = 2", "m = 4", and "p = 1" to verify the second layer.

[0078] <Regarding Component C-1> When substituting "n = 2", "m = 4", and "p = 1" into Component C-1 respectively, it becomes "the first '1' 4 / 2 (1-1) ' symbol groups arranged in ascending order in the layer", that is, "the first '16' symbol groups arranged in ascending order in the layer". <Regarding Component C-2> When substituting under the same conditions, Component C-2 becomes "grouping two of the symbol groups of '(4 - 1)' digits out of '(4 - (1 - 1))' digits excluding any of the following symbols from the symbol group arranged in ascending order in the '1'st layer", that is, "grouping two of the symbol groups of '3' digits out of '4' digits excluding any of the following symbols from the symbol group arranged in ascending order in the '1'st layer". <Regarding Component C-3> When substituting under the same conditions, Component C-3 becomes "using an arbitrary symbol for the different one digit in '2 4 / 2 1 ' symbol groups and arranging them in ascending order in the '1'+1'st layer above the '1'st layer", that is, "using an arbitrary symbol for the different one digit in '8' symbol groups and arranging them in ascending order in the '2'st layer above the '1'st layer". In Figure 4, for example, among the 16 symbol groups "0000" to "1111" arranged in the first layer, the symbol groups of 3 digits excluding the units digit are the same, such as "0000" and "0001" are grouped into one set, and the '8' symbol groups "000X" etc. with an arbitrary symbol X for the different one digit are arranged in ascending order in the second layer. Therefore, Component C conforms to the content of Figure 4 for the second layer.

[0079] <Regarding Component D> Figure 4 shows a tree-shaped symbol group map from the first layer to the fourth layer. Therefore, Component D conforms to the content of Figure 4 without the need for detailed comparison.

[0080] Just in case, we will also briefly verify for the third layer. For Components A, B, and D, those skilled in the art can understand that they are the same as in the case of the second layer without the need for detailed comparison, so the verification is omitted.

[0081] <Regarding the whole of Component C> Since Component C is defined as "arranged in ascending order in the 'p'th layer (p is each integer from 1 to m)", when looking at the third layer, "p = 2". <Regarding Component C-1> Component C-1 is "the above-mentioned '2 4 / 2 (『2』-1) ' symbol groups arranged in ascending order in the '2nd' layer", that is, "the above-mentioned '8' symbol groups arranged in ascending order in the '2nd' layer". <Regarding Component C-2> When Component C-2 is substituted in the same way, it becomes "grouping '2' of the symbol groups of '(4 - ('2' - 1))' digits out of which any symbol below is excluded from the symbol groups arranged in ascending order in the '2nd' layer into one group", that is, "grouping '2' of the symbol groups of '3' digits out of which any symbol below is excluded from the symbol groups arranged in ascending order in the '2nd' layer into one group". <Regarding Component C-3> When Component C-3 is substituted in the same way, it becomes "arranging '2 4 / 2 『2』 ' symbol groups with one different digit as an arbitrary symbol in ascending order in the '2nd + 1' layer above the '2nd' layer", that is, "arranging '4' symbol groups with one different digit as an arbitrary symbol in ascending order in the '3rd' layer above the '2nd' layer". In FIG. 4, for example, among the 8 symbol groups of "000X" to "111X" arranged in the 2nd layer, the symbol groups of 2 digits excluding the symbols in the units and tens places are grouped into one group, such as "000X" and "001X", and 4 symbol groups of "00XX" etc. with one different digit as an arbitrary symbol X are arranged in the 3rd layer above the 2nd layer. Therefore, Configuration C conforms to the content of FIG. 4 for the 3rd layer. Since it is the same for the 4th layer, the description is omitted so as not to be redundant.

[0082] Also, in this specification, (1) The route from the symbol group "0XXX" in the 4th layer, through the symbol group "00XX" in the 3rd layer and the symbol group "000X" in the 2nd layer, to the symbol group "0000" in the 1st layer is the 1st direct route, (2) The route from the symbol group "0XXX" in the 4th layer, through the symbol group "00XX" in the 3rd layer and the symbol group "000X" in the 2nd layer, to the symbol group "0001" in the 1st layer is the 2nd direct route, (3)… (16) Define the route from the symbol group "1XXX" in the fourth layer, through the symbol groups "11XX" in the third layer and "111X" in the second layer, to the symbol group "1111" in the first layer as the 16th direct route. Define it as such.

[0083] Figure 5 is an operation explanatory diagram when the central device 200 shown in Figure 1 acquires the unique address assigned to the terminal device 300 based on the symbol group map shown in Figure 4. In Figure 5, the operation is explained in units of "cycles".

[0084] First, the operation in cycle C1 will be explained.

[0085] When an administrator or the like of the communication system shown in Figure 1 inputs a unique address acquisition command to the central device 200, the control unit 246 first selects the symbol group specified in the command packet to be transmitted first, and selects the smallest symbol group "0XXX" among the symbol groups arranged in ascending order in the fourth layer as the initial value, and outputs it to the generation unit 220.

[0086] The generation unit 220 generates a command packet having an instruction to the effect that "a terminal device in which the specified symbol group '0XXX' is the same as the unique address assigned to the own device shall return a response packet including the unique address".

[0087] The communication unit 210 transmits the command packet generated by the generation unit 220 toward the terminal device 300 through the communication cable 100 during the period of cycle C1. The terminal devices 300 that satisfy this condition are the terminal devices 300A and 300B to which the symbol groups "0001" and "0100" belonging to the 2nd and 5th direct routes are assigned, as shown by the thick frames in Figure 4.

[0088] Therefore, each generation unit 320 of the terminal devices 300A and 300B generates a response packet including the unique addresses "0001" and "0100" assigned to the own device according to the instruction of the command packet.

[0089] Each communication unit 310 of the terminal devices 300A and 300B transmits the response packet generated by each generation unit 320 toward the central device 200 through the communication cable 100 so that the central device 200 can receive it within the period of cycle C1.

[0090] Here, since the terminal devices 300A and 300B return response packets, the state of the communication cable 100 changes. And since these response packets collide with each other in the communication cable 100, typically any of the response packets is damaged.

[0091] Therefore, the central device 200 cannot receive any of the response packets returned from the terminal devices 300A and 300B. For this reason, the discrimination unit 244 discriminates that the number of the terminal devices 300 that return the response packets is "a plurality" (step J1), and outputs the discrimination result to the control unit 246.

[0092] The control unit 246 inputs the discrimination result from the discrimination unit 244. Here, since it is discriminated as "a plurality", the symbol group specified by the next command packet to be transmitted is the symbol group (in this example, "0XXX") specified by the command packet transmitted most recently and belongs to the layer (in this example, "the fourth layer"), and the control unit 246 selects the smallest symbol group (in this example, "00XX") in the layer next lower (in this example, "the third layer") than the layer, and outputs the selection result to the generation unit 220. The above is the operation in cycle C1.

[0093] Next, the operation in cycle C2 will be described.

[0094] The generation unit 220 generates a command packet having an instruction to the effect that "a terminal device in which the specified symbol group 'XX' is the same as the unique address assigned to its own device shall return a response packet including the unique address" according to the selection result output from the control unit 246.

[0095] The communication unit 210 transmits the command packet generated by the generation unit 220 toward the terminal device 300 through the communication cable 100 during the period of cycle C2. The terminal device 300 that satisfies this condition is only the terminal device 300A to which the symbol group "0001" belonging to the second direct route is assigned.

[0096] Therefore, the generation unit 320 of the terminal device 300A generates a response packet including the unique address "0001" assigned to its own device according to the instruction of the command packet.

[0097] The communication unit 310 of the terminal device 300A transmits the response packet generated by its generation unit 320 toward the central device 200 through the communication cable 100 so that the central device 200 can receive it within the period of cycle C2.

[0098] Here, since the terminal device 300A returns a response packet, the state of the communication cable 100 changes. And since the situation where this response packet collides with other response packets in the communication cable 100 cannot occur, the response packet is not damaged.

[0099] Therefore, the central device 200 can receive the response packet returned from the terminal device 300A. For this reason, the discrimination unit 244 discriminates that the number of terminal devices 300 that return the response packet is "1" (step J2), and outputs the discrimination result to the control unit 246.

[0100] The control unit 246 receives the discrimination result from the discrimination unit 244. Here, since it is discriminated as "1" (i.e., not "plural"), the symbol group specified in the next command packet to be transmitted is the symbol group belonging to the same or higher layer (in this example, the "third layer" / "fourth layer") as the symbol group (in this example, "00XX") specified in the command packet transmitted most recently, and the largest symbol group (in this example, "01XX" in the "third layer") that is not the subject of investigation is selected, and the selection result is output to the generation unit 220.

[0101] In addition, since the control unit 246 obtains the information that the unique address assigned to the terminal device 300A is "0001", it outputs an instruction to the input unit 248 to input "terminal device 300A" and "0001" into the list in correspondence.

[0102] When the input unit 248 receives the instruction output from the control unit 246, it inputs "terminal device 300A" and "0001" into the list in correspondence according to the instruction. The list can be, for example, a database, although it is not limited to this. The above is the operation in cycle C2.

[0103] Here, in cycle C2, the symbol group specified in the command packet to be transmitted in cycle C3 is selected as "01XX". The reason is that there is no symbol group identical to the unique addresses assigned to the terminal devices 300B to 300D in the first to fourth direct routes to which the symbol group "00XX" investigated in cycle C2 belongs. That is, if the number of terminal devices 300 that returned the response packet becomes "1" / "0", there is no need to continue the investigation of the symbol group belonging to the direct route.

[0104] Therefore, since the central device 200 does not continue the investigation in the first to fourth direct routes, the investigation time of the unique address can be shortened compared to the case of conducting the investigation in a piecemeal manner by the amount of the investigation not executed.

[0105] Note that, although it is a rare case, there is a possibility that due to some reason such as a communication failure, the number of terminal devices 300 that have returned response packets is erroneously determined to be "1" even though it is actually "plural". In the present embodiment, in order to avoid such a situation, when the discrimination unit 244 determines that the number of terminal devices 300 that have returned response packets is "1", one method is for the control unit 246 to perform a truth determination.

[0106] In the example shown in cycle C2 of FIG. 5, although not shown on the premise that such mis-determination occurs, the truth determination here means that the symbol group (in this example, "00XX") specified by the command packet transmitted immediately before is included in the direct route (in this example, "the first to fourth direct routes"), and the symbol group (in this example, "0000" to "0011") other than the symbol group (in this example, "0001") specified by the command packet transmitted immediately before. If the terminal device with the unique address assigned to the own device returns a response packet including the unique address, the generation unit 220 may be caused to generate a command packet, and the communication unit 210 may transmit it.

[0107] If this truth determination is performed, if the reason such as a communication failure is not irreparable, the corresponding terminal device 300 will return a response packet, so the incorrect determination will be corrected. Note that incorrect determination can occur even without a communication failure. As a typical example, when the terminal device 300A / terminal device 300D located at a short distance / long distance from the central device 200 returns response packets in the same cycle, the response packets will collide with each other. At this time, the response packet returned from the terminal device 300D that transmits the communication cable 100 over a relatively long distance has a weak signal strength, so the packet is damaged, while the response packet returned from the terminal device 300A that transmits the communication cable 100 over a relatively short distance remains strong in signal strength, so the packet is not damaged.

[0108] Next, the operation in cycle C3 will be described. Although the operation is the same as that in cycle C2, it will be described in detail.

[0109] The generation unit 220 generates a command packet having an instruction to the effect that "a terminal device in which the designated symbol group '01XX' is the same as the unique address assigned to the own device shall return a response packet including the unique address" according to the selection result output from the control unit 246.

[0110] The communication unit 210 transmits the command packet generated by the generation unit 220 toward the terminal device 300 through the communication cable 100 during the period of cycle C3. The only terminal device 300 that satisfies this condition is the terminal device 300B to which the symbol group "0100" belonging to the fifth direct route is assigned.

[0111] Therefore, the generation unit 320 of the terminal device 300B generates a response packet including the unique address "0100" assigned to the own device according to the instruction of the command packet.

[0112] The communication unit 310 of the terminal device 300B transmits the response packet generated by the generation unit 320 toward the central device 200 through the communication cable 100 so that the central device 200 can receive it within the period of cycle C3.

[0113] Therefore, at the central device 200, the communication unit 210 can receive the response packet returned from the terminal device 300B. For this reason, the discrimination unit 244 discriminates that the number of terminal devices 300 that return the response packet is "1" (step J3), and outputs the discrimination result to the control unit 246.

[0114] The control unit 246 inputs the discrimination result from the discrimination unit 244. Here, since it is discriminated as "1" (i.e., not "plural"), the symbol group specified in the next command packet to be transmitted is the same or higher than the hierarchy (in this example, the "third hierarchy") to which the symbol group (in this example, "01XX") specified in the most recently transmitted command packet belongs. The largest symbol group (in this example, "1XXX" in the "fourth hierarchy") that is not the subject of investigation in the hierarchy (in this example, the "third hierarchy" / "fourth hierarchy") is selected, and the selection result is output to the generation unit 220.

[0115] Also, since the control unit 246 acquires the information that the unique address assigned to the terminal device 300B is "0100", it outputs an instruction to the input unit 248 to input "terminal device 300B" and "0100" into the list in correspondence.

[0116] When the input unit 248 inputs the instruction output from the control unit 246, it inputs "terminal device 300B" and "0100" into the list in correspondence according to the instruction. The above is the operation in cycle C3.

[0117] Therefore, since the central device 200 does not continue the investigation in the sixth to eighth direct routes, the investigation time of the unique address can be shortened compared to the case of conducting the investigation in a piecemeal manner by the amount of the investigation that is not executed.

[0118] Next, the operation in cycle C4 will be described. The operation is the same as in the case of cycle C1, but it will be described in detail.

[0119] The generation unit 220 generates a command packet having an instruction to the effect that "a terminal device in which the specified symbol group '1XXX' is the same as the unique address assigned to the own device shall return a response packet including the unique address" according to the selection result output from the control unit 246.

[0120] The communication unit 210 transmits the command packet generated by the generation unit 220 toward the terminal device 300 through the communication cable 100 during the period of cycle C4. The terminal devices 300 that satisfy this condition are the terminal devices 300C and 300D to which the symbol groups "1110" and "1111" belonging to the 15th and 16th direct routes are assigned, as shown by the thick frames in FIG. 4.

[0121] Therefore, each generation unit 320 of the terminal devices 300C and 300D generates a response packet including the unique addresses "1110" and "1111" assigned to its own device according to the instruction of the command packet.

[0122] Each communication unit 310 of the terminal devices 300C and 300D transmits the response packet generated by each generation unit 320 toward the central device 200 through the communication cable 100 so that the central device 200 can receive it within the period of cycle C4.

[0123] In the central device 200, in the same manner as in the case of step J1, the discrimination unit 244 discriminates that the number of terminal devices 300 that return the response packet is "plural" (step J4), and outputs the discrimination result to the control unit 246.

[0124] The control unit 246 inputs the discrimination result from the discrimination unit 244. Here, since it is discriminated as "plural", the symbol group specified in the next command packet to be transmitted is the symbol group (in this example, "1XXX") specified in the most recently transmitted command packet, and the symbol group belongs to the next lower layer (in this example, the "third layer") of the layer (in this example, the "fourth layer"). The smallest symbol group (in this example, "10XX") in the layer is selected, and the selection result is output to the generation unit 220. The above is the operation in cycle C4.

[0125] Next, the operation in cycle C5 will be described.

[0126] The generation unit 220 generates a command packet having an instruction to the effect that "a terminal device in which the designated symbol group '10XX' is the same as the unique address assigned to the own device shall return a response packet including the unique address" according to the selection result output from the control unit 246.

[0127] The communication unit 210 transmits the command packet generated by the generation unit 220 toward the terminal device 300 through the communication cable 100 during the period of cycle C5. There is no terminal device 300 that satisfies this condition.

[0128] Therefore, since none of the terminal devices 300 returns a response packet, the state of the communication cable 100 does not change. Then, as it is, the period of cycle C5 ends.

[0129] In the central device 200, the discrimination unit 244 discriminates that the number of terminal devices 300 that return the response packet is "0" (step J5), and outputs the discrimination result to the control unit 246.

[0130] The control unit 246 inputs the discrimination result from the discrimination unit 244. Here, since it is discriminated that the result is "0" (that is, not "a plurality"), the symbol group specified in the next command packet to be transmitted is the symbol group specified in the most recently transmitted command packet (in this example, "10XX") The largest symbol group (in this example, "11XX" in the "third layer") that is not the subject of investigation in the same or higher layer (in this example, "third layer" / "fourth layer") as the layer to which it belongs is selected, and the selection result is output to the generation unit 220. The above is the operation in cycle C5.

[0131] Therefore, since the central device 200 does not continue the investigation in the ninth to twelfth direct routes, the investigation time of the unique address can be shortened compared to the case where the investigation is carried out in a piecemeal manner by the amount of the investigation that is not executed.

[0132] The operations in cycles C6 and C7 are the same as those in cycles C4 and C5. The operations in cycles C8 to C10 are the same as those in cycles C1 to C3. Since all operations of this type have been fully described, they will not be described repeatedly.

[0133] In this example, as a result of executing the process of cycle C9, the central device 200 can identify that the unique address of the terminal device 300C is "1110". Therefore, it can be identified by the elimination method that the unique address of the terminal device 300D, which has not been investigated, is inevitably the only remaining symbol group "1111". Therefore, instead of executing all the processes of cycle C10, only the process of associating "terminal device 300D" with "1111" and inputting them into the list may be executed in cycle C9 to further shorten the investigation time.

[0134] According to the method described above, the investigation time of the unique address assigned to the terminal device 300 only needs to repeat 10 times the cycle with a fixed period of 1 cycle of 2 ms even if all the processes of cycle C10 are executed, so it only takes 20 ms. Moreover, the communication system of this embodiment can also create a correspondence list between the terminal device 300 and the unique address within this investigation time.

[0135] Note that the thick-bordered symbol groups shown in FIG. 4 are not arbitrarily selected to make it appear that the investigation time of the unique address can be deliberately shortened. This can be understood by comparing the fact that when the unique address assigned to the terminal device 300 is the symbol groups "0000", "0001", "0010", "0011" in the first to fourth direct routes, the shortest investigation period is 16 ms, and when the symbol groups are "0110", "0111", "1110", "1111" in the seventh, eighth, fifteenth, and sixteenth direct routes, the longest investigation time is 28 ms.

[0136] Also, if an investigation is conducted for lice crushing without adopting the method of this embodiment, since an investigation time of [number of symbol groups 16 × 2 ms = 32 ms] belonging to the first layer is required, when the method of this embodiment is adopted, the investigation time can be shortened by at least 12.5%.

[0137] Generalizing this investigation time, assuming that a 16-digit hexadecimal MAC address is used as the unique address, the number of symbol groups is "about 4.3 billion", and according to the RS-485 standard, the maximum number of terminal devices 300 connected to the communication cable 100 is "32". Therefore, the longest investigation period is [2 ms × 928 times ≒ 2 seconds]. If the investigation time for the unique address, which would take about 100 days without manual intervention, can be completed in less than 2 seconds, the effect is significant. Incidentally, if the number of terminal devices 300 connected to the communication cable 100 is "16", the minimum number of investigations is 30 times and the maximum number of investigations is 478 times, and the respective investigation times are 60 ms and 956 ms.

[0138] FIG. 6 is a diagram showing a modified example of the method for investigating a unique address described with reference to FIG. 5. Here, a method for further shortening the investigation time of the unique address will be mainly described with differences from what was described with reference to FIG. 5.

[0139] As described above, the communication system of this embodiment can perform the required communication without including information indicating the destination for each packet, on the condition that each of the central device 200 and the terminal devices 300A to 300D includes a time schedule and a timing means. The method for investigating the unique address shown in FIG. 6 uses this concept of time division.

[0140] In FIG. 6, those including the branch number "-1" like cycle C11-1 mean the first half in terms of time of cycle C11, and those including the branch number "-2" like cycle C11-2 mean the second half in terms of time of cycle C11. Although not explicitly shown in FIG. 6, in this specification, a general term for a set excluding these branch numbers is referred to as cycle C11.

[0141] First, when comparing the investigation methods shown in FIGS. 5 and 6 with each other, for example, they match in that a predetermined command packet is transmitted in cycles C1 and C11. However, in the case of the investigation method shown in FIG. 5, the response packet reply timing for the command packet is not divided into the first half and the second half, whereas in the case of the investigation method shown in FIG. 6, the response packet reply timing for the command packet is divided into the first half and the second half, which is a difference.

[0142] In FIG. 6, an instruction such as "If the unique address assigned to the own device is the same as the symbol group '0『0』XX', return a response packet in cycle C11-1. If the unique address assigned to the own device is the same as the symbol group '0『1』XX', return a response packet in the second half cycle C11-2" is included in the command packet, and as a time schedule, the allocation period required for transmitting the command packet is set to 1 ms, the allocation period required for returning the response packet in cycle C11-1 is set to 1 ms, and the allocation period required for returning the response packet in cycle C11-2 is set to 1 ms.

[0143] Then, during these total 3 ms of processing time, the number of terminal devices 300 that returned response packets in cycles C11-1 and C11-2 both results in a determination of "1" (steps J11-1, J11-2), and the unique addresses assigned to terminal devices 300A and 300B can be identified as "0001" and "0100" respectively, and the identification results regarding these are input into the list.

[0144] Next, in cycle C12-1, since the number of terminal devices 300 that returned response packets results in a determination of "0" (step J12-1), the investigation regarding the direct route to which the symbol group "1XXX" belongs is not continued. On the other hand, in cycle C12-2, since the number of terminal devices 300 that returned response packets results in a determination of "plural" (step J12-2), the investigation regarding the direct route to which the symbol group "1XXX" belongs is continued.

[0145] Therefore, in cycle C13, an investigation is conducted on the symbol group "11XX" at the lower level of the symbol group "1XXX". As shown in FIGS. 4 and 6, as a result, for the symbol group "11XX", the same processing as in cycle C12 is performed.

[0146] Next, in cycle C14, an investigation is conducted on the symbol group "111X" at the lower level of the symbol group "11XX". As shown in FIGS. 4 and 6, as a result, in both cycles C14-1 and C14-2, the number of terminal devices 300 that returned response packets is determined to be "1" (steps J14-1, J14-2), and the unique addresses assigned to terminal devices 300C and 300D can be identified as "1110" and "1111" respectively, and the specific results regarding these are input into the list.

[0147] According to the method described above, the investigation time for the unique address assigned to terminal device 300, in accordance with the aforementioned conditions, only needs to repeat 4 cycles with a fixed period of 3 ms per cycle, so it takes only 12 ms. Therefore, compared with the investigation method shown in FIG. 5, the investigation time can be reduced by 60%.

[0148] Here, if the MAC address is 8 digits in hexadecimal and the number of divisions in time division is 4, summarizing the generalized investigation times respectively explained using FIGS. 5 and 6 is as shown in Table 1. Therefore, it can be seen that adopting the time-division investigation method explained using FIG. 6 contributes to reducing the investigation time.

Table 1

[0149] Note that in Fig. 6, an example is shown in which cycle C11 is divided into the first and second halves, i.e., cycles C11-1 and C11-2. However, for example, it is also possible to divide it into four parts, i.e., the first to fourth cycles C11-a to C11-d. The allocated time corresponding to the first cycle C11-a may be set to "0 '00' X", the allocated time corresponding to the second cycle C11-b may be set to "0 '01' X", the allocated time corresponding to the third cycle C11-c may be set to "0 '10' X", and the allocated time corresponding to the fourth cycle C11-d may be set to "0 '11' X".

[0150] As described above, mainly with reference to Figs. 4 to 6, the method for investigating the unique address assigned to the terminal device 300 has been described. However, as a result of these investigations, the central device 200 can also perform the following processing after obtaining the unique address assigned to the terminal device 300.

[0151] <Acquisition of various information from the terminal device 300> The central device 200 can have an acquisition unit that acquires various setting information from the terminal device 300 using the unique address in the list as the destination. The setting information here includes, for example, information from the manufacturer such as the product model, information from the designer or administrator of the communication system such as the control program for the devices (fire detection sensors, fire alarms, etc.) connected to the terminal device 300, and information from the terminal device 300 such as the log information of the operation of the terminal device 300 recorded during the operation of the communication system. Various types of information are included.

[0152] The central device 200 uses the unique address in the list as the destination, generates a command packet including an instruction to the effect of "return a response packet including the setting information of the own device" by the generation unit 220, and transmits it to the terminal device 300 through the communication cable 100 by the communication unit 210.

[0153] The central device 200 receives, via the communication unit 210, the response packet returned from the terminal device 300, and the input unit 248 inputs the setting information into a list in association with the information indicating the source of the response. This enables the administrator of the communication system to grasp the replacement timing of the terminal device 300 and select a device with good compatibility when replacing the terminal device 300.

[0154] <Settings of various information, etc. for the terminal device 300> The central device 200 can set a unique local address for the terminal device 300 with the unique address in the list as the destination. The local address here is what the installer of the communication system used to set for the terminal device according to the list. The local address can also be used as the destination when sending a command packet.

[0155] For example, the central device 200 associates the local address to be set for the terminal device 300 with the corresponding unique address by the input unit 248, and the administrator of the communication system, etc. inputs it into the above-mentioned list in advance. Then, the central device 200 uses the unique address in the list as the destination, and the generation unit 220 generates a command packet including an instruction to the effect of "set the specified unique local address and return a response packet including information indicating that the setting process is completed", and the communication unit 210 transmits it to the terminal device 300 through the communication cable 100.

[0156] By transmitting a command packet through the communication cable 100, the central device 200 can set a unique local address for the terminal device 300, thus avoiding human errors that may occur when the installer of the communication system mistakenly sets the local address.

[0157] In addition, the central device 200 may include an instruction to the effect of "update the destination setting using the local address as the destination of future command packets, and when the update process is completed, return a response packet including information indicating that" in the command packet generated by the generation unit 220.

[0158] In this way, since the MAC address is generally 12 hexadecimal digits or more, which is relatively large even in terms of the number of bits, 48 bits or more, if the number of bits of the local address is made smaller, for example, 8 bits, which is 2 hexadecimal digits, and used as the destination, the usage capacity of the header can be reduced, and the number of bits per packet can also be reduced.

[0159] Also, the central device 200 can set the previous setting information for the other terminal device 300 when, for example, the terminal device 300 connected to the communication cable 100 is replaced with another terminal device 300 by the same method. The other terminal device 300 also includes those that are substituted while the previous terminal device 300 is being repaired due to a failure.

[0160] In particular, if the terminal device 300 (including other terminal devices 300) is a live-line plugging and unplugging compatible device, when the terminal device 300 is removed from the communication cable 100 or the terminal device 300 is connected to the communication cable 100, the central device 200 can detect this with the detection unit provided therein. Therefore, if the generation and transmission of the command packet are performed using this as a trigger, the previous setting information can be set for the other terminal device 300 without any manual intervention.

[0161] Also, when a new other terminal device 300 is added to the communication cable 100, if the setting information and local address to be set for the other terminal device 300 are associated with the corresponding unique address by the input unit 248 and the administrator of the communication system or the like inputs them to the above-mentioned list in advance, the setting information and local address can be set for the other terminal device 300 in the above-mentioned manner.

[0162] If the terminal device 300 (including other terminal devices 300) is a live-line plugging and unplugging compatible device, the terminal device 300 can also perform the setting of various information and the like for the terminal device 300 in a leading manner. For example, when the terminal device 300 connected to the communication cable 100 is removed and another terminal device 300 is connected to the communication cable 100, the other terminal device 300 generates a setting information request packet including the setting information such as the unique address assigned to its own device and the information of the intention to request to transmit a packet to its own device by the generation unit 320, checks the reception status of the packet for at least one cycle, and at a timing when there is no collision with other packets, transmits the setting information request packet to the central device 200 through the communication cable 100 by the communication unit 310.

[0163] When the central device 200 receives the setting information request packet transmitted from another terminal device 300, since it has detected that the terminal device 300 has been removed from the communication cable 100 and another terminal device 300 has been connected to the communication cable 100, it determines that the terminal device 300 has been replaced with the other terminal device 300, uses the unique address included in the setting information request packet as the destination, reads out the setting information of the terminal device 300 from the list, generates a setting information transmission packet, transmits it to the other terminal device 300 through the communication cable 100 by the communication unit 210, and may update the unique address in the list.

[0164] In addition, since the terminal device 300 may also act as the central device 200, all or some of the terminal devices 300 can also be provided with the input unit 248 and the list and the like in the same configuration as the central device 200. Thereby, the risk of the list disappearing in the central device 200 can be avoided. Incidentally, this can also be achieved by having two or more central devices 200.

[0165] However, when two or more central devices 200 are provided, they can be interconnected to synchronize with each other. In practice, however, multiple central devices 200 are often connected to a higher-level device (not shown) respectively. The higher-level device outputs the same instructions to each central device 200. Therefore, a configuration capable of dual-controlling the packet communication system by two or more central devices 200 can be realized.

[0166] In addition, the terminal device 300 (including other terminal devices 300) may be provided with a control inhibition unit that prevents communication with devices connected to the own device until the setting process of the local address and setting information is completed. This can avoid malfunction in device control even when a communication system administrator who is not familiar with the setting operation activates the communication system prior to the completion of the setting process.

[0167] Incidentally, although the probability is considered to be extremely low, the possibility that two central devices 200 or terminal devices 300 both fail is not zero. Therefore, the central device 200 or terminal device 300 may be provided with a reading unit that reads the setting information input in the list. Specifically, this reading unit can be composed of an external storage memory such as a USB (Universal Serial Bus) memory or an SD card, and a slot where the external storage memory is mounted and connected to the storage unit.

[0168] Thereby, the latest setting information input in the list by the reading unit may be read periodically, irregularly, or according to a predetermined rule so that it can be stored in a device separated from the communication cable 100.

[0169] Note that by providing the reading unit, the latest setting information input in the list can include log information on the past operations of the control target. Enabling the reading of this information has the effect of enabling effective utilization of big data.

Embodiment

[0170] (Example 1) FIG. 7 is an explanatory diagram of the infrastructure system according to Example 1 of the present invention. In this example, an example in which the communication system described in the embodiment is applied to road facilities that are infrastructure systems will be described.

[0171] In FIG. 7, the same parts as those shown in FIG. 1 and the like are denoted by the same reference numerals. As unique parts in FIG. 7, there are a tunnel 1000 and a vehicle 2000 passing through the tunnel.

[0172] The length of the communication cable 100 is determined according to the length of the tunnel 1000. It is not uncommon for the length of the tunnel 1000 to be several hundred meters to several kilometers. Therefore, the length of the communication cable 100 may also be several hundred meters or more.

[0173] The central device 200 is installed in a monitoring control room where a monitor or the like monitors the situation inside the tunnel 1000. The above-described upper device may be provided in the monitoring control room or may be provided at other locations.

[0174] The terminal devices 300A and 300C are connected to the environmental sensors 400A and 400C that collect environmental data inside the tunnel 1000. The environmental data inside the tunnel 1000 includes, but is not limited to, for example, the traffic volume of the vehicle 2000, the exhaust gas concentration inside the tunnel 1000, and the light quantity of the lamps 400B and 400D described below.

[0175] The terminal devices 300B and 300D are connected to the lamps 400B and 400D installed near the ceiling of the tunnel 1000. The terminal devices 300B and 300D perform lighting control such as the light quantity of the lamps 400B and 400D based on the detection results of the environmental sensors 400A and 400C.

[0176] According to the infrastructure system of this embodiment, the environment inside the tunnel 1000 can be improved, and the comfort of vehicle passage can be enhanced. That is, for example, when the lamps 400B and 400D reach the end of their service life and go out, the environmental sensors 400A and 400C can detect that the received light intensity has decreased. Therefore, the data collection terminal devices 300A and 300C can transmit this information to the central device 200 through the communication cable 100.

[0177] As a result, the monitor in the monitoring control room can replace the lamps 400B and 400D and can prevent the inside of the tunnel 1000 from getting dark, for example, by increasing the light quantity of the lamps around the lamp that has reached the end of its service life.

[0178] Also, when it is detected that the vehicle 2000 does not exist inside the tunnel 1000 as environmental data, energy saving can be achieved by reducing the light quantity of the lamps 400B and 400D.

[0179] Although not explicitly shown in FIG. 7, the vehicle 2000 also has various control targets. Specifically, there are on / off control of the room lamp, temperature control of the air conditioner called the car air conditioner, etc. Therefore, the above-described communication system can also be applied to the vehicle 2000 itself.

[0180] In this embodiment, the application example of the communication system is described by taking road facilities as an example. However, it is not limited to being applied to road facilities. As will be described below, it can be applied to various infrastructure systems.

[0181] For example, in river facilities including dams and bridges, controlling the opening and closing of the gate 400 based on the detection result of the water level sensor 400 can be mentioned.

[0182] For example, in railways and railway facilities, control may be performed such as causing an electric train to make an emergency stop based on the detection result by an infrared sensor 400 that a passenger has fallen from a station platform onto the track, or the opening and closing of a platform door may be controlled by attaching a human presence sensor 400 near the platform door installed on the station platform.

[0183] For example, in airplanes and airport facilities, control may be performed such as controlling the oil outflow amount based on the detection result of a hydraulic sensor 400 of an airplane, or controlling the light quantity of a runway guiding light 400 based on the detection result of an illuminance sensor 400 installed on the runway of the airport.

[0184] For example, in vehicle facilities including ships and port facilities, control may be performed such as controlling the angle of a rudder based on the detection result of a helmsman's rudder operation, or controlling the moving amount on a rail according to the loading and unloading operation of an operator of a gantry crane.

[0185] Thus, the infrastructure system of this embodiment can be applied to a wide variety of facilities, etc., from small-scale ones to large-scale ones, as long as they perform electrical control.

[0186] (Embodiment 2) FIG. 8 is an explanatory diagram of a factory automation system according to Embodiment 2 of the present invention. In this embodiment, an example in which the communication system described in the embodiment is applied to a robot arm which is factory automation will be described.

[0187] In the description in the embodiment of FIG. 7, an example in which a control target is connected to the terminal device 300 was used, but in this embodiment, an example in which the terminal device 300 with a sensor of the control target 400 is used will be described. Note that the illustration of the central device 200 itself is omitted.

[0188] The terminal device 300A with a pressure sensor and the terminal device 300B with an angle sensor both mainly perform detection for controlling the movement of the joints of a robotic arm and transmit the detection results to the central device 200.

[0189] The terminal device 300A with a pressure sensor is mainly provided at a finger joint and is used to control the gripping strength when grasping an object or to detect loads such as torque / load of the joint and control the driving torque. The terminal device 300B with an angle sensor is used to control an indirect angle.

[0190] If the communication system described in each embodiment is used in the factory automation system of this embodiment, high-speed packet communication between a relatively large number of terminal devices 300 and the central device 200 becomes possible, so the manufacturing throughput of products obtained by using a robotic arm can be improved.

[0191] Also, in this embodiment, although a robotic arm is taken as an example for the application example of the communication system, it is not limited to being applied to a robotic arm. For example, it can also be applied to the control of the movement of joints of various industrial robots, and can also be applied to the control of the movement amount, speed, rotation amount, etc. of a machine tool.

[0192] Furthermore, in a factory, it is not uncommon to be provided with fire detection facilities, air conditioning facilities, or an emergency stop mechanism for a machine tool to ensure the safety of workers. The communication system of the present invention can also be applied to various controls for these.

[0193] In this way, the factory automation system of this embodiment can be applied to a wide variety of facilities, etc., from small-scale to large-scale, as long as it performs electrical control.

[0194] (Embodiment 3) FIG. 9 is an explanatory diagram of the building automation system according to Embodiment 3 of the present invention. In this embodiment, an example of applying the communication system described in the embodiment to a commercial facility that is a building automation system will be described.

[0195] In FIG. 9, parts similar to those shown in FIG. 1 and the like are denoted by the same reference numerals. As unique parts in FIG. 9, there is a commercial facility 3000 such as a department store or a shopping center.

[0196] The length of the communication cable 100 is determined according to the scale of the commercial facility 3000. FIG. 9 illustrates a 20-story commercial facility 3000. In this case, the length of the communication cable 100 will be several hundred meters or more.

[0197] Note that the upper device and the central devices 200A to 200B can be remotely arranged from each other. In that case, they will be connected by wire or wirelessly via a line 100' different from the illustrated communication cable 100. The central devices 200A to 200B are respectively installed in a monitoring control room where a monitor or the like monitors the situation inside the commercial facility 3000.

[0198] The terminal device 300 is connected to control targets such as sensors (not shown) that collect various data inside the commercial facility 3000. Examples of the control targets installed in the commercial facility 3000 include elevators, room temperature sensors and air conditioning equipment, fire detectors and fire alarms, emergency call buttons and emergency shutters that are normally open but closed in case of emergency, and occupancy sensors and lighting.

[0199] According to the building automation system of this embodiment, a comfortable space and a safe and secure space inside the commercial facility 3000 can be provided.

[0200] In addition, in this embodiment, although the commercial facility 3000 has been described as an application example of the communication system, the building automation system is not limited to being applied to the commercial facility 3000. For example, it can also be applied to other buildings such as an office building or an apartment house, which is a collective housing.

[0201] Thus, the building automation system of this embodiment can be applied to a wide variety of facilities and the like, from small-scale ones to large-scale ones, as long as they perform electrical control.

Claims

1. A communication system in which a central device and a plurality of terminal devices are multi-drop connected through a communication cable, wherein the central device, When the unique address assigned to each of the plurality of terminal devices is any one of n symbol groups consisting of m digits in an n -ary number (both n and m are integers), arrange the n symbol groups in ascending order in the first layer, and for the p -th layer (p is each integer from 1 to m), arrange the n / n symbol groups in ascending order. Exclude any of the following symbols from the symbol groups arranged in ascending order in the p -th layer. Group n symbol groups in which (m - p) -digit symbol groups among (m - (p - 1)) -digit symbol groups match into one set, and use the different one digit as an arbitrary symbol. Create a symbol group map with a tree - like hierarchical structure in which the n / n symbol groups are arranged in ascending order in the p + 1 -th layer above the p -th layer. A creation unit that creates, ｍ When it is any one of n symbol groups consisting of m digits in an n -ary number (both n and m are integers), n ｍ Arrange the n symbol groups in ascending order in the first layer, and for the p -th layer (p is each integer from 1 to m), arrange the n ｍ / n （Ｐ－１） symbol groups. Exclude any of the following symbols from the symbol groups arranged in ascending order in the p -th layer. Group n symbol groups in which (m - p) -digit symbol groups among (m - (p - 1)) -digit symbol groups match into one set, and use the different one digit as an arbitrary symbol. n ｍ / n ｐ symbol groups are arranged in ascending order in the p + 1 -th layer above the p -th layer to create a symbol group map with a tree - like hierarchical structure. A creation unit that creates, a generation unit that generates a command packet including an instruction to the effect that a terminal device in which a specified symbol group among the symbol groups arranged in ascending order in the symbol group map created by the creation unit is the same as the unique address assigned to the own device shall return a response packet including the unique address; a determination unit that determines whether the number of terminal devices that have returned a response packet through the communication cable in response to the command packet when the command packet generated by the generation unit is transmitted through the communication cable is "plural", "one", or "zero"; a control unit that selects, as the symbol group to be specified in the next command packet to be transmitted, the smallest symbol group in the next lower layer of the layer to which the symbol group specified in the command packet transmitted most recently belongs when the number of terminal devices determined by the determination unit is "plural", and selects the largest symbol group that has not been the subject of investigation in the same or higher layer as the layer to which the symbol group specified in the command packet transmitted most recently belongs when the number of terminal devices determined by the determination unit is not "plural"; an input unit that, when the number of terminal devices determined by the determination unit is "one", inputs the unique address included in the response packet and the information indicating the source of the response packet into a list in association with each other; A communication system comprising the above.

2. The communication system according to claim 1, wherein the central device includes an acquisition unit that acquires setting information of each of the plurality of terminal devices.

3. The communication system according to claim 1, comprising a setting unit that sets a unique local address or setting information for each of the plurality of terminal devices.

4. The communication system according to claim 1, comprising a detection unit that detects that another terminal device has been connected to the communication cable.

5. An infrastructure system comprising the communication system according to claim 1.

6. A building automation system comprising the communication system according to claim 1.

7. A factory automation system comprising the communication system according to claim 1.

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