Description Title of Invention: RELAY SYSTEM Technical Field
[0001] The present invention relates to a technology for relaying data transmitted from a plurality of devices. Background Art
[0002] There is a facility management system in which a device (hereinafter referred to as a facility device) installed in a factory notifies operating status and error information of the facility device to a mobile terminal apparatus of a factory administrator who is at a remote location through a wireless communication device such as GSM(Global System for Mobile Communications) (GSM is a registered trademark) modem. In the facility management system, as illustrated in Fig. 15, the GSM modem and the facility device face each other and are connected to each other with a serial cable. Therefore, the same number of GSM modems as facility devices are required to manage the facility devices in the entire factory.
There is a problem that in a large scale factory, a communication cost of GSM modems becomes enormous (usually, the communication cost of each GSM modem is fixed monthly).
[0003] To solve such a problem, in a technology of Patent Literature 1, by using a converter that converts a serial signal into a signal for Ethernet (Ethernet is a registered trademark), the operating status of a plurality of facility devices is transmitted to a management server at a remote location via the Ethernet. Citation List Patent Literature [0004] Patent Literature 1: JP2005-222133A

Summary of Invention Technical Problem
[0005] However, when incorporating a method of Patent Literature 1 into a configuration of Fig. 15, it is necessary to newly install a PC (Personal Computer) server. In other words, when incorporating the method of Patent Literature 1 into the configuration of Fig. 15, it is necessary to connect the PC server to a plurality of facility devices via the Ethernet, and connect the PC server to one GSM modem. In such a configuration, the PC server inquiries each facility device by polling whether or not there is operating status to be notified to the mobile terminal apparatus of the factory manager. Each facility device transmits data notifying of the operating status to the PC server in response to the polling, when there is the operating status to be notified of. Further, the PC server transmits the operating status gathered from each facility device via the Ethernet to the mobile terminal apparatus of the factory manager through the GSM modem. In the configuration illustrated in Fig. 15, the facility device itself transmits data notifying of the operating status to the GSM modem. That is, the facility device does not transmit the data notifying of the operating status in response to the polling.
Therefore, in the system in which the method of Patent Literature 1 is incorporated into the configuration of Fig. 15, it is necessary to change a setting of each facility device so as to transmit data notifying of the operating status in response to the polling from the PC server. Also, it is necessary to change a setting of the GSM modem so as to conform to a communication method with the PC server.
Thus, in the system in which the method of Patent Literature 1 is incorporated into the configuration of Fig. 15, there is a problem that it is necessary to change the setting of the facility device and a setting of a wireless communication device such as

the GSM modem.
[0006] The present invention mainly aims to solve the problem described above. The
primary purpose of the present invention is to transmit data from a plurality of devices
using one wireless communication device without changing settings of the devices and
a setting of a wireless communication device.
Solution to Problem
[0007] A relay system according to the present invention includes:
a plurality of first relay apparatuses to relay data transmitted from a plurality of devices, according to a connection type communication protocol; and
a second relay apparatus to receive data relayed by the plurality of first relay apparatuses, according to the connection type communication protocol, and transmit the received data to a wireless communication device which communicates with a transmission destination device which is a data transmission destination of the plurality of devices,
wherein each of the plurality of first relay apparatuses requests the second relay apparatus to set a connection, according to the connection type communication protocol, prior to relaying data to the second relay apparatus, and
wherein the second relay apparatus, when being requested to set a connection by any one of the plurality of first relay apparatuses, determines whether or not a connection is set with another first relay apparatus, according to the connection type communication protocol, and sets the connection with a requesting first relay apparatus when the connection is not set with the another first relay apparatus. Advantageous Effects of Invention
[0008] According to the present invention, with the first relay apparatus and the second relay apparatus, it is possible to transmit data from the plurality of devices using .

one wireless communication device without changing the settings of the devices and the
setting of the wireless communication device.
Brief Description of Drawings
[0009] Fig. 1 is a diagram illustrating a configuration example of a facility
management system according to a first embodiment;
Fig. 2 is a diagram illustrating a functional configuration example of a facility device according to the first embodiment;
Fig. 3 is a diagram illustrating a functional configuration example of a client apparatus according to the first embodiment;
Fig. 4 is a diagram illustrating a functional configuration example of a server apparatus according to the first embodiment;
Fig. 5 is a diagram illustrating a functional configuration example of a GSM modem according to the first embodiment;
Fig. 6 is a diagram illustrating a communication sequence example according to the first embodiment;
Fig. 7 is a diagram illustrating a communication sequence example according to the first embodiment;
Fig. 8 is a diagram illustrating a functional configuration example of a client apparatus according to a second embodiment;.
Fig. 9 is a diagram illustrating a communication sequence example according to the second embodiment;
Fig. 10 is a diagram illustrating a hardware configuration example of the client apparatus and the server apparatus according to the first and second embodiments;
Fig. 11 is a diagram illustrating a hardware configuration example of the GSM modem according to the first and second embodiments;

Fig. 12 is a diagram illustrating a hardware configuration example of the facility device according to the first and second embodiments;
Fig. 13 is a flow chart illustrating an operational example of the client apparatus according to the first embodiment;
Fig. 14 is a flow chart illustrating an operational example of the server apparatus according to the first embodiment; and
Fig. 15 is a diagram illustrating a conventional art. Description of Embodiments [0010] First Embodiment. *** Description of Configuration ***
Fig. 1 illustrates a configuration example of a facility management system according to the present embodiment.
In Fig.l, a facility device (1) 101 and a facility device (2) 103 are arranged in a factory 100.
The facility device (1) 101 faces a client apparatus (1) 102 and is connected to the client apparatus (1) 102 with a serial cable. The facility device (2) 103 faces a client apparatus (2) 104 and is connected to the client apparatus (2) 104 with a serial cable.
The client apparatus (1) 102 and the client apparatus (2) 104 are connected to the server apparatus 105 via Ethernet or a wireless LAN (Local Area Network).
A server apparatus 105 is connected to a GSM modem 106.
The GSM modem 106 is connected to a mobile terminal apparatus 108 via a public mobile network 107.
[0011] The facility device (1) 101 transmits data notifying of operating status of the facility device (1) 101 to the client apparatus (1) 102. Further, the facility device (2) 103 transmits data notifying of operating status of the facility device (2) 103 to the

client apparatus (2) 104.
The client apparatus (1) 102 relays the data transmitted from the facility device (1) 101 to the server apparatus 105. The client apparatus (2) 104 relays the data transmitted from the facility device (2) 103 to the server apparatus 105. The client apparatus (1) 102 and the client apparatus (2) 104 transmit data to the server apparatus 105 according to a connection type communication protocol. More specifically, the client apparatus (1) 102 and the client apparatus (2) 104 transmit data to the server apparatus 105 according to TCP/IP (Transmission Control Protocol / Internet Protocol).
The server apparatus 105 receives the data relayed by the client apparatus (1) 102 and the data relayed by the client apparatus (2) 104 according to the connection type communication protocol (specifically the TCP/IP), and transmits the received data to the GSM modem 106.
The GSM modem 106 transmits the data received from the server apparatus 105 to the mobile terminal apparatus 108 which is a data transmission destination of the facility device (1) 101 and the facility device (2) 103 via a public mobile network 107.
Each of the client apparatus (1) 102 and the client apparatus (2) 104 corresponds to an example of a first relay apparatus. The server apparatus 105 corresponds to an example of a second relay apparatus. The GSM modem 106 corresponds to an example of a wireless communication device. The mobile terminal apparatus 108 corresponds to an example of a transmission destination device. Further, the client apparatus (1) 102, the client apparatus (2) 104, and the server apparatus 105 constitute a relay system.
In the following description, data notifying of the operating status of the facility device (1) 101 and data notifying of the operating status of the facility device (2) 103 are referred to as status information.
Further, in the following description, an example will be used, in which the

status information of the facility device (1) 101 and the status information of the facility device (2) 103 are transmited to the mobile terminal apparatus 108, using the GSM modem 106. Hoever, the wireless communication device need not be the GSM modem 106 as long as it has a wireless communication function.
In addition, Fig. 1 illustrates an example of two facility devices, however, as long as there are two or more facility devices, any number of facility devices may be used. [0012] Fig. 10 illustrates a hardware configuration example of the client apparatus (1) 102, the client apparatus (2) 104 and the server apparatus 105. Note that in the present embodiment, the hardware configurations of the client apparatus (1) 102, the client apparatus (2) 104 and the server apparatus 105 are the same.
Each of the client apparatus (1) 102, the client apparatus (2) 104, and the server apparatus 105 is a computer and includes a network interface 1001, a processor 1002, a serial interface 1003, and a storage device 1004.
The network interface 1001 is a circuit which serves as an interface with the Ethernet or the wireless LAN.
The serial interface 1003 is a circuit which serves as an interface with the serial cable.
The processor 1002 is an IC (Integrated Circuit) which performs processing. The processor 1002 is a CPU (Central Processing Units), a DSP (Digital Signal Processor) or the like. The processor 1002 executes programs. More specifically, each of the processor 1002 of the client apparatus (1) 102 and the processor 1002 of the client apparatus (2) 104 executes programs realizing a TCP/IP communication control unit 302 and a connection timer management unit 303 to be described later. Also, the processor 1002 of the server apparatus 105 executes a program realizing a TCP/IP communication control unit 402 to be described later.

The storage device 1004 is a RAM (Random Access Memory), a ROM (Read Only Memory), a flash memory, an HDD (Hard Disk Drive), or the like. The storage device 1004 stores the programs described above. That is, each of the storage device 1004 of the client apparatus (1) 102 and the storage device 1004 of the client apparatus (2) 104 stores the programs realizing the TCP/IP communication control unit 302 and the connection timer management unit 303. Also, the storage device 1004 of the server apparatus 105 stores the program realizing the TCP/IP communication control unit 402. Further, the storage device 1004 stores values used for a calculation of the processor 1002 and a calculation result of the processor 1002. [0013] Fig. 11 illustrates a hardware configuration example of the GSM modem 106.
The GSM modem 106 includes a wireless communication interface 1101, a processor 1102, a serial interface 1103, and a storage device 1104.
The wireless communication interface 1101 is a circuit which serves as an interface with the public mobile network 107.
The serial interface 1103 is a circuit which serves as an interface with the serial cable.
The processor 1102 is an IC which performs processing. The processor 1102 is a CPU, a DSP or the like. The processor 1102 executes a program. More specifically, the processor 1102 executes a program realizing a GSM communication control unit 502 to be described later.
The storage device 1104 is a RAM, a ROM, a flash memory, an HDD, or the like. The storage device 1104 stores the program realizing the GSM communication control unit 502. Also, the storage device 1104 stores values used for a calculation of the processor 1102 and a calculation result of the processor 1102. [0014] Fig. 12 illustrates a hardware configuration example of the facility device (1)

101 and the facility device (2) 103. Note that in the present embodiment, the hardware configurations of facility device (1) 101 and the facility device (2) 103 are the same.
Each of the facility device (1) 101 and the facility device (2) 103 includes a serial interface 1201, a processor 1202, an actuator 1203, and a storage device 1204.
The serial interface 1201 is a circuit which serves as an interface with the serial cable.
The processor 1202 is a CPU, a DSP or the like. The processor 1202 executes programs. More specifically, the processor 1202 executes programs realizing a GSM modem control unit 202, a status information generation unit 203, a device status monitor unit 204, and a device control unit 205 to be described later.
The storage device 1204 is a RAM, a ROM, a flash memory, or the like. The storage device 1204 stores the programs realizing the GSM modem control unit 202, the status information generation unit 203, the device status monitor unit 204, and the device control unit 205. Also, the storage device 1204 stores values used for a calculation of the processor 1202 and a calculation result of the processor 1202.
The actuator 1203 is a mechanical element which performs rotational motion, rectilinear motion, and the like.
[0015] Fig.2 illustrates a functional configuration example of the facility device (1) 101 and the facility device (2) 103. Note that in the present embodiment, the functional configurations of the facility device (1) 101 and the facility device (2) 103 are the same.
The device control unit 205 controls the actuator 1203.
The device status monitor unit 204 monitors a status of the device control unit 205.
The status information generation unit 203 generates status information to be transmitted to the facility administrator, based on the information from the device status

monitor unit 204.
The GSM modem control unit 202 controls the GSM modem 106 via the serial communication unit 201 with an input of the status information from the status information generation unit 203 as a trigger, and transmits the status information to the GSM modem 106.
The serial communication unit 201 controls serial communication with the client apparatus (1) 102 or the client apparatus (2) 104.
[0016] The serial communication unit 201 is realized by the serial interface 1201 in Fig. 12. The GSM modem control unit 202, the status information generation unit 203, the device status monitor unit 204, and the device control unit 205 are realized by the processor 1202 and the storage device 1204.
[0017] Fig.3 illustrates a functional configuration example of the client apparatus (1) 102 and the client apparatus (2) 104. In the present embodiment, the functional configurations of the client apparatus (1) 102 and the client apparatus (2) 104 are the same.
A network communication unit 301 controls communication with the Ethernet or communication with the wireless LAN.
A serial communication unit 304 controls serial communication with the facility device (1) 101 or the facility device (2) 103.
A communication destination address information storage unit 305 stores an IP address and a TCP port number of the server apparatus 105 which is a communication destination of the TCP/IP.
A TCP/IP communication control unit 302 transfers a data portion of a TCP/IP frame received by the network communication unit 301 to the serial communication unit 304. The TCP/IP communication control unit 302 also stores the data received by

the serial communication unit 304 in the TCP/IP frame, and transfers the TCP/IP frame to the network communication unit 301. In addition, the TCP/IP communication control unit 302 controls TCP/IP communication with an input from the serial communication unit 304 as trigger. More specifically, the TCP/IP communication control unit 302 transmits a connection establishment request (SYN) of TCP to the server apparatus 105 via the network communication unit 301. Then, when the network communication unit 301 receives a reset response (RST) to the connection establishment request (SYN), the TCP/IP communication control unit 302 retransmits the connection establishment request (SYN). The connection establishment request (SYN) is a packet that requests a setting of a connection. The reset response (RST) is a packet notifying that the setting of the connection is not permitted. Further, a connection establishment response (ACK) described later is a packet notifying that the setting of the connection has been permitted.
A connection timer management unit 303 monitors the TCP/IP communication control unit 302. The connection timer management unit 303 instructs the TCP/IP communication control unit 302 to disconnect a TCP connection when communication is not performed for a prescribed period of time.
[0018] The network communication unit 301 is realized by the network interface 1001 in Fig. 10. The serial communication unit 304 is realized by the serial interface 1003 in Fig. 10. The communication destination address information storage unit 305 is realized by the storage device 1004 in Fig. 10. The TCP/IP communication control unit 302 and the connection timer management unit 303 are realized by the processor 1002 and the storage device 1004.
[0019] Fig. 4 illustrates a functional configuration example of the server apparatus 105.

A network communication unit 401 controls communication with the Ethernet or communication with the wireless LAN.
A serial communication unit 403 controls serial communication with the GSM modem 106.
The TCP/IP communication control unit 402 controls TCP/IP communication. More specifically,the TCP/IP communication control unit 402 transfers a data portion of a TCP/IP frame received by the network communication unit 401 to the serial communication unit 403. The TCP/IP communication control unit 402 also stores the data received by the serial communication unit 403 in the TCP/IP frame, and transfers the TCP/IP frame to the network communication unit 401. Further, when the network communication unit 401 receives the connection establishment request (SYN), the TCP/IP communication control unit 402 transmits the connection establishment response (ACK) or the reset response (RST) to the sender of the connection establishment request (SYN) via the network communication unit 401. [0020] The network communication unit 401 is realized by the network interface 1001 in Fig. 10. The serial communication unit 403 is realized by the serial interface 1003 in Fig. 10. The TCP/IP communication control unit 402 is realized by the processor 1002 and the storage device 1004 in Fig. 10. [0021] Fig.5 illustrates a functional configuration example of the GSM modem 106.
A GSM communication unit 501 controls GSM communication with the public mobile network 107.
A serial communication unit 503 controls serial communication with the server apparatus 105.
The GSM communication control unit 502 controls the GSM communication unit 501 according to an AT command transmitted from the facility device (1) 101 or

the facility device (2) 103. The GSM communication control unit 502 transmits a response to the AT command to the facility device (1) 101 or the facility device (2) 103 via the serial communication unit 503. The AT command is a packet used for controlling the GSM modem 106.
[0022] The GSM communication unit 501 is realized by the wireless communication interface 1101 in Fig.l 1. The serial communication unit 503 is realized by the serial interface 1103 in Fig.l 1. The GSM communication control unit 502 is realized by the processor 1102 and the storage device 1104 in Fig. 11. [0023] *** Description of Operation ***
Next, communication operation of the facility management system according to the present embodiment will be described.
Fig.6 illustrates an example of a communication sequence at a time when the facility device (1) 101 transmits status information to the mobile terminal apparatus 108.
In Fig.6, an illustration of a communication sequence of communication from the GSM modem 106 to the mobile terminal apparatus 108 is omitted.
Also, in Fig.6, the connection connection request (SYN) is expressed as "SYN". The connection connection response (ACK) is expressed as "ACK". [0024] In the facility device (1) 101, prior to transmission of the status information, in order to set up a communication line between the facility device (1) 101 and the GSM modem 106, the GSM modem control unit 202 transmits an AT command (transmission) destined to the GSM modem 106 via the serial communication unit 201 (step 605).
In the client apparatus (1) 102, the TCP/IP communication control unit 302 receives the AT command (transmission) via the serial communication unit 304. Since the TCP connection is not established with the server apparatus 105, the TCP/IP

communication control unit 302 transmits the connection establishment request (SYN) to the server apparatus 105 via the network communication unit 301 (step 606).
In the server apparatus 105, the TCP/IP communication control unit 402 receives the connection establishment request (SYN) via the network communication unit 401. Then, the TCP/IP communication control unit 402 determines whether or not a connection has been established with another client apparatus (specifically, the client apparatus (2) 104). The TCP/IP communication control unit 402 manages a connection status table which describes a client apparatus with which a connection is established. The TCP/IP communication control unit 402 refers to the connection status table and determines whether or not the connection is established with another client apparatus. In Fig. 6, the connection is not established between the server apparatus 105 and the other client apparatus (client apparatus (2) 104). Therefore, the TCP/IP communication control unit 402 transmits the connection establishment response (ACK) to the client apparatus (1) 102 via the network communication unit 401 (step 607). As a result, the TCP connection is established between the client apparatus (1) 102 and the server apparatus 105. Further, the TCP/IP communication control unit 402 writes the client apparatus (1) 102 in the connection status table.
After establishing the connection, the TCP/IP communication control unit 302 of the client apparatus (1) 102 transmits the AT command (transmission) to the server apparatus 105 via the network communication unit 301 (step 608).
In the server apparatus 105, the TCP/IP communication control unit 402 receives the AT command (transmission) via the network communication unit 401 and transfers AT command (transmission) to the GSM modem 106 via the serial communication unit 403 (step 609).
In the GSM modem 106, the GSM communication control unit 502 receives

the AT command (transmission) via the serial communication unit 503 and transmits a response indicating a completion of transmission to the server apparatus 105 via the serial communication unit 503 (step 610).
In the server apparatus 105, the TCP/IP communication control unit 402 receives the response via the serial communication unit 403. The TCP/IP communication control unit 402 transmits the response to the client apparatus (1) 102 via the network communication unit 401 (step 611).
In the client apparatus (1) 102, the TCP/IP communication control unit 302 receives the response via the network communication unit 301 and transmits the response to the facility device (1) 101 via the serial communication unit 304 (step 612).
In the facility device (1) 101, the GSM modem control unit 202 receives a response via the serial communication unit 201, and transmits the status information generated by the status information generation unit 203 to the client apparatus (1) 102. The status information is transferred in an order of the client apparatus (1) 102, the server apparatus 105, and the GSM modem 106 (step 613). Ultimately, the status information is transmitted from the GSM modem 106 to the mobile terminal apparatus 108 via the public mobile network 107.
In the facility device (1) 101, when the transmission of the status information is completed, in order to disconnect the communication line with the GSM modem 106, the GSM modem control unit 202 transmits AT command (disconnection) to the client apparatus (1) 102 via the serial communication unit 201 (step 614).
In the client apparatus (1) 102, the TCP/IP communication control unit 302 receives the AT command (disconnection) via the serial communication unit 304 and transmits the AT command (disconnection) to the server apparatus 105 via the network communication unit 301 (step 615).

In the server apparatus 105, the TCP/IP communication control unit 402 receives the AT command (disconnection) via the network communication unit 401 and transmits the AT command (disconnection) to the GSM modem 106 via the serial communication unit 403 (step 616).
In the GSM modem 106, the GSM communication control unit 502 receives . the AT command (disconnection) via the serial communication unit 503, and transmits a response of a completion of disconnection to the server apparatus 105 via the serial communication unit 503 (step 617).
In the server apparatus 105, the TCP/IP communication control unit 402 receives the response via the serial communication unit 403 and transmits the response to the client apparatus (1) 102 via the network communication unit 401 (step 618).
In the client apparatus (1) 102, the TCP/IP communication control unit 302 receives the response via the network communication unit 301 and transmits the response to the facility device (1) 101 via the serial communication unit 304 (step 619).
Also, in the client apparatus (1) 102, in a case where there is no new TCP/IP communication from the last TCP/IP communication (step 618) until the non-communication time (621) set in the connection timer management unit 303 elapses, The TCP/IP communication control unit 302 performs disconnection (FIN/ACK) of the TCP connection (step 620). The TCP/IP communication control unit 402 of the server apparatus 105 deletes the client apparatus (1) 102 from the connection status table. [0025] Fig. 7 illustrates an example of a communication sequence in a case where the AT command (transmission) is transmitted from the facility device (1) 101 when a connection is established between the client apparatus (2) 104 and the server apparatus 105.
In Fig.7, an illustration of a communication sequence of communication from

the GSM modem 106 to the mobile terminal apparatus 108 is omitted.
Also, in Fig.7, the connection connection request (SYN) is expressed as "SYN". The connection connection response (ACK) is expressed as "ACK". The reset response (RST) is expressed as "RST".
[0026] In the facility device (1) 101, prior to transmission of the status information, in order to set up a communication line between the facility device (1) 101 and the GSM modem 106, the GSM modem control unit 202 transmits an AT command (transmission) destined to the GSM modem 106 via the serial communication unit 201 (step 705).
In the client apparatus (1) 102, the TCP/IP communication control unit 302 receives the AT command (transmission) via the serial communication unit 304. Since the TCP connection is not established with the server apparatus 105, the TCP/IP communication control unit 302 transmits the connection establishment request (SYN) to the server apparatus 105 via the network communication unit 301 (step 706).
In the server apparatus 105, the TCP/IP communication control unit 402 receives the connection establishment request (SYN) via the network communication unit 401. Then, the TCP/IP communication control unit 402 determines whether or not a connection has been established with another client apparatus (specifically, the client apparatus (2) 104). In Fig. 7, since the connection is established between the client apparatus (2) 104 and the server apparatus 105 (step 711), the TCP/IP communication control unit 402 transmits the reset response (RST) to the client apparatus (1) 102 (step 707).
In the client apparatus (1) 102, the TCP/IP communication control unit 302 receives the reset response (RST) via the network communication unit 301. Since the TCP/IP communication control unit 302 has received the reset response (RST), the

TCP/IP communication control unit 302 repeats retransmission of the connection establishment request (SYN) (steps 708 to 713) until receiving the connection establishment response (ACK).
Upon receiving the connection establishment response (ACK) (step 714), the TCP/IP communication control unit 302 transmits the AT command (transmission) to the server apparatus 105 via the network communication unit 301 (step 715).
Since the operations after the step 716 are the same as the operations after the step 609 in Fig. 6, an explanation will be be omitted.
[0027] As described above, according to the present invention, each of the client apparatus (1) 102 and the client apparatus (2) 104 requests the server apparatus 105 to set a connection, according to the TCP/IP, prior to relaying the status information to the the server apparatus 105.
When the client apparatus (1) 102 requests to set a connection, the server apparatus 105 determines whether or not a connection is set with the client apparatus (2) 104 which is another client apparatus, according to the TCP/IP, and set the connection with the client apparatus (1) 102 which is a requester, when the connection is not set with the client apparatus (2) 104.
On the other hand, when the connection is set with the client apparatus (2) 104, the server apparatus 105 responds to the client apparatus (1) 102 which is the requester that a setting of the connection is not permitted.
When the server apparatus 105 responds that the setting of the connection is not permitted, the client apparatus (1) 102 requests the the server apparatus 105 again to set the connection, according to the TCP/IP.
[0028] Fig. 13 is a flow chart explaining an operation of the client apparatus (1) 102 in the step 706 to the step 715 of Fig.7.

Hereinafter, the operation of the client apparatus (1) 102 will be described with reference to Fig. 13.
In the following description, the operation of the client apparatus (1) 102 will be described, however, the client apparatus (2) 104 also performs the same operation according to the flow chart of Fig. 13.
[0029] First, the TCP/IP communication control unit 302 receives the AT command (transmission) via the serial communication unit 304 (step SI301).
Next, the TCP/IP communication control unit 302 transmits the connection establishment request (SYN) to the server apparatus 105 via the network communication unit 301 (step S1302).
Next, when the network communication unit 301 has received a response from the server apparatus 105, the TCP/IP communication control unit 302 determines which of the connection establishment response (ACK) and the reset response (RST) the network communication unit 301 has received (step S1303).
If the network communication unit 301 has received the connection establishment response (ACK), the TCP/IP communication control unit 302 transmits the AT command (transmission) to the server apparatus 105 via the network communication unit 301 (step S13 04).
On the other hand, if the network communication unit 301 has received the reset response (RST), the TCP/IP communication control unit 302 transmits the connection establishment request (SYN) to the server apparatus 105 again via the network communication unit 301 (Step S 1302).
[0030] Fig. 14 is a flow chart explaining an operation of the server apparatus 105 in the step 706 to the step 716 of Fig.7.
Hereinafter, with reference to Fig. 14, the operation of the server apparatus 105

will be described.
In the following description, the operation of the server apparatus 105 in a case where the server apparatus 105 receives the connection establishment request (SYN) from the client apparatus (1) 102 will be described, but the server apparatus 105
» performs the same operation according to the flow chart of Fig. 14 also in a case where the server apparatus 105 receives the connection establishment request (SYN) from the client apparatus (2) 104.
[0031] First, the TCP/IP communication control unit 402 receives the connection establishment request (SYN) from the client apparatus (1) 102 via the network
) communication unit 401 (step S1401).
Next, the TCP/IP communication control unit 402 checks connection establishment status with the other client apparatus (specifically, the client apparatus (2) 104). As described above, the TCP/IP communication control unit 402 refers to a connection management table and checks whether the connection has been established
5 with the other client apparatus.
If the connection has been established with the other client apparatus (YES in step S1403), the TCP/IP communication control unit 402 transmits the reset response (RST) to the client apparatus (1) 102 via the network communication unit 401 (step S1407).
) On the other hand, if the connection has not been established with the other
client apparatus (NO in step S1403), the TCP/IP communication control unit 402 transmits the connection establishment response (ACK) to the client apparatus (1) 102 via the network communication unit 401 (step S1404).
Next, the TCP/IP communication control unit 402 receives the AT command
5 (transmission) from the client apparatus (1) 102 via the network communication unit

401 (step SI405), and transmits the received AT command (transmission) to the GSM modem 106 via the serial communication unit 403 (step SI406). [0032] *** Effect of Embodiment ***
As described above, in the present embodiment, since a communication conflict on the GSM modem is regulated using connection control of the TCP/IP, a plurality of facility devices can share one GSM modem. In other words, the relay system according to the present embodiment enables one GSM modem to transmit status information from the plurality of facility devices, without changing settings of the facility devices and settings of the GSM modem. Therefore, according to the present embodiment, an effect of reducing the number of GSM modems required for the whole factory can be obtained. [0033] Second Embodiment
In the first embodiment, as illustrated in Fig.6, disconnection (FIN/ACK) of the TCP connection is performed when there is no new TCP/IP communication until the non-communication time (621) elapses (step 620).
In the present embodiment, a procedure to disconnect earlier without waiting for disconnection of the connnection until the non-communication time has elapsed.
In the following, differences from the first embodiment will be described.
The matters not described below are the same as those in the first embodiment. [0034] Fig. 8 illustrates a functional configuration example of the client apparatus (1) 102 and the client apparatus (2) 104 according to the present embodiment.
In Fig. 8, a connection-disconnection trigger command management unit 806 is added to the configuration (the configuration illustrated in Fig.3) of the client apparatus (1) 102 and the client apparatus (2) 104 of the first embodiment.
When a connection with the server apparatus 105 is set, the connection-

disconnection trigger command management unit 806 monitors a TCP/IP communication control unit 802. Then, after detecting that the TCP/IP communication control unit 802 transmits a pre-specified command, the connection-disconnection trigger command management unit 806 instructs the TCP/IP communication control unit 802 to disconnect the connection, when detecting that the TCP/IP communication control unit 802 receives another pre-specified command.
More specifically, after the TCP/IP communication control unit 802 transmits to the server apparatus 105 a completion notification command notifying that transmission of the status information from the facility device (1) 101 or the facility device (2) 103 to the mobile terminal apparatus 108 is completed, the connection-disconnection trigger command management unit 806 instructs the TCP/IP communication control unit 802 to disconnect the connection with the server apparatus 105, when the TCP/IP communication control unit 802 receives a response command which is a response to the completion notification command from the server apparatus 105.
In Fig.8, a network communication unit 801 is the same as the network communication unit 301. The TCP/IP communication control unit 802 is the same as the TCP/IP communication control unit 302. A connection timer management unit 803 is the same as the connection timer management unit 303. A serial communication unit 804 is the same as the serial communication unit 304. A communication destination address information storage unit 805 is the same as the communication destination address information storage unit 305. Therefore, explanations will be omitted for the network communication unit 801, the TCP/IP communication control unit 802, the connection timer management unit 803, the serial communication unit 804, and the communication destination address information storage unit 805.

Also, the connection-disconnection trigger command management unit 806 is a program, realized by the processor 1002 and the storage device 1004 in Fig. 10. [0035] Fig.9 illustrates an example of communication sequence according to the present embodiment.
Steps 1005 to 1014 in Fig.9 are the same as the steps 605 to 614 in Fig.6, and step 1016, step 1017 and step 1019 in Fig.9 are the same as the step 616, the step 617 and the step 619 in Fig.6. Therefore, explanations will be omitted for these steps.
In Fig.9, step 1015 is different from the step 615 in Fig.6, step 1018 is different from the step 618 in Fig.6, step 1020 is different from the step 620 in Fig.6. Therefore, step 1015, step 1018, and step 1020 will be described.
[0036] In the present embodiment, the AT command (disconnection) (step 1015) being the completion notification command and the response (step 1018) being the response command are registered as trigger commands for disconnection of connection in the connection-disconnection trigger command management unit 806.
As described above, the connection-disconnection trigger command management unit 806 monitors the TCP/IP communication control unit 802. In step 1015, the connection-disconnection trigger command management unit 806 detects that the TCP/IP communication control unit 802 transmits the AT command (disconnection) to the server apparatus 105. In step 1018, the connection-disconnection trigger command management unit 806 detects that the TCP/IP communication control unit 802 receives the response. Since the trigger command is transmitted and received by the TCP/IP communication control unit 802 in this manner, the connection-disconnection trigger command management unit 806 instructs the TCP/IP communication control unit 802 to disconnect the connection.
As a result, the TCP/IP communication control unit 802 performs the

disconnection (FIN/ACK) of the TCP connection in step 1020.
In a case where the GSM modem 106 cannot return a response to the AT command (disconnection) due to an error or the like, the TCP/IP communication control unit 802 disconnets the TCP/IP connection if there is no new TCP/IP communication until the non-communication time elapses, the non-communication time being set in the connection timer management unit 803. [0037] * * * Effect of Embodiment * * *
In the first embodiment, as illustrated in Fig.6, it is not possible to disconnect the connection of the TCP until the non-communication time (621) elapses. However, in the present embodiment, as illustrated in Fig.9, it is possible to disconnect the connection immediately after receiving the response in the step 1018.
That is, in the present embodiment, it is possible to shorten waiting time until disconnection of the TCP connection, by registering commands which serve as triggers of the disconnection of the TCP connection in the client apparatus. Therefore, in a case where the connection has been established between the server apparatus 105 and the client apparatus (2) 104 when the facility device (1) 101 transmits the connection connection request (SYN) to server apparatus 105 as illustrate in Fig.7, it is possible to promptly establish the connection between the server apparatus 105 and the client apparatus (1) 102, by detecting transmission and reception of a trigger command and disconnecting the connection at an early stage by the client apparatus (2) 104. [0038] The embodiments of the present invention have been described above. Alternatively, the relay system may be implemented by combining these two embodiments together.
Alternatively, one of these two embodiments may be partially implemented.

Alternatively, the relay system may be implemented by partially combining these two embodiments together.
Note that the present invention is not limited to these embodiments and various changes may be made as necessary. *** Description of Hardware configuration ***
Finally, hardware configurations of the facility device(l)101, the client apparatus (1) 102, the facility device (2) 103, the client apparatus (2) 104, the server apparatus 105, and the GSM modem 106 are supplementarily explaned.
Although not mentioned in the explanation above, the processor 1002, the processor 1102, and the processor 1202 in Fig. 10 to Fig. 12 can execute a task management, a memory management, a file management, a communication control and the like, by executing an OS (Operating System).
In place of the processor 1002, the processor 1102, and the processor 1202, electronic circuits such as a logic IC (Integrated Circuit), a GA (Gate Array), an ASIC (Application Specific Integrated Circuit), an FPGA (Field-Programmable Gate Array) may be used.
The processor 1002, the processor 1102, the processor 1202, and the electronic circuit are collectively referred to as processing circuitry. Reference Signs List
[0039] 100: factory, 101: facility device (1), 102: client apparatus (1), 103: facility device (2), 104: client apparatus (2), 105: server apparatus, 106: GSM modem, 107: public mobile network, 108: mobile terminal apparatus, 201: serial communication unit, 202: GSM modem control unit, 203: status information generation unit, 204: device status monitor unit, 205: device control unit, 301: network communication unit, 302: TCP/IP communication control unit, 303: connection timer management unit,

304: serial communication unit, 305: communication destination address information storage unit, 401: network communication unit, 402: TCP/IP communication control unit, 403: serial communication unit, 501: GSM communication unit, 502: GSM communication control unit, 503: serial communication unit, 801: network communication unit, 802: TCP/IP communication control unit, 803: connection timer management unit, 804: serial communication unit, 805: communication destination address information storage unit, 806: connection-disconnection trigger command management unit, 1001 : network interface, 1002: processor, 1003: serial interface, 1004: storage device, 1101: wireless communication interface, 1102: processor, 1103: serial interface, 1104: storage device, 1201: serial interface, 1202: processor, 1203: actuator, 1204: storage device

We Claim:
[Claim 1] A relay system comprising:
a plurality of first relay apparatuses to relay data transmitted from a plurality of devices, according to a connection type communication protocol; and
a second relay apparatus to receive data relayed by the plurality of first relay apparatuses, according to the connection type communication protocol, and transmit the received data to a wireless communication device which communicates with a transmission destination device which is a data transmission destination of the plurality of devices,
wherein each of the plurality of first relay apparatuses requests the second relay apparatus to set a connection, according to the connection type communication protocol, prior to relaying data to the second relay apparatus, and
wherein the second relay apparatus, when being requested to set a connection by any one of the plurality of first relay apparatuses, determines whether or not a connection is set with another first relay apparatus, according to the connection type communication protocol, and sets the connection with a requesting first relay apparatus when the connection is not set with the another first relay apparatus. [Claim 2] The relay system according to claim 1,
wherein the second relay apparatus, when the connection is set with the another first relay apparatus, responds to the requesting first relay apparatus that a setting of the connection is not permitted, and
wherein each of the plurality of first relay apparatuses, when the second relay apparatus responds that the setting of the connection is not permitted, requests the second relay apparatus again to set the connection, according to the connection type communication protocol.

[Claim 3] The relay system according to claim 1,
wherein when the connection with the second relay apparatus is set, after transmitting a pre-specified command, each of the plurality of first relay apparatuses disconnects the connection with the second relay apparatus, when receiving another pre-specified command. [Claim 4] The relay system according to claim 1,
wherein, after transmitting a completion notification command notifying that data transmission from a sender of the data to the transmission destination device is completed, each of the plurality of first relay apparatuses disconnects the connection with the second relay apparatus, when receiving a response command which is a response to the completion notification command from the second relay apparatus. [Claim 5] The relay system according to claim 1,
wherein each of the plurality of first relay apparatuses requests the second relay apparatus to set the connection, according to TCP/IP (Transmission Control Protocol/Internet Protocol), prior to relaying data to the second relay apparatus, and
wherein the second relay apparatus, when being requested to set the connection by any one of the plurality of first relay apparatuses, determines whether or not the connection is set with another first relay apparatus, according to the TCP/IP, and sets the connection with the requesting first relay apparatus when the connection is not set with the another first relay apparatus.