Server device, communication device, and control system

Abstract

According to the present embodiment, a server device is provided with a communication unit, a determination unit, and a control calculation unit. The communication unit sequentially receives, via a network, a plurality of first packets each including the same first signal for a plurality of different pieces of connection information. The determination unit determines whether or not a first signal included in the first packet has been received. On the basis of the determination, the control calculation unit generates a second signal corresponding to the first signal when the first signal is not received.

Description

Technical Field

[0001] Embodiments of the present invention relate to a server device, a communication device, and a control system. Background Art

[0002] This paper discusses control systems that execute sequence control and process control by PLC (Programmable Logic Controller) in server devices via networks such as the Internet. Control systems such as factories and industrial systems operate in real time at a fixed cycle. In order to control the system normally, it is required to transmit input and output data within a certain time even if network delays occur.

[0003] Prior art literature

[0004] Patent Literature

[0005] Patent Document 1: Japanese Patent No. 5959452 Summary of the invention

[0006] Technical problem to be solved by the invention

[0007] However, the communication bandwidth and communication delay are not guaranteed in networks such as the Internet. Therefore, if control is performed via the network, it may not be possible to perform target control within a fixed period. In addition, even if multiple server devices are used, sudden communication delays may occur, and it may not be possible to perform fixed-period control. In addition, considering the security of the control system, if a firewall or proxy server is configured on the edge side of the network, it may not be possible to use communication protocols for real-time communication such as UDP (User Datagram Protocol).

[0008] In order to solve such a problem, an object of the present embodiment is to provide a server device, a communication device, and a control system that can perform control via a network more stably.

[0009] Means used to solve problems

[0010] According to this embodiment, the server device includes a communication unit, a judgment unit, and a control operation unit. The communication unit sequentially receives a plurality of first data packets containing the same first signal for a plurality of different connection information via a network. The judgment unit judges whether the first signal contained in the first data packet has been received. If it is judged that the first signal has not been received, the control operation unit generates a second signal corresponding to the first signal.

[0011] Effects of the Invention

[0012] Control via the network can be performed more stably. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] Figure 1 It is a diagram showing a configuration example of a control system according to the first embodiment.

[0014] Figure 2 This is a table showing examples of the transmission connection information used by the connection unit.

[0015] Figure 3 This is a diagram showing an example of the structure of an input signal data packet transmitted by the transmission management unit.

[0016] Figure 4 This is a table showing an example of a method for referring to connection information using the sending flag.

[0017] Figure 5 This is a diagram showing an example of the structure of an output signal data packet used by the transmission management unit.

[0018] Figure 6 This is the communication timing diagram for the initial connection.

[0019] Figure 7 This is a communication sequence diagram for sending input signals to the server device.

[0020] Figure 8 This is a communication sequence diagram for sending an output signal from a server device to a communication device.

[0021] Fig. 9 It is a diagram showing a configuration example of a control system according to the second embodiment.

[0022] Fig.10 It is a diagram showing an example of a communication sequence of an initial connection according to the second embodiment.

[0023] Fig.11 This is a communication sequence diagram for sending an input signal from a communication device to a server device.

[0024] Fig.12 This is a communication sequence diagram for sending an output signal from a server device to a communication device. DETAILED DESCRIPTION

[0025] Hereinafter, the server device, the communication device, and the control system of the embodiment of the present invention will be described in detail with reference to the accompanying drawings. In addition, the embodiment shown below is an example of the embodiment of the present invention, and the present invention is not limited to these embodiments for interpretation. In addition, in the drawings referred to in the present embodiment, the same parts or parts with the same functions are given the same symbols or similar symbols, and their repeated descriptions are sometimes omitted. In addition, for the convenience of explanation, the dimensional ratios of the drawings are sometimes different from the actual ratios, and a part of the structure is sometimes omitted from the drawings.

[0026] (First Embodiment)

[0027] (constitute)

[0028] Figure 1 FIG. 2 is a diagram showing an example of the configuration of a control system according to the first embodiment. Figure 1 As shown, the control system 1 includes a server device 10 and a communication device 20. The server device 10 and the communication device 20 are connected via a network 40. That is, the server device 10 is, for example, a computer including a CPU (Central Processing Units), a memory, a storage, etc., and controls devices such as actuators via the network 40 and the communication device 20.

[0029] The input device 41 inputs an input signal which is data obtained from a sensor or the like which generates state information of a device such as an actuator. The output device 42 is, for example, a device such as an actuator which is a control target of the server device 10. That is, the server device 10 generates an output signal for control based on the input signal obtained via the communication device 20 and the network 40. Then, the server device 10 outputs the output signal to the output device 42 via the network 40 and the communication device 20. In addition, the input signal of this embodiment corresponds to the first signal, and the output signal corresponds to the second signal.

[0030] More specifically, the server device 10 includes a control operation unit 11, a connection unit 12, a receiving unit 13, a sending unit 14, and a communication unit 19. The receiving unit 13 includes a receiving connection information storage unit 15 for storing receiving connection information and a redundant data packet determination unit 16. In addition, the sending unit 14 includes a sending connection information storage unit 17 for storing sending connection information and a sending management unit 18. Furthermore, the server device 10 can be configured to include the control operation unit 11, the connection unit 12, the receiving unit 13, the sending unit 14, and the communication unit 19 by, for example, executing a program stored in a memory. In addition, the redundant data packet determination unit 16 of the present embodiment corresponds to the determination unit. In addition, the sending management unit 18 of the present embodiment corresponds to the first generation unit. In addition, the connection unit 12 of the present embodiment is sometimes referred to as a connection acceptance unit.

[0031] The communication device 20 has, for example, a CPU (Central Processing Units) and a memory, and includes a connection unit 21, a receiving unit 23, a sending unit 22, a communication unit 28, a signal input unit 29, and a signal output unit 30. The sending unit 22 has the same configuration as the sending unit 14, and has a sending connection information storage unit 24 for storing sending connection information and a sending management unit 25. In addition, the receiving unit 23 has the same configuration as the receiving unit 13, and has a receiving connection information storage unit 26 for storing receiving connection information and a redundant packet judgment unit 27. The communication device 20 can be configured by, for example, executing a program stored in the memory to configure the connection unit 21, the receiving unit 23, the sending unit 22, the communication unit 28, the signal input unit 29, and the signal output unit 30. In addition, the redundant packet judgment unit 27 of this embodiment corresponds to the judgment unit, and the sending management unit 25 corresponds to the second generation unit. In addition, the connection unit 21 of this embodiment corresponds to the second connection unit, and the communication unit 28 corresponds to the second communication unit.

[0032] First, a more specific configuration of the communication device 20 will be described. Figure 2 : is a table showing an example of the transmission connection information used by the connection unit 21. Figure 2 As shown, the connection information for sending is a unique number assigned to a device that performs sending. ID0 to 4 correspond to independent sending units or independent communication devices. For example, ID0 to 4 are respectively assigned 10 to 14 as connection information for sending. That is, for example, an independent sending unit (or a transceiver unit described later) or an independent communication device can correspond to ID0 to 4 of this embodiment, respectively. Thus, the communication device 20 of this embodiment is one device, but the communication device 20 can also be subjected to the same communication processing as the communication processing of multiple communication devices or multiple sending units (or transceivers described later).

[0033] The connection unit 21 sends the connection requests of ID0 to 4 to the connection unit 12 of the server device 10 via the network 40. As a connection response, the connection unit 12 of the server device 10 that has accepted the connection request via the network 40 sends 10 to 14 as the connection information for transmission corresponding to ID0 to 4, respectively, to the communication device 20 via the network 40. Thus, the connection information for transmission 10 to 14 is allocated to ID0 to 4, respectively. Therefore, as described above, in the control system 1 of the present embodiment, the communication device 20 is one device, but the receiving side via the network 40 may also communicate in a manner in which the communication devices corresponding to the number of IDs or the transmission units corresponding to the number of IDs actually exist.

[0034] In addition, the connection unit 21 may, for example, notify the server device 10 side in advance of information of ID0 to 4 as a group. The connection unit 21 stores the transmission connection information 10 to 14 corresponding to ID0 to 4 as a group as transmission connection information or reception connection information in the transmission connection storage unit 24 of the transmission unit 22 and the reception connection information storage unit 26 of the reception unit 23. In this way, the transmission connection storage unit 24 stores the transmission connection information 10 to 14 corresponding to ID0 to 4 as a group as transmission connection information after communication is established. Similarly, the reception connection information storage unit 26 stores the transmission connection information 10 to 14 corresponding to ID0 to 4 as a group as reception connection information after communication is established.

[0035] Figure 3 1 is a diagram showing an example of the structure of an input signal data packet sent by the transmission management unit 25 of the communication device 20. The input signal data packet is composed of a device ID as an identification number of the communication device, a transmission cycle indicating the transmission cycle number, a transmission count indicating how many times the transmission is performed in the same cycle, and data of the input signal. In addition, the input signal data packet of this embodiment corresponds to the first data packet.

[0036] When the same transmission signal is continuously transmitted in the same cycle, the transmission management unit 25 stores the same value in the transmission cycle, and the number of transmissions is incremented by 1. In addition, when the transmission management unit 25 transmits in the next cycle, the transmission cycle is incremented by 1, and the number of transmissions is returned to the initial value. In addition, when it is not necessary to determine which number of transmitted data packets has been reached, the number of transmissions can be omitted. In addition, when there is only one communication device 20 for one server device 10, the device ID can sometimes be omitted.

[0037] For example, the transmission management unit 25 sometimes transmits the same transmission signal 10 times in one cycle. In this case, the transmission management unit 25 uses the file descriptor (filedescriptor) as the transmission connection information in the order of connection in the manner of 10→11→12→13→14→10→11... when the number of connections is 5. In this way, after the transmission connection information 10 to 14 is assigned to the device ID of each data packet in turn by polling (Round-Robin) method, the transmission connection information 10 to 14 is again assigned to the device ID of each data packet in turn. For example, in the case of the first transmission cycle, 1 is assigned to the transmission cycle of each data packet. Then, 0 to 9 are assigned to the number of transmissions of each data packet in turn. In this way, the transmission management unit 25 repeatedly assigns the above-mentioned multiple different connection information in order according to the order in which the data packets are generated.

[0038] More specifically, the transmission management unit 25 can, for example, sequentially assign information (connection information for transmission, transmission cycle, number of transmissions) to the data head of each data packet in the order of (10, 0, 0), (11, 0, 1), (12, 0, 2), (13, 0, 3), (14, 0, 4), (10, 0, 5), (11, 0, 6), (12, 0, 7), (13, 0, 8), (14, 0, 9) for the same transmission signal. In this way, the transmission management unit 25 can sequentially assign (connection information for transmission, transmission cycle, number of transmissions) so that the five communication devices having the connection information for transmission 10 to 14 transmit the data packets. That is, the same input signal is repeatedly transmitted from the communication device 20 side through the communication unit 28 by changing the connection information for transmission and the number of transmissions. Such data packets are sequentially transmitted from the transmission side by the transmission management unit 25, but the order of reception on the receiving side may be changed depending on the environment of the network 40. Alternatively, a data packet may be generated that is not received on the receiving side due to a firewall or the like.

[0039] In addition, the transmission management unit 25 has a transmission time management function for managing the time intervals when multiple packets with the same transmission signal are transmitted. The transmission management unit 25 dynamically changes the number of transmissions and the transmission intervals of the packets with the same transmission signal, for example, based on the combination of the network load, the packet loss rate, and the communication time. The network load is the amount of communication per unit time. The transmission management unit 25 can, for example, determine the amount of communication per unit time based on the return time of the confirmation (ACK). In addition, the transmission management unit 25 determines the packet loss rate based on the number of packets with the same transmission signal that arrive within a specified time relative to the number of connection information for transmission. The communication time is a time preset for the communication of a transmission signal.

[0040] Thus, the sending management unit 25 can reduce the network load by dynamically reducing the number of transmissions or increasing the standby time when the network load is high, for example. In addition, the sending management unit 25 increases the number of transmissions when the packet loss rate is high. Thus, even when packet loss occurs, the probability of data reaching the server device is increased.

[0041] In addition, the sending management unit 25 shortens the standby time when the communication delay is large. The sending management unit 25 can obtain information about the communication delay based on the return time of the confirmation (Ack), for example. As a result, the time required for repeated transmission times can be shortened. For example, the sending connection information storage unit 24 can pre-store the number of transmissions and the standby time corresponding to the network environment. In this way, the sending management unit 25 can set the number of transmissions and the standby time according to the network environment. In this case, the sending management unit 25 can measure the communication status and dynamically change the number of transmissions and the standby time according to each IO cycle.

[0042] Figure 4 The table shows an example of a method for referring to connection information using the sending flag. In addition to the above-mentioned polling method, the sending management unit 25 can also perform the following steps: Figure 4 Select an unused file descriptor for use as shown.

[0043] like Figure 4 As shown, when the number of connections is 5 and file descriptors 12 and 13 are in use, the sending management unit 25 uses file descriptors 10, 11, and 14 in three consecutive transmissions. The sending flag changes in each cycle, so a process of confirming the sending flag in each cycle is performed. The sending management unit 25 can store the information of the file descriptors in use as the sending flag (1) in the sending connection storage unit 24. Thus, the sending management unit 25 can refer to the information of the file descriptors in use stored in the sending connection storage unit 24 and use the file descriptors with the sending flag (0) that are not used in each cycle. In this way, the sending management unit 25 assigns the connection information (corresponding to the sending flag (0)) that is not used for the data packet in the sending among multiple different connection information to the next data packet to be generated, based on the sending flag (1) in the sending among multiple data packets having the same input signal.

[0044] As described above, the receiving unit 23 includes the receiving connection information storage unit 26 and the redundant packet determination unit 27. The receiving unit 23 can receive a plurality of packets having the same output signal transmitted from the server device 10 via the communication unit 28.

[0045] The redundant packet determination unit 27 of the receiving unit 23 determines whether a transmission signal having the same output signal has been transmitted. The redundant packet determination unit 27 refers to the reception connection information of the reception connection information storage unit 26, for example, and determines whether the transmission cycle is the same in the information of the combination of the transmission connection information to be received. For example, for packets (10, 0, 0), (11, 0, 1), (12, 0, 2), (13, 0, 3), (14, 0, 4), (10, 0, 5), (11, 0, 6), (12, 0, 7), (13, 0, 8), (14, 0, 9) to which the information (transmission connection information, transmission cycle, number of transmissions) is assigned, the redundant packet determination unit 27 first refers to the reception connection information stored in the reception connection information storage unit 26, and determines whether the transmission connection information is in the range of 10 to 14. Next, if the transmission connection information is in the range of 10 to 14, the redundant packet determination unit 27 determines whether the number of the transmission cycle in which the transmission cycle is first received is 0. If the number of the transmission cycle in which the transmission cycle is first received is 0, the redundant packet determination unit 27 outputs the received input signal to the signal output unit 30, and stores the number 0 of the transmission cycle as the reception connection information in the reception connection information storage unit 26.

[0046] On the other hand, the redundant data packet judgment unit 27 refers to the receiving connection information stored in the receiving connection information storage unit 26, and when the number 0 of the sending cycle has been received, it is judged to be a redundant input signal and its output signal is not output to the signal output unit 30.

[0047] The communication unit 28 of the communication device 20 communicates with the communication unit 19 of the server device 10 via the network interface. Similarly, the communication unit 19 of the server device 10 communicates with the communication unit 28 of the communication device 20 via the network interface.

[0048] The signal input unit 29 receives the input signal output from the input device 41 in time series and outputs the input signal to the transmission unit 22. The signal output unit 30 receives the output signal output from the reception unit 26 in time series and outputs the output signal to the output device 42.

[0049] Here, the detailed configuration of the server device 10 will be described. The control operation unit 11 generates an output signal according to an input signal supplied from the receiving unit 13 , and outputs the output signal to the transmitting unit 14 .

[0050] As described above, as a connection response to the connection request from the connection unit 21 of the communication device 20, the connection unit 12 of the server device 10 sends 10 to 14 (see Figure 2) is transmitted to the communication device 20 as transmission connection information corresponding to IDs 0 to 4, respectively. In addition, the connection unit 12 can also determine the number of issuances of a plurality of different connection information based on, for example, a combination of a transmission cycle, a transmission frequency, and a communication time.

[0051] In addition, in the present embodiment, the connection unit 21 of the communication device 20 makes a connection request, and the connection unit 12 of the server device 10 accepts the connection request, but the present invention is not limited to this. For example, the connection unit 12 of the server device 10 may make a connection request, and the connection unit 21 of the communication device 20 may accept the connection request. Alternatively, the connection unit 21 of the communication device 20 may make a connection request when the communication device 20 sends, and the connection unit 12 of the server device 10 may make a connection request when the server device 10 sends.

[0052] The receiving unit 13 has the same configuration as the receiving unit 26. That is, the receiving unit 13 can receive a plurality of data packets having the same input signal transmitted from the communication device 20 via the communication unit 19.

[0053] The redundant packet determination unit 16 of the receiving unit 13 determines whether a transmission signal having the same input signal has been transmitted. The redundant packet determination unit 16 refers to the reception connection information of the reception connection information storage unit 15, for example, and determines whether the transmission cycle is the same in the information of the combination of the transmission connection information to be received. For example, for packets (10, 0, 0), (11, 0, 1), (12, 0, 2), (13, 0, 3), (14, 0, 4), (10, 0, 5), (11, 0, 6), (12, 0, 7), (13, 0, 8), (14, 0, 9) to which the information (transmission connection information, transmission cycle, number of transmissions) is assigned, the redundant packet determination unit 16 first refers to the reception connection information stored in the reception connection information storage unit 15, and determines whether the transmission connection information is in the range of 10 to 14. Next, if the transmission connection information is in the range of 10 to 14, the redundant packet determination unit 16 determines whether the number of the transmission cycle in which the transmission cycle is first received is 0. If the number of the transmission cycle in which the transmission cycle is first received is 0, the redundant packet determination unit 16 outputs the received input signal to the control operation unit 11, and stores the number 0 of the transmission cycle as the reception connection information in the reception connection information storage unit 15.

[0054] On the other hand, the redundant packet determination unit 16 refers to the receiving connection information stored in the receiving connection information storage unit 15, and when receiving the transmission cycle number 0, determines that it is a redundant input signal and does not output the input signal to the control operation unit 11.

[0055] Figure 51 is a diagram showing an example of the structure of an output signal data packet used by the transmission management unit 18. Similar to the input signal data packet, information (connection information for transmission, transmission cycle, number of transmissions) is sequentially allocated to the header of each data packet for the same output signal. In addition, the output signal data packet of this embodiment corresponds to the second data packet.

[0056] The transmission unit 14 has the same configuration as the transmission unit 22. That is, when continuous transmission is performed in the same cycle, the transmission management unit 18 stores the same value in the transmission cycle and increases the number of transmissions by 1. When the transmission management unit 18 performs transmission in the next cycle, the transmission cycle is increased by 1 and the number of transmissions is returned to the initial value.

[0057] The transmission management unit 18 generates a Figure 5 The data packet of the output signal data packet shown in the figure. For example, for the same output signal, the information (connection information for sending, sending cycle, number of times of sending) is sequentially allocated to the data header of each data packet in the manner of (10, 3, 0), (11, 3, 1), (12, 3, 2), (13, 3, 3), (14, 3, 4), (10, 3, 5), (11, 3, 6), (12, 3, 7), (13, 3, 8), (14, 3, 9). In addition, in the present embodiment, for the connection information for sending, the information common to the server device 10 and the communication device 20 is used, but it is not limited to this. For example, the allocation of the connection information for sending corresponding to each ID 0 to 4 can also be re-requested from the communication device 20 side to the server device 10 side.

[0058] In this way, the headers of the data packets having the same output signal are sequentially assigned (connection information for transmission, transmission cycle, number of transmissions) in such a manner that exactly five communication devices transmit each data packet. Thus, the same output signal is repeatedly transmitted from the server device 10 side with the connection information for transmission and the number of transmissions changed. Such data packets are sequentially transmitted from the transmission side, but the order of reception on the receiving side may be reversed depending on the environment of the network 40. Alternatively, data packets that are not received on the receiving side due to a firewall or the like may be generated.

[0059] In addition, the sending management unit 18 has the same function as the sending management unit 25. That is, the sending management unit 18 has a sending time management function for managing the time interval when sending a data packet with the same output signal multiple times. That is, the sending management unit 18 dynamically changes the number of times and the sending interval of the data packet with the same output signal based on the combination of the network load, the packet loss rate and the communication time. The network load is the communication volume per unit time. The sending management unit 18 can, for example, determine the communication volume per unit time based on the return time of the confirmation (Ack). In addition, the sending management unit 18 determines the packet loss rate based on the number of data packets with the same transmission signal that arrive within a specified time relative to the number of connection information for transmission. The communication time is the time preset for the communication of a transmission signal. For example, the sending connection information storage unit 17 can pre-store the number of transmissions and the standby time corresponding to the network environment. As a result, the sending management unit 18 can set the number of transmissions and the standby time according to the network environment. In this case, the sending management unit 18 can measure the communication status and dynamically change it according to the IO cycle.

[0060] like Figure 2 As shown, the sending management unit 18 repeatedly assigns the above-mentioned multiple different connection information in sequence according to the order in which the data packets are generated. Figure 4 As shown, the sending management unit 18 can assign the unused connection information (corresponding to the sending flag (0)) of the sending data packets in multiple different connection information to the next data packet to be generated based on the sending flag (1) in the sending of multiple data packets having the same output signal.

[0061] In addition, the server device 10 can be a physical server or a virtualized server or cloud server. The protocol for accepting the connection in the connection unit 12 and the connection unit 21 is not only TCP (Transmission Control Protocol), but also HTTP (Hypertext Transfer Protocol), HTTPS (Hypertext Transfer Protocol Secure), MQTT (Message Queueing Telemetry Transport) and other TCP-based protocols or QUIC, MQTT-SN (MQTT for Sensor Networks) and other UDP-based protocols. In addition, the receiving unit 13 and the sending unit 14 can be assigned to different threads of the OS to operate in parallel. Similarly, the receiving unit 23 and the sending unit 22 can also be assigned to different threads of the OS to operate in parallel. In addition, QUIC is one of the communication protocols (protocols) used on IP networks such as the Internet, and aims to achieve both high speed and security.

[0062] In addition, the output device 42 may be an IO module that transmits an output signal to an actuator or other device. Alternatively, the output device 42 may be a module that transmits an input signal or an output signal to an IO module. In addition, the server device 10 may be, for example, a virtualized server or a cloud server. Furthermore, the transmission method in the network 40 may be a method via a network, a field bus, etc., or may be a method via an ASIC, an FPGA, etc. In addition, it may be a configuration in which a plurality of communication devices 20 are connected to one server device 10. The above is a description of the configuration of the control system 1 of the first embodiment, and the following describes the function.

[0063] (effect)

[0064] Figure 6 This is a communication sequence diagram of the initial connection of this embodiment, showing a processing example of the connection unit 21, the transmission unit 22, and the reception unit 22 of the communication device 20 and the connection unit 12, the reception unit 13, and the transmission unit 14 of the server device 10. Figure 6 The communication sequence in which the communication device 20 is connected to the server device 10 as a TCP client is shown, and the description of the sequence of ACK for TCP is omitted.

[0065] First, the connection unit 21 of the communication device 20 sends a connection request to the connection unit 12 of the server device 10 (step S100). The connection unit 12 of the server device 10 that receives the connection request sends a connection response including transmission connection information to the communication device 20 (step S102).

[0066] Next, the connection unit 21 of the communication device 20 performs connection termination processing (step S104), and notifies the receiving unit 23 and the transmitting unit 22 of the received transmission connection information (step S106). Next, the receiving connection information storage unit 26 and the transmission connection information storage unit 24 of the receiving unit 23 respectively store the transmission connection information (steps S108 and S110).

[0067] Next, the connection unit 12 of the server device 10 notifies the transmission connection information to the reception unit 13 and the transmission unit 14 (step S112). Next, the reception connection information storage unit 15 and the transmission connection information storage unit 17 of the reception unit 13 respectively store the transmission connection information (steps S108 and S110).

[0068] In order to make multiple connections, such connection processing (steps S100 to S110) is repeated according to the number of connections. Thus, the receiving connection information storage unit 15 and the sending connection information storage unit 17 of the server device 10, and the receiving connection information storage unit 26 and the sending connection information storage unit 24 of the communication device 20 store the connection information of the number of connections. Here, the number of connections can be calculated based on the cycle of sending input signals and output signals, the number of times the same data packet is continuously sent, and the average communication time.

[0069] In the case of TCP, data exceeding the window size cannot be sent continuously. In addition, the data can only be received by the application program in the order in which the data packets arrive. Therefore, in order to continuously send the same data packet, multiple connections are required. For example, when the average communication allocation time for each identical transmission signal between the server device 10 and the communication device 20 is about 1 second, if it is sent three times continuously in a 100ms cycle and the number of connections is set to more than 30 (the ID is set to more than 30), there will be no shortage of connections during continuous transmission. That is, 90 identical transmission signals can be sent between 3×100ms×30=900ms within 1 second.

[0070] Figure 7 1 is a diagram showing an example of a communication sequence for transmitting an input signal from the communication device 20 to the server device 10. The diagram shows an example of processing by the transmission unit 22 of the communication device 20 and the control operation unit 11 and the reception unit 13 of the server device 10.

[0071] The transmission management unit 25 of the transmission unit 22 obtains an input signal from the input device 41 (step S200), refers to the transmission connection information in the transmission connection information storage unit 24 (step S202), generates a data packet to be transmitted, and transmits the input signal data packet (step S204).

[0072] Then, the sending management unit 25 waits for a certain time as a standby process (step S206). If the data packets are continuously sent without waiting time, the communication volume per unit time increases, and the sending may be regarded as a DoS attack by the proxy server or firewall located in the network 30 and cut off. The sending management unit 25 sends the next input signal data packet after waiting for a certain time.

[0073] Next, the receiving unit 13 of the server device 10 receives the input signal data packet (step S208). Next, the redundant data packet determination unit 16 of the receiving unit 13 refers to the receiving connection information stored in the receiving connection information storage unit 15 to determine whether it is a received transmission signal (step S210). Since it is the first transmission process, the redundant data packet determination unit 16 determines that it has not been received and transmits the input signal to the control operation unit 11 (step S212). Then, the control operation unit 11 of the server device 10 generates an output signal corresponding to the input signal (step S214). In this way, the input signal submitted to the control operation unit 11 is used as an input for the control operation.

[0074] The transmitting unit 22 and the receiving unit 13 repeatedly perform such processing n times on the same input signal between IO cycles. In this case, the judgment processing of the redundant data packet judgment unit 16 after the second time is not the first transmission processing, so it is judged as a received redundant data packet and the input signal is not transmitted to the control operation unit 11 (step S216). The same transmission cycle (refer to Figure 3 ), therefore, as described above, the redundant packet determination unit 16 can make a determination by the combination of the device ID and the transmission cycle included in the input signal packet. In addition, after repeating such a process n times, the transmission management unit 25 performs a standby process until the next IO cycle starts (step S218). Then, the transmission unit 23 of the communication device 20 repeats the transmission process n times from the acquisition of the input signal in each IO cycle.

[0075] Figure 8The communication timing diagram shows the transmission of an output signal from the server device 10 to the communication device 20. The control operation unit 11 of the server device 10 performs control operation in a control cycle. The transmission unit 14 obtains the output signal as a result of the control operation from the control operation unit 11. Here, the transmission unit 14 can obtain the output signal synchronously with the control cycle, or can obtain the output signal asynchronously with the control cycle or in a different cycle. The transmission unit 14 generates an output signal data packet by referring to the connection information in the same way as when the communication device 20 transmits an input signal, and transmits the output signal data packet to the receiving unit 23 of the communication device 20, and waits for a certain time. The transmission process is repeated by the number of transmissions. In the case of transmitting an input signal and in the case of transmitting an output signal, the number of transmissions and the waiting time can also be changed.

[0076] Figure 8 1 is a diagram showing an example of a communication sequence for transmitting an output signal from the server device 10 to the communication device 20. It shows an example of processing by the receiving unit 23 of the communication device 20 and the control calculation unit 11 and the transmitting unit 14 of the server device 10.

[0077] The control operation unit 11 of the server device 10 generates an output signal corresponding to the input signal (step S214). The transmission management unit 18 of the transmission unit 14 obtains the output signal from the control operation unit 11 (step S300), refers to the transmission connection information of the transmission connection information storage unit 17 (step S302), generates a data packet to be transmitted, and transmits the output signal data packet (step S304).

[0078] Then, the transmission management unit 18 waits for a certain period of time as a standby process (step S306). Next, the receiving unit 23 of the communication device 20 receives the output signal data packet (step S308). Next, the redundant data packet determination unit 276 of the receiving unit 23 refers to the receiving connection information stored in the receiving connection information storage unit 26 to determine whether it is a received output signal (step S310). Since it is the first output signal, the redundant data packet determination unit 27 determines that it has not been received, and transmits the output signal to the output device 42 via the signal output unit 30 (step S312).

[0079] The transmitting unit 14 and the receiving unit 23 repeatedly perform such processing n times on the same output signal between the control cycles. In this case, the judgment processing of the redundant data packet judgment unit 27 after the second time is not the first transmission processing, so it is judged as a received redundant data packet and the output signal is not transmitted to the output device 42 (step S314). The same transmission cycle (refer to Figure 5), therefore, the redundant packet determination unit 27 can make a determination based on the device ID and the transmission cycle group included in the output signal packet. In addition, after repeating such processing n times, the transmission management unit 18 performs a standby process until the next control cycle starts (step S316). Then, the transmission unit 14 of the server device 10 repeats the transmission process n times from the acquisition of the output signal in each control cycle.

[0080] (Effect)

[0081] The sending side of the server device 10 and the communication device 20 uses a plurality of connection information to continuously send data packets with the same signal for multiple times. As a result, the receiving side can perform the same receiving processing as when data packets with the same signal are sent from multiple devices respectively. Therefore, even in the case of packet loss or communication delay of a data packet using connection information corresponding to a certain device ID, it is possible to receive data packets using connection information corresponding to other device IDs. As a result, even in a TCP-based communication protocol, communication delays can be suppressed, thereby performing fixed-cycle control. In addition, even in the case where the sending side uses a plurality of connection information to continuously send data packets with the same signal for multiple times, the redundant data packet judgment unit 16, 27 on the receiving side only transmits the data packet with the same signal once or performs non-output processing, thereby suppressing the occurrence of redundant processing in the device on the receiving side.

[0082] Furthermore, the sending management unit 18, 25 of the sending side sets a waiting time when sending data packets with the same signal multiple times in succession. Thus, the following situations can be made possible: reducing the communication load of the network 40, allowing data packets to pass through a proxy server configured with a firewall or a proxy server, etc.

[0083] Furthermore, the connection unit 12 of the server device 10 and the connection unit 21 of the communication device 20 determine the number of connections based on the transmission cycle or the number of transmissions and the communication time, and perform connection processing for the number of connections in advance. Thus, even if a sudden delay occurs, continuous transmission can be performed without insufficient connection number.

[0084] In addition, the sending management unit 18, 25 on the sending side dynamically changes the number of transmissions and the waiting time according to the communication load, packet loss rate, and any information in the communication time of the network 40 in the periodic communication. Thus, the number of transmissions and the waiting time can be changed to the number of transmissions and the waiting time corresponding to the network environment of the network 40, and the packet arrival rate can be improved.

[0085] In addition, the transmission management unit 18, 25 on the transmission side gives connection information to each data packet having the same signal by polling. Thus, it is not necessary to determine whether each data packet having each transmission connection information is being transmitted. Therefore, the transmission management unit 18, 25 on the transmission side can give connection information to each data packet having the same signal at a higher speed.

[0086] In addition, the transmission management unit 18, 25 on the transmission side sets a transmission flag in each connection information after communication is established. Thus, when the transmission management unit 18, 25 on the transmission side gives connection information to each data packet having the same signal, it can continuously transmit using the connection information that is not being transmitted.

[0087] In addition, the transmission management unit 25 on the transmission side stores the transmission cycle in the input signal data packet, and the redundant data packet determination unit 17 on the receiving side determines the data packet storing the same transmission cycle as a redundant data packet. Thus, the redundant data packet determination process can be performed at a high speed. Similarly, the transmission management unit 18 on the transmission side stores the transmission cycle in the output signal data packet, and the redundant data packet determination unit 27 on the receiving side determines the data packet with the same transmission cycle as a redundant data packet. Thus, the redundant data packet determination process can be performed at a high speed.

[0088] Furthermore, the transmission management unit 25 on the transmission side stores the connection information and the transmission cycle corresponding to the device ID in the input signal data packet, and the connection unit 21 notifies the receiving side of the connection information as a group. In addition, the redundant data packet judgment unit 17 on the receiving side judges the data packets having the connection information as a group and storing the same transmission cycle as redundant data packets. Thus, even when there are multiple communication devices 20, the redundant data packet judgment process can be performed at a high speed. Similarly, the transmission management unit 18 on the transmission side stores the device ID and the transmission cycle in the output signal data packet, and the redundant data packet judgment unit 27 on the receiving side judges the data packets storing the same device ID and the same transmission cycle as redundant data packets. Thus, even when there are multiple communication devices 20, the redundant data packet judgment process can be performed at a high speed.

[0089] (Second Embodiment)

[0090] Unlike the server device 10 and the communication device 20 in the control system 1 of the first embodiment, which each has a single transmission unit and a single reception unit, the server device 10 and the communication device 20 in the control system 2 of the second embodiment each have a plurality of transmission and reception units. The following describes the differences from the control system 1 of the first embodiment.

[0091] (constitute)

[0092] Fig. 9FIG. 2 is a diagram showing a configuration example of a control system 2 according to a second embodiment. Figure 1 The same elements are given the same reference numerals, and their description is omitted.

[0093] The control system 2 includes a server device 50 and a communication device 60. The server device 50 and the communication device 60 are connected via a network 40. That is, the communication device 60 receives an input signal including data obtained from an input device 41, and transmits the input signal to the server device 50 via the network 40. The server device 50 generates an output signal corresponding to the received input signal, and outputs the output signal to the output device 42 via the network 40. The server device 50 is, for example, a multi-core server, and includes a CPU (Central Processing Units), a memory, a storage, and the like.

[0094] The server device 50 includes a control operation unit 11, a communication unit 19, a connection unit 51, a plurality of transceiver units 52A to G, a redundant packet determination unit 54, and a communication time management unit 55. In addition, the plurality of transceiver units 52A to G respectively include connection information storage units 53A to G. In addition, the number of the plurality of transceiver units 52A to G can be set to any number. The server device 50 can be configured to include the control operation unit 11, the communication unit 19, the connection unit 51, the plurality of transceiver units 52A to G, the redundant packet determination unit 54, and the communication time management unit 55 by, for example, executing a program stored in a memory. In addition, the redundant packet determination unit 54 of the present embodiment corresponds to the determination unit.

[0095] The communication device 60 has, for example, a CPU (Central Processing Units) and a memory, and includes a communication unit 28, a signal input unit 29, a signal output unit 30, a connection unit 61, a plurality of transceiver units 62A to G, a redundant packet determination unit 64, and a transmission time management unit 65. In addition, the plurality of transceiver units 62A to G respectively have connection information storage units 63A to G. In addition, the number of the plurality of transceiver units 62A to G can be set to any number. The communication device 60 can be configured by, for example, executing a program stored in the memory to form the communication unit 28, the signal input unit 29, the signal output unit 30, the connection unit 61, a plurality of transceiver units 62A to G, a redundant packet determination unit 64, and a communication time management unit 65. In addition, the redundant packet determination unit 64 of the present embodiment corresponds to the determination unit, and the transceiver units 62A to G correspond to independent transmission units.

[0096] First, the configuration of the server device 50 will be described in detail. The connection unit 51 of the server device 50 issues transmission connection information corresponding to a plurality of IDs in response to a request from the connection unit 61 (see Figure 5). The connection unit 51 sequentially distributes the transmission connection information corresponding to the plurality of IDs to the transmission and reception units 52A to 52G. Then, each of the connection information storage units 53A to 53G stores the transmission connection information distributed to itself.

[0097] Each of the plurality of transceiver units 52A to 52G receives an input signal packet having transmission connection information assigned to itself via the communication unit 19 (see Figure 3 ), and outputs the input signal data packet to the redundant data packet judgment unit 54. The redundant data packet judgment unit 54 judges whether a transmission signal having the same input signal has been sent. The redundant data packet judgment unit 54, for example, refers to the communication connection information to judge whether the same transmission cycle is in the information of the combination of the transmission connection information as the receiving object, thereby judging whether a transmission signal having the same output signal has been sent. The redundant data packet judgment unit 16 transmits the input signal to the control operation unit 11 when the transmission signal having the same input signal is sent for the first time. On the other hand, the redundant data packet judgment unit 54 judges that it is a redundant input signal when the transmission signal having the same input signal is not sent for the first time, and performs processing not to output the input signal to the control operation unit 11.

[0098] In addition, each of the plurality of transceiver units 52A to 52G generates an output signal packet including the transmission connection information assigned to itself and the transmission cycle, the number of transmissions, and the output signal supplied from the transmission time management unit 55 (see Figure 5 ).

[0099] The transmission time management unit 55 supplies the transmission cycle, the number of transmissions, and the output signal to each of the plurality of transceivers 52A to G whenever an output signal is supplied from the control operation unit 11. That is, when the transmission time management unit 55 continuously transmits the same output signal in the same cycle, it supplies the same value as the transmission cycle and increases the number of transmissions by 1. When the transmission time management unit 55 transmits in the next cycle, it increases the transmission cycle by 1 and returns the number of transmissions to the initial value. Thus, for the same output signal, the connection information for transmission and the number of transmissions of the output signal data packets generated by each of the plurality of transceivers 52A to G are different, but the transmission cycle is the same. In addition, the transmission time management unit 55 has a transmission time management function for managing the time interval when the same data packet is transmitted multiple times. In addition, the number of the plurality of transceivers 52A to G is configured according to the number of connections. The plurality of transceivers 52A to G, the redundant packet determination unit 54, and the transmission time management unit 55 can be assigned to different threads of the OS to operate in parallel. In addition, the configuration of the transmission time management unit 55 and the transmission and reception units 52A to 52G of the present embodiment corresponds to a first generation unit, and the transmission and reception units 52A to 52G correspond to a plurality of generation units.

[0100] Next, the configuration of the communication device 60 will be described in detail. The connection unit 61 of the communication device 60 requests the connection unit 51 of the server device 50 to send connection information corresponding to a plurality of IDs (see Figure 5 ) is issued. The connection unit 61 sequentially distributes the transmission connection information corresponding to the issued plurality of IDs to the transmission and reception units 62A to 62G. Then, each connection information storage unit 63A to 63G stores the transmission connection information respectively distributed to itself.

[0101] Each of the plurality of transceiver units 62A to 62G receives an output signal packet having transmission connection information assigned to itself via the communication unit 28 (see Figure 5 ), and outputs the output signal packet to the redundant packet judgment unit 64. The redundant packet judgment unit 64 judges whether a transmission signal having the same output signal has been sent. The redundant packet judgment unit 64, for example, refers to the communication connection information to judge whether the same transmission cycle is in the information of the combination of the transmission connection information as the receiving object, thereby judging whether a transmission signal having the same output signal has been sent. When the redundant packet judgment unit 64 is the first to send a transmission signal having the same output signal, the redundant packet judgment unit 64 sends the output signal to the output device 42 via the output unit 30. On the other hand, when the transmission signal having the same output signal is not sent for the first time, the redundant packet judgment unit 64 judges that it is a redundant input signal and performs processing not to transmit the input signal to the output device 42. In addition, the number of the plurality of transceiver units 62A to G is configured according to the number of connections. The plurality of transceiver units 62A to G, the redundant packet judgment unit 64, and the transmission time management unit 65 can be assigned to different threads of the OS to operate in parallel.

[0102] Each of the plurality of transceiver units 62A to 62G generates an input signal packet including the transmission connection information assigned to itself and the transmission cycle, the number of transmissions, and the input signal supplied from the transmission time management unit 65 (see Figure 3 ).

[0103] Whenever an input signal is supplied from the input device 41 via the signal input unit 29, the transmission time management unit 65 supplies a transmission cycle, a number of transmissions, and an input signal to each of the plurality of transceiver units 62A to 62G. That is, when the transmission management unit 65 continuously transmits the same input signal in the same cycle, it supplies the same value as the transmission cycle and increases the number of transmissions by 1. When the transmission management unit 65 transmits in the next cycle, it increases the transmission cycle by 1 and returns the number of transmissions to the initial value. Thus, for the same input signal, the input signal data packets generated by each of the plurality of transceiver units 62A to 62G (see Figure 3) are different in connection information and number of transmissions, but the transmission cycle is the same. In addition, the transmission time management unit 65 has a transmission time management function for managing the time intervals when the same data packet is transmitted multiple times. In addition, the transmission time management unit 65 and the transceiver units 62A to G of this embodiment correspond to the second generation unit, and the transceiver units 62A to G correspond to multiple generation units.

[0104] (effect)

[0105] Fig.10 This is a diagram showing an example of a communication sequence for initial connection in the second embodiment. It shows a processing example of the connection unit 61 and the transceiver units 62A to 62G of the communication device 60 and the connection unit 51 and the transceiver units 52A to 52G of the server device 50. Fig.10 The communication sequence in which the communication device 60 is connected to the server device 50 as a TCP client is shown, and the description of the sequence of ACK for TCP is omitted.

[0106] First, the connection unit 61 of the communication device 60 transmits a connection request to the connection unit 51 of the server device 50 (step S400). The connection unit 51 of the server device 50 that receives the connection request transmits a connection response including transmission connection information to the communication device 60 (step S402).

[0107] Next, the connection unit 61 of the communication device 60 performs connection termination processing (step S404), and notifies the transceiver unit 62A of the received transmission connection information (step S406). Next, the connection information storage unit 63A of the transceiver unit 62A stores the transmission connection information (step S408).

[0108] Next, the connection unit 51 of the server device 50 notifies the transmission connection information to the transmission and reception unit 52A (step S410). Next, the connection information storage unit 53A of the transmission and reception unit 52A stores the transmission connection information (step S412).

[0109] In order to make multiple connections, such connection processing is repeated according to the number of connections (steps S400 to S412). In this case, in the second connection processing, the transmission connection information is stored in the connection information storage unit 63B of the transceiver unit 62B (step S414), and is stored in the connection information storage unit 53B of the transceiver unit 52B (step S416). Similarly, in the third and subsequent connection processing, the transmission connection information is sequentially stored in different connection information storage units 63C to G and connection information storage units 53C to G.

[0110] Fig.11This figure shows an example of a communication sequence for sending an input signal from the communication device 60 to the server device 50. It shows a processing example of the transmission timing management unit 65 and the transceiver 62A~G of the communication device 60, the control operation unit 11 transceiver 52A~G of the server device 50, and the redundant packet determination unit 54.

[0111] The transmission time management unit 65 obtains an input signal from the input device 41 (step S500), and transmits the transmission cycle, the number of transmissions, and the input signal to the transceiver 62A (step S502). Then, the transmission management unit 25 waits for a certain period of time as a standby process (step S504).

[0112] Next, the transceiver 62A generates a transmission packet signal including its own transmission connection information, transmission cycle, number of transmissions, and input signal, and transmits the transmission packet signal to the server device 50 (step S506).

[0113] Next, the transceiver 52A among the transceivers 52A to G of the server device 50 receives the transmission data packet signal containing its own transmission connection information (step S508), and transmits the transmission data packet signal to the redundant data packet determination unit 54 (step S510). Next, the redundant data packet determination unit 54 determines whether the input signal is redundant (step S512). Since the input signal is sent for the first time, the redundant data packet determination unit 54 determines that it is not redundant, and transmits the input signal to the control operation unit 11 (step S514). The control operation unit 11 generates an output signal corresponding to the input signal (step S516).

[0114] Under the control of the transmission time management unit 65 during the IO cycle, the transceiver units 62A to 62G repeatedly perform such processing. In this case, since it is not the first transmission processing, the redundant data packet judgment unit 54 judges that it is a received redundant data packet after the second time, and does not transmit the input signal to the control operation unit 11 (step S518). In addition, after the transmission time management unit 65 repeats such processing until A to G, it performs a standby process until the next IO cycle starts (step S520). Then, the transmission time management unit 65 repeats the transmission processing until A to G from the acquisition of the input signal in each IO cycle.

[0115] Fig.12 This figure shows an example of a communication sequence for sending an output signal from the server device 50 to the communication device 60. It shows a processing example of the transceiver 62A to G and the redundant packet determination unit 64 of the communication device 60 and the control operation unit 11, the transceiver 52A to G and the transmission time management unit 55 of the server device 50.

[0116] The control operation unit 11 of the server device 50 generates an output signal corresponding to the input signal (step S516). The transmission time management unit 55 obtains the output signal from the control operation unit 11 (step S600), and transmits the transmission cycle, the number of transmissions, and the output signal to the transceiver unit 52A (step S602). Then, the transmission time management unit 55 waits for a certain period of time as a standby process (step S604).

[0117] Next, the transceiver 52A generates an output signal packet including its own transmission connection information, transmission cycle, number of transmissions, and output signal (see Figure 5 ) and sends the output signal data packet to the communication device 60 (step S606).

[0118] Next, the transceiver 62A among the transceivers 62A-G of the communication device 60 receives the output signal packet containing its own transmission connection information (step S608), and transmits the output signal packet to the redundant packet determination unit 64 (step S610). Next, the redundant packet determination unit 64 determines whether the output signal is redundant (step S612). Since the output signal is sent for the first time, the redundant packet determination unit 64 determines that it is not redundant, and transmits the output signal to the output device 42 via the signal output unit 30 (step S614).

[0119] Under the control of the transmission time management unit 55 for such processing during the control cycle, the transceiver units 52A to 52G repeatedly perform such processing. In this case, since it is not the first transmission processing, the redundant data packet judgment unit 64 judges that it is a received redundant data packet after the second time, and does not transmit the output signal to the output device 42 (step S616). In addition, after the transmission time management unit 55 repeatedly performs such processing until A to G, it performs a standby process until the next control cycle starts (step S618). Then, the transmission time management unit 55 repeatedly performs the transmission processing until A to G from the acquisition of the output signal in each control cycle.

[0120] (Effect)

[0121] In the control system 2 of the present embodiment, the transceivers 52A to G independently transmit input signals under the control of the transmission time management unit 55, and the transceivers 62A to G independently transmit output signals under the control of the transmission time management unit 65. Thus, in addition to the effects of the control system 1 of the present embodiment, the CPU of the multi-core server can be efficiently used by operating the plurality of transceivers 52A to G, 62A to G in parallel, and data packets can be transmitted at accurate time intervals.

[0122] Several embodiments have been described above, but these embodiments are disclosed as examples and are not intended to limit the scope of the invention. The novel devices, methods, and programs described in this specification may be implemented in various other ways. In addition, various omissions, substitutions, and changes may be made to the devices, methods, and programs described in this specification without departing from the scope of the invention.

Claims

1. A server device comprising: A communication unit, receiving a plurality of first data packets sequentially via a network, wherein the plurality of first data packets respectively include the same first signal for a plurality of different connection information; A determination unit, configured to determine whether the first signal contained in the first data packet has been received; and The control operation unit generates a second signal corresponding to the first signal based on the above determination if the first signal has not been received.

2. The server device according to claim 1, wherein: Also available: a connecting unit that provides any one of the plurality of different connection information via the network to the plurality of independent connection requests via the network, The determination unit determines whether the first signal has been received for the first data packet having any one of the plurality of different connection information.

3. The server device according to claim 1 or 2, wherein: Also available: a first generating unit generating a plurality of second data packets by respectively assigning any one of the plurality of different connection information to the second signal; The communication unit transmits the plurality of second data packets via the network.

4. The server device according to claim 3, wherein: The first generating unit may be capable of changing a transmission interval of the plurality of second data packets.

5. The server device according to claim 3, wherein: The first generating unit includes a plurality of generating units, and the plurality of generating units generate a second data packet corresponding to any one of a plurality of different connection information and assigning the corresponding connection information to the second signal. The plurality of generating units independently transmit the plurality of second data packets to the network via the communication unit.

6. The server device according to claim 3, wherein: The plurality of connection requests correspond to a plurality of independent transmission units or a plurality of independent communication devices.

7. The server device according to claim 2, wherein: The connection unit determines the number of issuances of the plurality of different connection information based on a combination of a transmission cycle, a transmission frequency, and a communication time.

8. The server device according to claim 3, wherein: The first generation unit dynamically changes the number of transmissions and the transmission interval of the plurality of second data packets based on a combination of the load, packet loss rate, and communication time of the network.

9. The server according to claim 3, wherein: The first generating unit repeatedly and sequentially adds the plurality of different connection information according to the order of generating the second data packet.

10. The server device according to claim 3, wherein: The first generating unit adds connection information not used by the second data packet being transmitted among the plurality of different connection information to the second data packet to be generated, based on the transmission flag in the plurality of second data packets.

11. The server device according to claim 3, wherein: The first generating unit includes at least one of connection information corresponding to the identification number of the communication device, a transmission cycle indicating the transmission cycle number, and a transmission count indicating how many times transmission has been performed in the same cycle in the second data packet.

12. A communication device comprising: A second connection unit requests a plurality of connection requests to a communication target device via a network; a second generating unit generating a plurality of first data packets by assigning any one of a plurality of connection information corresponding to the plurality of connection requests to a first signal; and The second communication unit sequentially transmits the plurality of first data packets via the network.

13. A control system comprising a server device and a communication device, wherein: The server device has: A connection unit that provides any one of the plurality of different connection information via the network in response to a plurality of independent connection requests via the network; A communication unit, receiving a plurality of first data packets in sequence via the network, wherein the plurality of first data packets respectively include the same first signal for the plurality of different connection information; A determination unit, configured to determine whether the first signal included in the plurality of first data packets has been received; and The control operation unit generates a second signal corresponding to the first signal based on the above determination, if the signal has not been received. The communication device has: A second connection unit, requesting the server device via the network the plurality of independent connection requests respectively corresponding to the plurality of independent sending units; A second generating unit generates the plurality of first data packets obtained by respectively assigning any one of the plurality of different connection information obtained via the network to the first signal; as well as The second communication unit sequentially transmits the plurality of first data packets to the server device via the network.

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