Industrial wireless communication system

Abstract

An industrial wireless communication system (10) has a base wireless device (14) and a remote wireless device (16). The base wireless device has a synchronization connection transmission section (25) that transmits a synchronization connection signal for synchronization connection to the remote wireless device by broadcasting only at an individual synchronization connection period (Tsc) that is an integral multiple of a hop period. The synchronization connection transmission section transmits the synchronization connection signal at a plurality of synchronization communication frequencies within one hop period by sequentially switching the synchronization communication frequencies. The remote wireless device has a synchronization connection reception section (36) that performs a reception standby process for the synchronization connection signal at a plurality of synchronization communication frequencies by sequentially switching the synchronization communication frequencies at a switching period (Tcg) that is longer than the hop period and shorter than twice the hop period.

Description

Technical Field

[0001] This invention relates to an industrial wireless communication system. Background Technology

[0002] Japanese Patent No. 5497730 discloses a FA system that connects a PC and a controller via a field network, with the controller functioning as a host and transmitting and receiving wireless information between the host and the slave unit.

[0003] However, previous systems were not always able to establish a synchronization connection quickly. Summary of the Invention

[0004] The purpose of this invention is to provide an industrial wireless communication system capable of rapidly establishing synchronous connections.

[0005] An industrial wireless communication system according to one aspect of the present invention includes: a computer for monitoring and controlling industrial equipment; a base wireless device connected to the computer via a fieldbus; and a plurality of remote wireless devices disposed in each of a plurality of machines constituting the industrial equipment, the plurality of remote wireless devices communicating wirelessly with the base wireless device, the synchronously connected base wireless device and the remote wireless devices transmitting and receiving data by switching transition frequencies at a predetermined transition period, wherein the base wireless device has a synchronous connection transmitting unit that performs transmission processing by broadcasting when not synchronously connected to the remote wireless devices. The transmission process transmits a synchronization connection signal for synchronizing with the remote wireless device only in a single synchronization connection period that is an integer multiple of the transition period. The synchronization connection transmitting unit transmits the synchronization connection signal in multiple synchronization communication frequencies within one transition period by sequentially switching the synchronization communication frequencies used for synchronization. The remote wireless device has a synchronization connection receiving unit that, in the absence of a synchronization connection with the base wireless device, sequentially switches the synchronization communication frequencies in a switching period that is longer than the transition period and shorter than twice the transition period, thereby performing the reception processing of the synchronization connection signal in multiple synchronization communication frequencies.

[0006] According to the present invention, an industrial wireless communication system capable of rapid synchronous connection can be provided. Attached Figure Description

[0007] Figure 1 This is a diagram illustrating the structure of an industrial wireless communication system according to one implementation.

[0008] Figure 2This is a block diagram illustrating one implementation of an industrial wireless communication system.

[0009] Figure 3 It is a diagram that conceptually represents the transmission and reception of synchronous connection signals.

[0010] Figure 4 This is a diagram representing an example of a time-based graph.

[0011] Figure 5A and Figure 5B This is a timeline diagram illustrating an example of the switching sequence of communication frequencies used for synchronization.

[0012] Figure 6 This is a diagram illustrating an example of the operation of an industrial wireless communication system according to one implementation.

[0013] Figure 7 This is a diagram illustrating an example of the operation of an industrial wireless communication system according to one implementation.

[0014] Figure 8 This is a diagram illustrating an example of the operation of an industrial wireless communication system according to one implementation.

[0015] Figure 9 This is a diagram illustrating an example of the operation of an industrial wireless communication system according to one implementation.

[0016] Figure 10 This is a time graph representing an example of an interrupt cycle Tir. Detailed Implementation

[0017] Hereinafter, suitable embodiments of the industrial wireless communication system of the present invention will be described in detail with reference to the accompanying drawings.

[0018] [One implementation method]

[0019] For one implementation of an industrial wireless communication system Figures 1-9 Please provide an explanation. Figure 1 This is a diagram showing the structure of the industrial wireless communication system according to this embodiment. Figure 2 This is a block diagram illustrating an industrial wireless communication system according to this embodiment.

[0020] like Figure 1 As shown, the industrial wireless communication system 10 of this embodiment includes a computer 12, base wireless devices 14, and remote wireless devices 16. The industrial wireless communication system 10 includes multiple base wireless devices 14. A computer 12 can connect to multiple base wireless devices 14 via a fieldbus 17. A base wireless device 14 can be synchronously connected to multiple remote wireless devices 16. By synchronously connecting multiple remote wireless devices 16 to each base wireless device 14, multiple networks 43 can be formed.

[0021] Computer 12 is capable of monitoring and controlling industrial equipment. Such computer 12 can be, for example, constructed from a PLC (Programmable Logic Controller), but is not limited to this. Figure 2 As shown, the computer 12 includes, for example, an arithmetic unit (processing unit) 18 and a storage unit 19.

[0022] The arithmetic unit 18 can be configured as a processor, such as a CPU (Central Processing Unit). That is, the arithmetic unit 18 can be configured as a processing circuitry. A control unit 20 is included in the arithmetic unit 18. The arithmetic unit 18 may also include components other than the control unit 20, but for simplicity, these components are omitted here. The control unit 20 manages the overall control of the computer 12. The control unit 20 can perform monitoring and control of industrial equipment. The control unit 20 can be implemented by the arithmetic unit 18 executing a program stored in the storage unit 19. Furthermore, at least a portion of the control unit 20 can be implemented using integrated circuits such as ASICs (Application Specific Integrated Circuits) or FPGAs (Field-Programmable Gate Arrays). Moreover, at least a portion of the control unit 20 can also be configured as electronic circuitry including discrete components.

[0023] The storage unit 19 can be composed of volatile memory (not shown) and non-volatile memory (not shown). Examples of volatile memory include listable RAM (Random Access Memory). Examples of non-volatile memory include listable ROM (Read Only Memory) and flash memory. Data can be stored in, for example, volatile memory. Programs, diagrams, mappings, etc., can be stored in, for example, non-volatile memory. At least a portion of the storage unit 19 can also be included in processors, integrated circuits, etc., as described above.

[0024] Computer 12 has an input / output interface 21 for implementing fieldbus connections. Computer 12 can communicate with base wireless device 14 via fieldbus 17.

[0025] The base wireless device 14, i.e., the wireless device host, includes, for example, an arithmetic unit (processing unit) 22 and a storage unit 23.

[0026] The arithmetic unit 22 can be configured as a processor (processing circuit) such as a CPU. The arithmetic unit 22 includes a control unit 24, a synchronous connection transmission unit 25, a transceiver processing unit 26, a connection status determination unit 27, and a forced disconnection signal transmission unit 28. The arithmetic unit 22 may also include components other than these, but for simplicity, these components are omitted here. The control unit 24, synchronous connection transmission unit 25, transceiver processing unit 26, connection status determination unit 27, and forced disconnection signal transmission unit 28 can be implemented by the arithmetic unit 22 executing a program stored in the storage unit 23. Furthermore, at least a portion of the control unit 24, synchronous connection transmission unit 25, transceiver processing unit 26, connection status determination unit 27, and forced disconnection signal transmission unit 28 can be implemented using integrated circuits such as ASICs and FPGAs. Moreover, at least a portion of the control unit 24, synchronous connection transmission unit 25, transceiver processing unit 26, connection status determination unit 27, and forced disconnection signal transmission unit 28 can also be configured using electronic circuits including discrete components.

[0027] The storage unit 23 can be composed of volatile memory (not shown) and non-volatile memory (not shown). Examples of volatile memory include listable RAM. Examples of non-volatile memory include listable ROM and flash memory. Data can be stored in, for example, volatile memory. Programs, diagrams, mappings, etc., can be stored in, for example, non-volatile memory. At least a portion of the storage unit 23 can also be included in processors, integrated circuits, etc., as described above.

[0028] The base wireless device 14 has an input / output interface 29 for implementing fieldbus connection. The base wireless device 14 can be connected to the computer 12 via the fieldbus 17 as described above.

[0029] The base wireless device 14 includes a communication unit 30 for wireless communication. The base wireless device 14 can use the communication unit 30 to communicate wirelessly with the remote wireless device 16.

[0030] The remote wireless device 16, i.e., the wireless device slave unit, can be used in multiple machines 44 (refer to) that constitute industrial equipment. Figure 1 Each of these components is included. Such a machine 44 can include, but is not limited to, sensors, valves, etc. The remote wireless device 16, for example, includes an arithmetic unit (processing unit) 32 and a storage unit 34.

[0031] The arithmetic unit 32 can be configured as a processor (processing circuit) such as a CPU. The arithmetic unit 32 includes a control unit 35, a synchronization connection receiving unit 36, a transceiver processing unit 37, a reception completion notification sending unit 38, a forced disconnection signal sending unit 39, a diagnostic information sending unit 40, and a power monitoring unit 41. While the arithmetic unit 32 can also include components other than these, for the sake of simplicity, these components are omitted here. The control unit 35, synchronization connection receiving unit 36, transceiver processing unit 37, and reception completion notification sending unit 38 can be implemented by the arithmetic unit 32 executing a program stored in the storage unit 34. Furthermore, the forced disconnection signal sending unit 39, the diagnostic information sending unit 40, and the power monitoring unit 41 can be implemented by the arithmetic unit 32 executing a program stored in the storage unit 34. Furthermore, at least a portion of the control unit 35, synchronous connection receiving unit 36, transceiver processing unit 37, reception completion notification sending unit 38, forced disconnection signal sending unit 39, diagnostic information sending unit 40, and power monitoring unit 41 can also be implemented using integrated circuits such as ASICs and FPGAs. Moreover, at least a portion of the control unit 35, synchronous connection receiving unit 36, transceiver processing unit 37, reception completion notification sending unit 38, forced disconnection signal sending unit 39, diagnostic information sending unit 40, and power monitoring unit 41 can also be constructed using electronic circuits including discrete components.

[0032] The storage unit 34 can be constructed using volatile memory (not shown) and non-volatile memory (not shown). Examples of volatile memory include listable RAM. Examples of non-volatile memory include listable ROM and flash memory. Data can be stored in, for example, volatile memory. Programs, diagrams, mappings, etc., can be stored in, for example, non-volatile memory. At least a portion of the storage unit 34 can also be included in processors, integrated circuits, etc., as described above.

[0033] The remote wireless device 16 includes a communication unit 42 for wireless communication. The remote wireless device 16 can use the communication unit 42 to communicate wirelessly with the base wireless device 14.

[0034] Frequency-hopping communication is possible between the base wireless device 14 and the remote wireless device 16. That is, data transmission and reception can be performed by switching the hopping frequency at a predetermined hopping period Tfh between the base wireless device 14 and the remote wireless device 16. The switching of the hopping frequency can be performed according to a predetermined hopping pattern. Since the base wireless device 14 and the remote wireless device 16, which are synchronously connected, use the same hopping pattern, communication can be performed between the base wireless device 14 and the remote wireless device 16 while switching communication frequencies. The communication frequency is the carrier frequency. The processing of frequency-hopping communication is handled by the transceiver processing unit 26 provided in the base wireless device 14 and the transceiver processing unit 37 provided in the remote wireless device 16. In other words, the processing of data transmission and reception under frequency-hopping mode is handled by the transceiver processing unit 26 provided in the base wireless device 14 and the transceiver processing unit 37 provided in the remote wireless device 16.

[0035] In frequency-hopping wireless communication, for example, the 2.4GHz band can be used. When the minimum frequency is 2403MHz, the maximum frequency is 2481MHz, and the occupied frequency bandwidth of each channel is 1MHz, the number of channels is 79.

[0036] The base wireless device 14 and the remote wireless device 16 can be pre-paired. Even if the base wireless device 14 and the remote wireless device 16 are paired, they cannot communicate via frequency hopping if they are not synchronized. Therefore, before communicating via frequency hopping, the base wireless device 14 and the remote wireless device 16 exchange synchronization connection signals for synchronization.

[0037] The synchronization connection signal may include identification information of the base wireless device 14, identification information of the remote wireless device 16 that is the destination of the synchronization connection signal, and time information. The identification information of the base wireless device 14 may be, for example, the product ID of the base wireless device 14, but is not limited thereto. The identification information of the remote wireless device 16 may be, for example, the product ID of the remote wireless device 16, but is not limited thereto.

[0038] The transmission and reception of synchronization connection signals for establishing a synchronization connection can occur, for example, when an unestablished network 43 is established, between all the remote wireless devices 16 constituting the network 43 and the base wireless device 14. In the operation of network 43, when a remote wireless device 16 becomes disconnected for some reason, the transmission and reception of synchronization connection signals between that remote wireless device 16 and the base wireless device 14 can also occur. A disconnected state refers to a state where the remote wireless device 16 and the base wireless device 14 are not synchronously connected.

[0039] As described above, the base wireless device 14 includes a synchronization connection transmitting unit 25. When at least one of the plurality of remote wireless devices 16 constituting the network 43 is not synchronously connected to the base wireless device 14, the synchronization connection transmitting unit 25 of the base wireless device 14 performs the following process: That is, in this case, the synchronization connection transmitting unit 25 performs a transmission process of a synchronization connection signal, which is used to establish a synchronization connection with the remote wireless devices 16 that are not synchronously connected. This transmission process can be performed by broadcasting to the plurality of remote wireless devices 16 constituting the network 43. This transmission process is performed only during a single synchronization connection period Tsc that is an integer multiple of the transition period Tfh. That is, this transmission process is performed only during a predetermined synchronization connection period Tsc. In other words, this transmission process can be performed during a predetermined interruption period. The synchronization connection period Tsc can be set to, for example, 250 ms, but is not limited to this.

[0040] Furthermore, the base wireless device 14 and the remote wireless device 16, which are synchronously connected, can also transmit and receive signals for maintaining the synchronization connection. The transmission and reception of these signals can be performed via wireless communication in a frequency-hopping manner. The transmission and reception of these signals can, for example, be performed at a period of 100 ms, but is not limited to this. The signals for maintaining the synchronization connection can include time information. Therefore, by transmitting and receiving these signals, the discrepancy between the time information of the base wireless device 14 and the time information of the remote wireless device 16 can be eliminated.

[0041] The reason why the synchronization connection signal is sent only during the synchronization connection period Tsc is that outside of the synchronization connection period Tsc, data transmission and reception in frequency hopping mode occurs between the already synchronized remote wireless device 16 and the base wireless device 14. That is, in order to prevent obstacles to the transmission and reception of data in frequency hopping mode, the synchronization connection signal used for synchronization connection is sent only during the predetermined synchronization connection period Tsc.

[0042] The synchronization connection transmitting unit 25 transmits a synchronization connection signal at multiple synchronization communication frequencies within one transition period Tfh by sequentially switching the synchronization communication frequencies used for synchronization. The reason for using multiple synchronization communication frequencies when transmitting the synchronization connection signal is as follows: Even if the transmission and reception of the synchronization connection signal at a certain synchronization communication frequency is hindered by factors such as radio wave interference, sometimes it is possible to transmit and receive the synchronization connection signal as long as the synchronization communication frequency is different from that frequency. For this reason, multiple synchronization communication frequencies are used when transmitting the synchronization connection signal.

[0043] As described above, the remote wireless device 16 includes a synchronization connection receiving unit 36. When there is no synchronization connection between the remote wireless device 16 and the base wireless device 14, the synchronization connection receiving unit 36 ​​performs reception processing of the synchronization connection signal. This reception processing is performed using multiple synchronization communication frequencies by sequentially switching the synchronization communication frequencies at a predetermined switching period Tcg. The multiple synchronization communication frequencies used when transmitting the synchronization connection signal are the same as the multiple synchronization communication frequencies used during reception processing. For example, if the multiple synchronization communication frequencies used by the base wireless device 14 when transmitting the synchronization connection signal are f1, f2, and f3, the multiple synchronization communication frequencies used by the remote wireless device 16 during reception processing are also set to f1, f2, and f3.

[0044] When the synchronization communication frequency set by the remote wireless device 16 during the receiving process is inconsistent with the synchronization communication frequency used by the base wireless device 14 when sending the synchronization connection signal, the synchronization connection signal cannot be received by the remote wireless device 16. When the synchronization communication frequency set by the remote wireless device 16 during the receiving process is consistent with the synchronization communication frequency used by the base wireless device 14 when sending the synchronization connection signal, the synchronization connection signal can be received by the remote wireless device 16.

[0045] The switching period Tcg is set to be longer than the transition period Tfh, but shorter than twice the transition period Tfh. The reason for setting the switching period Tcg in this way is as follows: If the switching period Tcg is set in this way, the relative time relationship between the timing of the transmission processing of the synchronization connection signal and the timing of the switching of the synchronization communication frequency for the receiving processing gradually changes over time. This ensures that the synchronization communication frequency used in the transmission processing quickly matches the synchronization communication frequency used in the receiving processing. Based on this reasoning, the switching period Tcg is set to be longer than the transition period Tfh, but shorter than twice the transition period Tfh.

[0046] The transition period Tfh can be, for example, 5 ms or less, but is not limited to this. However, from the viewpoint of achieving high-speed communication in the transition mode, it is preferable that the transition period Tfh is 5 ms or less. Here, we will take the case where the transition period Tfh is 5 ms as an example. When the transition period Tfh is 5 ms, the switching period Tcg can be, for example, 6 ms, but is not limited to this.

[0047] When the transition period Tfh is 5 ms, the number of synchronization communication frequencies used in the transmission and reception processes can be, for example, 3, but is not limited to this. The number of synchronization communication frequencies used in the transmission and reception processes can be, for example, 2 or 4. Here, we will explain the case where the number of synchronization communication frequencies used in the transmission and reception processes is 3.

[0048] The control unit 35 of the remote wireless device 16 performs the following processing when it receives a synchronization connection signal via the transceiver processing unit 37: In this case, the control unit 35 determines whether the synchronization connection signal is a synchronization connection signal sent from the base wireless device 14 to the remote wireless device 16 based on information contained in the synchronization connection signal. Specifically, the control unit 35 determines whether the synchronization connection signal is a synchronization connection signal sent from the base wireless device 14 to the remote wireless device 16 based on the identification information of the base wireless device 14 and the identification information of the remote wireless device 16.

[0049] Figure 3 It is a diagram that conceptually represents the transmission and reception of synchronous connection signals. Figure 3 The up and down directions in the text indicate the elapsed time since a certain point in time.

[0050] As described above, the base wireless device 14 sends a synchronization connection signal with a synchronization connection period Tsc. Figure 3 This represents an example where the synchronization connection period Tsc is 250msec.

[0051] As described above, the transmission processing of the synchronization connection signal is performed within the transition period Tfh. Figure 3 This represents an example where the transition period Tfh is 5 msec.

[0052] As described above, the remote wireless device 16 switches the synchronization communication frequency to be received and processed with a predetermined switching period Tcg. Figure 3 This represents an example where the switching period Tcg is 6 msec.

[0053] exist Figure 3In the example shown, within one transition period Tfh, the base wireless device 14 transmits a synchronization connection signal at a synchronization communication frequency of f1, a synchronization connection signal at a synchronization communication frequency of f2, and a synchronization connection signal at a synchronization communication frequency of f3. Furthermore, in Figure 3 In the example shown, during the transition period Tfh, which has an elapsed time of 0 ms, the synchronization connection signal is transmitted from the base wireless device 14. Furthermore, in Figure 3 In the example shown, during the transition period Tfh, which lasts for 250 milliseconds, the synchronization connection signal is transmitted from the base wireless device 14. Furthermore, in Figure 3 In the example shown, the synchronization connection signal is transmitted from the base wireless device 14 during the transition period Tfh, which lasts for 500 ms. In the case of a remote wireless device 16 that is not synchronized, the same process of transmitting the synchronization connection signal from the base wireless device 14 can also be performed thereafter, for example, every 250 ms, but this is omitted here.

[0054] exist Figure 3 In the example shown, the timing of the switching of the synchronization communication frequency during the receiving process deviates by 1 msec from each of the multiple remote wireless devices 16A to 16P. When describing the remote wireless devices generally, the symbol 16 is used; when describing individual remote wireless devices 16, the symbols 16A to 16P are used. Since the remote wireless devices 16 do not synchronize with each other, the actual timing of the switching of the synchronization communication frequency during the receiving process does not necessarily have to deviate by 1 msec from each of the multiple remote wireless devices 16. Here, for ease of explanation, the timing of the switching of the synchronization communication frequency during the receiving process is represented by a deviation of 1 msec from each of the multiple remote wireless devices 16A to 16P.

[0055] exist Figure 3 In the example shown, when the elapsed time is 0 msec, 6 msec, 12 msec, ..., the synchronization communication frequency in the receiving process is switched via the remote wireless device 16A. Figure 3 In the example shown, when the elapsed time is greater than 0 ms but less than 6 ms, the synchronization communication frequency in the receiving process is set to f1 by the remote wireless device 16A. Furthermore, in Figure 3 In the example shown, when the elapsed time is more than 6 ms but less than 12 ms, the synchronization communication frequency in the receiving process is set to f2 by the remote wireless device 16A. Furthermore, in Figure 3In the example shown, when the elapsed time is more than 12 ms but less than 18 ms, the synchronization communication frequency for receiving and processing is set to f3 by the remote wireless device 16A. The remote wireless device 16A continues to switch the synchronization communication frequency for receiving and processing in the same order as above, f1, f2, f3, until a synchronization connection is established with the base wireless device 14.

[0056] exist Figure 3 In the example shown, the timing of the switching of the synchronization communication frequency in the receiving process within the remote wireless device 16B is delayed by 1 msec relative to the timing of the switching of the synchronization communication frequency in the receiving process within the remote wireless device 16A. That is, in Figure 3 In the example shown, when the elapsed time is 1 msec, 7 msec, 13 msec, ..., the synchronization communication frequency to be received is switched by the remote wireless device 16B in the order of f1, f2, f3. The remote wireless device 16B also continues to switch the synchronization communication frequency to be received in the same order of f1, f2, f3 as the remote wireless device 16A, until a synchronization connection is established with the base wireless device 14.

[0057] As mentioned above, in Figure 3 In the example shown, the timing of switching the synchronization communication frequency during the receiving process varies by 1 msec among the multiple remote wireless devices 16A to 16P. Similarly, remote wireless devices 16C to 16P continue to switch the synchronization communication frequency during the receiving process in the same order as remote wireless devices 16A and 16B, according to f1, f2, and f3, until a synchronization connection is established with the base wireless device 14.

[0058] In the case where the address of the synchronization connection signal sent from the base wireless device 14 during the transition period Tfh, which has an elapsed time of 0 msec, is the address of the remote wireless device 16A, Figure 3 In the example shown, it becomes as follows. That is, in Figure 3 In the example shown, when 0 ms have elapsed, the base wireless device 14 transmits a synchronization connection signal at the synchronization communication frequency f1. When 0 ms have elapsed, the synchronization communication frequency to be processed is set to f1 in the remote wireless device 16A. Therefore, the synchronization connection signal transmitted from the base wireless device 14 at the synchronization communication frequency f1 when 0 ms have elapsed is received in the remote wireless device 16A. Figure 3In the example shown, after 2 ms, the base wireless device 14 transmits a synchronization connection signal at the synchronization communication frequency f2. After 2 ms, the synchronization communication frequency being processed in the remote wireless device 16A is set to f1. Therefore, the synchronization connection signal transmitted from the base wireless device 14 at the synchronization communication frequency f2 after 2 ms is not received in the remote wireless device 16A. Figure 3 In the example shown, after 4 ms, the base wireless device 14 transmits a synchronization connection signal at the synchronization communication frequency f3. After 4 ms, the synchronization communication frequency to be processed is set to f1 in the remote wireless device 16A. Therefore, the synchronization connection signal transmitted from the base wireless device 14 at the synchronization communication frequency f3 after 4 ms is not received in the remote wireless device 16A.

[0059] In the case where the address of the synchronization connection signal transmitted from the base wireless device 14 during the transition period Tfh, which lasts for 250 msec, is the address of the remote wireless device 16K, then... Figure 3 In the example shown, it becomes as follows. That is, in Figure 3 In the example shown, after 250 ms, the base wireless device 14 transmits a synchronization connection signal at the synchronization communication frequency f1. After 250 ms, the synchronization communication frequency being processed in the remote wireless device 16K is set to f2. Therefore, the synchronization connection signal transmitted from the base wireless device 14 at the synchronization communication frequency f1 after 250 ms is not received by the remote wireless device 16K. Figure 3 In the example shown, after 252 ms, the base wireless device 14 transmits a synchronization connection signal at the synchronization communication frequency f2. After 252 ms, the synchronization communication frequency to be processed is set to f2 in the remote wireless device 16K. Therefore, the synchronization connection signal transmitted from the base wireless device 14 at the synchronization communication frequency f2 after 252 ms is received in the remote wireless device 16K. Figure 3 In the example shown, after 254 ms, the base wireless device 14 transmits a synchronization connection signal at the synchronization communication frequency f3. After 254 ms, the synchronization communication frequency to be processed is set to f2 in the remote wireless device 16K. Therefore, the synchronization connection signal transmitted from the base wireless device 14 at the synchronization communication frequency f3 after 254 ms is not received in the remote wireless device 16K.

[0060] In the case where the address of the synchronization connection signal transmitted from the base wireless device 14 during the transition period Tfh, which lasts for 500 ms, is the address of the remote wireless device 16D, Figure 3 In the example shown, it becomes as follows. That is, in Figure 3 In the example shown, after 500 ms, the base wireless device 14 transmits a synchronization connection signal at the synchronization communication frequency f1. After 500 ms, the synchronization communication frequency to be processed in the remote wireless device 16D is set to f2. Therefore, the synchronization connection signal transmitted from the base wireless device 14 at the synchronization communication frequency f1 after 500 ms is not received in the remote wireless device 16D. Figure 3 In the example shown, after 502 ms, the base wireless device 14 transmits a synchronization connection signal at the synchronization communication frequency f2. After 502 ms, the synchronization communication frequency to be processed is set to f3 in the remote wireless device 16D. Therefore, the synchronization connection signal transmitted from the base wireless device 14 at the synchronization communication frequency f2 after 502 ms is not received in the remote wireless device 16D. Figure 3 In the example shown, after 504 ms, the base wireless device 14 transmits a synchronization connection signal at the synchronization communication frequency f3. After 504 ms, the synchronization communication frequency to be processed is set to f3 in the remote wireless device 16D. Therefore, the synchronization connection signal transmitted from the base wireless device 14 at the synchronization communication frequency f3 after 504 ms is received in the remote wireless device 16D.

[0061] As described above, the remote wireless device 16 includes a reception completion notification sending unit 38. When a synchronization connection signal is received via the synchronization connection receiving unit 36, the reception completion notification sending unit 38 can send a reception completion notification Ack to the base wireless device 14 at the next hopping period Tfh after the hopping period Tfh in which the synchronization connection signal was received. That is, when the control unit 35 determines that the signal is a synchronization connection signal destined for the remote wireless device 16, the reception completion notification sending unit 38 performs the following processing: In this case, the reception completion notification sending unit 38 sends a reception completion notification Ack to the base wireless device 14 at the next hopping period Tfh after the hopping period Tfh in which the synchronization connection signal was received. Furthermore, this reception completion notification Ack can be performed during data transmission and reception in a frequency hopping mode. By receiving this reception completion notification Ack, the synchronization connection between the base wireless device 14 and the remote wireless device 16 is completed.

[0062] Figure 4 This is a diagram representing an example of a timeline. In Figure 4 The signal represents the synchronization connection signal Tx sent from the base wireless device 14, and the reply of the reception completion notification Ack received from the remote wireless device 16, which is the address of the synchronization connection signal Tx.

[0063] like Figure 4 As shown, in the transition period Tfh(1), the synchronization communication frequency is switched in the order of f1, f2, f3 to send the synchronization connection signal. When the transition period is generally described, the symbol Tfh is used. When the transition periods are described individually, the symbols Tfh(1), Tfh(2), ..., Tfh(n) are used.

[0064] In the remote wireless device 16 that becomes the address of the synchronization connection signal, when the synchronization connection signal is received, a reply of reception completion notification Ack is received from the remote wireless device 16 in the next transition period Tfh(2) after the transition period Tfh(1).

[0065] As described above, in wireless communication using a frequency-hopping method, for example, a 2.4 GHz band, the number of channels is, for example, 79. Since the number of channels, i.e., the number of synchronization communication frequencies, is limited to 79, in an industrial wireless communication system 10 equipped with multiple base wireless devices 14, the following situation can occur: the combination of multiple synchronization communication frequencies used when transmitting synchronization connection signals can be consistent between one base wireless device 14 and another. When the multiple synchronization communication frequencies used in the transmission process of transmitting synchronization connection signals are consistent between one base wireless device 14 and another, the possibility of the transmission of synchronization connection signals being hindered by radio wave interference increases. In such cases, by making the switching order of the multiple synchronization communication frequencies different among these base wireless devices 14, the situation where the transmission of synchronization connection signals is hindered by radio wave interference can be suppressed.

[0066] Figure 5A and Figure 5B This is a timeline diagram illustrating an example of the switching sequence of communication frequencies used for synchronization. Figure 5A Examples illustrating the context of this implementation. That is, in Figure 5A The text describes an example where the switching order of multiple synchronous communication frequencies differs from each other. Figure 5B The example in the text represents a comparative instance. That is, in... Figure 5B This represents an example where the switching order of multiple synchronization communication frequencies is set to be the same for each other. Figure 5A and Figure 5BIn this context, we have an example where the synchronization connection period Tsc1 in one base radio device 14 overlaps with the synchronization connection period Tsc2 in another base radio device 14. Figure 5A and Figure 5B In the example shown, the combination of multiple synchronization communication frequencies used when sending the synchronization connection signal is set to f1, f2, and f3 in both one base wireless device 14 and the other base wireless device 14. Figure 5A and Figure 5B Tx1 in the diagram represents a synchronization connection signal sent from a base wireless device 14. Figure 5A and Figure 5B Tx2 in the text represents a synchronization connection signal sent from another base wireless device 14.

[0067] like Figure 5B As shown, in a comparative example, one base radio device 14 switches the synchronization communication frequency for transmitting the synchronization connection signal in the order of f1, f2, f3. Another base radio device 14 also switches the synchronization communication frequency for transmitting the synchronization connection signal in the order of f1, f2, f3. When the synchronization communication frequency is switched in this order, if the synchronization connection period Tsc1 in one base radio device 14 coincides with the synchronization connection period Tsc2 in another base radio device 14, the following occurs: When one base radio device 14 transmits the synchronization connection signal at synchronization communication frequency f1, the other base radio device 14 also transmits the synchronization connection signal at synchronization communication frequency f1. Since the synchronization communication frequency for transmitting the synchronization connection signal is the same, radio wave interference occurs when the synchronization connection signal is transmitted at synchronization communication frequency f1. Furthermore, when one base radio device 14 transmits the synchronization connection signal at synchronization communication frequency f2, the other base radio device 14 also transmits the synchronization connection signal at synchronization communication frequency f2. Because the synchronization communication frequency is the same when transmitting the synchronization connection signal, radio wave interference will also occur when transmitting the synchronization connection signal at the synchronization communication frequency f2. Furthermore, when one base wireless device 14 transmits the synchronization connection signal at the synchronization communication frequency f3, and another base wireless device 14 also transmits the synchronization connection signal at the synchronization communication frequency f3, radio wave interference will also occur when transmitting the synchronization connection signal at the synchronization communication frequency f3.

[0068] In contrast, in this embodiment, such as Figure 5A As shown, a base wireless device 14 switches the synchronization communication frequency used when transmitting synchronization connection signals, for example, in the order of f1, f2, and f3. Furthermore, in this embodiment, Figure 5AAs shown, the other base wireless device 14 switches the synchronization communication frequency for transmitting the synchronization connection signal, for example, in the order of f3, f2, f1. When the synchronization communication frequency is switched in this order, even if the synchronization connection period Tsc1 in one base wireless device 14 overlaps with the synchronization connection period Tsc2 in another base wireless device 14, the following applies: When one base wireless device 14 transmits the synchronization connection signal at synchronization communication frequency f1, another base wireless device 14 transmits the synchronization connection signal at synchronization communication frequency f3. Since the synchronization communication frequencies for transmitting the synchronization connection signal are different, no radio wave interference occurs between them. Furthermore, when one base wireless device 14 transmits the synchronization connection signal at synchronization communication frequency f3, another base wireless device 14 transmits the synchronization connection signal at synchronization communication frequency f1. Since the synchronization communication frequencies for transmitting the synchronization connection signal are different, no radio wave interference occurs between them. Radio wave interference only occurs when one base wireless device 14 and another base wireless device 14 transmit the synchronization connection signal at synchronization communication frequency f2.

[0069] Thus, in this embodiment, when the combination of multiple synchronization communication frequencies used when transmitting the synchronization connection signal is consistent among the multiple base radio devices 14, the switching order of the multiple synchronization communication frequencies is made different among these base radio devices 14. In this way, it is possible to suppress the situation where the transmission of the synchronization connection signal is hindered by radio wave interference.

[0070] Sometimes the power supply to the synchronously connected remote wireless device 16 may be cut off. For example, it can be determined whether the remote wireless device 16 is in a disconnected state as follows: When the base wireless device 14 and the remote wireless device 16 are synchronously connected, for example, the remote wireless device 16 sends data to the base wireless device 14 every 2 seconds to indicate that the remote wireless device 16 is in a connected state. When the remote wireless device 16 is in a disconnected state, it does not send data to the base wireless device 14 to indicate that the remote wireless device 16 is in a connected state. In this embodiment, regardless of whether the elapsed time from the moment such data reception begins reaches a time threshold TTH, if no new data is received from the remote wireless device 16, the following processing is performed: That is, the connection state determination unit 27 determines that the remote wireless device 16 is in a disconnected state. The time threshold TTH can be, for example, 5 seconds, but is not limited to this. Thus, in this embodiment, the remote wireless device 16 is determined to be in a disconnected state based on the time during which no data is received from the synchronously connected remote wireless device 16 reaches a predetermined time threshold TTH. Therefore, in this embodiment, in the event of a power outage or other condition affecting the remote wireless device 16, it can be accurately determined that the remote wireless device 16 is in a disconnected state. Furthermore, diagnostic information, described later, can be sent along with data indicating that the remote wireless device 16 is in a connected state. This diagnostic information serves as information indicating whether a malfunction has occurred in the machine 44 equipped with the remote wireless device 16.

[0071] Figure 6 This is a diagram illustrating an example of the operation of the industrial wireless communication system according to this embodiment. Figure 6 This example illustrates a situation where the remote wireless device 16 is determined to be in a disconnected state based on the time threshold TTH during which no data is received from the remote wireless device 16.

[0072] In step S1, the connection status determination unit 27 determines whether the base wireless device 14 has received data from the remote wireless device 16. If the base wireless device 14 has received data from the remote wireless device 16 (YES in step S1), Figure 6 The process shown ends. If the base wireless device 14 does not receive data from the remote wireless device 16 (NO in step S1), proceed to step S2.

[0073] In step S2, the connection status determination unit 27 determines whether the elapsed time since the moment data from the remote wireless device 16 was received has reached the time threshold TTH. If the elapsed time since the moment data from the remote wireless device 16 was received has reached the time threshold TTH (YES in step S2), the process proceeds to step S3. If the elapsed time since the moment data from the remote wireless device 16 was received has not reached the time threshold TTH (NO in step S2), the processing after step S1 is repeated.

[0074] In step S3, the connection status determination unit 27 determines that the remote wireless device 16 is in a disconnected state. Thus, Figure 6 The processing shown is now complete.

[0075] The determination of a disconnected state for the remote wireless device 16 can also be performed as follows: Regardless of whether data has been sent from the base wireless device 14 to the remote wireless device 16, if no reception completion notification (Ack) is received from the remote wireless device 16, the base wireless device 14 performs the following processing: In this case, the base wireless device 14 retransmits data to the remote wireless device 16. That is, in this case, the base wireless device 14 retryes. If no reception completion notification (Ack) is received from the remote wireless device 16, the base wireless device 14 also retransmits data until the number of attempts (NTH) is reached. In this embodiment, regardless of whether the number of data transmissions reaches the number of attempts (NTH), if no reception completion notification (Ack) is received from the remote wireless device 16, the connection state determination unit 27 determines that the remote wireless device 16 is in a disconnected state. Such a number of attempts (NTH) can be, for example, 32 times, but is not limited to this. In this way, regardless of whether the number of times data is repeatedly sent to the synchronously connected remote wireless device 16 reaches the threshold NTH, the remote wireless device 16 can be determined to be in a non-connected state based on the fact that no reception completion notification Ack has been received.

[0076] Figure 7 This is a diagram illustrating an example of the operation of the industrial wireless communication system according to this embodiment. Figure 7 This example illustrates a situation where the remote wireless device 16 is determined to be in a disconnected state based on the number of times data is repeatedly transmitted to the remote wireless device 16 reaches a threshold NTH.

[0077] In step S11, the transceiver processing unit 26 transmits data to the remote wireless device 16 in a frequency hopping mode. Afterwards, the process transitions to step S12.

[0078] In step S12, the connection status determination unit 27 determines whether a reception completion notification (Ack) has been received from the remote wireless device 16 via the transceiver processing unit 26. If a reception completion notification (Ack) has been received from the remote wireless device 16 via the transceiver processing unit 26 (YES in step S12), Figure 7 The process shown ends. If no reception completion notification Ack is received from the remote wireless device 16 through the transceiver processing unit 26 (NO in step S12), proceed to step S13.

[0079] In step S13, the connection status determination unit 27 determines whether the number of times data has been repeatedly transmitted to the remote wireless device 16 has reached the number threshold NTH. If the number of times data has been repeatedly transmitted to the remote wireless device 16 has not reached the number threshold NTH (NO in step S13), the processing after step S11 is repeated. If the number of times data has been repeatedly transmitted to the remote wireless device 16 has reached the number threshold NTH (YES in step S13), the process proceeds to step S14.

[0080] In step S14, the connection status determination unit 27 determines that the remote wireless device 16 is in a disconnected state. Thus, Figure 7 The processing shown is now complete.

[0081] The base wireless device 14 has the function of forcibly severing the connection between itself and a synchronously connected remote wireless device 16. That is, as described above, the base wireless device 14 has a forced disconnection signal transmitting unit 28. The forced disconnection signal transmitting unit 28 can send a forced disconnection signal to a remote wireless device 16 to forcibly sever the connection between itself and that synchronously connected remote wireless device 16. When the forced disconnection signal is sent to a remote wireless device 16 by the forced disconnection signal transmitting unit 28, the connection status determination unit 27 of the base wireless device 14 can determine that the remote wireless device 16 is in a disconnected state.

[0082] Figure 8 This is a diagram illustrating an example of the operation of an industrial wireless communication system based on this embodiment. Figure 8 This example illustrates a situation where, when a forced disconnection signal is sent to the remote wireless device 16 via the forced disconnection signal transmission unit 28, the remote wireless device 16 is determined to be in a disconnected state.

[0083] In step S21, the connection status determination unit 27 determines whether a forced disconnection signal has been sent to the remote wireless device 16 via the forced disconnection signal transmission unit 28. If a forced disconnection signal has been sent to the remote wireless device 16 via the forced disconnection signal transmission unit 28 (YES in step S21), the process proceeds to step S22. If a forced disconnection signal has not been sent to the remote wireless device 16 via the forced disconnection signal transmission unit 28 (NO in step S21), Figure 8 The processing shown is now complete.

[0084] In step S22, the connection status determination unit 27 determines that the remote wireless device 16 is in a disconnected state. Thus, Figure 8 The processing shown is now complete.

[0085] The remote wireless device 16 has the function of forcibly severing the connection between itself and the synchronously connected base wireless device 14. That is, as described above, the remote wireless device 16 includes a forced disconnection signal transmitter 39 and a power monitoring unit 41. The forced disconnection signal transmitter 39 can transmit a forced disconnection signal to the base wireless device 14 to forcibly sever the synchronous connection between the remote wireless device 16 and the base wireless device 14. For example, if the power supply voltage monitored by the power monitoring unit 41 is below a voltage threshold, the forced disconnection signal transmitter 39 can transmit a forced disconnection signal to the base wireless device 14 to forcibly sever the synchronous connection. Upon receiving the forced disconnection signal from the remote wireless device 16, the connection status determination unit 27 of the base wireless device 14 can determine that the remote wireless device 16 is in a disconnected state.

[0086] Furthermore, while an example has been described here of sending a forced disconnect signal from the remote wireless device 16 when the power supply voltage monitored by the power supply monitoring unit 41 is below the voltage threshold, this is not an exception. A forced disconnect signal may also be sent from the remote wireless device 16 to another base wireless device 14 that is not currently connected to the same base wireless device 14, in order to establish a synchronization connection.

[0087] Figure 9 This is a diagram illustrating an example of the operation of the industrial wireless communication system according to this embodiment. Figure 9 This example illustrates a situation where, upon receiving a forced disconnection signal from the remote wireless device 16, the remote wireless device 16 is determined to be in a disconnected state.

[0088] In step S31, the connection status determination unit 27 determines whether a forced disconnection signal has been received from the remote wireless device 16 via the transceiver processing unit 26. If a forced disconnection signal has been received via the transceiver processing unit 26 (YES in step S31), the process proceeds to step S32. If no forced disconnection signal has been received via the transceiver processing unit 26 (NO in step S31), Figure 9 The processing shown is now complete.

[0089] In step S32, the connection status determination unit 27 determines that the remote wireless device 16 is in a disconnected state. Thus, Figure 9 The processing shown is now complete.

[0090] When the connection between the synchronously connected remote wireless devices 16 is severed, the base wireless device 14 performs a synchronization connection signal transmission process to re-establish a synchronization connection with the remote wireless devices 16. Specifically, the synchronization connection transmission unit 25 of the base wireless device 14 performs the following process when the connection between the synchronously connected remote wireless devices 16 is severed: In this case, the synchronization connection transmission unit 25 performs a broadcast transmission process, transmitting a synchronization connection signal to re-establish a synchronization connection with the synchronously connected remote wireless devices 16 at a synchronization connection period Tsc.

[0091] As described above, the remote wireless device 16 includes a diagnostic information transmission unit 40. The diagnostic information transmission unit 40 can transmit diagnostic information about the machine 44 equipped with the remote wireless device 16 to the base wireless device 14. For example, the diagnostic information can list information indicating whether the machine 44 equipped with the remote wireless device 16 has experienced any abnormalities. Such diagnostic information transmission and reception can be performed during data transmission and reception in a frequency-hopping mode. Furthermore, such diagnostic information transmission and reception can also be performed during data transmission and reception in a frequency-hopping mode, and also during a predetermined interrupt period Tir. Figure 10 This is a time graph representing an example of an interrupt period Tir. The interrupt period Tir can be, for example, 500 ms, but is not limited to this.

[0092] Thus, in this embodiment, a synchronization connection signal for synchronizing with the remote wireless device 16 is broadcast from the base wireless device 14 to the remote wireless device 16 only within a single synchronization connection period Tsc, which is an integer multiple of the transition period Tfh. During the transmission of the synchronization connection signal, the synchronization connection signal is transmitted at multiple synchronization communication frequencies within one transition period Tfh by sequentially switching the synchronization communication frequency. Furthermore, in this embodiment, the synchronization communication frequency is sequentially switched at a switching period Tcg that is longer than the transition period Tfh but shorter than twice the transition period Tfh, thereby performing the reception processing of the synchronization connection signal at multiple synchronization communication frequencies. Therefore, this embodiment provides an industrial wireless communication system 10 capable of rapidly establishing a synchronization connection.

[0093] [Modified Implementation]

[0094] The above describes suitable embodiments of the present invention, but the present invention is not limited to the above embodiments, and various changes can be made without departing from the spirit of the present invention.

[0095] For example, in the above embodiment, the case where the switching period Tfh is 5 ms has been described as an example, but it is not limited to this. The switching period Tfh can also be 2 ms, for example. In this case, the number of multiple synchronization communication frequencies used in the transmission processing and the receiving processing can be, for example, 2, but it is not limited to this. The number of synchronization communication frequencies used in the transmission processing and the receiving processing can also be, for example, 3. When the switching period Tfh is, for example, 2 ms, the synchronization connection receiving unit 36 ​​can, for example, switch the synchronization communication frequencies sequentially at a period of 3 ms, but it is not limited to this.

[0096] The above implementation methods are summarized as follows.

[0097] An industrial wireless communication system (10) includes: a computer (12) for monitoring and controlling industrial equipment; a base wireless device (14) connected to the computer via a fieldbus (17); and multiple remote wireless devices (16) installed in each of the multiple machines (44) constituting the industrial equipment, and the multiple remote wireless devices wirelessly communicating with the base wireless device. The synchronously connected base wireless device and the remote wireless device transmit and receive data by switching the switching frequency with a predetermined switching period (Tfh). The base wireless device has a synchronous connection transmitting unit (25), which performs transmission processing by broadcasting when not synchronously connected with the remote wireless device. The transmission process transmits a synchronization connection signal for synchronizing with the remote wireless device only within a single synchronization connection period (Tsc), which is an integer multiple of the transition period. The synchronization connection transmitting unit transmits the synchronization connection signal within one transition period using multiple synchronization communication frequencies by sequentially switching the synchronization communication frequencies (f1, f2, f3) used for synchronization. The remote wireless device has a synchronization connection receiving unit (36), which, when not synchronized with the base wireless device, sequentially switches the synchronization communication frequencies with a switching period (Tcg) that is longer than the transition period but shorter than twice the transition period, thereby performing reception processing of the synchronization connection signal at multiple synchronization communication frequencies. According to this structure, a synchronization connection signal for synchronizing with the remote wireless device is transmitted from the base wireless device to the remote wireless device via broadcast only within a single synchronization connection period, which is an integer multiple of the transition period. In the transmission processing of the synchronization connection signal, the synchronization connection signal is transmitted within one transition period using multiple synchronization communication frequencies by sequentially switching the synchronization communication frequencies. Furthermore, by sequentially switching the synchronization communication frequency with a switching period that is longer than the switching period but shorter than twice the switching period, the synchronous connection signal can be processed for reception using multiple synchronization communication frequencies. Therefore, an industrial wireless communication system capable of rapidly establishing a synchronization connection can be provided.

[0098] Alternatively, multiple base wireless devices may be used, and multiple remote wireless devices may be synchronously connected to each of the base wireless devices to form multiple networks (43).

[0099] The synchronization connection period can also be less than 250ms.

[0100] The transition period can also be less than 5 msec.

[0101] Alternatively, the transition period can be 5ms, and the number of the multiple synchronization communication frequencies used in the transmission process and the receiving process can be any one of 2 to 4.

[0102] The synchronization connection receiving unit can also switch the synchronization communication frequency sequentially at a period of 6 ms.

[0103] Alternatively, the transition period can be 2ms, and the number of the multiple synchronization communication frequencies used in the transmission process and the receiving process can be 2 or 3.

[0104] The synchronization connection receiving unit can also switch the synchronization communication frequency sequentially at a period of 3ms.

[0105] Alternatively, the synchronization connection signal may include the identification information of the base wireless device, the identification information of the remote wireless device that becomes the object of the synchronization connection, and time information.

[0106] Alternatively, the remote wireless device may also include a reception completion notification sending unit (38), which sends a reception completion notification (Ack) to the base wireless device in the next transition period after the transition period of receiving the synchronization connection signal through the synchronization connection receiving unit.

[0107] Alternatively, among the multiple base radio devices using the same combination of multiple synchronization communication frequencies in the transmission process, the switching order of the multiple synchronization communication frequencies may be different from each other. With this structure, it is possible to suppress situations where the transmission of the synchronization connection signal is hindered by radio wave interference.

[0108] The base wireless device also includes a connection status determination unit (27), which determines that a remote wireless device is in a disconnected state if the time during which no data is received from a synchronously connected remote wireless device reaches a predetermined time threshold (TTH). With this structure, it is possible to accurately determine that a remote wireless device is in a disconnected state.

[0109] Alternatively, the base wireless device may also include a connection status determination unit. Regardless of whether the number of times data is repeatedly sent to a synchronously connected remote wireless device has reached a threshold number (NTH), the connection status determination unit determines that the remote wireless device is in a disconnected state based on the absence of a reception completion notification from the remote wireless device. With this structure, it is possible to accurately determine whether a remote wireless device is in a disconnected state.

[0110] Alternatively, the base wireless device may further include: a forced disconnection signal transmitting unit (28) that transmits a forced disconnection signal to the remote wireless device for forcibly disconnecting the connection with the synchronously connected remote wireless device; and a connection status determination unit that, when the forced disconnection signal is transmitted to the remote wireless device by the forced disconnection signal transmitting unit, determines that the remote wireless device is in a disconnected state. With this structure, the synchronous connection with the remote wireless device can be forcibly disconnected, and the remote wireless device can be accurately determined to be in a disconnected state.

[0111] Alternatively, the remote wireless device may further include a forced disconnection signal transmitting unit, which sends a forced disconnection signal to the base wireless device to forcibly disconnect the connection with the synchronously connected base wireless device. The base wireless device also includes a connection status determination unit, which determines that the remote wireless device is in a disconnected state upon receiving the forced disconnection signal from one of the remote wireless devices. With this structure, the synchronous connection with the base wireless device can be forcibly disconnected from the remote wireless device side, and the remote wireless device can accurately determine that it is in a disconnected state from the base wireless device side.

[0112] Alternatively, if the connection with the synchronously connected remote wireless device is severed, the synchronization connection transmitting unit performs a broadcast transmission process, which sends a synchronization connection signal at the synchronization connection cycle to re-establish a synchronization connection with the synchronously connected remote wireless device. With this structure, the synchronization connection can be quickly re-established.

[0113] Alternatively, the remote wireless device may also include a diagnostic information transmitting unit (40), which transmits diagnostic information of the machine equipped with the remote wireless device to the base wireless device during data transmission and reception by switching the switching frequency at the switching period. With this structure, diagnostic information can be rapidly transmitted from the remote wireless device to the base wireless device.

Claims

1. An industrial wireless communication system (10), comprising: Computer (12), which performs monitoring and control of industrial equipment; Base wireless device (14), which is connected to the computer via fieldbus (17); and Multiple remote wireless devices (16) are installed in each of the multiple machines (44) constituting the industrial equipment, and the multiple remote wireless devices communicate wirelessly with the base wireless device. The synchronously connected base wireless device and the remote wireless device transmit and receive data by switching the hopping frequency according to a predetermined hopping period (Tfh), characterized in that... The base wireless device has a synchronization connection transmitting unit (25), which, in the absence of a synchronized connection with the remote wireless device, performs transmission processing via broadcast. This transmission processing transmits a synchronization connection signal for synchronizing with the remote wireless device only at individual synchronization connection cycles (Tsc) that are integer multiples of the transition cycle. The synchronization connection transmitting unit transmits the synchronization connection signal at multiple synchronization communication frequencies within one transition cycle by sequentially switching between synchronization communication frequencies (f1, f2, f3) used for synchronization. The remote wireless device has a synchronization connection receiving unit (36). When not synchronously connected with the base wireless device, the synchronization connection receiving unit sequentially switches the synchronization communication frequency with a switching period (Tcg) that is longer than the switching period and shorter than twice the switching period, thereby performing the receiving processing of the synchronization connection signal with multiple synchronization communication frequencies.

2. The industrial wireless communication system as described in claim 1, characterized in that, Having multiple of the aforementioned base wireless devices, Multiple networks (43) are formed by synchronously connecting multiple remote wireless devices with each of the base wireless devices.

3. The industrial wireless communication system as described in claim 1 or 2, characterized in that, The synchronization connection period is less than 250ms.

4. The industrial wireless communication system as described in claim 1 or 2, characterized in that, The transition period is less than 5 msec.

5. The industrial wireless communication system as described in claim 4, characterized in that, The transition period is 5 msec. The number of the multiple synchronization communication frequencies used in the transmission process and the receiving process is any one of 2 to 4.

6. The industrial wireless communication system as described in claim 5, characterized in that, The synchronization connection receiving unit switches the synchronization communication frequency sequentially at a period of 6 msec.

7. The industrial wireless communication system as described in claim 4, characterized in that, The transition period is 2 msec. The number of the multiple synchronization communication frequencies used in the sending process and the receiving process is 2 or 3.

8. The industrial wireless communication system as described in claim 7, characterized in that, The synchronization connection receiving unit switches the synchronization communication frequency sequentially at a period of 3ms.

9. The industrial wireless communication system as described in claim 1 or 2, characterized in that, The synchronization connection signal includes the identification information of the base wireless device, the identification information of the remote wireless device that becomes the object of the synchronization connection, and time information.

10. The industrial wireless communication system as described in claim 1 or 2, characterized in that, The remote wireless device also includes a reception completion notification sending unit (38), which sends a reception completion notification (Ack) to the base wireless device at the next transition period after the transition period of receiving the synchronization connection signal through the synchronization connection receiving unit.

11. The industrial wireless communication system as described in claim 1 or 2, characterized in that, Among the multiple base radio devices that use a combination of multiple synchronization communication frequencies in the transmission process, the switching order of the multiple synchronization communication frequencies is made different from each other.

12. The industrial wireless communication system as described in claim 1 or 2, characterized in that, The base wireless device also includes a connection status determination unit (27), which determines that the remote wireless device is in a non-connected state based on the condition that the time for which no data is received from a synchronously connected remote wireless device reaches a predetermined time threshold (TTH).

13. The industrial wireless communication system as described in claim 1 or 2, characterized in that, The base wireless device also includes a connection status determination unit. Regardless of whether the number of times data is repeatedly sent to a synchronously connected remote wireless device has reached a threshold number (NTH), the connection status determination unit determines that the remote wireless device is in a non-connected state based on the fact that no reception completion notification has been received from the remote wireless device.

14. The industrial wireless communication system as described in claim 1 or 2, characterized in that, The base wireless device also features: Forced disconnection signal transmitting unit (28) transmits a forced disconnection signal to one of the remote wireless devices for forcibly disconnecting the connection with another remote wireless device that is synchronously connected; as well as When the connection status determination unit sends the forced disconnect signal to the remote wireless device through the forced disconnect signal transmission unit, the connection status determination unit determines that the remote wireless device is in a disconnected state.

15. The industrial wireless communication system as described in claim 1 or 2, characterized in that, The remote wireless device also includes a forced disconnect signal transmitter, which sends a forced disconnect signal to the base wireless device to forcibly disconnect the connection with the synchronously connected base wireless device. The base wireless device also includes a connection status determination unit, which determines that the remote wireless device is in a non-connected state when the forced disconnection signal is received from one of the remote wireless devices.

16. The industrial wireless communication system as described in claim 1 or 2, characterized in that, In the event that the connection with the synchronously connected remote wireless device is severed, the synchronization connection transmitting unit performs a transmission process via broadcast, which transmits a synchronization connection signal at the synchronization connection cycle for re-establishing a synchronization connection with the synchronously connected remote wireless device.

17. The industrial wireless communication system as described in claim 1 or 2, characterized in that, The remote wireless device also includes a diagnostic information transmission unit (40), which transmits diagnostic information of the machine equipped with the remote wireless device to the base wireless device during the transmission and reception of data by switching the switching frequency with the switching period.

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