JP6757976B2 - Base stations, control systems, and base station control methods - Google Patents

Description

The present invention relates to a base station, a control system, and a method of controlling the base station.

The control communication network of industrial equipment deployed in factories and the like is constructed by connecting to mobile equipment such as robots or automatic guided vehicles in addition to fixedly arranged equipment. A wired network using a cable is used to connect fixedly arranged devices. On the other hand, a wireless network using a wireless link is useful for connecting mobile devices.

Ring-type communication standards such as EtherCAT (registered trademark) and FL-net are used for networks of industrial equipment from the viewpoint of redundancy and immediacy.

Patent Document 1 discloses a communication device capable of making some links in a wired network of industrial equipment cableless, that is, wireless.

Japanese Unexamined Patent Publication No. 2015-103926

Due to the arrangement of equipment in factories and the range of movement of mobile equipment, it may not be possible to properly lay a ring-type wired network. If some links of the ring-type wired network are made wireless by using the technology disclosed in Patent Document 1, the wiring laying can be omitted, but the topology of the wired network (connection form or physical). The degree of freedom of placement) does not improve much.

The present invention has been made to solve the above problems, and an object of the present invention is to provide a base station or the like that improves the degree of freedom of the network topology of control communication.

In order to solve the above problems, the base station according to one aspect of the present invention has an input port and an output port connected to a ring-shaped wired network, and a radio connected to a controlled device via wireless communication. An interface, a device control unit that transmits the received command to the controlled device through the wireless interface when a command to the controlled device is received by the input port, and the device received through the wireless interface. It includes a response control unit that outputs response data indicating a response by the control device through the output port.

According to this, the base station controls a controlled device that is not directly connected to the ring-shaped wired network via wireless communication, and also obtains a response from the controlled device via wireless communication and is wired. Send to the network. As a result, the base station can be wireless even when the controlled device is a mobile device and when it is impossible or difficult to lay the wiring because the controlled device is physically separated from the controlled device. Communication can be used to control the controlled device as if it were connected to a wired network. Therefore, the base station can improve the degree of freedom of the network topology of control communication.

Further, when the device control unit receives a read command for reading the response by the controlled device from the input port, the response control unit sends a response by the controlled device to the frame including the read command. The indicated response data may be written and output from the output port.

According to this, the base station writes the response data from the controlled device connected via the wireless interface to the read command received from the wired network, and transmits it to the wired network again. As a result, the base station can imitate as if the device responded appropriately to the read command from the master.

Further, when the response data cannot be received from the controlled device, the response control unit further writes data indicating that there is no response data for the command in the frame including the received command, and the output port. May be output by.

According to this, the base station avoids the transmission delay of the command, which may occur when the response to the command received from the wired network is not immediately obtained. Therefore, the base station improves the degree of freedom of the network topology of control communication and avoids the occurrence of command transmission delay in the wired network.

When the device control unit receives the command for the plurality of controlled devices, the device control unit sequentially unicasts the received command to each of the plurality of controlled devices, and responds by sequentially transmitting the command. The control unit may sequentially receive response data from the controlled device.

According to this, the base station can transmit and receive the command by more reliable wireless communication by utilizing the arrival confirmation and retransmission control mechanism provided in the unicast transmission.

Further, when the device control unit receives the command for the plurality of controlled devices, the device control unit may broadcast the received command to the plurality of controlled devices.

According to this, the base station can reduce the wireless communication band by having a plurality of slave units receive commands in one transmission by using broadcast transmission.

Further, the device control unit may generate a wireless frame including information indicating a time when each of the plurality of controlled devices should transmit response data to the command, and broadcast the generated wireless frame. ..

According to this, after the base station broadcasts the radio frame containing the command, it is possible to control so that there is a time lag in the time when the plurality of slave units transmit the radio frame including the response data. Therefore, it is possible to prevent the wireless frames including the response data transmitted by the plurality of slave units from colliding with each other.

Further, the device control unit may generate a wireless frame including information indicating a time when each of the plurality of controlled devices should transmit response data to the command, and broadcast the generated wireless frame. ..

According to this, after the base station broadcasts the radio frame containing the command, there is a time lag in the time when the plurality of slave units transmit the radio frame containing the response data, and as a result, the base station receives these radio frames. There is a time difference in time. Therefore, it is possible to prevent the reception processing by the base station from being concentrated in a short time.

In addition, the device control unit manages a device list in which the identifier of the controlled device and the MAC address or IP address to be used for communication with the controlled device are linked, and the device list is referred to. Then, the command may be transmitted to the MAC address or the IP address to be used for communication with the controlled device to which the command is transmitted.

According to this, the base station can transmit the wireless frame by using the MAC address or the IP address as the destination of the wireless frame. The base station can communicate with the controlled device using the available address of the MAC address and the IP address. When it is difficult to allocate an IP address, the destination IP address of the wireless frame can be broadcast and the MAC address of the controlled device can be used as the destination MAC address. In this way, the base station can adopt an appropriate transmission method according to the network environment.

Further, the base station includes two physical ports connected to the wired network, and the base station further has (a) the two physical ports when both of the two physical ports are in a link-up state. One of the ports is made to function as the input port, the other of the two physical ports is made to function as the output port, and (b) only one of the two physical ports is linked. When it is in the up state, it may be provided with a wired control unit that causes the one physical port to function as the input port and the output port.

According to this, the base station is configured as a base station having only one physical port, and the degree of freedom of the network topology of control communication can be improved.

Further, the base station may be connected to the wired network and may include one physical port that functions as the input port and the output port.

According to this, the base station is configured as a base station having two physical ports, and the degree of freedom of the network topology of control communication can be improved.

Further, the control system according to one aspect of the present invention includes the above base station and a slave unit connected to the wireless interface of the base station by wireless communication, and the slave unit is the wireless of the base station. The slave unit side wireless interface that is connected to the interface by wireless communication and receives the command transmitted by the device control unit of the base station, the slave unit side wired interface that is connected to the controlled device by a wired link, and the above. The command received by the slave unit side wireless interface is transmitted to the controlled device via the slave unit side wired interface, and the response data transmitted by the controlled device is acquired in response to the transmitted command to obtain the response data. It includes a slave unit side control unit that transmits to the base station via the slave unit side wireless interface.

According to this, the same effect as that of the above base station is obtained.

Further, in the base station control method according to one aspect of the present invention, the base station is connected to a controlled device via wireless communication with an input port and an output port connected to a ring-shaped wired network. The control method includes a device control step of transmitting the received command to the controlled device through the wireless interface when a command to the controlled device is received by the input port. Includes a response control step in which response data indicating a response by the controlled device received through the wireless interface is output by the output port.

According to this, the same effect as that of the above base station is obtained.

The present invention can be realized not only as a device, but also as a method in which the processing means constituting the device is used as a step, as a program for causing a computer to execute those steps, or as a computer reading in which the program is recorded. It can also be realized as a possible recording medium such as a CD-ROM, or as information, data or a signal indicating the program. Then, those programs, information, data and signals may be distributed via a communication network such as the Internet.

According to the present invention, the base station can improve the degree of freedom of the network topology of control communication.

FIG. 1 is a schematic diagram showing a configuration of a communication system including a base station according to an embodiment. FIG. 2 is a block diagram showing functional blocks of the base station and the slave unit according to the embodiment. FIG. 3 is an explanatory diagram showing the assignment of the functions of the input port and the output port when the base station according to the embodiment has only one physical port. FIG. 4 is an explanatory diagram showing the assignment of the functions of the input port and the output port when the base station according to the embodiment has two physical ports. FIG. 5 is an explanatory diagram of a first example of a device list stored in the device control unit according to the embodiment. FIG. 6 is an explanatory diagram of a second example of the device list stored in the device control unit according to the embodiment. FIG. 7 is a first explanatory diagram of a wireless frame including commands according to the embodiment. FIG. 8 is a second explanatory diagram of the radio frame including the command according to the embodiment. FIG. 9 is an explanatory diagram of the writing process to the wireless frame according to the embodiment. FIG. 10 is a flow chart showing processing when the base station according to the embodiment receives a command. FIG. 11 is a flow chart showing processing when the base station according to the embodiment receives a read command. FIG. 12 is a flow chart showing processing when the slave unit according to the embodiment receives a command. FIG. 13 is a flow chart showing processing when the slave unit according to the embodiment receives the response data. FIG. 14 is an explanatory diagram of a radio frame including time information transmitted by a base station according to a modified example of the embodiment.

Hereinafter, embodiments will be specifically described with reference to the drawings.

Each of the embodiments described below shows a preferred specific example of the present invention. Numerical values, shapes, materials, components, arrangement positions and connection forms of components, steps, order of steps, etc. shown in the following embodiments are examples, and are not intended to limit the present invention. Further, among the components in the following embodiments, the components not described in the independent claims indicating the highest level concept of the present invention will be described as arbitrary components constituting the more preferable form.

The same components may be designated by the same reference numerals and description thereof may be omitted.

(Embodiment)
In the present embodiment, a base station, a communication system, and the like that improve the degree of freedom of the network topology of control communication will be described.

FIG. 1 is a schematic diagram showing a configuration of a communication system 1 including a base station 10 according to the present embodiment.

As shown in FIG. 1, the communication system 1 includes a master M, devices S1, S2, S3, S11, S12 and S13, a base station 10, and slave units 20A, 20B and 20C. The master M, the devices S1, S2 and S3, and the base station 10 are communicably connected by a ring-shaped wired network N. Here, the base station 10 and the slave units 20A, 20B, and 20C are also referred to as control systems.

The master M is a control device that is connected to the network N and controls the devices S1, S2, and S3 that are also connected to the network N, and controls the devices S11, S12, and S13 via the base station 10. is there. The network N is, for example, a network that conforms to EtherCAT, and although this case will be described below as an example, a ring-type communication standard such as FL-net may also be adopted.

The master M transmits an EtherCAT frame (also simply referred to as a frame) to the ring-shaped wired network N. The frame transmitted by the master M goes around the network N and returns to the master M again. For example, when the master M transmits a frame in the D direction, the frame returns to the master M via the device S1, the base station 10, the devices S2 and S3 in this order. When passing through the device S1 or the like and the base station 10, the device S1 or the like and the base station 10 read a command or data or write a response data.

The device S1 is a controlled device corresponding to a slave that operates based on control by the master M. The device S1 is connected to the network N. The device S1 receives a frame transmitted by the master M from the network N, reads a command included in the received frame, or writes data to the received frame, and transmits the frame to the network N.

When the device S1 receives a frame including a command, the device S1 operates according to the command included in the received frame. Here, the command includes a write command for writing data to the controlled device, a read command for requesting response data from the controlled device, and the like. When the device S1 receives the frame including the write command, the device S1 writes predetermined data according to the write command. When the device S1 receives the frame including the read command, the device S1 writes the response data in a predetermined field in the received frame and transmits the frame to the network N.

Further, the device S1 is provided with two physical ports in principle, and when both of the two physical ports are in the link-up state, one of the two physical ports functions as an input port, and the two physical ports are used. The other of them functions as an output port. The device S1 may have only one physical port. In this case, one physical port is used as an input port and an output port. Even if the device S1 has two physical ports, if only one of the physical ports is in the link-up state, it is the same as if the device S1 has only one physical port. Make it work like this.

The devices S2 and S3 are controlled devices similar to the device S1, respectively.

The base station 10 is a base station device that controls the device S11 and the like via wireless communication. The base station 10 is connected to the network N, and is also connected to the slave unit 20A and the like by wireless communication. The base station 10 transmits a frame including a command for the device S11 and the like transmitted by the master M to the device S11 via the slave unit 20A. Further, the base station 10 receives the response data transmitted by the device S11 via the slave unit 20A and transmits the response data to the master M.

The slave unit 20A is a wireless device that relays communication between the base station 10 and the device S11. The slave unit 20A is wirelessly connected to the base station 10 through the wireless link L1. Further, the slave unit 20A is connected to the device S11 by the wired link L4. When the slave unit 20A receives the wireless frame including the command from the base station 10, the slave unit 20A transmits the wireless frame to the device S11. When the response data is received from the device S11, the response data is transmitted to the base station 10.

The slave units 20B and 20C are wireless devices similar to the slave units 20A. The slave units 20B and 20C are connected to the base station 10 through the wireless links L2 and L3, respectively, and are connected to the devices S12 and S13 through the wired links L5 and L6, respectively.

The device S11 is a controlled device corresponding to a slave that operates under the control of the master M. The device S11 is connected to the slave unit 20A via the wired link L4. The device S11 receives a command from the base station 10 via the slave unit 20A, and operates according to the received command. Further, the device S11 transmits the response data to the slave unit 20A. The device S11 may be a device having the same function as the device S1 or the like.

The devices S12 and S13 are controlled devices similar to the device S11, respectively.

The slave unit 20A and the device S11 may be realized as a mobile device in which they move together. This is because the base station 10 and the slave unit 20A are connected by wireless communication, so that there are no restrictions on movement by the communication line.

In the communication system 1, the master M can control not only the devices S1, S2, and S3 that are directly connected to the network N, but also the devices S11, S12, and S13 that are not directly connected to the network N. .. For the connection between the master M and the devices S11, S12 and S13 that are not directly connected to the network N, wireless communication by the base station 10 and the slave unit 20A or the like is used. As described above, according to the communication system 1, it is impossible or difficult to lay the wiring when the device S11 or the like is a mobile device and because the base station 10 is physically separated from the device S11 or the like. There is an advantage that the device S11 and the like can be controlled even in such a case. As described above, the communication system 1 can improve the degree of freedom of the network topology of the control communication by using the control system (base station 10 and slave unit 20A, etc.).

Hereinafter, the functional blocks and operations of the base station 10 and the slave unit 20A will be described in detail. The slave units 20A, 20B and 20C will be described with the slave unit 20A as a representative, and the devices S11, S12 and S13 will be described with the device S11 as a representative, but the same description holds for other slave units and other devices. To do.

FIG. 2 is a block diagram showing functional blocks of the base station 10 and the slave unit 20A according to the present embodiment.

As shown in FIG. 2, the base station 10 includes an input port 11, an output port 12, a wired control unit 13, a device control unit 14, a response control unit 15, and a wireless IF (interface) 16. To be equipped with.

The input port 11 is a port that is connected to the network N and receives a frame from the network N. The input port 11 is assigned to one physical port.

The output port 12 is a port that is connected to the network N and transmits a frame to the network N. The output port 12 is assigned to one physical port. The output port 12 may be further assigned to the port to which the input port 11 is assigned.

The wired control unit 13 is a processing unit that controls the assignment of the functions of the input port 11 and the output port 12 to the physical port and the transmission / reception of frames by the input port 11 and the output port 12. The wired control unit 13 is realized as a control module for the input port 11 and the output port 12.

The device control unit 14 is a processing unit that controls the device S11 based on the frame received by the input port 11. The device control unit 14 stores a device list 14A, which is a list of devices that can be controlled via the slave unit 20A or the like. When the device control unit 14 receives a command for controlling the device S11 or the like through the input port 11, the device control unit 14 acquires an identifier of the device (also referred to as a target device) that is the target of the received command. Then, the device control unit 14 encapsulates the command in a predetermined format and transmits it to the target device via the wireless IF 16. The device control unit 14 can be realized by the processor executing a program using a memory or the like.

When there are a plurality of target devices, the device control unit 14 may sequentially unicast and transmit commands to each of the plurality of target devices. Since the unicast transmission has a mechanism for confirming arrival and controlling retransmission, there is an advantage that a command can be transmitted by more reliable wireless communication.

Further, when there are a plurality of target devices, the device control unit 14 may broadcast a command to the plurality of target devices. If broadcast transmission is used, the advantage of reducing the wireless communication band can be obtained by having a plurality of slave units 20A or the like receive commands in one transmission.

The response control unit 15 is a processing unit that controls writing of response data transmitted by the device S11 or the like to a frame. The response control unit 15 outputs the response data indicating the response by the device S11 received through the wireless IF 16 through the output port 12. More specifically, when the response control unit 15 receives the read command for reading the response by the device S11 from the input port 11, the response control unit 15 writes the response data indicating the response by the device S11 in the frame including the read command. Outputs through the output port 12. Here, the response data is data indicating a response by the device S11 based on the control related to the command transmitted by the device control unit 14. The response control unit 15 can be realized by the processor executing a program using a memory or the like.

The response control unit 15 receives the wireless frame in which the response data is encapsulated in a predetermined format from the device S11 or the like by the wireless IF 16. Further, the response control unit 15 includes a buffer 15A which is a storage device (memory or storage) for temporarily storing the response data received from the device S11 or the like, and when the response data is received from the device S11, the response control unit 15 is provided. The response data is temporarily stored in the buffer 15A, and then written to the frame received by the input port 11.

Further, when a command is received by the input port 11, the response control unit 15 writes data indicating that there is no response data for the control in the frame including the received command, and outputs the data through the output port 12. You may. When a command is received, a response as a result of control for the device S11 or the like based on the command may not be obtained. In that case, there is an advantage that the transmission delay of the frame can be reduced by writing and outputting the data indicating that there is no response data to the control as described above. The response data related to the above response is subsequently written in a frame including a read command received by the input port 11. That is, the response data stored in the buffer 15A is written in the frame including the read command.

The wireless IF 16 is a communication interface for wireless communication between the slave unit 20A and the wireless link L1. The wireless IF 16 is connected to the slave unit 20A by, for example, wireless communication conforming to communication standards such as IEEE802.11a, b, g, and n.

Further, the slave unit 20A includes a wireless IF 21, a control unit 22, and a wired IF 23.

The wireless IF 21 is a communication interface that wirelessly communicates with the base station 10 through the wireless link L1. The wireless IF 21 is connected to the base station 10 by wireless communication conforming to a wireless standard conforming to the base station 10 (for example, communication standards such as IEEE802.11a, b, g, and n). The wireless IF 21 receives a command transmitted by the device control unit 14 of the base station 10 by the wireless IF 16. The wireless IF21 is also referred to as a slave unit side wireless interface.

The control unit 22 is a processing unit that relays the exchange of command and response data between the base station 10 and the device S11. The control unit 22 transmits the command received by the wireless IF 21 to the device S11 via the wired IF 23. Further, the control unit 22 acquires the response data transmitted by the device S11 and transmits it to the base station 10 via the wireless IF 21. The control unit 22 is also referred to as a slave unit side control unit. The control unit 22 can be realized by the processor executing a program using a memory or the like.

The wired IF23 is a wired communication interface connected to the device S11 by a wired link L4. The wired link L4 is, for example, a link according to EtherCAT. The wired IF23 is also referred to as a slave unit side wired interface.

When the EtherCAT frame is encapsulated in a UDP (User Datagram Protocol) datagram or an IP (Internet Protocol) packet (described later), it is necessary that an IP address is set in the wireless IF 16 and the wireless IF 21.

An IP address is individually set for the wireless IF 16 which is the source of the frame, but an individual IP address may or may not be set for the wireless IF 21. When an IP address is not individually set for the wireless IF 21, wireless communication is executed by broadcasting from the wireless IF 16. In this case, the slave unit 20A determines that the data is addressed to itself by analyzing the destination MAC address of the Ethernet (registered trademark) header in the PSDU or the destination IP address in the IP header.

Needless to say, the wireless communication of the wireless IFs 16 and 21 is not limited to the wireless communication conforming to the communication standards such as IEEE802.11a, b, g, and n.

Hereinafter, regarding the mode of assigning functions to the physical ports of the input port 11 and the output port 12, (1) the case where the base station 10 includes only one physical port 31, and (2) the base station 10 Each includes two physical ports 32 and 33.

(1) FIG. 3 is an explanatory diagram showing the allocation of functions of the input port 11 and the output port 12 when the base station 10 has only one physical port 31.

As shown in FIG. 3, when the base station 10 has only one physical port 31, the wired control unit 13 causes the physical port 31 to function as an input port 11 and an output port 12. In this case, the base station 10 transmits and receives frames using one physical port 31.

(2) FIG. 4 is an explanatory diagram showing the assignment of the functions of the input port 11 and the output port 12 when the base station 10 has two physical ports.

As shown in FIG. 4A, when the base station 10 has two physical ports 32 and 33 and both the two physical ports 32 and 33 are in the link-up state, it is wired. The control unit 13 causes one of the two physical ports 32 and 33 (for example, the physical port 32) to function as the input port 11, and the other (for example, the physical port 33) to function as the output port 12. For example, the base station 10 receives a frame through the physical port 32 and transmits the frame through the physical port 33 to transmit and receive the frame.

Even if the base station 10 has two physical ports 32 and 33, if one of the two physical ports 32 and 33 is in the link-down state (see FIG. 4B), the link is linked. One of the up states (for example, the physical port 32) is made to function as the input port 11 and the output port 12.

The wired control unit 13 controls the functions of the input port 11 and the output port 12 as described above, depending on whether or not each of the physical ports 32 and 33 is in the link-up state.

5 and 6 are explanatory views of the device lists 14A and 14B stored in the device control unit 14 according to the present embodiment. The device control unit 14 may store both the device lists 14A and 14B, or may store only one of them.

As shown in FIG. 5, the device list 14A is a list having a plurality of entries (rows) corresponding to one device. Each entry in the device list 14A contains information in which the device ID and the IP address are associated with each other. This IP address can be used as the destination IP address of the IP header stored in the PSDU. The device list 14A shown in FIG. 5 shows a case where the wireless communication between the base station 10 (device control unit 14 and response control unit 15) and the slave unit 20A uses a frame encapsulated in a UDP datagram or an IP packet. An example of is shown.

The device ID is an identifier of the device corresponding to the entry. Here, for convenience of explanation, it is assumed that the device ID of the device S11 or the like is "S11" or the like which is the same as the code thereof.

The IP address indicates an IP address used for controlling the device corresponding to the entry. This IP address is the same as the IP address of the slave unit connected to the device.

For example, in the device list 14A shown in FIG. 5, the base station 10 is connected to a device having a device ID of "S11" (that is, device S11) and a device having a device ID of "S12" (that is, device S12). It shows that it has been done. The IP address used for controlling the device S11, that is, the IP address of the slave unit 20A is 192.168.0.1, and the IP address used for controlling the device S12, that is, the IP address of the slave unit 20B is 192. It is shown to be 168.0.2.

When wireless communication between the base station 10 and the slave unit 20A or the like uses a frame encapsulated in communication conforming to the IEEE802.11 standard, MAC (Media Access) is used instead of the IP address as shown in the device list 14B. Control) address is used.

For example, the device list 14B shown in FIG. 6 is a list having a plurality of entries (rows) corresponding to one device, like the device list 14A. Each entry in the device list 14B contains information in which the device ID and the MAC address are associated with each other. This MAC address can be used as the destination MAC address of the Ethernet header stored in the PSDU. Since the content shown in the device list 14B can be easily inferred from the content shown in the device list 14A, detailed description thereof will be omitted.

7 and 8 are explanatory views of the wireless frame 40 including the command according to the present embodiment.

FIG. 7A is an explanatory diagram showing the entire radio frame 40 including command or response data.

As shown in FIG. 7A, the radio frame 40 includes a PLCP (Physical Layer Convergence Protocol) preamble 41, a PLCP header 42, an 802.11 header 43, data 44, and an FCS (Frame Check Sequence). Includes 45 and. The wireless frame 40 is a wireless frame conforming to the existing IEEE 802.11 standard.

The PLCP preamble 41 is a field including a synchronization signal added to the beginning of the IEEE802.11 frame.

The PLCP header 42 is a field containing information such as the modulation method, transmission speed, and data length of the IEEE802.11 frame.

The IEEE802.11 header 43 is a field containing information such as the frame type, destination MAC address, and source MAC address of the IEEE802.11 frame. When the wireless frame 40 includes a command, the destination MAC address is the slave unit 20A and the source MAC address is the base station 10. When the wireless frame 40 includes response data, the destination MAC address is the base station 10 and the source MAC address is the slave unit 20A.

The data 44 is a field containing the data carried by the IEEE 802.11 frame. Data 44 includes EtherCAT frames containing command or response data.

The FCS 45 is a field including a checksum calculated from the fields of the IEEE 802.11 header 43 and the data 44.

The fields included in the data 44 will be described in more detail. Data 44 includes EtherCAT frames. In other words, the data 44 encapsulates an EtherCAT frame. As the encapsulation method, various methods can be adopted. For example, a method of encapsulating in a UDP datagram, a method of encapsulating in an IP packet, a method of encapsulating in an IEEE802.11 frame, or the like can be adopted.

FIG. 7B shows data 44 when the EtherCAT frame is encapsulated in a UDP datagram. As shown in FIG. 7B, the data 44 includes an Ethernet header 50, an IP header 51, a UDP header 52, an Ethernet header 53, and an Ethernet datagram 54.

The Ethernet header 50 is a field containing a source MAC address, a destination MAC address and a type. When the wireless frame 40 includes a command, the MAC address of the slave unit 20A is the destination, and the MAC address of the base station 10 is the transmission source. When the wireless frame 40 includes response data, the MAC address of the base station 10 is the destination, and the MAC address of the slave unit 20A is the transmission source. The type is "0x0800" which means IP.

The IP header 51 is a field including a source IP address and a destination IP address. When the wireless frame 40 includes a command, the IP address of the slave unit 20A is the destination and the IP address of the base station 10 is the transmission source. When the wireless frame 40 includes response data, the IP address of the base station 10 is the destination, and the IP address of the slave unit 20A is the transmission source.

The UDP header 52 is a field including a source port number, a destination port number, and the like. A predetermined value may be adopted for the UDP port number.

The EtherCAT header 53 is a header of the EtherCAT frame, and includes the data length of the EtherCAT frame and the like.

The EtherCAT datagram 54 is a field containing data carried by the EtherCAT frame. The EtherCAT datagram 54 can include data destined for a plurality of devices. When data addressed to a plurality of devices is included, it has a configuration in which a plurality of datagrams including an identifier of the device to be the destination and data to be transmitted to the device are concatenated. For example, the EtherCAT datagram 54 has a configuration in which a datagram addressed to the device S11 (datagram 56 in FIG. 8) and a datagram addressed to the device S12 (datagram 57 in FIG. 8) are concatenated.

FIG. 8 is an explanatory diagram showing the entire EtherCAT datagram 54.

As shown in FIG. 8, the datagram 56 includes the command 56A, device ID 56B, and data length 56C fields. In addition, data 56D may be further included.

The command 56A is a field indicating the type of the command included in the datagram 56, and indicates a command type such as a write command or a read command.

The device ID 56B is a field indicating the destination of the datagram 56, and includes the device ID of the device S11.

The data length 56C indicates the data length of the data 56D included in the datagram 56. The data length 56C is, for example, in bytes.

The data 56D is the data included in the datagram 56. The data 56D is not essential. When there is no data 56D, the data length 56C can be set to zero and the data 56D can be omitted.

The datagram 57 includes the command 57A, device ID 57B, and data length 57C fields, as described above. In addition, data 57D may be further included. The device ID 57B includes the device ID of the device S12.

The data 44 may also take the form of encapsulating an Ethernet CAT frame in an Ethernet frame (see (c) of FIG. 7). In this case, the data 44 includes an Ethernet header 50, an EtherCAT header 53, and an EtherCAT datagram 54. This configuration corresponds to the frame configuration in which the IP header 51 and the UDP header 52 in FIG. 7B are omitted. Since the meaning of each field is the same as that in FIG. 7B, the description thereof will be omitted.

The data 44 may also be in the form of encapsulating an EtherCAT frame into an IEEE802.11 frame (see FIG. 7D). In this case, the data 44 includes the EtherCAT header 53 and the EtherCAT datagram 54. This configuration corresponds to the frame configuration in which the Ethernet header 50, the IP header 51, and the UDP header 52 in FIG. 7B are omitted. Since the meaning of each field is the same as that in FIG. 7B, the description thereof will be omitted.

FIG. 9 is an explanatory diagram of the writing process to the wireless frame according to the present embodiment. FIG. 9 shows a state in which the response control unit 15 writes data to the datagram 56 including each of the write command and the read command.

FIG. 9A shows a state in which the response control unit 15 writes data to the datagram 56 including the write command received from the network N. As shown in FIG. 9A, the response control unit 15 writes data indicating that there is no response from the device in the frame including the write command. Specifically, the response control unit 15 writes zero in the data length 56C.

FIG. 9B shows an example of a state in which the response control unit 15 writes data to the datagram 56 including the read command received from the network N. As shown in FIG. 9B, the response control unit 15 writes the response data received from the device in the frame including the read command. For example, the response control unit 15 writes 5 bytes of response data to the data 56D, and writes “5”, which means 5 bytes, which is the data length of the response data, to the data length 56C.

Note that FIGS. 9A and 9B show a state in which the response control unit 15 writes data to the datagram 56 including the write command and the read command as examples of the command, respectively. , These command types are just examples, and the same applies to other commands.

The processing of the base station 10 and the slave unit 20A configured as described above will be described in detail.

FIG. 10 is a flow chart showing processing when the base station 10 according to the present embodiment receives a command (for example, a write command).

In step S101, the wired control unit 13 determines whether or not a command has been received from the network N. If the command is received (Yes in step S101), the process proceeds to step S102, and if not (No in step S101), step S101 is executed again. In other words, the device control unit 14 is in a standby state until it receives a command from the network N.

In step S102, the device control unit 14 determines whether or not the target device of the command received in step S101, that is, the device ID 56B included in the command is included in the device list 14A. If it is determined that the target device is included in the device list 14A (Yes in step S102), the process proceeds to step S103, and if not (No in step S102), the process proceeds to step S108.

In step S103, the response control unit 15 writes data indicating that there is no response in the frame including the command received by the wired control unit 13 in step S101.

In step S104, the wired control unit 13 transmits the frame after the writing by the response control unit 15 in step S103 to the network N.

In step S105, the device control unit 14 transmits the wireless frame including the command received in step S101 to the slave unit connected to the target device by the wireless IF16. The slave unit connected to the target device can be selected with reference to the device list 14A. For example, when the target device is the device S11, the command is transmitted with the IP address 192.168.0.1, that is, the slave unit 20A as the destination with reference to the device list 14A.

In step S106, the response control unit 15 determines whether or not the response data has been received by the wireless IF 16. If the response data is received (Yes in step S106), the process proceeds to step S107, and if not (No in step S106), step S106 is executed again. In other words, the response control unit 15 takes a standby state until response data is received from the slave unit 20A.

In step S107, the response control unit 15 stores the response data received in step S106 in the buffer 15A and temporarily stores it. When step S107 is completed, a series of processes shown in FIG. 10 is completed.

In step S108, the wired control unit 13 transmits a frame including the command received in step S101 to the network N. When step S108 is completed, the series of processes shown in FIG. 10 is completed.

By a series of processes shown in FIG. 10, when the base station 10 receives a command for the device S11 from the network N, the base station 10 transmits the command to the device S11 and stores the response data from the device S11 in the buffer 15A. It becomes.

FIG. 11 is a flow chart showing processing when the base station 10 according to the present embodiment receives a read command.

In step S201, the wired control unit 13 determines whether or not a read command has been received from the network N. If the read command is received (Yes in step S201), the process proceeds to step S202, and if not (No in step S201), step S201 is executed again. In other words, the device control unit 14 is in a standby state until it receives a read command from the network N.

In step S202, the response control unit 15 determines whether or not the response data is stored in the buffer 15A. If the response data is stored in the buffer 15A (Yes in step S202), the process proceeds to step S203, and if not (No in step S202), the process proceeds to step S211.

In step S203, the response control unit 15 reads the response data from the buffer 15A. Then, the response data read from the buffer 15A is written in the frame including the read command received by the wired control unit 13 in step S101.

In step S204, the wired control unit 13 transmits the frame after the writing by the response control unit 15 in step S203 to the network N. When step S204 is completed, the series of processes shown in FIG. 11 is completed.

In step S211 the response control unit 15 writes data indicating that there is no response in the frame including the read command received by the wired control unit 13 in step S201.

In step S212, the wired control unit 13 transmits the frame after the writing by the response control unit 15 in step S211 to the network N. When step S212 is completed, the series of processes shown in FIG. 11 is completed.

Through the series of processes shown in FIG. 11, when the base station 10 receives the read command from the network N, the base station 10 can write the response data from the device S11 in the frame including the read command and transmit it to the network N.

Next, the processing of the slave unit 20A will be described.

FIG. 12 is a flow chart showing processing when the slave unit 20A according to the present embodiment receives a command.

In step S301, the control unit 22 determines whether or not a command has been received from the base station 10 by the wireless IF 21. If it is determined that the command has been received (Yes in step S301), the process proceeds to step S302, and if not (No in step S301), step S301 is executed again. In other words, the control unit 22 is in a standby state until it receives a command from the base station 10.

In step S302, the control unit 22 transmits the command received in step S301 to the target device S11 through the wired IF23. After that, the device S11 receives the command and operates according to the command.

FIG. 13 is a flow chart showing processing when the slave unit 20A according to the present embodiment receives response data.

In step S401, the control unit 22 determines whether or not response data has been received from the target device S11 or the like. The response data includes, for example, information indicating the result of the operation of the device S11 based on the command transmitted in step S302. If the control unit 22 determines that the response data has been received (Yes in step S401), the process proceeds to step S402, and if not (No in step S401), step S401 is executed again. In other words, the control unit 22 is in a standby state until response data is received from the device S11 or the like.

In step S402, the control unit 22 transmits the response data received in step S401 to the base station 10 through the radio IF 21.

(Modified example of the embodiment)
In this modification, a technique for suppressing collision of wireless frames will be described for a base station, a communication system, and the like that improve the degree of freedom of the network topology of control communication. More specifically, when the device control unit 14 of the base station 10 broadcasts a wireless frame containing a command, a technique for suppressing the wireless frames containing the response data transmitted by the slave unit 20A or the like from colliding with each other is provided. explain.

FIG. 14 is an explanatory diagram of a radio frame including time information transmitted by the base station 10 according to this modification. More specifically, FIG. 14 shows the EtherCAT datagram 54 contained in the radio frame.

As shown in FIG. 14, the datagram 76 included in the EtherCAT datagram 54 of the wireless frame includes a transmission time 56F and a response time 56G in addition to the command 56A and the like described above. Further, the datagram 77 includes a transmission time 57F and a response time 57G in addition to the command 57A and the like.

The transmission time 56F is information indicating the time when the base station 10 transmits the radio frame. The response time 56G is information indicating a time when the slave unit 20A should transmit a wireless frame including response data including a response to a command included in the wireless frame.

The transmission time 57F is the same as the transmission time 56F. The response time 57G is information indicating a time when the slave unit 20B should transmit a wireless frame including response data including a response to a command included in the wireless frame. The response time 57G is set to a time different from the response time 56G. For example, the time difference between the response time 57G and the response time 56G is set to be about 500 μsec or 1 msec.

When the base station 10 broadcasts a radio frame containing the EtherCAT datagram 54 shown in FIG. 14, all the slave units including the slave units 20A and 20B receive the radio frame.

When the slave unit 20A receives the radio frame including the EtherCAT datagram 54, the slave unit 20A sets the transmission time 56F to the current time of the own device. Then, as in the case of the above embodiment, the command is transmitted to the device S11 through the wired IF23, and the response data from the device S11 is acquired. Then, the slave unit 20A transmits the response data to the base station 10 when the current time reaches the response time 56G.

When the slave unit 20B receives the radio frame including the EtherCAT datagram 54, the slave unit 20B performs the same processing as the slave unit 20A. Since there is a time difference between the response time 56G and the response time 57G, there is a time difference between the time when the response data transmitted by the slave unit 20A and the response data transmitted by the slave unit 20B are transmitted. As a result, the collision of the above two response data is suppressed.

As described above, the base station in the present embodiment and the present modification controls the controlled device that is not directly connected to the ring-shaped wired network via wireless communication, and also via wireless communication. The response from the controlled device is acquired and sent to the wired network. As a result, the base station can be wireless even when the controlled device is a mobile device and when it is impossible or difficult to lay the wiring because the controlled device is physically separated from the controlled device. Communication can be used to control the controlled device as if it were connected to a wired network. Therefore, the base station can improve the degree of freedom of the network topology of control communication.

Further, the base station writes the response data from the controlled device connected via the wireless interface to the read command received from the wired network, and transmits the response data to the wired network again. As a result, the base station can imitate as if the device responded appropriately to the read command from the master.

In addition, the base station avoids command transmission delays that may occur when a response to a command received from a wired network cannot be obtained immediately. Therefore, the base station improves the degree of freedom of the network topology of control communication and avoids the occurrence of command transmission delay in the wired network.

In addition, the base station can transmit and receive commands by more reliable wireless communication by utilizing the arrival confirmation and retransmission control mechanism provided in the unicast transmission.

Further, the base station can reduce the wireless communication band by causing a plurality of slave units to receive a command in one transmission by using broadcast transmission.

Further, after the base station broadcasts the wireless frame including the command, it is possible to control so that there is a time lag in the time when the plurality of slave units transmit the wireless frame including the response data. Therefore, it is possible to prevent the wireless frames including the response data transmitted by the plurality of slave units from colliding with each other.

In addition, after the base station broadcasts the radio frame containing the command, there is a time difference in the time when the plurality of slave units transmit the radio frame containing the response data, and as a result, the time difference in the time when the base station receives these radio frames Occurs. Therefore, it is possible to prevent the reception processing by the base station from being concentrated in a short time.

Further, the base station can transmit the wireless frame to the destination of the wireless frame by using the MAC address or the IP address. The base station can communicate with the controlled device using the available address of the MAC address and the IP address. When it is difficult to allocate an IP address, the destination IP address of the wireless frame can be broadcast and the MAC address of the controlled device can be used as the destination MAC address. In this way, the base station can adopt an appropriate transmission method according to the network environment.

Further, the base station is configured as a base station having only one physical port, and the degree of freedom of the network topology of control communication can be improved.

Further, the base station is configured as a base station having two physical ports, and the degree of freedom of the network topology of control communication can be improved.

Although the base station, the control system, and the control method of the base station of the present invention have been described above based on the embodiment, the present invention is not limited to this embodiment. As long as the gist of the present invention is not deviated, various modifications that can be conceived by those skilled in the art are applied to the present embodiment, and a form constructed by combining components in different embodiments is also included in the scope of the present invention. ..

The present invention can be applied to a base station or the like that improves the degree of freedom in the network topology of control communication. More specifically, it can be applied to a base station or the like constituting a control communication network of industrial equipment.

1 Communication system 10 Base station 11 Input port 12 Output port 13 Wired control unit 14 Equipment control unit 14A, 14B Equipment list 15 Response control unit 15A Buffer 16, 21 Wireless IF
20A, 20B, 20C slave unit 22 Control unit 23 Wired IF
31, 32, 33 Physical port 40 Radio frame 41 PLCP preamble 42 PLCP header 43 IEEE802.11 header 44, 56D, 57D Data 45 FCS
51 IP Header 52 UDP Header 53, 61 EtherCAT Header 54, 62 EtherCAT Datagram 56, 57, 76, 77 Datagram 56A, 57A Command 56B, 57B Device ID
56C, 57C Data length 56F, 57F Transmission time 56G, 57G Response time L1, L2, L3 Wireless link L4, L5, L6 Wired link M master N network S1, S2, S3, S11, S12, S13 Equipment

Claims (11)

Input port and output port connected to the ring-shaped wired network,
A wireless interface connected to a controlled device via wireless communication,
A device control unit that transmits the received first command to the controlled device through the wireless interface when the first command to the controlled device is received by the input port.
A response control unit that writes data indicating that there is no response data to the first command in a frame including the first command received by the device control unit and outputs the data by the output port is provided.
The device control unit further
After receiving the first command, the second command to the controlled device is received by the input port.
The response control unit further
The frame containing the second command the device control unit receives, you output by the output port the writing response data indicating a response by the controlled device relative to the first command received via the wireless interface
base station. The second command, the base station according to claim 1, before Symbol device control unit includes a read command for reading the response by the controlled device. The device control unit, when receiving the first command for a plurality of the controlled device, the first command received, sequentially unicast to each of a plurality of the controlled devices, The base station according to claim 1 or 2 , wherein the response control unit sequentially receives response data from the controlled device. The device control unit, when receiving the first command for a plurality of the controlled device, the first command received, to claim 1 or 2 broadcasts to a plurality of the controlled devices The listed base station. The device control unit
The base station according to claim 4 , wherein each of the plurality of controlled devices generates a wireless frame including information indicating a time when response data to the first command should be transmitted, and broadcasts the generated wireless frame. The base station according to claim 4 or 5 , wherein the response control unit sequentially receives response data to be transmitted according to information indicating a time when each of the plurality of controlled devices should transmit response data to the first command. .. The device control unit manages a device list in which the identifier of the controlled device is associated with the MAC address or IP address to be used for communication with the controlled device, and the device control unit manages the device list with reference to the device list. The item according to any one of claims 1 to 6 , wherein the first command is transmitted to the MAC address or the IP address to be used for communication with the controlled device to which the first command is transmitted. base station. The base station comprises two physical ports connected to the wired network.
The base station further
(A) When both of the two physical ports are in the link-up state, one of the two physical ports functions as the input port, and the other of the two physical ports is the output port. To function as
(B) A claim including a wired control unit that allows the one physical port to function as the input port and the output port when only one of the two physical ports is in the link-up state. The base station according to any one of 1 to 7 . The base station according to any one of claims 1 to 7 , wherein the base station is connected to the wired network and includes an input port and one physical port that functions as the output port. The base station according to any one of claims 1 to 9 and
A slave unit connected to the wireless interface of the base station by wireless communication is provided.
The slave unit
A wireless interface on the slave unit side that is connected to the wireless interface of the base station by wireless communication and receives the first command transmitted by the device control unit of the base station.
A wired interface on the slave unit side connected to the controlled device by a wired link,
The first command received by the slave unit side wireless interface is transmitted to the controlled device via the slave unit side wired interface, and the response data transmitted by the controlled device in response to the transmitted first command is transmitted. A control system including a slave unit side control unit that acquires and transmits the slave unit side wireless interface to the base station. It ’s a base station control method.
The base station
Input port and output port connected to the ring-shaped wired network,
Equipped with a wireless interface that connects to controlled devices via wireless communication
The control method is
A device control step of transmitting the received first command to the controlled device through the wireless interface when the first command to the controlled device is received by the input port.
The frame including the first command received in the device control step includes a response control step in which data indicating that there is no response data to the first command is written and output by the output port.
In the device control step, further
After receiving the first command, the second command to the controlled device is received by the input port.
In the response control step, further
The frame containing the second command received by the device control step, you output by the output port the writing response data indicating a response by the controlled device relative to the first command received via the wireless interface
Control method.

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