WO2023248551A1 - Control system, relay device, and communication method - Google Patents

Abstract

This control system includes a first controller that has an interface for connecting to a first transmission path, a second controller that has an interface for connecting to a second transmission path, and a relay unit that has a first interface for connecting to the first transmission path and a second interface for connecting to the second transmission path. The relay unit transmits, to the second controller in accordance with transfer settings, output data that has been transmitted by cyclic communication from the first controller, and transmits, to the second controller, output data that has been transmitted by message communication from the first controller.

Description

Control system, relay device and communication method

The present invention relates to a control system, a relay device, and a communication method.

With the rapid development of information and communication technology in recent years, there is an increasing need for industrial equipment to process more data. More specifically, technological innovation using communication technology, typified by IoT (Internet of Things) and Industry 4.0, is progressing. As a result, the amount of data exchanged within the system is increasing.

As one solution to this increase in the amount of data processing, International Publication No. 2013/137023 (Patent Document 1) proposes a method for more appropriately updating data between devices in a configuration including multiple communication lines. Discloses a configuration that allows this.

When configuring a network distributed control system by connecting multiple controllers using multiple networks, a relay unit that is a gateway in charge of data transfer between networks is used. In such a network distributed control system, a controller belonging to a certain network exchanges data with a controller belonging to another network via a relay unit. Such data exchange realizes control status monitoring and control between controllers.

International Publication No. 2013/137023

As the amount of data exchanged between controllers increases, the time required for data exchange becomes longer, and control performance may deteriorate. Therefore, there is a need for a configuration that can exchange more data while suppressing deterioration in control performance.

A control system according to an example of the present invention includes a first controller having an interface for connecting to a first transmission line, a second controller having an interface for connecting to a second transmission line, and a second controller for connecting to the first transmission line. and a relay unit having a first interface for connecting to the second transmission line and a second interface for connecting to the second transmission line. The relay unit transmits the output data transmitted from the first controller through cyclic communication to the second controller according to the transfer settings, and also transmits the output data transmitted from the first controller through message communication to the second controller.

According to this configuration, data can be transmitted from the first controller to the second controller by both cyclic communication and message communication, so more data can be exchanged. Additionally, since either cyclic communication or message communication can be selected depending on the characteristics of the data, deterioration in control performance can be suppressed.

The relay unit transmits the output data transmitted from the first controller through cyclic communication to the second controller through cyclic communication, and transmits the output data transmitted from the first controller through message communication to the second controller through message communication. You may also do so. According to this configuration, by transmitting data from the first controller to the relay unit and from the relay unit to the second controller using the same method, processing related to data transfer can be simplified.

The relay unit may transmit output data transmitted from the second controller through cyclic communication to the first controller, and transmit output data transmitted from the second controller through message communication to the first controller. . According to this configuration, data can be transmitted from the second controller to the first controller by both cyclic communication and message communication, so that more data can be exchanged. Additionally, since either cyclic communication or message communication can be selected depending on the characteristics of the data, deterioration in control performance can be suppressed.

The relay unit may sequentially transmit the output data transmitted from the first controller through message communication to the second controller through message communication. According to this configuration, since data transmitted through message communication is transmitted sequentially, processing related to data transfer can be simplified.

The relay unit may hold output data sent from the first controller through message communication, and may also send the held data to the second controller in response to access from the second controller. According to this configuration, the second controller can acquire data at appropriate timing depending on the control state of the second controller.

The relay unit may notify the second controller that it holds the output data transmitted by message communication from the first controller. According to this configuration, the second controller can execute the process of acquiring data from the relay unit based on the notification from the relay unit.

The relay unit may notify the second controller through cyclic communication that it holds the output data transmitted from the first controller through message communication. According to this configuration, the second controller can acquire notifications from the relay unit through cyclic communication, so it can be determined whether or not to acquire data from the relay unit at each cycle of control calculation in the second controller. .

The control system may provide a user interface for creating transfer settings in response to user operations. According to this configuration, the user can easily create transfer settings via the user interface.

According to another example of the present invention, a relay unit is provided that is connected to a first controller via a first transmission path and connected to a second controller via a second transmission path. The relay unit has a first interface for connecting to the first transmission path, a second interface for connecting to the second transmission path, and a relay unit that transmits output data transmitted by cyclic communication from the first controller to the first interface according to transfer settings. and a processing circuit that transmits output data transmitted by message communication from the first controller to the second controller.

According to yet another example of the present invention, communication in a control system comprising a first controller having an interface for connecting to a first transmission path, and a second controller having an interface for connecting to a second transmission path. A method is provided. The communication method includes the steps of transmitting the output data transmitted from the first controller through cyclic communication to the second controller according to the transfer settings, and transmitting the output data transmitted from the first controller through message communication to the second controller. and steps.

According to the present invention, a configuration is provided in which more data can be exchanged while suppressing a decline in control performance.

FIG. 2 is a schematic diagram showing an example of application of the control system according to the present embodiment. FIG. 1 is a schematic diagram showing an example of the overall configuration of a control system according to the present embodiment. FIG. 2 is a block diagram showing an example of a hardware configuration of an arithmetic unit of the main control device according to the present embodiment. FIG. 2 is a block diagram showing an example of a hardware configuration of an arithmetic unit of a sub-control device according to the present embodiment. FIG. 3 is a block diagram showing an example of the hardware configuration of a relay unit of the sub-control device according to the present embodiment. FIG. 2 is a schematic diagram showing an overview of data communication in the control system according to the present embodiment. FIG. 2 is a schematic diagram showing an example of a data structure used for data communication in the control system according to the present embodiment. FIG. 3 is a diagram for explaining processing in a relay unit in the control system according to the present embodiment. FIG. 3 is a diagram for explaining I/O data transmission by cyclic communication in the control system according to the present embodiment. FIG. 3 is a diagram for explaining I/O data transmission by message communication (sequential transmission method) in the control system according to the present embodiment. FIG. 3 is a diagram for explaining I/O data transmission by message communication (temporary holding method) in the control system according to the present embodiment. 12 is a diagram for explaining processing related to the data presence flag shown in FIG. 11. FIG. FIG. 2 is a sequence diagram illustrating an example of a procedure for data transmission by message communication in the control system according to the present embodiment. FIG. 2 is a sequence diagram showing an example of a data transfer procedure in the control system according to the present embodiment. 3 is a flowchart illustrating an example of a processing procedure for I/O data transmission by cyclic communication of a relay unit according to the present embodiment. 3 is a flowchart illustrating an example of a processing procedure for I/O data transmission (sequential transmission method) by message communication of a relay unit according to the present embodiment. 3 is a flowchart illustrating an example of a processing procedure for I/O data transmission (temporary holding method) by message communication of a relay unit according to the present embodiment. FIG. 2 is a schematic diagram showing an example of a user interface for creating transfer settings for a relay unit in the control system according to the present embodiment.

Embodiments of the present invention will be described in detail with reference to the drawings. Note that the same or corresponding parts in the figures are designated by the same reference numerals, and the description thereof will not be repeated.

<A. Application example＞
First, an example of a scene to which the present invention is applied will be described.

FIG. 1 is a schematic diagram showing an application example of a control system 1 according to the present embodiment. Referring to FIG. 1, control system 1 includes a first controller and a second controller. The first controller has an interface for connecting to the first transmission path. The second controller has an interface for connecting to the second transmission path.

The control system 1 further includes a relay unit having a first interface for connecting to the first transmission path and a second interface for connecting to the second transmission path. The relay unit is a kind of gateway, and transmits the output data transmitted from the first controller through cyclic communication to the second controller according to the transfer settings, and also transmits the output data transmitted from the first controller through message communication to the second controller. Send to controller.

In this specification, "cyclic communication" is a method of transmitting predetermined data at every predetermined transmission cycle (for example, 1 msec to several 100 msec).

In this specification, "message communication" is a method of transmitting data in response to a request from a source or a destination. "Message communication" includes acyclic communication and event-driven communication.

In this specification, the terms "input data" and "output data" indicate what meaning the target data has from the perspective of the controller in focus.

More specifically, "input data" means data input to the controller of interest (data referenced by the controller of interest). The "input data" includes, for example, command values given from other controllers, state values acquired by sensors connected to other controllers, and the like.

On the other hand, "output data" means data output by the unit of interest (data whose value is changed by the unit of interest). "Output data" includes, for example, command values given to other controllers and/or actuators connected to other controllers.

In the configuration example shown in FIG. 1, data is transferred from the first controller to the second controller via the relay unit. Even if the data is the same, it can be seen as "output data" from the perspective of the first controller that is the source, and as "input data" when seen from the second controller that is the destination.

In the following description, "input data" and "output data" may be collectively referred to as "input/output data" or "I/O data." However, "input/output data" and "I/O data" may include only input data or only output data.

The data transmitted by the cyclic communication shown in FIG. 1 has a relatively high priority and a relatively small amount of data. On the other hand, data transmitted through message communication has a relatively low priority and a relatively large amount of data. In this way, in addition to cyclic communication, which is a high-frequency data exchange method, message communication without time constraints can be used. By exchanging data with relatively low update frequency through message communication, the amount of data exchanged through cyclic communication can be reduced.

In the control system 1 according to the present embodiment, it is possible to arbitrarily set whether to use cyclic communication or message communication depending on the characteristics of the data to be transmitted.

In this way, in a control system that exchanges I/O data between controllers via a relay unit (gateway), a configuration is adopted in which I/O data can be transmitted not only by cyclic communication but also by message communication. By adopting such a configuration, it is possible to increase the amount of data that can be transmitted, thereby allowing more data to be exchanged while suppressing deterioration in control performance. That is, it is possible to improve control performance and increase the capacity of communication between controllers.

<B. Overall configuration example>
Next, an example of the overall configuration of the control system 1 according to the present embodiment will be described.

FIG. 2 is a schematic diagram showing an example of the overall configuration of the control system 1 according to the present embodiment. Referring to FIG. 2, control system 1 according to the present embodiment includes main control device 10 and one or more sub-control devices 20.

In this specification, the terms "main controller" and "sub controller" are used for convenience of explanation, and they may have substantially the same hardware configuration or have substantially the same functions. It may be a configuration. The main control device and the sub-control device may be a type of computer such as a PLC (programmable logic controller).

The main control device 10 and one or more sub-control devices 20 are connected via a field network 4. Field network 4 supports cyclic communication and message communication. Examples of the field network 4 include EtherCAT (registered trademark), EtherNet/IP (registered trademark), PROFINET (registered trademark), PROFIBUS (registered trademark), DeviceNet (registered trademark), FL-net, CompoNet (registered trademark), etc. may also be used.

In this way, the main control device 10 corresponds to a first controller having an interface for connecting to the field network 4, which corresponds to a first transmission path.

The main control device 10 includes a calculation unit 100 that executes control calculations. The arithmetic unit 100 is capable of data communication via the field network 4. The main controller 10 may further include a power supply unit, an I/O unit, a special unit, and the like.

The sub-control device 20 includes a calculation unit 200 that performs control calculations and a relay unit 250 that performs data communication via the field network 4. The sub-control device 20 may further include a power supply unit, an I/O unit, a special unit, and the like.

The arithmetic unit 200 and the relay unit 250 are connected via an internal bus 6 (see FIGS. 4 and 5). Note that if the sub-control device 20 includes an I/O unit and/or a special unit, the units are also connected via the internal bus 6.

In this way, the arithmetic unit 200 corresponds to a second controller having an interface for connecting to the internal bus 6, which corresponds to a second transmission line.

The relay unit 250 relays data transmitted from the main control device 10 so that it can be referenced by the calculation unit 200, and also relays data output from the calculation unit 200 so that it can be transmitted to the main control device 10. That is, the relay unit 250 is a gateway having a first interface for connecting to the field network 4 (first transmission path) and a second interface for connecting to the internal bus 6 (second transmission path).

The control system 1 may include a support device 300 for creating and changing programs, settings, etc. executed by the main control device 10 and/or the sub-control device 20. The support device 300 may be connected to the calculation unit 200 of the sub-control device 20 or the calculation unit 100 of the main control device 10.

<C. Hardware configuration example>
Next, an example of the hardware configuration of the main devices of the control system 1 according to the present embodiment will be described.

(c1: calculation unit 100)
FIG. 3 is a block diagram showing an example of the hardware configuration of the arithmetic unit 100 of the main control device 10 according to the present embodiment. Referring to FIG. 3, the arithmetic unit 100 includes a processor 102 such as a CPU (Central Processing Unit) or an MPU (Micro-Processing Unit), a chipset 104, a memory 106, a storage 108, and an upper network interface 110. , a USB (Universal Serial Bus) interface 112, a memory card interface 114, and a field network interface 120.

The processor 102 reads various programs stored in the storage 108, expands them to the memory 106, and executes them, thereby realizing necessary processing in the arithmetic unit 100. The chipset 104 controls data communication between the processor 102 and each component.

The storage 108 typically stores a system program 131 and a user program 132 that includes computer-readable codes necessary for control calculations.

By executing the program stored in the storage 108, the arithmetic unit 100, which is a computer, executes the processing described in this specification, and the functional configuration described in this specification in the arithmetic unit 100, which is a computer, is executed. Make it happen.

The upper network interface 110 controls data communication with other devices via the upper network. USB interface 112 controls data communication to and from supporting devices via a USB connection.

The memory card interface 114 is configured to allow a memory card 116 to be attached or removed, and is capable of writing data to the memory card 116 and reading various data (user programs, trace data, etc.) from the memory card 116. There is.

The field network interface 120 controls data communication with the sub-control device 20 via the field network 4. More specifically, field network interface 120 includes a receive buffer 121 for holding received data and a transmit buffer 122 used for generating data to be transmitted.

(c2: calculation unit 200)
FIG. 4 is a block diagram showing an example of the hardware configuration of the arithmetic unit 200 of the sub-control device 20 according to the present embodiment. Referring to FIG. 4, the arithmetic unit 200 includes a processor 202 such as a CPU or an MPU, a chipset 204, a memory 206, a storage 208, an upper network interface 210, a USB interface 212, and a memory card interface 214. , an internal bus interface 220.

The processor 202 reads various programs stored in the storage 208, expands them to the memory 206, and executes them, thereby realizing necessary processing in the arithmetic unit 200. Chipset 204 controls data communication between processor 202 and each component.

The storage 208 typically stores a system program 231 and a user program 232 that includes computer-readable codes necessary for control calculations.

By executing the program stored in the storage 208, the arithmetic unit 200, which is a computer, executes the processing described in this specification, and the functional configuration described in this specification is performed in the arithmetic unit 200, which is a computer. Make it happen.

The upper network interface 210 controls data communication with other devices via the upper network. USB interface 212 controls data communication to and from supporting devices via a USB connection.

The memory card interface 214 is configured to allow a memory card 216 to be attached or removed, and is capable of writing data to the memory card 216 and reading various data (user programs, trace data, etc.) from the memory card 216. There is.

The internal bus interface 220 controls data communication with one or more units (including the relay unit 250) via the internal bus 6. More specifically, internal bus interface 220 includes a receive buffer 221 for holding received data and a transmit buffer 222 used for generating data to be transmitted.

Similarly to the field network 4, the internal bus 6 supports cyclic communication and message communication. As the internal bus 6, a communication method exclusive to the manufacturer may be adopted, for example, EtherCAT (registered trademark), EtherNet/IP (registered trademark), PROFINET (registered trademark), PROFIBUS (registered trademark), DeviceNet (registered trademark). Trademark), FL-net, CompoNet (registered trademark), etc. may also be used.

(c3: relay unit 250)
FIG. 5 is a block diagram showing an example of the hardware configuration of relay unit 250 of sub-control device 20 according to the present embodiment. Referring to FIG. 5, relay unit 250 includes a processing circuit 260, a field network interface 270, and an internal bus interface 280.

The processing circuit 260 realizes the processing and functions of the relay unit 250 as described below. More specifically, processing circuit 260 includes a processor 262, memory 264, and storage 266. The processor 262 reads the system program (firmware) stored in the storage 266, expands it to the memory 264, and executes it, thereby realizing necessary processing in the relay unit 250. In addition to the system program, the storage 266 stores transfer settings 268 for realizing data transfer.

Although FIG. 5 shows an example in which the transfer settings 268 are stored in the storage 266, they may be obtained from the main control device 10 and the calculation unit 200 as necessary. That is, the transfer settings 268 are not stored in advance in the storage 266 of the relay unit 250, and the transfer settings are acquired from each of the main controller 10 and the calculation unit 200 when the relay unit 250 is started. You can.

The transfer settings 268 mainly include settings for transferring I/O data between the main control device 10 and the arithmetic unit 200 by cyclic communication. Note that the transfer settings 268 may include settings necessary for transferring I/O data between the main control device 10 and the arithmetic unit 200 by message communication.

The field network interface 270 controls data communication with the main controller 10 via the field network 4. More specifically, field network interface 270 includes a reception buffer 271 for holding received data and a transmission buffer 272 used for generating data to be transmitted.

The internal bus interface 280 controls data communication with one or more units (including the arithmetic unit 200) via the internal bus 6. More specifically, internal bus interface 280 includes a receive buffer 281 for holding received data and a transmit buffer 282 used for generating data to be transmitted.

(c4: Other configurations)
FIGS. 3 to 5 show configuration examples in which necessary functions are provided by a processor executing a program, but some or all of these provided functions can be implemented using dedicated hardware circuits (e.g. , an ASIC (Application Specific Integrated Circuit), an FPGA (Field-Programmable Gate Array), etc.).

In this specification, a "processor" is not limited to a narrowly defined processor that executes processing using a stored program method, but may include hard-wired circuits such as ASIC and FPGA. Therefore, the term "processor" can also be read as a processing circuitry whose processing is predefined by computer readable code and/or hardwired circuitry.

The main part of the arithmetic unit may be realized using hardware that follows a general-purpose architecture (for example, an industrial personal computer based on a general-purpose personal computer). In this case, virtualization technology may be used to run multiple OSs (Operating Systems) for different purposes in parallel, and to run necessary applications on each OS.

(c5: Support device 300)
The support device 300 according to this embodiment is configured, for example, by a general-purpose computer that follows a general-purpose architecture. Since examples of the hardware configuration of general-purpose computers are well known, detailed explanations will not be provided.

<D. Data communication>
Next, data communication in the control system 1 according to this embodiment will be explained.

FIG. 6 is a schematic diagram showing an overview of data communication in the control system 1 according to the present embodiment. FIG. 6 shows an example of transmission of I/O data between the main controller 10 and the arithmetic unit 200.

Referring to FIG. 6, a relay unit 250 is arranged as a gateway between main controller 10 and arithmetic unit 200. The main control device 10 and the relay unit 250 are connected via a field network 4 corresponding to a first transmission path.

It is assumed that the output data of the main controller 10 is transmitted to the arithmetic unit 200 via the relay unit 250 and the case that the output data of the arithmetic unit 200 is transmitted to the main controller 10 via the relay unit 250. Ru. In this embodiment, for both types of transmission, a method using cyclic communication and a method using message communication are possible.

In a general control system, I/O data is transmitted only by cyclic communication, but in this embodiment, cyclic communication is It is also possible to choose between communication and message communication.

The data (output data) transmitted from the main control device 10 is transmitted to the relay unit 250. Relay unit 250 transmits data received as output data from main controller 10 to arithmetic unit 200 as input data to arithmetic unit 200 .

On the other hand, data (output data) transmitted from the calculation unit 200 is transmitted to the relay unit 250. Relay unit 250 transmits the data received as output data of arithmetic unit 200 to main control device 10 as input data of main control device 10 .

In this way, the relay unit 250 transfers data between the main control device 10 and the calculation unit 200. That is, the relay unit 250 transmits the output data transmitted from the main controller 10 (first controller) through cyclic communication to the arithmetic unit 200 (second controller) according to the transfer setting 268 (FIG. 5), and also Output data sent from the device 10 via message communication is sent to the arithmetic unit 200.

Similarly, the relay unit 250 transmits the output data transmitted from the arithmetic unit 200 through cyclic communication to the main controller 10 according to the transfer settings 268, and also controls the output data transmitted from the arithmetic unit 200 through message communication to the main controller 10. Send to device 10.

At this time, the relay unit 250 transmits the output data transmitted from the main controller 10 through cyclic communication to the calculation unit 200 through cyclic communication, and transmits the output data transmitted from the main controller 10 through message communication through the message communication. Alternatively, the data may be transmitted to the calculation unit 200. Alternatively, the method of transmitting data from main controller 10 to relay unit 250 and the method of transmitting data from relay unit 250 to calculation unit 200 may be different.

In cyclic communication, data is transmitted every predetermined transmission cycle, so the latest data is always available at the destination.

FIG. 7 is a schematic diagram showing an example of a data structure used for data communication in the control system 1 according to the present embodiment.

Referring to FIG. 7, in the field network 4, communication bands are divided for each transmission cycle. Each transmission cycle includes a cyclic communication band 12 and a message communication band 14. In the cyclic communication band 12, a frame 16 having a predetermined data size is transmitted. The frames 16 are sequentially transferred between devices (units) connected to the field network 4. As a result, the frame 16 cyclically circulates through the field network 4.

In the cyclic communication band 12, an area is prepared for writing output data for each device connected to the field network 4. FIG. 7 shows an example in which N areas are prepared for each of N devices to write output data. A device connected to the field network 4 can refer to data stored in an area other than the area for writing data (that is, data written by another device).

Furthermore, in the cyclic communication band 12, in addition to an area where output data can be written, an area is also provided to store management information (communication management information 18) necessary for communication.

On the other hand, the message communication band 14 is transmitted from a designated device to one or more other devices according to instructions from a device (for example, referred to as a "communication master" or "master") that manages the field network 4. Used for message communication. Note that in message communication, data with a larger data size than that sent in one cyclic communication may be transmitted, so one data transmission requires the bandwidth for multiple cyclic communications. Sometimes it's necessary.

Note that in the internal bus 6 as well, similarly to FIG. 7, communication bands are divided for each transmission period, and each transmission period includes a cyclic communication band and a message communication band.

FIG. 8 is a diagram for explaining processing in relay unit 250 in control system 1 according to the present embodiment.

Referring to FIG. 8, relay unit 250 includes a field network interface 270 connected to field network 4 and an internal bus interface 280 connected to internal bus 6.

The field network interface 270 has a reception buffer 271 and a transmission buffer 272. The reception buffer 271 holds data received from the main control device 10, and the transmission buffer 272 holds data to be sent to the main control device 10.

The internal bus interface 280 has a receive buffer 281 and a transmit buffer 282. The reception buffer 281 holds data received from the calculation unit 200, and the transmission buffer 282 holds data to be sent to the calculation unit 200.

The relay unit 250 copies the data held by the receive buffer 271 of the field network interface 270 to the send buffer 282 of the internal bus interface 280, and also copies the data held by the receive buffer 281 of the internal bus interface 280 to the field. Copy the data to the transmission buffer 272 of the network interface 270.

The relay unit 250 realizes data transfer by copying data between buffers.

<E. I/O data transmission using cyclic communication>
Next, I/O data transmission by cyclic communication in the control system 1 according to the present embodiment will be explained.

FIG. 9 is a diagram for explaining I/O data transmission by cyclic communication in the control system 1 according to the present embodiment. FIG. 9 shows a frame 16A that cyclically circulates through the field network 4 and a frame 16B that cyclically circulates through the internal bus 6.

FIG. 9(A) shows a processing example for realizing data transmission from the main controller 10 to the arithmetic unit 200. Referring to FIG. 9(A), main controller 10 writes output data to the area allocated to frame 16A. Frame 16A is then transmitted to relay unit 250.

The relay unit 250 extracts the output data of the main control device 10 included in the frame 16A, and writes the extracted output data of the main control device 10 in the area allocated to the frame 16B. That is, frame 16B includes output data of main controller 10 as output data of relay unit 250. Frame 16B is then sent to computing unit 200. Arithmetic unit 200 extracts the output data of relay unit 250 (output data of main controller 10) included in frame 16B as input data.

FIG. 9(B) shows an example of processing for realizing data transmission from the sub-control device 20 to the main control device 10. Referring to FIG. 9(B), arithmetic unit 200 writes output data to the area allocated to frame 16B. Frame 16B is then transmitted to relay unit 250.

The relay unit 250 extracts the output data of the arithmetic unit 200 included in the frame 16B, and writes the extracted output data of the arithmetic unit 200 to the area allocated to the frame 16A. That is, frame 16A includes output data of arithmetic unit 200 as output data of relay unit 250. Thereafter, frame 16A is transmitted to main controller 10. The main control device 10 extracts the output data of the relay unit 250 (output data of the arithmetic unit 200) included in the frame 16A as input data.

As shown in FIG. 9, the relay unit 250 exchanges (copies) data between the frame 16A that cyclically circulates through the field network 4 and the frame 16B that cyclically circulates the internal bus 6. , realizes I/O data transmission by cyclic communication.

<F. I/O data transmission via message communication>
Next, I/O data transmission by message communication in the control system 1 according to the present embodiment will be explained. I/O data transmission by message communication may employ either a sequential transmission method or a temporary retention method, for example.

(f1: sequential transmission method)
The relay unit 250 sequentially transmits the output data transmitted from the main control device 10 through message communication to the calculation unit 200 through message communication, and also transmits the output data transmitted from the calculation unit 200 through message communication to the main control device through message communication. 10 may be transmitted sequentially.

FIG. 10 is a diagram for explaining I/O data transmission by message communication (sequential transmission method) in the control system 1 according to the present embodiment.

Referring to FIG. 10, in message communication of the sequential transmission method, data (output data) transmitted from main controller 10 to relay unit 250 by message communication is then transferred from relay unit 250 to arithmetic unit as input data. 200 by message communication. Similarly, data (output data) transmitted from the arithmetic unit 200 to the relay unit 250 by message communication is then transmitted as input data from the relay unit 250 to the main controller 10 by message communication.

In this way, in the sequential transmission method, when the relay unit 250 receives data from the main controller 10 or the arithmetic unit 200 through message communication, the relay unit 250 transmits the received data to the arithmetic unit 200 or the main controller 10 through the message communication. . Here, data transmission by message communication is performed sequentially depending on the availability of the message communication band 14 of the field network 4 and the internal bus 6.

In the sequential transmission method, after the relay unit 250 receives data, a delay may occur depending on the priority of message communication until the data is transmitted to the destination. However, basically, the data is transmitted in the order in which the relay unit 250 receives the data.

(f2: Temporary holding method)
In the temporary holding method, the relay unit 250 temporarily holds data received from the transmission source through message communication, and then the transmission destination acquires the data through message communication.

That is, even if the relay unit 250 holds the output data sent from the main controller 10 by message communication, and also sends the held data to the calculation unit 200 in response to access from the calculation unit 200. good. Conversely, the main control device 10 holds the output data sent from the relay unit 250 through message communication, and also sends the held data to the calculation unit 200 in response to access from the main control device 10. You can.

In this way, the relay unit 250 receives access from the destination and reads the data to be transmitted. Therefore, the relay unit 250 may notify the data destination that it holds the data. Upon receiving this notification, the destination accesses (polles) the relay unit 250.

That is, the relay unit 250 notifies the calculation unit 200 that it holds the output data sent from the main controller 10 through message communication, and also holds the output data sent from the calculation unit 200 through message communication. The main control device 10 may be notified that the

FIG. 11 is a diagram for explaining I/O data transmission by message communication (temporary holding method) in the control system 1 according to the present embodiment.

Referring to FIG. 11(A), main controller 10 transmits data to relay unit 250 by message communication. Relay unit 250 holds data from main controller 10 .

Referring to FIG. 11(B), relay unit 250 notifies that it holds data from main controller 10. This notification is realized, for example, by setting the data presence flag included in the output data of the relay unit 250 to ON. That is, the data presence flag is included in frames that circulate cyclically.

Referring to FIG. 11(C), in response to the data presence flag being set to ON, the arithmetic unit 200 acquires the data held in the relay unit 250 through message communication. When the data is acquired by the calculation unit 200, the relay unit 250 sets the data presence flag to OFF. Note that the relay unit 250 may delete the data it has held, or may hold the data as is until it receives new data.

In this way, the relay unit 250 notifies the arithmetic unit 200 through cyclic communication that it holds the output data transmitted from the main controller 10 through message communication, and also notifies the arithmetic unit 200 that it holds the output data transmitted from the arithmetic unit 200 through message communication. The main control device 10 may be notified by cyclic communication that the output data is held.

FIG. 12 is a diagram for explaining processing related to the data presence flag shown in FIG. 11.
Referring to FIG. 12, when main controller 10 transmits data to relay unit 250 by message communication, relay unit 250 holds the data from main controller 10. In response to data being held, the data presence flag is set to ON.

The arithmetic unit 200 recognizes that data is held in the relay unit 250 (data exists) by setting the data presence flag to ON. The arithmetic unit 200 then accesses the relay unit 250 and acquires the data (more specifically, reads the data).

Since the data presence flag is included in the output data of the relay unit 250, it can be referenced from the application executed by the arithmetic unit 200 (and the main control device 10). Therefore, by including in the application a code that controls the timing of access to the relay unit 250, data can be exchanged using only a data presence flag (a type of interlock signal) related to data exchange.

Note that, for convenience of explanation, FIGS. 11 and 12 show an example in which data is transmitted from the main controller 10 to the arithmetic unit 200 of the sub-control device 20. However, the same applies when transmitting data from the arithmetic unit 200 of the sub-control device 20 to the main control device 10.

Here, an example of a procedure for transmitting data through message communication will be described. The control system 1 according to this embodiment employs a master-slave communication system. For example, in the field network 4, the main controller 10 serves as a communication master (hereinafter simply referred to as "master"), and the relay unit 250 serves as a communication slave (hereinafter simply referred to as "slave").

FIG. 13 is a sequence diagram showing an example of a procedure for data transmission by message communication in the control system 1 according to the present embodiment. Referring to FIG. 13, in field network 4 to which main controller 10 and relay unit 250 are connected, frames circulate at every transmission cycle.

The cyclically circulating frame includes communication management information 18 (see FIG. 7) in addition to I/O data. Communication management information 18 may include a message presence flag for requesting message communication by relay unit 250, which is a slave. That is, the main control device 10, which is the master, manages the field network 4 and therefore knows the available bandwidth, so it performs message communication at an appropriate timing.

On the other hand, the relay unit 250, which is a slave, does not know when to perform message communication. Therefore, when the relay unit 250 becomes in a state where message communication is necessary, it sets the message presence flag of the communication management information 18 to ON. The main controller 10, which is the master, accesses the relay unit 250 in response to the message presence flag included in the communication management information 18 being set to ON, and transmits data to be transmitted by message communication. read out.

In FIG. 13, the communication management information 18 whose message presence flag is set to ON is represented by a solid line, and the communication management information 18 whose message presence flag is set to OFF is represented by a broken line.

Exchange using the message presence flag included in the communication management information 18 is realized by, for example, a field network interface or an internal bus interface. In this case, the application (user program) executed by the main control device 10 and the arithmetic unit 200 may perform processing to request data transmission.

More specifically, when an application requests data transmission, main controller 10 writes a message containing the requested data to relay unit 250. Relay unit 250 processes the written messages. For example, processing for holding data included in a message is performed.

When the relay unit 250 completes the processing of the message, it prepares a response to the writing of the message and sets the message presence flag of the communication management information 18 to ON. The main control device 10 accesses the relay unit 250 and reads the response from the relay unit 250. The application of the main control device 10 confirms that the message writing was successful based on the read response. Then, data transmission through a series of message communications is completed.

The application of the main control device 10 understands that data transmission is completed based on the response read information.

Although FIG. 13 shows an example in which data is transmitted from the main control device 10 to the relay unit 250 by message communication, data may also be transmitted from the arithmetic unit 200 of the sub-control device 20 to the relay unit 250 by message communication. The same is true.

FIG. 13 shows an example in which a response is read by setting the message presence flag to ON in the communication management information 18, but the same process is performed when any data other than the response is sent from the slave to the master. executed.

FIG. 14 is a sequence diagram showing an example of a data transfer procedure in the control system 1 according to the present embodiment. FIG. 14 shows a process when data is transferred from the main control device 10 to the arithmetic unit 200 of the sub-control device 20 via the relay unit 250. However, the same applies to the case where data is transferred from the arithmetic unit 200 of the sub-control device 20 to the main control device 10 via the relay unit 250.

Referring to FIG. 14, a frame 16A that circulates through the field network 4 at each transmission cycle and a frame 16B that circulates through the internal bus 6 at each transmission cycle are shown. Frame 16A includes a data presence flag 22A as part of the output data of relay unit 250. Further, the frame 16A includes communication management information 18A in addition to I/O data. Similarly, frame 16B includes data presence flag 22B as part of the output data of relay unit 250. Further, the frame 16B includes communication management information 18B in addition to I/O data.

In FIG. 14, the state in which the data presence flags 22A and 22B are set to ON is represented by a solid line, and the state in which the data presence flags 22A and 22B are set to OFF is represented by a broken line. Further, the communication management information 18A, 18B whose message presence flag is set to ON is represented by a solid line, and the communication management information 18A, 18B whose message presence flag is set to OFF is represented by a broken line.

Referring to FIG. 14, when the application of main controller 10 requests data transmission (sequence SQ2), main controller 10 writes a message containing the requested data to relay unit 250 (sequence SQ4). Relay unit 250 processes the written message (sequence SQ6).

When the relay unit 250 completes the processing of the message, it prepares a response to the writing of the message and sets the message presence flag of the communication management information 18A to ON (sequence SQ8). Main controller 10 accesses relay unit 250 and reads the response from relay unit 250 (sequence SQ10). The application of the main control device 10 confirms that the message writing was successful based on the read response (sequence SQ12). This completes data transmission by message communication from main controller 10 to relay unit 250.

On the other hand, the relay unit 250 sets the data presence flag 22B to ON (sequence SQ12). The application of the arithmetic unit 200 requests data acquisition (reading) in response to the data presence flag 22B being set to ON (sequence SQ14). Then, main controller 10 accesses relay unit 250 and reads data held in relay unit 250 (sequence SQ16).

When the data is read, the relay unit 250 processes the message (data) it holds and prepares a response to the message read (sequence SQ18). Then, the relay unit 250 sets the message presence flag of the communication management information 18B to ON (sequence SQ20).

The arithmetic unit 200 accesses the relay unit 250 and reads the response from the relay unit 250 according to the message presence flag included in the communication management information 18B (sequence SQ22). The application of the arithmetic unit 200 confirms that the message has been successfully read based on the read response (sequence SQ24). This completes the data transmission from the relay unit 250 to the arithmetic unit 200 by message communication.

<G. Processing procedure example>
Next, an example of a processing procedure of relay unit 250 in control system 1 according to the present embodiment will be described.

FIG. 15 is a flowchart illustrating an example of a processing procedure for I/O data transmission by cyclic communication of relay unit 250 according to the present embodiment. Each step shown in FIG. 15 may be realized by the processor 262 of the relay unit 250 executing a system program.

Referring to FIG. 15, relay unit 250 determines whether the frame update cycle via field network 4 has arrived (step S2). When the frame update period via the field network 4 arrives (YES in step S2), the relay unit 250 extracts the output data of the main controller 10 included in the received frame (step S4), and is held in the transmission buffer associated with the internal bus 6 (step S6). The relay unit 250 then reconstructs the frame including the data held in the transmission buffer associated with the field network 4 (step S8), and transmits the reconstructed frame via the field network 4 (step S10). ).

It is determined whether the frame update cycle via the internal bus 6 has arrived (step S12). When the update cycle of the frame via the internal bus 6 arrives (YES in step S12), the relay unit 250 extracts the output data of the arithmetic unit 200 included in the received frame (step S14), and transmits the extracted data. It is held in the transmission buffer associated with the field network 4 (step S16). The relay unit 250 then reconstructs the frame including the data held in the transmission buffer associated with the internal bus 6 (step S18), and transmits the reconstructed frame via the internal bus 6 (step S20). ).

Thereafter, the processes of steps S2 to S20 are repeated.
FIG. 16 is a flowchart illustrating an example of a processing procedure for I/O data transmission (sequential transmission method) by relay unit 250 through message communication according to the present embodiment. Each step shown in FIG. 16 may be realized by the processor 262 of the relay unit 250 executing a system program.

Referring to FIG. 16, relay unit 250 determines whether the message presence flag of communication management information 18 of the frame cyclically circulating on internal bus 6 is ON (step S30). If the message presence flag of the communication management information 18 of the frame cyclically circulating on the internal bus 6 is OFF (NO in step S30), the relay unit 250 receives the message from the main controller 10 via the field network 4. It is determined whether data has been received (step S32). That is, it is determined whether data has been received from the main controller 10 in a state where data can be transmitted to the arithmetic unit 200.

If data is received by message communication from the main controller 10 via the field network 4 (YES in step S32), the relay unit 250 holds the received data in the buffer associated with the internal bus 6 (step S34). Then, the relay unit 250 sets the message presence flag of the communication management information 18 of the frame cyclically circulating on the internal bus 6 to ON (step S36).

If data is not received by message communication from the main control device 10 via the field network 4 (NO in step S32), the processes of steps S34 to S36 are skipped.

If the message presence flag of the communication management information 18 of the frame cyclically circulating on the internal bus 6 is ON (YES in step S30), the relay unit 250 determines whether the arithmetic unit 200 has read the data held in the buffer. It is determined whether or not (step S38). If the arithmetic unit 200 has not read the data held in the buffer (NO in step S38), the process of step S40 is skipped.

If the arithmetic unit 200 has read the data held in the buffer (YES in step S38), the relay unit 250 turns off the message presence flag of the communication management information 18 of the frame cyclically circulating the internal bus 6. settings (step S40). Then, the processing from step S30 onwards is repeated.

In parallel, the relay unit 250 determines whether the message presence flag of the communication management information 18 of the frame cyclically circulating in the field network 4 is ON (step S50). If the message presence flag of the communication management information 18 of the frame cyclically circulating in the field network 4 is OFF (NO in step S50), the relay unit 250 receives data from the arithmetic unit 200 via the internal bus 6 by message communication. is received (step S52). That is, it is determined whether data has been received from the arithmetic unit 200 in a state where data can be transmitted to the main control device 10.

If data is received by message communication from the main controller 10 via the internal bus 6 (YES in step S52), the relay unit 250 holds the received data in a buffer associated with the field network 4 (step S54). Then, the relay unit 250 sets the message presence flag of the communication management information 18 of the frame cyclically circulating the field network 4 to ON (step S56).

If data is not received by message communication from the arithmetic unit 200 via the internal bus 6 (NO in step S52), the processes of steps S54 to S56 are skipped.

If the message presence flag of the communication management information 18 of the frame cyclically circulating in the field network 4 is ON (YES in step S50), the relay unit 250 reads the data held in the buffer by the main controller 10. It is determined whether or not it has been completed (step S58). If the main controller 10 has not read the data held in the buffer (NO in step S58), the process in step S60 is skipped.

If the main controller 10 has read the data held in the buffer (YES in step S58), the relay unit 250 turns off the message presence flag of the communication management information 18 of the frame cyclically circulating the field network 4. (step S60). Then, the processing from step S50 onwards is repeated.

FIG. 17 is a flowchart illustrating an example of a processing procedure for I/O data transmission (temporary holding method) by message communication of the relay unit 250 according to the present embodiment. Each step shown in FIG. 17 may be realized by the processor 262 of the relay unit 250 executing a system program.

Referring to FIG. 17, relay unit 250 determines whether the data presence flag of the frame cyclically circulating on internal bus 6 is ON (step S70). If the data presence flag of the frame cyclically circulating on the internal bus 6 is OFF (NO in step S70), the relay unit 250 determines whether the data has been received by message communication from the main controller 10 via the field network 4. It is determined whether or not (step S72). That is, it is determined whether data has been received from the main controller 10 in a state where data can be transmitted to the arithmetic unit 200.

If data is received by message communication from the main controller 10 via the field network 4 (YES in step S72), the relay unit 250 holds the received data in the buffer associated with the internal bus 6 (step S72). S74). Then, the relay unit 250 sets the data presence flag of the frame cyclically circulating on the internal bus 6 to ON (step S76).

If data is not received by message communication from the main control device 10 via the field network 4 (NO in step S72), the processes of steps S74 to S76 are skipped.

If the data presence flag of the frame cyclically circulating on the internal bus 6 is ON (YES in step S70), the relay unit 250 determines whether or not the arithmetic unit 200 has read the data held in the buffer. (Step S78). If the arithmetic unit 200 has not read out the data held in the buffer (NO in step S78), the processes in steps S80 to S84 are skipped.

If the arithmetic unit 200 has read the data held in the buffer (YES in step S78), the relay unit 250 prepares a response (step S80), and determines whether the arithmetic unit 200 has read the response. (Step S82). If the arithmetic unit 200 has not read the response (NO in step S82), the process of step S82 is repeated.

If the arithmetic unit 200 has read the response (YES in step S82), the relay unit 250 sets the data presence flag of the frame cyclically circulating on the internal bus 6 to OFF (step S84). Then, the processing from step S70 onwards is repeated.

In parallel, the relay unit 250 determines whether the data presence flag of the frame cyclically circulating in the field network 4 is ON (step S90). If the data presence flag of the frame cyclically circulating through the field network 4 is OFF (NO in step S90), the relay unit 250 determines whether data has been received by message communication from the arithmetic unit 200 via the internal bus 6. (Step S92). That is, it is determined whether data has been received from the arithmetic unit 200 in a state where data can be transmitted to the main control device 10.

If data is received by message communication from the arithmetic unit 200 via the internal bus 6 (YES in step S92), the relay unit 250 holds the received data in the buffer associated with the field network 4 (step S94). ). Then, the relay unit 250 sets the data presence flag of the frame cyclically circulating in the field network 4 to ON (step S96).

If data is not received by message communication from the arithmetic unit 200 via the internal bus 6 (NO in step S92), the processing in steps S94 to S96 is skipped.

If the data presence flag of the frame cyclically circulating in the field network 4 is ON (YES in step S90), the relay unit 250 determines whether the main controller 10 has read the data held in the buffer. (Step S98). If the main control device 10 has not read the data held in the buffer (NO in step S98), the processes in steps S100 to S104 are skipped.

If the main controller 10 has read the data held in the buffer (YES in step S98), the relay unit 250 prepares a response (step S100) and determines whether the main controller 10 has read the response. A judgment is made (step S102). If the main controller 10 has not read the response (NO in step S102), the process of step S102 is repeated.

If the main control device 10 has read the response (YES in step S102), the relay unit 250 sets the data presence flag of the frame cyclically circulating the field network 4 to OFF (step S104). Then, the processing from step S90 onwards is repeated.

<H. User interface example>
Next, an example of a user interface for creating transfer settings 268 for relay unit 250 in control system 1 according to the present embodiment will be described.

FIG. 18 is a schematic diagram showing an example of a user interface for creating transfer settings 268 for relay unit 250 in control system 1 according to the present embodiment. For example, the support device 300 provides the user interface shown in FIG.

Referring to FIG. 18, a setting screen 350 displays a setting item group 352 for data to be transferred from the arithmetic unit 200 to the main controller 10, and a setting item group 354 for data to be transferred from the main controller 10 to the arithmetic unit 200. include. Each of the setting item groups 352 and 354 includes multiple types of settings according to data structure and data type. The setting screen 350 includes a data candidate group 356 to be data transferred.

The user selects the target item from the setting item groups 352 and 354, and then selects the data to be transferred from the data candidate group 356. By pressing the add button 358, the selected data is added as a transfer target, and by pressing the delete button 360, the selected data is deleted from the transfer target.

The transfer settings 268 created by the user by operating the settings screen 350 are stored in the relay unit 250, and the corresponding settings are also stored in the main controller 10 and the calculation unit 200.

Note that the user interface is not limited to the example shown in FIG. 18, and any interface may be provided, or the transfer settings 268 may be created using any method without providing a user interface.

Furthermore, the user interface may not be provided by the support device 300, but may be provided directly by the calculation unit 200 or the relay unit 250. In this case, for example, a web server function may be incorporated into the computing unit 200 or the relay unit 250.

In this way, the control system 1 may provide a user interface for creating the transfer settings 268 in response to user operations.

<I. Additional notes＞
This embodiment as described above includes the following technical idea.

[Configuration 1]
a first controller (10) having an interface (120) for connecting to the first transmission path (4);
a second controller (200) having an interface (220) for connecting to the second transmission path (6);
comprising a relay unit (250) having a first interface (270) for connecting to the first transmission line and a second interface (280) for connecting to the second transmission line,
The relay unit transmits the output data transmitted from the first controller through cyclic communication to the second controller according to the transfer setting (268), and transmits the output data transmitted from the first controller through message communication to the second controller. A control system transmitting to a second controller.

[Configuration 2]
The relay unit transmits the output data transmitted from the first controller by cyclic communication to the second controller by cyclic communication, and transmits the output data transmitted from the first controller by message communication to the second controller by message communication. The control system according to configuration 1, transmitting to the second controller.

[Configuration 3]
The relay unit transmits output data transmitted from the second controller through cyclic communication to the first controller, and transmits output data transmitted from the second controller through message communication to the first controller. , the control system according to configuration 1 or 2.

[Configuration 4]
4. The control system according to any one of configurations 1 to 3, wherein the relay unit sequentially transmits the output data transmitted from the first controller by message communication to the second controller by message communication.

[Configuration 5]
The relay unit holds the output data transmitted by message communication from the first controller, and transmits the held data to the second controller in response to access from the second controller. 4. The control system according to any one of 4.

[Configuration 6]
6. The control system according to configuration 5, wherein the relay unit notifies the second controller that it holds the output data transmitted from the first controller by message communication.

[Configuration 7]
7. The control system according to configuration 6, wherein the relay unit notifies the second controller by cyclic communication that it holds the output data transmitted from the first controller by message communication.

[Configuration 8]
The control system according to any one of configurations 1 to 7, wherein the control system provides a user interface (350) for creating the transfer settings in response to a user operation.

[Configuration 9]
A relay unit (250) connected to the first controller (10) via the first transmission line (4) and connected to the second controller via the second transmission line (6),
a first interface (270) for connecting to the first transmission line;
a second interface (280) for connecting to the second transmission path;
Sending the output data sent from the first controller through cyclic communication to the second controller according to transfer settings (268), and sending the output data sent from the first controller through message communication to the second controller. A relay device comprising a processing circuit (260).

[Configuration 10]
A first controller (10) having an interface (120) for connecting to the first transmission line (4), and a second controller (200) having an interface (220) for connecting to the second transmission line. A communication method in a control system (1), comprising:
transmitting the output data transmitted by cyclic communication from the first controller to the second controller according to the transfer settings (S4 to S10);
A communication method comprising the step of transmitting output data transmitted from the first controller by message communication to the second controller (S30 to S40; S70 to S84).

The embodiments disclosed this time should be considered to be illustrative in all respects and not restrictive. The scope of the present invention is indicated by the claims rather than the above description, and it is intended that equivalent meanings and all changes within the scope of the claims are included.

1 Control system, 4 Field network, 6 Internal bus, 10 Main controller, 12 Cyclic communication band, 14 Message communication band, 16, 16A, 16B frame, 18, 18A, 18B Communication management information, 20 Sub-control device , 22A, 22B data presence flag, 100, 200 arithmetic unit, 102, 202, 262 processor, 104, 204 chipset, 106, 206, 264 memory, 108, 208, 266 storage, 110, 210 upper network interface, 112, 212 Interface, 114, 214 Memory card interface, 116, 216 Memory card, 120, 270 Field network interface, 121, 221, 271, 281 Reception buffer, 122, 222, 272, 282 Transmission buffer, 131, 231 System program, 132 , 232 User program, 220, 280 Internal bus interface, 250 Relay unit, 260 Processing circuit, 268 Transfer settings, 300 Support device, 350 Setting screen, 352, 354 Setting item group, 356 Data candidate group, 358 Add button, 360 Delete button.

Claims (10)

1. a first controller having an interface for connecting to the first transmission path;
   a second controller having an interface for connecting to a second transmission path;
   a relay unit having a first interface for connecting to the first transmission line and a second interface for connecting to the second transmission line,
   The relay unit transmits output data transmitted from the first controller through cyclic communication to the second controller according to transfer settings, and transmits output data transmitted from the first controller through message communication to the second controller. control system.
2. The relay unit transmits the output data transmitted from the first controller by cyclic communication to the second controller by cyclic communication, and transmits the output data transmitted from the first controller by message communication to the second controller by message communication. The control system of claim 1, wherein the control system transmits to a second controller.
3. The relay unit transmits output data transmitted from the second controller through cyclic communication to the first controller, and transmits output data transmitted from the second controller through message communication to the first controller. , the control system according to claim 1 or 2.
4. The control system according to any one of claims 1 to 3, wherein the relay unit sequentially transmits the output data transmitted from the first controller by message communication to the second controller by message communication.
5. 2. The relay unit retains the output data transmitted by message communication from the first controller, and transmits the retained data to the second controller in response to access from the second controller. 4. The control system according to any one of items 4 to 4.
6. The control system according to claim 5, wherein the relay unit notifies the second controller that it holds the output data transmitted from the first controller by message communication.
7. The control system according to claim 6, wherein the relay unit notifies the second controller by cyclic communication that it holds the output data transmitted from the first controller by message communication.
8. The control system according to any one of claims 1 to 7, wherein the control system provides a user interface for creating the transfer settings in response to a user operation.
9. A relay unit connected to a first controller via a first transmission path and connected to a second controller via a second transmission path,
   a first interface for connecting to the first transmission line;
   a second interface for connecting to the second transmission line;
   A processing circuit that transmits output data transmitted from the first controller through cyclic communication to the second controller according to transfer settings, and transmits output data transmitted from the first controller through message communication to the second controller. A relay device comprising:
10. A communication method in a control system comprising a first controller having an interface for connecting to a first transmission path, and a second controller having an interface for connecting to a second transmission path,
    transmitting the output data transmitted by cyclic communication from the first controller to the second controller according to the transfer settings;
    A communication method comprising the step of transmitting output data transmitted by message communication from the first controller to the second controller.

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