CN105519050B - Control system and relay - Google Patents

Abstract

In the control system with dual control device and data transmission path, even if the amount of data transmitted to the control device increases, it will not hinder the execution of the original calculation of the control device, and will not cause the switching speed of the working system/standby system to slow down And carry out the equalization of monitoring data. The first equalization cables are used to connect the control devices of the working system and the standby system, and the second equalization cables are used to connect the network devices of the working system and the standby system to each other. Each network device is caused to transmit the monitoring data received from the IO slave device to the control device of the connection destination, and each network device is caused to determine whether communication via the second equalized cable is possible. If the communication is possible, each network device performs equalization of the monitoring data by communication via the second equalization cable, and if the communication is not possible, the monitoring data is equalized by communication via the first equalization cable. Each network device performs equalization of monitoring data.

Description

Control system and relay device

technical field

The present invention relates to a control system including control devices of working system and standby system and its relay device.

Background technique

In many industrial facilities such as factories and various factories, a communication system called a control system is constructed to control various operations. The control system includes a control device that collects monitoring data from sensors installed in industrial facilities, and performs drive control of motors and the like based on the collected results. As such a control device, a DCS (Distributed Control System: Distributed Control System) or a Programmable Logic Controller (Programmable Logic Controller) is used. Hereinafter, a device such as a motor to be controlled by the control device is referred to as a "control target device", and a device such as the above-mentioned sensor to which the control device collects monitoring data and the control target device are referred to as an "IO slave device". The IO slaves are connected to a network or serial bus called an IO network. The control device is connected to the IO network via a network device such as a relay device. An example of the relay device is a gateway device. In addition, below, a programmable logic controller is expressed as "PLC". PLCs are often used as control devices in general FA (Factory Automation) systems, and DCSs are often used as control devices in factory equipment requiring high reliability. This is because DCS is more reliable than PLC.

In such a control system, in general, in order to avoid downtime due to a failure of the control device or the like, duplication of the control device and duplication of data transmission paths for monitoring data are performed. The duplication of the control devices means that two control devices are installed, one of which is operated as a working system device, and the other is operated as a standby system device. These two control devices respectively collect monitoring data, and perform predetermined calculations for facility control using the collected monitoring data, or using the collected monitoring data and past calculation results. The work-system control device performs control based on the calculation result, and the standby-system control device is used to prevent the work-system control device from stopping. Then, when the work-system control device is about to stop or has stopped, the standby-system control device operates as the work-system device and continues equipment control. Here, as specific examples of stoppage of the work system control device, unexpected stoppage due to occurrence of some kind of failure or malfunction, planned stoppage due to maintenance, etc. can be considered. The standby system control device is used to guard against both of these two stoppages. The duplication of the data transmission path refers to, for example, separately separating the data transmission path from the IO slave device to one of the duplexed control devices and the data transmission path from the IO slave device to the other duplexed control device. set up. Hereinafter, a control system in which both the control device and the data transmission path are duplicated is referred to as a "redundant control system".

FIG. 18 is a diagram showing a configuration example of a redundant control system. The system shown in FIG. 18 is a control system that collects monitoring data output from IO slave devices S1 to Sn such as various sensors installed in industrial facilities, and uses these monitoring data or uses the monitoring data and past calculation results. , to perform a prescribed calculation, and to control the operation of the motor and the like based on the result of the calculation. In addition, n is a natural number of 2 or more. This control system includes two control devices, two control devices 10A and 10B, and two network devices, two network devices 20A and 20B. In the system shown in FIG. 18 , one of the control device 10A and the control device 10B serves as a work-system device, and the other serves as a standby-system device to prevent stoppage of the work-system device. A monitoring system 50 for monitoring the operating states of the control device 10A and the control device 10B is connected to the control device 10A and the control device 10B. In addition, the control device 10A is connected to the IO network 30A via the network device 20A, and the control device 10B is connected to the IO network 30B via the network device 20B. Each of the IO slave devices S1 to Sn is connected to both the IO network 30A and the IO network 30B.

In the system shown in FIG. 18 , the control device 10A and the control device 10B are connected to each other by an equalization cable 40 so that each can monitor the other's state. As mentioned above, the standby system control device is used to prevent unexpected stop due to failure of the work system control device or planned stop such as maintenance, etc., and the case of stop due to failure will be described below as an example. Each of the control device 10A and the control device 10B transmits state data indicating the presence or absence of a failure, that is, the state of the own device, to the other party via the equalization cable 40 . For example, when control device 10A is an operating system device, control device 10B, which is a standby system device, refers to status data sent from control device 10A via equalization cable 40 to monitor failure occurrence in control device 10A. Then, when the control device 10B detects a failure of the control device 10A from the state data received via the equalization cable 40 , it starts to operate as a work-system device thereafter. On the other hand, the control device 10A detects that the control device 10B has started to operate as an active system device through communication via the equalization cable 40 , and then operates as a standby system device.

In the redundant control system, even if the control device of the working system fails, it is possible to continue to collect data from the IO slave devices S1 to Sn by switching between the working system and the standby system, and to perform calculations based on the collected results, and Control is performed based on the result of this calculation. However, if only switching between the active system and the standby system is performed, problems such as sudden changes in the above-mentioned calculation results may occur before and after the switching. This is because the monitoring data transmitted from the IO slaves S1 to Sn to the control device 10A and the control device 10B are not necessarily completely identical.

In order to avoid such troubles, in a redundant control system, each control device generally executes the equalization of the monitoring data sent from the IO slave devices S1 to Sn to each control device, and the equalization of the calculation results. class processing. The equalization of monitoring data refers to sending the monitoring data received by the operating system control device via the network device to the standby system control device through the equalization cable 40, and using the monitoring data to overwrite the monitoring data received by the standby system control device via the network. received monitoring data. In addition, the equalization of the calculation result refers to sending data representing the calculation result in the operating system device to the standby system control device through the equalization cable 40 and overwriting the calculation result in the standby system device with the data. As an example of the prior art related to such a redundant control system and equalization, the technique disclosed by patent document 1 and patent document 2 is mentioned.

Patent Document 1: Japanese Patent Laid-Open No. 2013-12094

Patent Document 2: Japanese Patent Laid-Open No. 2013-152631

Contents of the invention

The problem to be solved by the invention

In recent years, with the diversification and increase in the number of IO slave devices included in the control system, and the increase in data transmission speed in the IO network, the amount of monitoring data sent to the control device via the network device per unit time has increased significantly. . If the amount of monitoring data received by the control device via the network device increases, the processing load of equalization processing for these monitoring data will increase, and there may be cases where it is difficult to understand the original role of the control device, that is, for equipment control. The execution of the operation, and the control of the device corresponding to the result of the operation allocate sufficient resources. In addition, in recent years, there has been an increasing need to connect a plurality of network devices to one control device, but the same problem arises when the number of network devices connected to the control device increases. Furthermore, if the amount of monitoring data per unit time received by the control device via the network device increases, there is also a problem that switching between the active system and the standby system cannot be quickly performed when the active system fails. This is because, as described above, unless the equalization of the monitoring data received by the control device via the network device is completed, switching between the active system and the standby system cannot be performed while avoiding sudden changes in calculation results.

The present invention has been made in view of the problems described above, and an object of the present invention is to provide a technique in which, in a redundant control system, even if the amount of monitoring data transmitted to each control device via a network increases, the control device Equalization of monitoring data is performed without causing any obstacle in the execution of the original calculation and without incurring a decrease in the switching speed of the active system/standby system.

solutions to problems

In order to solve the above problems, the present invention provides a control system having the following first control device, second control device, first relay device, and second relay device as slaves connected to the first network and the second network A control system in which one or more devices collect monitoring data and control based on that monitoring data. The first control device and the second control device are connected via an inter-control device communication unit. The inter-control device communication unit is, for example, an equalized cable, and mediates (Japanese: broker) the communication between the first control device and the second control device. One of the first control device and the second control device is a working system device to perform the control, and the other is a standby system device. Specific examples of the first relay device and the second relay device include the aforementioned network devices. The first relay device is connected to the first control device and the first network, and the second relay device is connected to the second control device and the second network. The first relay device and the second relay device are connected to the inter-relay device communication unit. The inter-relay device communication unit is, for example, an equalized cable, and mediates the communication between the first relay device and the second relay device. The first relay device and the second relay device include a judging unit for judging whether communication can be performed via the inter-relay device communication unit. The first relay device and the second relay device respectively transmit the monitoring data received from one or a plurality of devices to the control device of the connection destination, and, when it is determined by the determination unit that communication is possible, transmit the monitoring data via the relay Equalization of monitoring data is performed by communicating with the device-to-device communication unit. On the other hand, when it is determined by the determination means that communication is impossible, the first relay device and the second relay device perform equalization of the monitoring data by communication via the inter-control device communication means.

In the control system of the present invention, the equalization of the monitoring data transmitted from each device to the first control device and the second control device is performed by the first relay device and the second relay device. Therefore, even if the amount of monitoring data increases, the processing load on each of the first control device and the second control device does not become excessively high due to the equalization of the monitoring data, and each of the first control device and the second control device There will be no hindrance in the execution of the above operations in . In addition, the data equalized by the first relay device and the second relay device are provided to the first control device and the second control device, respectively. Therefore, when one of the first control device and the second control device functions as an active system device, the other functions as a standby system device, and the operation system/standby system is switched by stopping the operation system device, In the case of , it is possible to quickly switch between the active system and the standby system without waiting for the completion of equalization of the monitoring data.

In the conventional redundant control system shown in FIG. 18, when the equalization cable 40 connecting the control device 10A and the control device 10B is cut, the monitoring data cannot be equalized at all. . On the other hand, in the control system of the present invention, the communication unit that mediates data communication for equalizing monitoring data is doubled by the communication unit between control devices and the communication unit between relay devices. It is possible to perform communication via either one, and it is possible to perform equalization of monitoring data without any problem. In addition, the first control device and the second control device may also be made to execute the following process: determine whether communication can be performed via the communication unit between control devices, and if communication is possible, send and receive information indicating that there is an error in the device through the communication unit between control devices. If there is no fault status data, the other party is monitored for faults, and if communication is not possible, the other party is monitored for faults by sending and receiving status data via the communication unit between relay devices. In addition, the relay device pair included in the control system of the present invention, that is, the relay device pair composed of the first relay device and the second relay device that communicate via the inter-relay device communication unit is not limited to one, It can also be multiple. Specifically, the following mode may be considered: a plurality of first relay devices and a plurality of second relay devices are provided, and the plurality of first relay devices are respectively connected to a plurality of first networks to which different devices are respectively connected. , and are respectively connected to the first control device, the plurality of second relay devices are respectively paired with the plurality of first relay devices, are respectively connected to a plurality of second networks connected with the above-mentioned devices, and are connected to the second The control devices are respectively connected, and the relay devices that are paired with each other among the plurality of first relay devices and the plurality of second relay devices communicate through the inter-relay device communication unit.

Here, various methods are conceivable as a concrete realization method of the equalization of monitoring data by communication via the inter-relay device communication means. A method may be considered in which monitoring data is transmitted from one of the first relay device and the second relay device to the other, and the other relay device executes using the monitoring data received via the inter-relay device communication unit. Overwrite the monitoring data received via the network, that is, execute the processing of replacing the latter monitoring data with the former monitoring data. For example, monitoring data is sent from one relay device connected to the work-system control device to the other relay device, and the other relay device receives the monitoring data via the inter-relay device communication unit or the inter-control device communication unit. Surveillance data received over the network.

In addition, in another preferred mode, a mode in which the following first processing unit and second processing unit are respectively provided in the first relay device and the second relay device may be considered. The first processing unit transmits the monitoring data received from the network of the connection destination to the relay device of the other party. In more detail, when it is determined that communication is possible by the above-mentioned determination unit, the first processing unit transmits the monitoring data to the other relay device via the communication unit between relay devices, and when it is determined that communication is impossible, The first processing unit transmits the monitoring data to the other relay device via the inter-control device communication unit. The second processing unit confirms whether it is possible to communicate with the device of the source of the monitoring data received from the other relay device, and if communication is not possible, the monitoring data that should have been received from the device is used from the other party's relay device. It complements the monitoring data received by the relay device. In the conventional redundant control system, when the network connected to the relay device that transmits the monitoring data to the work system control device fails, or the IO master that connects each device to the network fails Even in the event of a failure, it is necessary to switch between the active system and the standby system. On the other hand, according to this aspect, it is not necessary to switch between the active system and the standby system due to a failure of the network or the like, and the frequency of switching between the active system and the standby system can be reduced. This point will be described in detail using a fourth embodiment of the present invention.

In a more preferable aspect, either one of the first relay device and the second relay device is connected to the third network. And, the relay device connected to the third network collects monitoring data from the equipment connected to the third network, transmits the collected monitoring data to the control device of the connection destination, and transmits to the other relay device to make it equal. If a non-duplicated network is connected to the relay device of the conventional redundant control system shown in Figure 18, there will be various problems, and this connection method cannot be easily adopted. The details are specified in the description of the method. On the other hand, according to this aspect, a non-duplex network can be easily connected to such a relay device.

In addition, in another preferred aspect, the first relay device and the second relay device include load measuring means for measuring a processing load borne by a control device of a connection destination, and the first relay device When the processing load measured by the load measurement unit is equal to or greater than a predetermined threshold and the determination unit determines that communication is possible with the second relay device, the device and the second relay device monitor by communicating through the inter-relay device communication unit. In other cases, the equalization of data is carried out by communication via the communication means between control devices. According to this aspect, the data communication for equalizing the monitoring data can be duplexed while distributing the processing load on each of the first control device and the second control device.

In addition, in order to solve the above-mentioned problems, the present invention provides the following communication interface unit and control unit in the relay device, wherein the relay device and a first control unit that controls one as an active system and the other as a standby system One of the device and the second control device is connected, and is connected to the first network to which one or more devices that transmit monitoring data are connected, and transmits the monitoring data sent from the one or more devices to the control device of the connection destination . The communication interface unit is connected to other relay devices via inter-relay device communication means. The other relay device is connected to the second network to which one or more devices are connected, and the other of the first control device and the second control device. The control unit is, for example, a CPU (Central Processing Unit: Central Processing Unit). This control unit executes the following relay processing, determination processing, and equalization processing. The relay process is a process of transmitting monitoring data received from one or a plurality of devices via the first network to a control device of a connection destination. The judging process is a process of judging whether communication can be performed via the inter-relay device communication unit. Furthermore, the equalization process is a process of performing communication for equalizing the monitoring data via the inter-relay device communication unit when it is determined that the communication is possible by the determination process, and on the other hand, when the determination process is determined When the communication is not possible, the communication for equalizing the monitoring data is performed via the inter-control device communication means. In the redundant control system, by replacing the relay device connecting the control device and the data transmission path, that is, the network device 20A and the network device 20B in the system example shown in FIG. 18, with the relay device of the present invention, This existing redundant control system can be made to function as the control system of this invention.

In addition, as another means for solving the above-mentioned problems, it is conceivable to provide a program that causes a general computer such as a CPU to function as the above-mentioned relay device. This is because, by operating a general computer according to such a program, the computer can be made to function as the relay device of the present invention. In addition, the following methods are conceivable as specific ways of providing the above-mentioned program: a method of distributing by downloading via an electric communication line such as the Internet; writing to a CD-ROM (Compact Disk-Read Only Memory: Compact Disk A method of distributing in a computer-readable recording medium such as a flash ROM.

The effect of the invention

As described above, according to the present invention, in the redundant control system, even if the amount of monitoring data transmitted to each control device via the network increases, it is possible to prevent any obstacle to the execution of the original calculation of the control device, and Equalization of monitoring data is performed without incurring a reduction in the switching speed of the active system/standby system.

Description of drawings

FIG. 1 is a diagram showing a configuration example of a communication system 1A including a network device 200 as an example of a relay device of the present invention, that is, a communication system according to a first embodiment of the present invention.

FIG. 2 is a diagram showing a configuration example of a network device 200 included in the communication system 1A.

FIG. 3 is a flowchart showing the flow of equalization processing 2542 b executed by the control unit 210 of the network device 200 according to the relay control program 2542 .

FIG. 4 is a diagram for explaining operations executed by the control unit 210 of the network device 200 according to the relay control program 2542 .

FIG. 5 is a diagram for explaining the effect of the first embodiment.

FIG. 6 is a diagram for explaining a modified example of the first embodiment.

FIG. 7 is a diagram for explaining another modified example of the first embodiment.

FIG. 8 is a diagram showing a configuration example of a network device 200' according to the second embodiment of the present invention.

FIG. 9 is a diagram showing a schematic configuration and an operation example of a communication system including the network device 200'.

FIG. 10 is a diagram for explaining a third embodiment of the present invention.

FIG. 11 is a diagram for explaining a fourth embodiment of the present invention.

FIG. 12 is a diagram showing a configuration example of a network device 200"' according to the fourth embodiment.

FIG. 13 is a diagram for explaining operations executed by the control unit 210 of the network device 200"' in accordance with the relay control program 2542"'.

FIG. 14 is a flowchart showing the flow of equalization reception processing 2542b2 executed by the control unit 210 in accordance with the relay control program 2542'''.

FIG. 15 is a diagram for explaining the effects of the fourth embodiment.

FIG. 16 is a diagram for explaining the effects of the fourth embodiment.

FIG. 17 is a diagram for explaining a modified example of the fourth embodiment.

FIG. 18 is a diagram showing a conventional example of a control system.

Detailed ways

Embodiments of the present invention will be described below with reference to the drawings.

(A: first embodiment)

FIG. 1 is a diagram showing a configuration example of a communication system 1A according to a first embodiment of the present invention.

This communication system 1A is a control system installed in an industrial facility similarly to the system shown in FIG. 18 described above. In FIG. 1 , the same reference signs are assigned to the same constituent elements as those in FIG. 18 . Comparing FIG. 1 with FIG. 18 clearly shows that the communication system 1A is different from the conventional redundant control system shown in FIG. 18 in the following three points. First, a control device 100A and a control device 100B are provided instead of the control device 10A and the control device 10B. Second, a network device 200A and a network device 200B are provided instead of the network device 20A and the network device 20B. Then, thirdly, the network device 200A and the network device 200B are connected through the equalization cable 400 .

The network device 200A and the network device 200B are each an embodiment of the relay device of the present invention, and the equivalent cable 400 serves as an inter-relay device communication unit that mediates communication between the relay devices. . The network device 200A and the network device 200B are gateway devices similarly to the network device 20A and the network device 20B in FIG. 18 . In the communication system 1A shown in FIG. 1 , the monitoring data respectively sent from the IO slave devices S1, S2...Sn are transmitted to the control device 100A via the IO network 30A and the network device 200A, and are transmitted to the control device 100A via the IO network 30B and the network device 200B. transmitted to the control device 100B. The control device 100A and the control device 100B perform calculations using the monitoring data collected from the IO slave devices S1, S2...Sn and past calculation results, that is, perform calculations for the control device 10A and the control device 10B in FIG. A device-controlled operation that stores the result of that operation. The control device 100A and the control device 100B may be a PLC or a DCS.

In the communication system 1A shown in FIG. 1 , one of the control device 100A and the control device 100B is an operating system device that controls other equipment based on the above calculation results, and the other is a standby system device that prevents the operating system device from stopping. . As mentioned above, the stoppage of work-system devices includes the following two types: unexpected stoppage due to occurrence of certain failures or adverse conditions; and preplanned stoppage due to maintenance and the like. Furthermore, when the work-system device is stopped, the control device that is originally the standby-system device operates as the work-system device thereafter. In addition, switching between the working system and the standby system can be realized by the same method as that of the conventional redundant control system.

As mentioned above, in order to avoid sudden changes in the calculation results when switching between the working system and the standby system, it is necessary to equalize the monitoring data and the calculation results. In the conventional redundant control system shown in FIG. 18, the control device 10A and the control device 10B perform equalization of monitoring data and equalization of calculation results. Also in this embodiment, the equalization of calculation results is performed by the control device 100A and the control device 100B, and this point is not changed from the conventional redundant control system shown in FIG. 18 . Described in more detail, one of the control device 100A and the control device 100B, which is an operating system device, uses monitoring data received from a connected network device to perform calculations for device control, and data representing the results of the calculations The calculation result is equalized by transmitting to the other control device via the equalization cable 40 . That is, the standby system control device overwrites the data of the calculation result in its own device with the data received via the equalization cable 40 . The communication system 1A of the present embodiment differs from the conventional redundant control system shown in FIG. 18 in that the network device 200A and the network device 200B perform equalization of monitoring data. The following description focuses on the network device 200A and the network device 200B that notably exhibit the features of the present embodiment. In addition, since the network device 200A and the network device 200B have the same configuration, they will be described as "network device 200" below when there is no need to distinguish between them.

In this embodiment, the network device 200 is also classified into an active system and a standby system. More specifically, the network device 200 communicates with its own control device at the connection destination, and determines whether the control device at the connection destination is an operating system device. Then, if the control device at the connection destination is an active system device, the network device 200 operates as an active network device, and conversely, if the control device at the connection destination is a standby system device, the network device 200 operates as a standby network device. action. That is, in the present embodiment, one of the network device 200A and the network device 200B that is connected to the operation-system control device is an operation-system device, and one that is connected to the standby-system control device is a standby-system device. Furthermore, when switching between the active system and the standby system of the control device occurs, the network device 200 also switches between the active system and the standby system in connection with the switching. In the present embodiment, the case where switching of the operating system/standby system for the network device 200 is accompanied by switching of the operating system/standby system for the control device is described. The state of the other party is monitored by transmitting and receiving state data, and the operation/standby state of the network device 200 is switched independently of the operation/standby state switching of the control device based on the result of the state monitoring.

FIG. 2 is a block diagram showing a configuration example of the network device 200 .

As shown in FIG. 2 , the network device 200 includes a control unit 210, a first communication interface (hereinafter referred to as “I/F”) unit 220, a second communication I/F unit 230, a third communication I/F unit 240, The storage unit 250 and the bus 260 mediate the data exchange between these structural elements.

The control unit 210 is, for example, a CPU. The control unit 210 functions as a control center of the network device 200 by executing the relay control program 2542 stored in the storage unit 250 . More precisely, the relay control program 2542 is stored in the nonvolatile storage unit 254 . The nonvolatile storage unit 254 is one of a plurality of constituent elements constituting the storage unit 250 . The details of the processing executed by the control unit 210 according to the relay control program 2542 will be clearly described later. The first communication I/F unit 220 , the second communication I/F unit 230 , and the third communication I/F unit 240 are, for example, NICs (Network Interface Cards). The roles of these communication I/F units are as follows.

The first communication I/F unit 220 is connected to the IO network. More specifically, the first communication I/F unit 220 of the network device 200A is connected to the IO network 30A, and the first communication I/F unit 220 of the network device 200B is connected to the IO network 30B. The first communication I/F unit 220 receives data transmitted from the IO network of the connection destination and sends data to the IO network of the connection destination. The first communication I/F unit 220 has a communication buffer that stores data received from the IO network of the connection destination. In FIG. 2 , illustration of this communication buffer is omitted.

The second communication I/F unit 230 is connected to the control device via a communication line. More specifically, the second communication I/F unit 230 of the network device 200A is connected to the control device 100A, and the second communication I/F unit 230 of the network device 200B is connected to the control device 100B. The second communication I/F unit 230 receives data transmitted from the control device of the connection destination and sends data to the control device of the connection destination. The second communication I/F unit 230 has a communication buffer for storing data to be transmitted to the control device of the connection destination. In FIG. 2 , illustration of this communication buffer is omitted.

The third communication I/F unit 240 has a port for connecting an equalization cable, and the equalization cable 400 is connected to this port. The third communication I/F unit 240 communicates with the other network device via the equalization cable 400 for equalization of monitoring data.

As shown in FIG. 2 , the storage unit 250 has a volatile storage unit 252 and a nonvolatile storage unit 254 . The volatile storage unit 252 is, for example, RAM (Random Access Memory: Random Access Memory). The volatile storage section 252 is used as a work area for executing the relay control program 2542 . In addition, the volatile storage unit 252 also functions as a monitoring data buffer 2522 that temporarily stores monitoring data transmitted to the control device. In addition, the volatile storage unit 252 stores an active/standby flag indicating whether the network device 200 having the volatile storage unit 252 is operating as an active system device or as a standby system device. The nonvolatile storage unit 254 is, for example, a flash ROM. The relay control program 2542 is stored in advance in the nonvolatile storage unit 254 .

The control unit 210 reads the relay control program 2542 from the nonvolatile storage unit 254 to the volatile storage unit 252 when the network device 200 is powered on or reset, and starts executing the program. In FIG. 2 , the illustration of the power supply of the network device 200 is omitted. The control unit 210 operating in accordance with the relay control program 2542 executes the relay process 2542a and equalization, in addition to the process of monitoring the operating state of the control device at the connection destination and setting the active/standby flag based on the monitoring result. Process 2542b. The details of the relay processing 2542a and the equalization processing 2542b are clarified in the operation example, and their outlines are as follows. The equalization process 2542 b is a process of equalizing the monitoring data collected from the IO slave devices S1 to Sn by communication via the equalization cable 400 . FIG. 3 is a flowchart showing the flow of the equalization process 2542b. Referring to FIG. 3 , it is clear that the processing content of the equalization process 2542b is different when operating as an active system device and when operating as a standby system device. The details of the processing content of this equalization processing 2542b will be clarified in the description of the operation example. The relay process 2542a is a process of transferring the monitoring data equalized by the equalization process 2542b to the control device connected to the second communication I/F unit 230 .

The above is the configuration of the network device 200 .

Next, the operation of the network device 200 will be described with reference to FIGS. 3 and 4 . In addition, in the operation examples described below, it is assumed that the control device 100A and the network device 200A are operating system devices, and the control device 100B and network device 200B are standby system devices. In addition, in the operation examples described below, a case will be described in which the monitoring data buffers 2522 of the network device 200A and the network device 200B are empty at the time of operation start.

The IO slave devices S1 to Sn respectively sample input signals or output signals of sensors to generate monitoring data to be sent to the control device 100A and the control device 100B, and send the monitoring data to the IO network 30A and the IO network 30B, respectively. The monitoring data transmitted from the IO slaves S1 to Sn is provided with a header including information indicating the destination and source of the monitoring data, an identifier uniquely indicating the monitoring data, and the like. Specific examples of the information indicating the destination of the monitoring data include the communication address and the node number of the device of the destination. The same applies to the information indicating the source of the monitoring data. The monitoring data transmitted from the IO slave devices S1 to Sn are respectively transmitted to the network device 200A and the network device 200B via the IO network 30A and the IO network 30B, respectively. Hereinafter, the monitoring data transmitted to the network device 200A is referred to as "monitoring data A", and the monitoring data transmitted to the network device 200B is referred to as "monitoring data B". The monitoring data A and the monitoring data B are basically the same data, but may be slightly different due to a deviation in sampling timing when each monitoring data is sampled.

When the first communication I/F unit 220 of the network device 200A receives the monitoring data transmitted from the IO network 30A, it writes the received monitoring data into the communication buffer in the first communication I/F unit 220 . Similarly, in the network device 200B, the monitoring data received from the IO network 30B is written into the communication buffer of the first communication I/F unit 220 of the network device 200B. That is, in this operation example, the monitoring data A is stored in the communication buffer in the first communication I/F unit 220 of the network device 200A, and the monitoring data B is stored in the first communication I/F unit 220 of the network device 200B. within the communication buffer.

The control unit 210 of the network device 200A is executing when the monitoring data is written into the communication buffer in the first communication I/F unit 220 , in other words, when the monitoring data is received from the IO network 30A of the connection destination. Process 2542a continues. As shown in FIG. 4, in the relay processing 2542a, the control unit 210 reads the monitoring data from the communication buffer in the first communication I/F unit 220 ((A): S100 in FIG. 2522 writes the monitoring data ((A) of FIG. 4 : S110 ). Therefore, in this operation example, the monitoring data A is stored in the monitoring data buffer 2522 of the network device 200A. The processes of S100 and S110 are similarly executed in the network device 200B (see (B) of FIG. 4 ), and the monitoring data B is stored in the monitoring data buffer 2522 . In addition, when writing monitoring data into the monitoring data buffer 2522, the control unit 210 sets a first value indicating that it has not been equalized to the flag indicating whether it has been equalized, and gives the flag with the first value set to the above-mentioned After monitoring the data, the monitoring data is written into the monitoring data buffer 2522 . As a specific example of the first value, 0 is mentioned.

In the network device 200A, the control unit 210 executes the equalization process 2542 b when the monitoring data to which the flag indicating that the equalization is not performed is written into the monitoring data buffer 2522 . As shown in FIG. 3 , in the equalization process 2542b, the control unit 210 first determines whether or not the own device is operating as a work-system device (step SA100 ). Specifically, the control unit 210 refers to the active/standby flag stored in the volatile storage unit 252 , and if the value of the flag is a value indicating an operating system device, it determines that the own device is operating as an operating system device. Then, if the determination result of step SA100 is "Yes", the control unit 210 executes the processing of step SA110, otherwise, if the determination result of step SA100 is "No", the control unit 210 executes the processing after step SA120. As described above, in this operation example, the network device 200A operates as a work-system device. Therefore, in the equalization process 2542b executed by the control unit 210 of the network device 200A, the determination result of step SA100 is "Yes", and the process of step SA110 is executed.

In step SA110 executed when the determination result of step SA100 is "Yes", the control unit 210 reads out the monitor data to which the flag indicating that the equalization is not performed is given from the monitor data buffer 2522 (FIG. 4(A) : S120), and transmit the monitoring data to the network device of the connection destination via the third communication I/F unit 240 ((A) of FIG. 4 : S130). As described above, the monitoring data A is stored in the monitoring data buffer 2522 of the network device 200A as the monitoring data to which the flag indicating that it has not been equalized is added. Therefore, in this operation example, the monitoring data A is transmitted from the network device 200A to the network device 200B via the equalization cable 400 .

In the network device 200B, the control unit 210 executes the equalization process 2542b when the third communication I/F unit 240 receives the data transmitted via the equalization cable 400 as an opportunity. The above-described determination in step SA100 is also performed in the equalization process 2542b executed by the control unit 210 of the network device 200B. In this operation example, network device 200B operates as a standby device, so the determination result of step SA100 in equalization process 2542b executed by control unit 210 of network device 200B is "No", and the processing after step SA120 is executed. In step SA120, the control unit 210 acquires the monitoring data received through the third communication I/F unit 240 from the third communication I/F unit 240 ((B) of FIG. 4 : S140 ), and uses the monitoring data to overwrite For the corresponding monitoring data stored in the monitoring data buffer 2522 ( FIG. 4(B): S150 ), the flag given to the monitoring data is rewritten to a second value indicating that it has been equalized. The above-mentioned corresponding monitoring data refers to the monitoring data whose transmission source is the same as the monitoring data acquired through S140 of (B) in FIG. 4 and whose identifier is consistent with the monitoring data acquired through S140 of (B) in FIG. 4 . Moreover, 1 is mentioned as a specific example of the said 2nd value. As a result, the monitoring data stored in the monitoring data buffer 2522 of the network device 200B is updated from the monitoring data B to the monitoring data A.

When the control unit 210 of the network device 200B completes the equalization of the monitoring data as described above, it notifies the network device 200A of the completion of the equalization via the equalization cable 400 ( FIG. 3 : step SA130 ). The control unit 210 of the network device 200A updates the flag of the monitoring data transmitted in S130 of FIG. 4(A) to the second value when the notification is received. As a result of the above operations, the monitoring data A is stored in the monitoring data buffer 2522 of the network device 200A and the network device 200B, and the monitoring data A is given a flag indicating that it has been equalized.

The control unit 210 of the network device 200A restarts the relay process 2542a and executes (A) of FIG. Each processing of S160 and S170. In the process of S160 , the control unit 210 reads out the monitor data to which the flag indicating equalization has been given from the monitor data buffer 2522 . Then, in the process of S170 , the control unit 210 writes the monitoring data read in S160 into the communication buffer of the second communication I/F unit 230 . The network device 200B also restarts the relay process 2542a upon transmission of the equalization completion notification, and executes the processes of S160 and S170 in (B) of FIG. 4 .

The second communication I/F unit 230 of the network device 200A transmits the monitoring data written in the communication buffer in the manner described above to the control device of the connection destination. Similarly, the second communication I/F unit 230 of the network device 200B transmits the monitoring data written in the communication buffer in the manner described above to the control device of the connection destination. Therefore, in this operation example, the monitoring data A is transmitted from the network device 200A to the control device 100A, and the monitoring data A is also transmitted from the network device 200B to the control device 100B. In addition, since the notification can be transmitted and received at a sufficiently high speed compared with the transmission and reception of monitoring data, the update of the above-mentioned flags in the network device 200A and the network device 200B are executed substantially synchronously, and each of S160 and S170 Processing is also performed approximately synchronously. Therefore, the transmission of the monitoring data A from the network device 200A to the control device 100A and the transmission of the monitoring data A from the network device 200B to the control device 100B are executed substantially synchronously.

The above is the operation of this embodiment.

In the conventional redundant control system shown in FIG. 18, the control devices, that is, the control device 10A and the control device 10B, equalize the monitoring data. Therefore, there is a problem that when the data volume of the monitoring data increases, the The amount of equalization increases the processing load on the control device, which hinders the high-speed execution of original calculations. FIG. 5 is a schematic diagram of a communication system 1A according to this embodiment. In this embodiment, although the equalization of calculation results is performed by the control device 100A and the control device 100B through communication via the equalization cable 40 in FIG. 5 , the equalization of monitoring data is performed by the network The device 200A and the network device 200B are performed by communication via the equalization cable 400 in FIG. 5 . Therefore, even if the amount of monitoring data transmitted to the control device 100A and the control device 100B increases due to an increase in the number of IO slave devices connected to the IO network, etc., the processing load on the control device 100A and the control device 100B will not be as much as it is. The amount of equalization increases accordingly, and there is no obstacle in the execution of the original calculation.

In addition, in this embodiment, the equalized monitoring data is transmitted from the network device 200A to the control device 100A via the communication line LA in FIG. From the network device 200B to the control device 100B. Furthermore, the equalization of the calculation result based on the monitoring data is realized by communication via the equalization cable 40 in FIG. 5 . Since the equalized monitoring data is transmitted to the control device 100A and the control device 100B, even if the operation system/standby system is switched due to the stop of the operation system control device, there is no need to wait for the monitoring data in the control device. Equalization is done, but can be switched immediately. That is, according to the present embodiment, the switching speed between the active system and the standby system does not decrease.

To summarize the above-mentioned contents, according to this embodiment, a control system is provided, which collects monitoring data from one or more devices connected to the first network and the second network, and performs control based on the monitoring data. , the control system is characterized in that it has: a first control device and a second control device, one of the first control device and the second control device is used as a working device for control, and the other is a standby device; the first A relay device, which is connected to the first control device and the first network; a second relay device, which is connected to the second control device and the second network; a communication unit between control devices, which communicates between the first control device and the second control device The communication of the device is mediated; and the inter-relay device communication unit is used to mediate the communication between the first relay device and the second relay device, wherein the first relay device and the second relay device are respectively connected to the The control device at the destination transmits the monitoring data received from one or more devices, and performs communication for equalizing the monitoring data via the communication unit between relay devices, and the first control device and the second control device One of the operating system devices uses the monitoring data received from the relay device of the connection destination to perform calculations for control, and transmits the calculation results to the control device that is a standby system device via the inter-control device communication unit. The calculation result is equalized. That is, in the present invention, one of the first control device and the second control device that becomes the work-system device uses the monitoring data received from the relay device of the connection destination to perform calculations for control, and the The calculation result is transmitted to the control device serving as the standby system device via the inter-control device communication means. Therefore, only the calculation results that do not include the monitoring data can be equalized between the control devices. Incidentally, only calculation results can be equalized between the control devices of the present invention. Therefore, according to the present embodiment, in the redundant control system, even if the data amount of the monitoring data transmitted to the control device increases, it is possible not to cause any obstacle to the execution of the original calculation of the control device, and not to cause a problem between the active system and the standby system. The switching speed is reduced.

In addition, in the conventional redundant control system shown in FIG. 18, the only unit that mediates the data communication between the active system device and the standby system device is the unit that mediates the communication between the control devices. The equalization cable 40 of the inter-device communication unit is controlled. Therefore, when the equalization cable 40 is cut, the data communication between the active system device and the standby system device cannot be performed, and even the communication for mutual status monitoring cannot be performed. . Therefore, in the conventional redundant control system, there is the following problem: when the equalization cable 40 is cut off, it is already impossible to switch between the active system device and the standby system device. In the event of multiple failures such as failures, it becomes impossible to control the equipment at all.

On the other hand, in this embodiment, the means for mediating data communication between the active system device and the standby system device is doubled by the equalization cable 40 and the equalization cable 400, so even if Even if the equivalent cable 40 is cut, communication for mutual state monitoring will not become impossible. For example, even if the equalization cable 40 is cut at the position indicated by the mark B in FIG. Send and receive status data. Specifically, it is possible to cause the control device 100A to execute the process of transmitting the state data indicating the state of its own device to the control device 100B via the communication line LA, the network device 200A, the equalization cable 400, the network device 200B, and the communication line LB. The processing causes the control device 100B to execute the process of transmitting the state data indicating the state of the own device to the control device 100A via the communication line LB, the network device 200B, the equalization cable 400 , the network device 200A, and the communication line LA.

In addition, in the embodiment described above, one network device is connected to one control device, but as shown in FIG. 7 , a modification may be made such that a plurality of network devices are connected to one control device. In the system shown in FIG. 7, two network devices are connected to one control device. This is because, in the conventional redundant control system, when a plurality of network devices are connected to the control device, the data volume of the monitoring data transmitted to the control device increases, which causes problems in the execution of the original calculation of the control device. , or a decrease in the switching speed of the active system/standby system, etc., but in this embodiment, such a problem does not occur.

Even when a plurality of network devices 200 are connected to one control device as shown in FIG. The equalization of the monitoring data transmitted by the device 100A and the control device 100B is performed by the network device 200C and the network device 200D through communication via the equalization cable 400B. Equalization of monitoring data. Therefore, even if the amount of monitoring data transmitted to the control device increases due to the connection of a plurality of network devices to one control device, the processing load on the control device does not increase corresponding to the equivalent value.

(B: Second Embodiment)

In the first embodiment described above, a case was described in which the network device 200A and the network device 200B perform equalization of monitoring data by communication through the equalization cable 400 . However, this method has a problem that, when the equalization cable 400 is cut, the monitoring data cannot be equalized. The network device 200A' and the network device 200B' of this embodiment aim to solve this problem. The network device 200A' and the network device 200B' of this embodiment determine whether data communication is possible via the equalization cable 400, and when the determination result that data communication is possible is obtained, the network device 200B' through the equalization cable 400 Equalization of monitoring data through data communication. On the other hand, when the determination result that data communication is not possible is obtained, the network device 200A' and the network device 200B' perform monitoring data communication through the communication via the control device 100A, the equalization cable 40, and the control device 100B. Equalization. Hereinafter, when it is not necessary to distinguish between the network device 200A' and the network device 200B', it is expressed as "the network device 200'".

FIG. 8 is a diagram showing a configuration example of a network device 200'. Comparing FIG. 8 with FIG. 2, it can be clearly seen that the structure of the network device 200' is different from that of the network device 200 in the following respects: instead of the relay control program 2542, the relay control program 2542' is stored in the non-volatile in the storage unit 254 . The relay control program 2542' is a program that causes the control unit 210 to execute the relay processing 2542a, the equalization processing 2542b', and the determination processing 2542c. The judgment process 2542c is a process of judging whether communication can be performed via the equalized cable 400 which is the inter-relay device communication unit. The equalization process 2542b' is a process of performing communication for equalizing monitoring data via the inter-relay device communication means when it is determined that the communication is possible in the determination process 2542c, and on the other hand, when it is determined that the communication is possible. If the communication is not possible, the communication is performed via the equalization cable 40 which is the communication means between control devices. That is, the control unit 210 that operates in accordance with the relay control program 2542' functions as a relay unit that executes the relay process 2542a, a judgment unit that executes the judgment process 2542c, and an equalization unit that executes the equalization process 2542b'. .

FIG. 9 is a diagram showing a schematic configuration and an operation example of a control system including the network device 200'. In addition, in FIG. 9, a network device is abbreviated as "NW device". In addition, in FIG. 9 , in order to clarify the characteristics of this embodiment, it is clearly shown that the network device 200 ′ has a determination unit. If the equalization cable 400 is disconnected at the position indicated by the mark B in FIG. 9 , the network device 200A′ and the network device 200B′ cannot communicate via the equalization cable 400 . In this case, the network device 200A' and the network device 200B' perform data communication along the communication path C2 indicated by the dotted arrow in FIG. 9 to perform equalization of the monitoring data. In more detail, the network device 200A' transmits the monitoring data received from the IO network 30A along a transmission path sequentially passing through the communication line LA, the control device 100A, the equalization cable 40, the control device 100B, and the communication line LB. to network device 200B'. The network device 200B' receives the above-mentioned monitoring data, overwrites the corresponding monitoring data of its own device with the monitoring data, and sends back an equalization completion notice. In this way, the equalization completion notification sent back from the network device 200B' passes through the communication line LB, the control device 100B, the equalization cable 40, the control device 100A, and the communication line LA in order, and then is transmitted to the network device 200A', and the monitoring data Equalization is complete.

In the present embodiment, the control device 100A and the control device 100B function only as a data transmission path mediating data communication for equalization. Therefore, compared with the conventional redundant control system, The processing load imposed on these control devices can be reduced. As a specific example of the determination process 2542c described above, the process of sending a ping to the counterparty device via the equalization cable 400, determining that communication is possible if there is a response within a predetermined time, and determining that communication is not possible if there is no response. In addition, regarding the transmission and reception of status data between the control device 100A and the control device 100B, the transmission path may be switched depending on whether data communication is possible via the equalization cable 40 . Specifically, the control device 100A and the control device 100B may respectively execute the following process: if the data communication via the equalization cable 40 is possible, the state data is transmitted to the other control device through the equalization cable 40 , If data communication cannot be performed via the equalization cable 40 , the status data is transmitted to the other control device through the equalization cable 400 .

It is also possible to switch between performing data communication for equalizing monitoring data via the equalizing cable 400 and performing data communication for equalizing monitoring data via the equalizing cable 40 . , switching is performed not based on whether or not data communication can be performed via the equalization cable 400, but based on the processing load of the control device. For example, the control units of the network devices of the active system and the standby system may execute a process of causing the network device 200' to measure the processing load of the control device of the connection destination, and when the measured processing load is smaller than a predetermined threshold In this case, the monitoring data is equalized by data communication via each control device of the active system and the standby system and the equalization cable 40, and when the processing load of the control device is equal to or greater than a predetermined threshold value, by The data communication of the equalization cable 400 is equivalent to the monitoring data. Here, as a specific method of measuring the processing load of the control device, it is conceivable that the network device 200 executes a process of acquiring data indicating the CPU usage rate, memory usage rate, etc. of the control device from the control device of the connection destination. Furthermore, the possibility of data communication via the equalization cable 400 and the processing load of the control device may be used simultaneously to switch the transmission path of the monitoring data. Specifically, when the processing load of the control device is equal to or greater than a predetermined threshold and it is determined that communication via the equalization cable 400 is possible, the monitoring data may be performed through communication through the equalization cable 400 . In other cases, that is, when the processing load of the control device is less than a predetermined threshold or when the processing load is above a predetermined threshold but communication cannot be performed via the equalization cable 400, the Equalization of the monitoring data is performed through the communication of the quantization cable 40 .

In addition, it is also conceivable to decide in advance whether to equalize the monitoring data on the control device side or to perform monitoring data on the relay device side, that is, the network device side, for each IO slave device that is the source of the monitoring data. The equalization distribution mode distributes the processing load related to the equalization of monitoring data between the control device and the network device. For example, the monitoring data transmitted from the IO slave device S1 is equalized on the control device side, and the monitoring data transmitted from the IO slave device S2 is valued on the network device side. In this regard, it may be as follows: the control devices 100A and 100B and the network devices 200A' and 200B' store an allocation pattern table in advance. A flag indicating which of the network device side and the network device side performs equalization of the monitoring data. Then, the network devices 200A' and 200B' perform equalization on the monitoring data determined to be equalized on the relay device side in the distribution table, and the control devices 100A and 100B make the pair determined as The monitor data that is equalized on the controller side is equalized. In addition, a plurality of the above-mentioned allocation tables may be prepared according to the processing load of the control device, and the storage content may be such that the higher the processing load is, the more the monitoring data to be equivalentized on the relay device side is. many.

(C: third embodiment)

FIG. 10 is a diagram showing a configuration example of a communication system 1C according to a third embodiment of the present invention.

This communication system 1C is also a control system installed in industrial facilities. In FIG. 10 , the same elements as those in FIG. 1 are assigned the same symbols. Comparing FIG. 10 with FIG. 1 clearly shows that the communication system 1C is different from the communication system 1A in the following three points. First, a control device 100A' and a control device 100B' are provided instead of the control device 100A and the control device 100B. Second, a network device 200A" and a network device 200B" are provided instead of the network device 200A and the network device 200B. Then, thirdly, the IO network 30C is connected to the network device 200A".

IO slave devices S1' to Sn' are connected to the IO network 30C. The IO network 30C mediates the data communication between the IO slave devices S1'~Sn' and the network device 200A". As described above, the network that transmits the data sent from the IO slave devices S1~Sn to the control device passes through the IO network 30A and the IO network 30B, but this duplication is not implemented for the network that transmits the data sent from the IO slave devices S1'～Sn' to the control device. That is to say, the network device 200A" and the dualized network and unduplicated network connections. Hereinafter, a network that is not duplexed will be referred to as a "single network".

The network device 200A" relays the data communication between the IO network 30A and the control device 100A' similarly to the network device 200A in the first embodiment. The network device 200B" is also the same as the network device 200B in the first embodiment. The ground relays the data communication between the IO network 30B and the control device 100B'. In addition, the network device 200A" and the network device 200B" perform equalization of monitoring data by data communication via the equalization cable 400 similarly to the network device 200A' and the network device 200B' in the second embodiment. However, the network device 200A" and the network device 200B" are different from the network device 200 in that regardless of whether the control device of the connection destination is an active system device or a standby system device, the operation system/standby system is performed by mutual status monitoring. switch.

In addition to this, the network device 200A" and the network device 200B" also perform the same processing as the above-mentioned equalization with respect to the monitoring data received from 30 C of IO networks. That is, the control unit of the network device 200A″ transmits the monitoring data received from the IO network 30C to the network device 200B″ via the equalization cable 400, and the control unit of the network device 200B″ writes the monitoring data into the monitoring data buffer Then, the network device 200A" and the network device 200B" transmit the monitoring data transmitted from the IO network 30C to the control devices of the respective connection destinations.

The control device 100A' and the control device 100B' execute the first calculation using the data and the device control according to the calculation result of the first calculation when receiving the data transmitted from the IO slaves S1 to Sn. In addition, the work system control device executes the second calculation using the data when it receives the data transmitted from the IO slave devices S1' to Sn'. That is to say, the work system control device in this embodiment has both the function of collecting data from the IO slave devices S1-Sn to perform the first calculation and the function of collecting data from the IO slave devices S1'-Sn' to perform the second calculation. .

If in the redundant control system, the control device that collects data from the IO slave device and performs certain calculations through the dual network can also be used to collect data and perform other calculations through the single network, then there is no need to use the dual network The system and the system for single network are constructed independently, and it is expected to reduce the development and operation cost of the system, but it is difficult to meet this expectation in the conventional redundant control system. The reason for this is as follows.

For example, assume that only a single network is connected to the network device 20A in FIG. 18 . In this case, the data received from the single network and the data received from the dualized network are provided from the network device 20A to the control device 10A, while the network device 20B is provided only from the dualized network to the control device 10B. data received by the network. When the data supplied to the control device 10A and the control device 10B are inconsistency, it may be judged as an error in a redundant control system, and in such a system, the connection method as described above cannot be used originally.

In addition, even when the above-mentioned inconsistency is not judged as an error, there is a problem that when switching between the working system and the standby system occurs due to a failure of the working system control device or the like in the connection system as described above, At this time, the received data from the single network will not be provided to the switched operation system control device, so that the data sent from the single network cannot be continuously collected and the calculation using the data cannot be continued. That is, even if data via a single network can be supplied to one of the dualized control devices included in the conventional redundant control system to perform predetermined calculations, stable execution of the calculations cannot be guaranteed.

On the other hand, according to the present embodiment, even if the control device is switched between the active system and the standby system, the monitoring data received from the single network will continue to be provided to the switched active system control device, so that it can be performed without problems. Continue to collect this monitoring data and use this data to perform calculations. For example, even if the active-system device is switched from the control device 100A' to the control device 100B' in the communication system 1C shown in FIG. device. Therefore, the monitoring data sent from the IO slave devices S1' to Sn' are transmitted to the control device 100B in the following manner: IO network 30C→network device 200A″→equalized cable 400→network device 200B″→control device 100B′ '. That is to say, according to this embodiment, in the redundant control system, the control device that collects data from the IO slave device via the duplexed network and performs certain calculations can also perform the role of collecting data via the single network and performing other calculations. Therefore, it is possible to reduce the development and operation cost of the system compared to the case where the system for the dual network and the system for the single network are separately constructed. In addition, in the case where switching of the active system/standby system for the network device is accompanied by switching of the active system/standby system for the control device, it is only necessary to make the network device connected to a single network execute the following process: regardless of the Regardless of whether the network device is an operating system device, the monitoring data received via the single network is transmitted to the other network device through the communication unit between relay devices or the communication unit between control devices, so that the monitoring data can be equivalent .

(D: fourth embodiment)

FIG. 11 is a diagram showing a configuration example of a communication system 1D according to a fourth embodiment of the present invention.

This communication system 1D is also a control system installed in industrial facilities. In FIG. 11 , the same elements as those in FIG. 1 are assigned the same symbols. FIG. 11 is different from FIG. 1 in that the detailed connection form of the IO slaves S1 to S3 is connected to the IO networks 30A and 30B. As shown in FIG. 11 , the IO slaves Sn (n=1 to 3) are connected to the IO network 30A via the IO master MAn, and are connected to the IO network 30B via the IO master MBn. In addition, in FIG. 11, the IO master is abbreviated as "IOM". The IO master MAn sends the monitoring data output from the IO slave device Sn to the IO network 30A. The IO master MBn sends the monitoring data output from the IO slave device Sn to the IO network 30B. In addition, in FIG. 1 , the illustration of the detailed connection manner of the IO slave devices S1 to Sn is omitted, which is the same as that in FIG. 11 .

Comparing FIG. 11 with FIG. 1 clearly shows that the communication system 1D differs from the communication system 1A of the first embodiment in that a network device 200A"' and a network device 200B"' are provided instead of the network device 200A and the network device 200A. Device 200B. Also in the network device 200A"' and the network device 200B"' of this embodiment, one operates as an active system device, and the other operates as a standby system device. In the present embodiment, one of the network device 200A"' and the network device 200B"' connected to the work-system control device 100 operates as a work-system device similarly to the aforementioned first embodiment. Hereinafter, similarly to the description of the first embodiment, when it is not necessary to distinguish between the network device 200A"' and the network device 200B"', it will be described as "the network device 200"'".

In the conventional redundant control system shown in FIG. 18 , it is of course necessary to switch between the active system and the standby system when some kind of failure occurs in the active system control device. In the case of some kind of failure of the IO network of the IO network and the IO master connecting the IO slave device to the IO network, it is also necessary to switch between the working system and the standby system. This is because, if the above-mentioned IO network or IO master fails, monitoring data via the IO network or IO master cannot reach the work system control device. On the other hand, in this embodiment, by making the network device 200"' execute the processing unique to this embodiment, even if some kind of failure occurs in the IO network or the IO master, it is not necessary to switch between the active system and the standby system. This is the feature of this embodiment. The network device 200"' that notably exhibits the features of this embodiment will be described below.

Fig. 12 is a diagram showing a configuration example of the network device 200 "'. In Fig. 12, the same constituent elements as those in Fig. 2 are given the same symbols. Comparing Fig. 12 with Fig. 2, it is clear that , the structure of the network device 200"' is different from that of the network device 200 in that the relay control program 2542"' is stored in the nonvolatile storage unit 254 instead of the relay control program 2542. The relay control program 2542 "' is different from the relay control program 2542 of the first embodiment in that the control unit 210 executes the equalization transmission process 2542b1 and the equalization reception process 2542b2 instead of the equalization process 2542b.

The control unit 210 of the network device 200"' reads the relay control information from the nonvolatile storage unit 254 to the volatile storage unit 252 when the power supply (not shown) of the network device 200"' is turned on or reset. program 2542"', and start to execute the program. FIG. 13 is a diagram for explaining the operation performed by the control unit 210 of the network device 200"' according to the relay control program 2542"'. In FIG. 13, the The same processing in the same process is marked with the same symbol. The control unit 210 that operates according to the relay control program 2542"' is the same as the control unit 210 in the first embodiment described above, so that the monitoring data is written to the first communication The communication buffer in the I/F unit 220 executes the relay process 2542a when the monitoring data is received from the connected IO network 30 as a trigger. As mentioned above, in the relay processing 2542a, the control unit 210 reads the monitoring data from the communication buffer in the first communication I/F unit 220 (FIG. 13: S100), and writes the monitoring data into the monitoring data buffer 2522. data (FIG. 13: S110). In addition, when writing the monitor data into the monitor data buffer 2522, the point that the monitor data is written into the monitor data buffer 2522 after the flag to which the first value is not equalized is set is set, which is also the same as the first One embodiment is the same.

Comparing FIG. 13 with FIG. 4 , it is clear that the combination of the equalization transmission process 2542b1 and the equalization reception process 2542b2 corresponds to the equalization process 2542b. The execution timing of the equalization process 2542b in the first embodiment differs between the active network device and the standby network device. For example, in the operating system, the equalization process 2542b is executed when the monitor data to which the flag indicating that the value is not equalized is written into the monitor data buffer 2522, and in the standby system, the equalization process 2542b is executed via the The value conversion process 2542b is executed when the value conversion cable 400 receives the monitoring data. On the other hand, there is no difference in the execution timing of the equalization transmission process 2542b1 between the active network device and the standby system network device, and there is no difference in the execution timing of the equalization reception process 2542b2.

More specifically, regardless of whether the control unit 210 of the network device 200"' is operating as a work-system device or not, the monitoring data to which the flag indicating that it has not been equalized is written to the monitoring data buffer 2522 as a trigger. Execute the equalization transmission process 2542b1. In the equalization transmission process 2542b1, the control unit 210 reads out the monitoring data (FIG. The monitoring data is provided to the third communication I/F part 240 (FIG. 13: S130), thereby being transmitted to the network device of the other party. Therefore, in this embodiment, the monitoring data received by the network device 200A"' from the IO network 30A A is transmitted to the network device 200B"' through the equalization cable 400, and the monitoring data B received by the network device 200B"' from the IO network 30B is also transmitted to the network device 200A"' through the equalization cable 400.

The control unit 210 operating in accordance with the relay control program 2542"' executes the equalization reception process 2542b2 when monitoring data is received from the other network device 200"' via the equalization cable 400. FIG. 14 is a flowchart showing the flow of the equalization reception process 2542b2. As shown in FIG. 14 , the control unit 210 first determines whether it is possible to communicate with the IO slave device of the transmission source of the monitoring data received from the other network device 200 "' via the equalization cable 400 (step SB100). As a specific method for judging whether or not communication with the IO slave device that is the source of the monitoring data can be communicated, for example, a conventional method such as ping may be considered.

When the result of determination in step SB100 is "No", that is, when communication is impossible, the control unit 210 uses the monitoring data received from the other network device 200"' via the equalization cable 400 to supplement the original The monitoring data that should be received via the IO network 30 of the connection destination of this device, that is, the monitoring data sent to the control device 100 connected to this device (step SB110). Since it cannot communicate with the IO slave device, it will not receive the monitoring data from the IO network 30. The monitoring data of this IO slave device, step SB110 is the processing that is used for supplementing the absence of this monitoring data.More specifically, in step SB110, control part 210 will receive via equalization cable 400 the mark of monitoring data The information indicating the destination in the header is rewritten with the information indicating the control device 100 connected to this device, and the monitoring data is written into the monitoring data buffer after adding the first value indicating that the equalization is not set. 2522. Next, the control unit 210 updates the flag of the monitoring data written into the monitoring data buffer 2522 through step SB110 to a second value representing equivalent value, and notifies the other network device that the equal value is completed (step SB150), the equalization receiving process 2542b2 is completed. In addition, when the determination result of step SB100 is "No" as described above, the network device 200 "' of the other party will not be passed through the equalization cable 400 Therefore, the other network device only needs to detect the completion of the equalization and update the corresponding monitoring data flag when receiving the above-mentioned notification.

On the other hand, when the determination result in step SB100 is "YES", that is, when communication is possible, control unit 210 determines whether the own device is a work-based device (step SB120 ), similarly to step SA100 described above. When the result of determination in step SB120 is “Yes”, that is, when the own device is an operating system device, the control unit 210 transmits the monitoring data received from the other network device 200″’ via the equalization cable 400 Discard (step SB130), and the equalization flag of the monitoring data written in the monitoring data buffer 2522 corresponding to the monitoring data is updated to a second value (step SB150), and the equalization receiving process 2542b2 ends Conversely, when the determination result in step SB120 is "No", that is, if the device is a standby device, the control unit 210 uses The monitoring data received by the other network device 200"' replaces the monitoring data written in the monitoring data buffer 2522 as corresponding to the monitoring data (step SB140), and then executes the processing of step SB150, and ends. Value reception process 2542b2.

The above is the structure of the network device 200"'.

Next, this embodiment will be described by taking the case where the control device 100A is an active device and the control device 100B is a standby device, that is, the network device 200A"' is an active device and the network device 200B"' is a standby device. Actions. If all the IO master MAn (n=1～3) and the IO master MBn (n=1～3) are operating soundly, and neither the IO network 30A nor the IO network 30B has a failure such as disconnection, the IO slave device Sn (n=1 to 3) The monitoring data An transmitted reaches the network device 200A"' via the IO network 30A, and the monitoring data Bn transmitted from the IO slave device Sn reaches the network device 200B"' via the IO network 30B.

As described above, in the network device 200A"' and the network device 200B"', the relay process 2542a is executed when monitoring data is received via the first communication I/F unit 220, respectively. As a result, as shown in (A) of FIG. 15 , monitoring data An is stored in monitoring data buffer 2522 of network device 200A"', and monitoring data Bn is stored in monitoring data buffer 2522 of network device 200B"'. In addition, when the unequalized monitoring data is written in the monitoring data buffer 2522, the network device 200"' executes the equalized transmission process 2542b1. As a result, as shown in (A) of FIG. 15 The monitoring data An is transmitted from the network device 200A"' to the network device 200B"' via the equalization cable 400, and the monitoring data Bn is transmitted from the network device 200B"' to the network device 200A"' via the equalization cable 400.

As described above, the control unit 210 of the network device 200"' executes the equalization receiving process 2542b2 every time monitoring data is received via the third communication I/F unit 240. Specifically, the network device 200A"' The control unit 210 executes the equalization reception process 2542b2 every time the monitoring data Bn is received via the third communication I/F unit 240 . In this operation example, all the IO masters MAn (n=1 to 3) are operating soundly, and no failure such as disconnection occurs in the IO network 30A. Therefore, in the equalization receiving process 2542b2 performed by the control unit 210 of the network device 200A"', the determination result of step SB100 is "Yes", and the processes after step SB120 are executed. Since the network device 200A"' is an operating system device , so the determination result of step SB120 is "Yes", and the processing of step SB130 is executed. That is, all monitoring data Bn received by the network device 200A"' via the third communication I/F unit 240 is discarded.

Similarly, in the network device 200B"', the equalization receiving process 2542b2 is executed every time the monitoring data An is received via the third communication I/F part 240. The control part 210 of the network device 200B"' executes In the equalization receiving process 2542b2, the determination result of step SB100 is also "Yes", and the processes after step SB120 are executed. Since the network device 200B"' is a standby device, the determination result of step SB120 is "No", and the processing of step SB140 is executed. That is, all the monitoring data Bn stored in the monitoring data buffer 2522 of the network device 200B"' are replaced. It is the monitoring data An (refer to (B) of FIG. 15 ) received from the network device 200A"' via the third communication I/F section 240. As a result, the monitoring data An is transmitted to the control device 100A via the network device 200A"' , the monitoring data An is also transmitted to the control device 100B via the network device 200B"'.

On the other hand, when some kind of failure occurs in the IO master MA1 and the IO master MB2, as shown in (A) of FIG. Monitoring data B2 received by device 200B"' is also missing. In addition, NULL in (A) of FIG. 16 indicates absence of monitoring data. In this case, as shown in (A) of FIG. 16 , the monitoring data A2 and A3 are transmitted from the network device 200A"' to the network device 200B"' via the equalization cable 400, and from the network device 200B"' to the network device 200A″′ transmits monitoring data B1 and B3 via equalization cable 400 .

In the equalization receiving process 2542b2 executed in the network device 200A"' when the monitoring data B1 is received via the third communication I/F unit 240, the result of determination in step SB100 is "No", and the process in step SB110 is executed. As a result, as shown in (B) of FIG. 16 , the monitoring data A1 that should have been originally received by the network device 200A"' is supplemented with the monitoring data B1. Similarly, in the equalization receiving process 2542b2 executed in the network device 200B"' triggered by the reception of the monitoring data A2 via the third communication I/F unit 240, the result of determination in step SB100 is also "No", The process of step SB110 is executed. As a result, as shown in (B) of FIG. 16 , the monitoring data B2 that should have been originally received by the network device 200B"' is supplemented with the monitoring data A2. In this operation example, the monitoring data B1, monitoring data A2, and monitoring data A3 are transmitted from the network device 200A"' to the control device 100A as equalized monitoring data, and the monitoring data B1, monitoring data A2, and monitoring data A3 are transmitted as equalized monitoring data. The equalized monitoring data is transmitted from the network device 200B"' to the control device 100B. In this operation example, since the equalized monitoring data is transmitted from the network device 200A"' to the control device 100A as the work-system control device, the control of the control target device and the like can be continued without any problem.

In this way, according to this embodiment, there is an effect that even if a failure occurs in the IO network connected to the work system control device via the network device or in any one of the plurality of IO masters connected to the IO network, there is no need to perform an operation. With regard to switching between the active system and the standby system of the control device, the frequency of occurrence of switching between the active system and the standby system in the redundant control system can be reduced. Furthermore, according to this embodiment, there is an effect that even if a failure occurs in the IO master connected to the IO network connected to the operating system control device via the network device, the IO network connected to the standby system control device via the network device In the case of multiple failures such as failures of the IO masters connected to the above, as long as these IO masters are not connected to the same IO device, the control of the controlled device can be continued, and compared with the first embodiment described above, it can further improve Resistance to multiple failures. In addition, in this embodiment, the standby network device transmits all monitoring data received from the IO network to the active network device via the equalization cable 400 between network devices, but it is also possible to transmit only Missing monitoring data in . Various methods are conceivable as a method of causing the standby network device to detect the absence of monitoring data in the active device. For example, a list of identifier information of monitoring data received by the active network device may be transmitted from the active network device to the standby network device via an equalization cable between the network devices, and the standby network device may be configured based on This list is used to detect the absence of monitoring data in the work-system device. In addition, when the standby system network device receives the monitoring data via the IO network and does not receive the data corresponding to the monitoring data via the equalization cable between the network devices after a predetermined period of time, the standby system network device may be set to The network device determines that monitoring data in the work-system device is missing.

In addition, when the control target device is included in the IO slave devices S1 to S3, the calculation data transmitted from the control device 100 to the control target device, that is, the transmission control of the data indicating the calculation result based on the equalized monitoring data , may also be performed in the same manner depending on whether or not the IO master connected to the control target device to the IO network 30 is faulty. For example, when the IO slave devices S1 to S3 in (B) of FIG. → Network device 200B"' → IO network 30B through a transmission path to transmit calculation data. Similarly, for the IO slave devices S2 and S3, the calculation data can be transmitted along the transmission path of the control device 100A→the network device 200A"'→the IO network 30A.

In addition, in this embodiment as well, the network device 200"' performs the equalization of the monitoring data, so of course, the following effects are obtained in the same way as in the above-mentioned first embodiment: Even if the monitoring data transmitted to the control device The increase in the amount of data does not cause any obstacle to the execution of the original calculation of the control device, and does not cause a decrease in the switching speed between the active system and the standby system.

In the above-mentioned embodiment, it was explained that some kind of failure occurred in the IO master, but in the case of a failure such as disconnection of the IO network 30, or a failure of the communication line connecting the IO network 30 and the network device 200"' In the event of a failure such as a disconnection, it is self-evident that the above-mentioned supplement is performed on all the monitoring data that should have been received via the IO network 30. In addition, in the above-mentioned embodiment, only the network device 200"' One duplex IO network is connected, but a plurality of duplex IO nets can also be connected as shown in FIG. 17 . For example, FIG. 17 illustrates a case where two dual IO networks are connected to the network device 200"'.

In general, in a redundant control system, it is not desirable to change the transmission path of data from the IO slave device to the work system control device 100 or the transmission path in the opposite direction. Therefore, the control unit 210 of the network device 200"' may also be made to execute a process of writing identification information indicating a transmission source determined to be incommunicable in step SB100 into a predetermined storage area of the volatile storage unit 252, and thereafter The monitoring data from the device whose identification information is stored in the storage area is always supplemented or replaced with the monitoring data received via the equalization cable 400, and the above-mentioned storage is performed when the device is powered off or reset. Area initialization. According to this method, even if the IO master or the like is repaired after the above-mentioned complement etc., it is no longer necessary to perform complement etc., until the network device 200"' is powered off or reset, from the IO slave device to the work system control The transmission path of the data of the device 100 is not switched to a path that does not perform the above-mentioned complement, etc., and the influence caused by switching paths can be avoided.

(E: deformation)

The first, second, third, and fourth embodiments of the present invention have been described above, but the following modifications may be added to these embodiments.

(1) In the above-mentioned first embodiment, the case of realizing the equalization of monitoring data by using push-type data communication is described as follows: from network device 200A and network device 200B The active network device transmits monitoring data to the standby network device via the equalization cable 400 and causes the standby network device to store the monitoring data. However, it is also possible to realize the equalization of monitoring data by using a pull-type data communication in which the standby network device executes Process to acquire monitoring data and update the monitoring data of this device. The same applies to other embodiments.

(2) It is also possible to combine the second embodiment and the third embodiment described above. Specifically, the network device 200A″ and the network device 200B″ can respectively perform the following processing: determine whether data communication can be performed through the equalization cable 400, and if data communication is possible, send data to the other through the equalization cable 400. One network device transmits the monitoring data, and if data communication is not possible, the monitoring data is transmitted to the other network device via the equalization cable 40 . Likewise, the second embodiment and the fourth embodiment may be combined, and the second, third, and fourth embodiments may also be combined.

(3) In each of the above-mentioned embodiments, an application example in which the present invention is applied to a gateway device that transmits monitoring data collected from an IO slave device to a control device has been described. However, the application object of the present invention is not limited to the gateway device, and may be other types of relay devices such as routers, repeaters, and switching hubs. In addition, the network connected to the relay device in the present invention is not limited to a control system network such as an IO network or a serial bus, and may be a general information system network that mediates data communication following a general communication protocol such as TCP. In short, the present invention can be applied to any relay device that collects monitoring data, is connected to a control device that performs calculations using the monitoring data, and is connected to a network connected to a device that outputs the monitoring data. Data received via the network are transmitted to the control device.

(4) The network device included in the communication system of each of the above embodiments, that is, the relay device may be provided as a single unit, that is, the relay device may be manufactured and sold as a single unit. This is because such a network device can be used to replace the network devices in the conventional redundant control system, and these network devices can be connected to each other by equalizing cables between relay devices, thereby making the conventional redundant control system The system functions as the communication system of each of the above-described embodiments.

(5) In each of the above-mentioned embodiments, the relay processing 2542a and the equalization processing 2542b (in the fourth embodiment, the equalization transmission processing 2542b1 and the equalization Receive processing 2542b2). However, it is also possible to configure the relay unit for executing the relay processing 2542a and the equalization unit for performing the equalization processing 2542b by circuits, and combine these circuits to configure the networks of the above-mentioned first to third embodiments. device. The same applies to the network device 200"' of the fourth embodiment. In addition, in the above-mentioned embodiment, an equalized cable is used as a communication unit between relay devices, but a wireless communication unit such as a wireless LAN interface may also be used as a communication unit between relay devices. Communication unit between relay devices. In addition, in the case where the network device 200A and the network device 200B are installed in one housing, the bus to which the two devices are connected can also be used as a communication unit between relay devices. Regarding communication between control devices The same applies to units.

(6) In each of the above-mentioned embodiments, it has been described that the control device 100A and the control device 100B, or the control device 100A' and the control device 100B' each use the network device of the connection destination regardless of whether it is an active system device or a standby system device. The case where calculations for device control are performed on the received monitoring data, that is, the case where the present invention is applied to a control system of a hot standby method is described. However, the application target of the present invention is not limited to the control system of the hot standby system, and the present invention can also be applied to the control system of the warm standby system. The control system of the warm standby method is the same as the control system of the hot standby method in that one of the dual control devices becomes the working device to perform the above calculations, and the other becomes the standby device to prevent the failure of the working device. The stand-by system control device is different in that the above calculation is performed. In addition, in the first to third embodiments described above, the standby network device also executes the process of writing the monitoring data received through the first communication I/F unit 220 into the monitoring data buffer 2522 (FIG. 4 (B): each processing of S100 and S110), however, this processing may be omitted in the standby network device. This is because the monitoring data written in the monitoring data buffer 2522 by the processes of S100 and S110 in (B) of FIG. 4 are overwritten in the process of step SA120 of the equalization process 2542b.

Explanation of reference signs

1A, 1C, 1D: communication system; 10A, 10B, 100A, 100B, 100A′, 100B′: control device; 20A, 20B, 200A, 200B, 200A′, 200B′, 200A″, 200B″, 200A″′, 200B″': relay device; 210: control unit; 220: first communication I/F unit; 230: second communication I/F unit; 240: third communication I/F unit; 250: storage unit; 252: Volatile storage unit; 2522: monitoring data buffer; 254: non-volatile storage unit; 2542, 2542′, 2542″′: relay control program; 2542a: relay processing; 2542b: equalization processing; 260 : bus; 30A, 30B, 30C: IO network; 40, 400, 400A, 400B: equivalent cables; 50: monitoring system; S1～Sn, S1′～Sn′: IO slave devices.

Claims (11)

1. A control system that collects monitoring data from one or more devices connected to the first network and the second network, and performs control based on the monitoring data, the control system is characterized in that it has: a first control device and a second control device, wherein one of the first control device and the second control device is an active system device and performs the control, and the other is a standby system device; a first relay device connected to the first control device and the first network; a second relay device connected to the second control device and the second network; an inter-relay device communication unit that mediates communication between the first relay device and the second relay device; and an inter-control device communication unit that mediates communication between the first control device and the second control device, Wherein, the first relay device and the second relay device include a judging unit that judges whether communication can be performed via the inter-relay device communication unit, The first relay device and the second relay device each transmit the monitoring data received from the one or more devices to a control device of a connection destination, and, when determined by the determination unit to be able to communicate In the case of , the first relay device and the second relay device perform equalization of monitoring data through communication via the inter-relay device communication unit, and on the other hand, the determination unit When it is determined that communication is impossible, the first relay device and the second relay device perform equalization of monitoring data through communication via the inter-control device communication unit, One of the first control device and the second control device that becomes the work-system device performs the control using the monitoring data received from the relay device of the connection destination. 2. The control system of claim 1, wherein: One of the first relay device and the second relay device executes a process of transmitting the monitoring data received from the network of the connection destination to the other relay device as the equivalent of the monitoring data processing, The other of the first relay device and the second relay device executes, as the process of equalizing the monitoring data, the following process: The monitoring data received from the network of the connection destination is replaced with the monitoring data received from the one relay device. 3. The control system according to claim 1 or 2, characterized in that, the first control device and the second control device determine whether communication via the inter-control device communication unit is possible, When it is determined that communication can be performed via the inter-control device communication unit, status data indicating whether there is a failure in the own device is transmitted and received via the inter-control device communication unit, thereby monitoring whether the other party has a failure, When it is determined that communication via the inter-control device communication unit is not possible and the determination unit determines that communication is possible via the inter-relay device communication unit, via the inter-relay device communication unit To send and receive the status data, thereby monitoring whether the other party has a fault. 4. The control system of claim 1, wherein: The first relay device and the second relay device receive monitoring data respectively transmitted from a plurality of devices, The control system determines in advance, for each of the plurality of devices, whether to perform equalization of the monitoring data transmitted from the device on the relay device side, or to perform the equalization of the monitoring data transmitted from the device on the control device side. equalization, The first relay device and the second relay device each perform equalization of monitoring data received from a device determined to be equalized by the relay device side, The first control device and the second control device each perform monitoring data transmitted from a device determined to be equalized on the control device side, among monitoring data received via a relay device of a connection destination. Equalization. 5. The control system of claim 1, wherein: The first relay device and the second relay device respectively have: a first processing unit that transmits the monitoring data received from the network of the connection destination to the relay device of the other party; and The second processing unit judges whether it is possible to communicate with the source device of the monitoring data received from the other relay device, and uses the monitoring data originally received from the device judged to be incommunicable by using the monitoring data from the other party. It complements the monitoring data received by the relay device. 6. The control system of claim 5, wherein: The second processing unit causes the storage device to store identification information indicating a device judged to be incapable of communication, and complements the device whose identification information is stored in the storage device using monitoring data received from the other relay device. Alternatively, on the other hand, the stored content of the storage device is initialized when the device is powered off or reset. 7. The control system of claim 1, wherein: The first relay device and the second relay device include a load measuring unit that measures a processing load borne by a control device of a connection destination, When the processing load measured by the load measuring unit is equal to or greater than a predetermined threshold value and the determination unit determines that communication is possible, the first relay device and the second relay device transmit via The monitoring data is equalized by relaying the communication of the inter-device communication means, and otherwise the monitoring data is equalized by communication via the inter-control device communication means. 8. The control system of claim 1, wherein: The first relay device and the second relay device include a load measurement unit that measures a processing load borne by a control device of a connection destination, and, In such a manner that the higher the processing load of the first control device and the second control device, the more monitoring data to be equivalentized on the relay device side, multiple types of monitoring data are determined according to the processing load. Whether the monitoring data is equalized on the relay device side or the distribution mode of the monitoring data is equalized on the control device side, The first relay device and the second relay device each perform monitoring data determined to be equalized on the relay device side in an allocation mode corresponding to the processing load measured by the load measuring unit. the equalization of Each of the first control device and the second control device performs equalization of the monitoring data determined to be equalized on the control device side in an allocation pattern corresponding to the processing load of the own device. 9. The control system of claim 1, wherein: Either one of the first relay device and the second relay device is connected to a third network, The relay device connected to the third network collects monitoring data from the equipment connected to the third network, and transmits the collected monitoring data to the control device connected to the device and to the other party's relay device. 10. The control system of claim 1, wherein: There are a plurality of relay device pairs consisting of the first relay device and the second relay device communicating via the inter-relay device communication unit. 11. A relay device connected to one of the first control device and the second control device connected to the inter-control device communication unit, and connected to the first network connected with one or more devices that transmit monitoring data, transmitting the monitoring data sent from the one or a plurality of devices to a control device of a connection destination, wherein one of the first control device and the second control device is controlled as an active system device, and the other is a standby system device , the relay device is characterized in that it has: a communication interface unit connected to an inter-relay device communication unit that mediates communications between the relay device and other relay devices, and the other relay devices are connected to the second network to which the one or more devices are connected and a relay device to which the other of the first control device and the second control device is connected; and a control unit that executes relay processing, determination processing, and equalization processing in which the monitoring device received from the one or a plurality of devices via the first network is transmitted to a control device of a connection destination. In the determination process, it is determined whether or not communication can be performed via the inter-relay device communication unit, and in the equalization process, when it is determined in the determination process that communication is possible, the communication is performed via the intermediate device Communication for equalizing the monitoring data is performed via the inter-device communication unit, and on the other hand, when it is determined that communication is impossible, the communication for making the monitoring data, etc. is performed via the inter-device communication unit. valued communication.