WO2016129075A1

WO2016129075A1 - Control system and relay device

Info

Publication number: WO2016129075A1
Application number: PCT/JP2015/053787
Authority: WO
Inventors: 史彦藤田; 浩一坂上
Original assignee: 富士電機株式会社
Priority date: 2015-02-12
Filing date: 2015-02-12
Publication date: 2016-08-18
Also published as: CN105519050B; KR101815202B1; KR20160110346A; TWI674488B; TW201640243A; CN105519050A

Abstract

Provided is a control system with redundant control devices and data transfer paths, with which it is possible to carry out equalization of monitor data without affecting computations executed by the control devices and without causing a degradation in speed of switchover between an active system and a backup system even if the volume of data transferred to the control devices increases. The respective control devices of the active system and the backup system are connected by a first equalizing cable, and respective network devices of the active system and the backup system are connected to each other by a second equalizing cable. Each of the network devices transfers monitor data which is received from I/O slave devices to the control device to which the respective network device is connected, and determines whether communication via the second equalizing cable is possible. If the said communication is possible, equalization of the monitor data is carried out upon each of the respective network devices by communication via the second equalizing cable, and if the said communication is not possible, the equalization of the monitor data is carried out upon each of the respective network devices by communication via the second equalizing cable.

Description

Control system and relay device

The present invention relates to a control system including an active system and a standby system control apparatus and its relay apparatus.

In industrial facilities such as factories and various plants, a communication system called a control system is often constructed to control various operations. The control system includes a control device that collects monitoring data from sensors installed in an industrial facility and performs drive control of an electric motor or the like according to the collection result. As such a control device, a DCS (Distributed Control System) or a programmable logic controller is used. Hereinafter, a device to be controlled by a control device such as an electric motor is referred to as a “control target device”, and a device to be monitored by a control device such as the sensor and a control target device are referred to as an “IO slave device”. Call it. The IO slave device is connected to a network called an IO network or a serial bus. The control device is connected to the IO network via a network device such as a relay device. An example of this relay device is a gateway device. Hereinafter, the programmable logic controller is referred to as “PLC”. In a general FA (Factory Automation) system, a PLC is often used as a control device, and in plant facilities that require high reliability, a DCS is often used as a control device. This is because DCS is more reliable than PLC.

In this type of control system, in order to avoid operation stoppage due to a failure of the control device or the like, it is common to double the control device and the data transmission path of the monitoring data. Redundant control device means that two control devices are provided and one of them is operated as an active system and the other as a standby system. Each of these two control devices collects monitoring data and performs a predetermined calculation for device control using the collected monitoring data or using the collected monitoring data and past calculation results. The active control device performs control based on the calculation result, and the standby control device prepares for the stop of the active control device. Then, the standby control device operates as an active system when the active system stops or stops, and continues device control. Here, as a specific example of the stop of the active control device, an unexpected stop due to the occurrence of some failure or malfunction, a pre-scheduled stop due to maintenance, or the like can be considered. The standby control device provides for both of these two types of stops. Duplexing of data transmission paths means that, for example, a data transmission path from an IO slave device to one of the duplexed control devices and a data transmission path to the other are provided separately. 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 illustrating a configuration example of a redundant control system. The system shown in FIG. 18 collects monitoring data output from IO slave devices S1 to Sn such as various sensors installed in an industrial facility, and based on the monitoring data or the monitoring data and past calculation results. Is a control system that performs a predetermined calculation using and and controls the operation of an electric motor or the like according to the calculation result. Note that n is a natural number of 2 or more. This control system has two control devices, a control device 10A and a control device 10B, and two network devices, a network device 20A and a network device 20B. In the system shown in FIG. 18, one of the control device 10 </ b> A and the control device 10 </ b> B is an active system, and the other is a standby system to prepare for the stop of the active system. A monitoring system 50 for monitoring the operating state of the control device 10A and the control device 10B is connected to the control device 10A and the control device 10B. 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, each of the control device 10A and the control device 10B is connected by an equalization cable 40 so that the other state can be monitored. As described above, the standby control device prepares for an unexpected stop caused by a failure or a planned stop such as a maintenance for the active control device. Let's take an example. Each of the control device 10A and the control device 10B transmits the status data indicating the presence or absence of the failure, that is, the status of the own device, to the other via the equalization cable 40. For example, when the control device 10A is an active system, the control device 10B which is a standby system refers to the state data transmitted from the control device 10A via the equalization cable 40 and a failure occurs in the control device 10A. To monitor. When the control device 10B detects a failure of the control device 10A from the state data received via the equalization cable 40, the control device 10B starts operation as an active system thereafter. On the other hand, the control device 10A detects that the control device 10B has started operation as an active system by communication via the equalization cable 40, and thereafter operates as a standby system.

In a redundant control system, even if a failure occurs in the active control device, data is collected from each of the IO slave devices S1 to Sn and calculation according to the result of collection is performed by switching between the active and standby systems. And the control according to the calculation result can be continued. However, simply switching the active / standby system may cause problems such as sudden changes in the calculation result before and after the switching. This is due to the fact that the monitoring data sent from each of the IO slave devices S1 to Sn to the control device 10A and the control device 10B is not completely the same.

In order to avoid the occurrence of such a problem, in the redundant control system, processing such as equalization of monitoring data transmitted from each of the IO slave devices S1 to Sn to each control device and equalization of calculation results is performed. Is generally executed by each control device. Equalization of monitoring data means that monitoring data received by the active control device via the network device is transmitted to the standby control device via the equalization cable 40, and the standby control device is used as the monitoring data. Says to overwrite the monitoring data received via the network. The equalization of the calculation result means that data indicating the calculation result in the active system is transmitted to the standby control device via the equalization cable 40, and the calculation result in the standby system is overwritten with the data. To tell. As an example of the prior art relating to such a redundant control system and equalization, there are techniques disclosed in Patent Document 1 and Patent Document 2.

JP 2013-12094 A JP 2013-152631 A

In recent years, with the diversification and increase in the number of IO slave devices included in the control system and the improvement in data transmission speed in the IO network, the amount of monitoring data transmitted to the control device via the network device per unit time Has increased significantly. When the amount of monitoring data received by the control device via the network device increases, the processing load of equalization processing on the monitoring data increases, and execution of operations for device control that is the original role of the control device It may be difficult to allocate sufficient resources for device control according to the calculation result. In recent years, there has been an increasing need to connect a plurality of network devices to one control device, but the same problem occurs when the number of network devices connected to the control device increases. Furthermore, when the amount of monitoring data per unit time received by the control device via the network device increases, there is a problem that switching between the active system and the standby system cannot be performed quickly when a failure occurs in the active system. As described above, the switching between the active system and the standby system is performed while avoiding the occurrence of a sudden change in the operation result unless the equalization of the monitoring data received by the control device via the network device is completed. Because you can't.

The present invention has been made in view of the problems described above, and in a redundant control system, even if the amount of monitoring data transferred to each control device via a network increases, It is an object of the present invention to provide a technique that makes it possible to equalize monitoring data without causing any trouble in the execution of computations and without causing a decrease in switching speed between the active system and the standby system.

In order to solve the above problems, the present invention provides a control system that collects monitoring data from one or a plurality of devices connected to the first and second networks, and performs control based on the monitoring data. Provided is a control system having first and second control devices and first and second relay devices. The first control device and the second control device are connected via communication means between control devices. The communication device between control devices is, for example, an equalization cable, and mediates communication between the first control device and the second control device. One of the first and second control devices is an active system and performs the control, and the other is a standby system. Specific examples of the first and second relay devices include the network devices described above. 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 and second relay devices are connected to the inter-relay device communication means. The inter-relay device communication means is, for example, an equalization cable, and mediates communication between the first relay device and the second relay device. The first and second relay devices include a determination unit that determines whether communication is possible via the inter-relay device communication unit. Each of the first and second relay apparatuses transfers the monitoring data received from one or more devices to the connection destination control apparatus, and when the determination means determines that communication is possible, the inter-relay apparatus communication means The monitoring data is equalized by communication via. On the other hand, when it is determined that communication is impossible by the determination unit, the first and second relay devices perform monitoring data equalization by communication via the inter-control device communication unit.

In the control system of the present invention, equalization of monitoring data transmitted from each device to the first and second control devices is performed by the first and second relay devices. Therefore, even if the amount of monitoring data increases, the processing load of each of the first and second control devices does not become excessive due to the equalization of the monitoring data, and the first and second control devices There is no problem in the execution of the above calculation in each of the above. Each of the first and second control devices is given data that has been equalized by the first and second relay devices. For this reason, when one of the first and second control devices functions as an active system and the other functions as a standby system, the monitoring data is switched when the active system / standby system is switched due to the stop of the active system. There is no need to wait for the equalization to be completed, and switching between the active system and the standby system can be performed quickly.

In the conventional redundant control system shown in FIG. 18, when the equalization cable 40 that connects the control device 10A and the control device 10B is disconnected, the monitoring data cannot be equalized at all. On the other hand, in the control system of the present invention, the communication means that mediates data communication for equalization of the monitoring data is duplicated by the communication means between the control devices and the communication means between the relay devices. If communication via the network is possible, the monitoring data can be equalized without any problem. The first and second control devices are allowed to determine whether or not communication via the inter-control device communication means is possible, and if possible, state data indicating the presence or absence of a failure in the own device is transmitted to the control device. The process of monitoring the presence / absence of the other failure by monitoring the presence / absence of the other failure by transmitting / receiving status data via the communication device between relay devices, if not possible. It may be executed. Further, the relay device pair included in the control system of the present invention, that is, the relay device pair consisting of the first and second relay devices communicating via the inter-relay device communication means is not limited to one, There may be more than one. Specifically, a plurality of first relay devices connected to a plurality of first networks to which different devices are respectively connected and connected to a first control device, respectively, and a plurality of first relay devices A plurality of second relay devices paired with each of the relay devices, each of which is connected to a plurality of second networks to which the respective devices are connected, and is connected to a second control device. It is possible to consider a mode in which a plurality of first relay devices and a plurality of second relay devices communicate with each other via inter-relay device communication means.

Here, various modes are conceivable as specific implementation methods for the equalization of the monitoring data by communication via the inter-relay device communication means. Monitoring data is transmitted from one of the first relay device and the second relay device to the other, and the other relay device receives the monitoring data received via the network via the inter-relay device communication means. A mode in which a process of overwriting with monitoring data, that is, a process of replacing the former monitoring data with the latter monitoring data is considered. For example, the monitoring data is transmitted from the relay device connected to the active control device to the other relay device, and the monitoring data received via the network is transmitted to the other relay device. It is overwritten with the monitoring data received via the inter-controller communication means.

In another preferred mode, a mode in which the following first and second processing means are provided in each of the first and second relay devices is conceivable. The first processing means transfers the monitoring data received from the connection destination network to the other relay device. More specifically, the first processing means transfers the monitoring data to the other relay apparatus via the inter-relay apparatus communication means when the determination means determines that communication is possible, and determines that communication is impossible. In the case of monitoring, the monitoring data is transmitted to the other relay device via the communication device between control devices. The second processing means checks whether or not communication with the monitoring data transmission source device received from the other relay device is possible, and if the communication is impossible, the second processing means should receive from the device concerned. The existing monitoring data is supplemented with the monitoring data received from the other relay device. In a conventional redundant control system, when a failure occurs in a network connected to a relay device that transfers monitoring data to an active control device, or a failure occurs in an IO master for connecting each device to the network. Even when this occurred, it was 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 the active system / standby system due to the failure of the network or the like, and it is possible to reduce the frequency of occurrence of switching between the active system / standby system. . This point will be described in detail in the fourth embodiment of the present invention.

In a more preferred aspect, a third network is connected to one of the first and second relay devices. The relay device connected to the third network collects the monitoring data from the devices connected to the third network, transfers the collected monitoring data to the connection destination control device, and the other relay. Transfer to the device to perform equalization. Although details will be clarified in the description of the third embodiment of the present invention, there are various problems in connecting a non-redundant network to the relay device of the conventional redundant control system shown in FIG. Such a connection form could not be easily adopted. On the other hand, according to this aspect, it becomes possible to easily connect a network that is not duplicated to such a relay device.

In another preferred embodiment, the first and second relay devices include load measuring means for measuring a processing load applied to a connection destination control device, and the first and second relay devices are When the processing load measured by the load measuring means is equal to or greater than a predetermined threshold value and the determination means determines that communication is possible, the monitoring data is equalized by communication via the inter-relay device communication means. In other cases, the monitoring data is equalized by communication through the communication means between the control devices. According to such an aspect, it is possible to duplicate data communication for equalizing monitoring data while distributing the processing load applied to each of the first and second control devices.

In order to solve the above problem, the present invention is connected to one of the first and second control devices, one of which is an active system and the other is a standby system, and transmits monitoring data. The following communication interface unit and control unit are connected to a relay device that is connected to a first network to which one or more devices are connected, and that transfers monitoring data transmitted from the one or more devices to a connected control device. Is provided. The communication interface unit is connected to another relay device via the communication device between relay devices. The other relay device is connected to a second network to which one or more devices are connected and the other of the first and second control devices. The control unit is, for example, a CPU (Central Processing Unit). This control unit executes the following relay processing, determination processing, and equalization processing. The relay process is a process for transferring monitoring data received from one or more devices via the first network to a connection destination control device. The determination process is a process for determining whether communication is possible via the inter-relay device communication means. In the equalization processing, when it is determined that communication is possible in the determination processing, communication for equalizing the monitoring data is performed via the inter-relay device communication unit, while it is determined that communication is impossible. In this case, the communication is performed through the inter-control device communication means. By replacing the relay device that connects the control device and the data transmission path in the redundant control system, that is, the network device 20A and the network device 20B in the system example shown in FIG. The control system can be made to function as the control system of the present invention.

Also, as another aspect for solving the above-described problem, an aspect in which a program for causing a general computer such as a CPU to function as the relay device is conceivable. This is because by operating a general computer according to such a program, the computer can function as the relay device of the present invention. As a specific provision mode of the above program, a mode of distribution by downloading via an electric communication line such as the Internet, a computer-readable recording medium such as a CD-ROM (Compact Disk-Read Memory) or a flash ROM It is possible to write in and distribute in

As described above, according to the present invention, in the redundant control system, even if the amount of monitoring data transferred to each control device via the network increases, there is no problem in the execution of the original operation of the control device. It is possible to equalize the monitoring data without reducing the switching speed of the active system / standby system.

It is a figure which shows the structural example of the communication system 1A containing the network apparatus 200 of an example of the relay apparatus of this invention, ie, the communication system of 1st Embodiment of this invention. It is a figure which shows the structural example of the network device 200 contained in the communication system 1A. 7 is a flowchart showing a flow of equalization processing 2542b executed by the control unit 210 of the network device 200 in accordance with the relay control program 2542. FIG. 10 is a diagram for explaining an operation executed by the control unit 210 of the network device 200 according to a relay control program 2542. It is a figure for demonstrating the effect of 1st Embodiment. It is a figure for demonstrating the modification of 1st Embodiment. It is a figure for demonstrating the other modification of 1st Embodiment. It is a figure which shows the structural example of network apparatus 200 'of 2nd Embodiment of this invention. FIG. 2 is a diagram illustrating a schematic configuration and an operation example of a communication system including the network device 200 ′. It is a figure for demonstrating 3rd Embodiment of this invention. It is a figure for demonstrating 4th Embodiment of this invention. It is a figure which shows the structural example of network device 200 '' 'of the 4th embodiment. It is a figure for demonstrating the operation | movement which the control part 210 of the same network apparatus 200 '' '' performs according to relay control program 2542 ''. It is a flowchart which shows the flow of the equalization reception process 2542b2 which the same control part 210 performs according to the relay control program 2542 "". It is a figure for demonstrating the effect of the 4th Embodiment. It is a figure for demonstrating the effect of the 4th Embodiment. It is a figure for demonstrating the modification of the 4th Embodiment. It is a figure which shows the prior art example of a control system.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
(A: 1st Embodiment)
FIG. 1 is a diagram showing a configuration example of a communication system 1A according to the first embodiment of the present invention.
This communication system 1A is a control system laid in an industrial facility, like the system shown in FIG. In FIG. 1, the same components as those in FIG. 18 are denoted by the same reference numerals. As is clear from the comparison between FIG. 1 and FIG. 18, the communication system 1A is different from the conventional redundant control system shown in FIG. 18 in the following three points. First, it has a control device 100A and a control device 100B instead of the control device 10A and the control device 10B. Second, the network device 200A and the network device 200B are provided instead of the network device 20A and the network device 20B. Third, the network device 200A and the network device 200B are connected by an equalization cable 400.

Each of the network device 200A and the network device 200B is an embodiment of the relay device of the present invention, and the equalization cable 400 serves as a communication device between relay devices that mediates communication between the relay devices. The network device 200A and the network device 200B are gateway devices like the network device 20A and the network device 20B in FIG. In the communication system 1A shown in FIG. 1, monitoring data transmitted from each of the IO slave devices S1, S2,... Sn is transmitted to the control device 100A via the IO network 30A and the network device 200A, and the IO network. It is transmitted to the control device 100B via 30B and the network device 200B. Each of the control device 100A and the control device 100B is similar to the control device 10A and the control device 10B in FIG. 18, and uses the monitoring data collected from the IO slave devices S1, S2,. In other words, calculations for device control and storage of the calculation results are performed. The control device 100A and the control device 100B may be PLCs or DCSs.

In the communication system 1A shown in FIG. 1, one of the control device 100A and the control device 100B becomes an active system to execute control of other devices based on the calculation result, and the other becomes a standby system. Prepare for the suspension. As described above, there are two types of stoppages of the active system: an unexpected stop due to the occurrence of some failure or malfunction and a planned stoppage due to maintenance or the like. When the active system stops, the control device that has been in the standby system thereafter operates as the active system. Note that switching between the active system and the standby system may be realized by the same method as in the conventional redundant control system.

As described above, when switching between the active system and the standby system, it is necessary to equalize the monitoring data and equalize the calculation results in order to avoid sudden changes in the calculation results. In the conventional redundant control system shown in FIG. 18, the control device 10A and the control device 10B are made to equalize the monitoring data and the calculation result. Also in this embodiment, the control device 100A and the control device 100B execute equalization of the calculation result is the same as the conventional redundant control system shown in FIG. More specifically, the active one of the control device 100A and the control device 100B performs calculation for device control using the monitoring data received from the network device of the connection destination, and the calculation result is obtained. The indicated data is transferred to the other control device via the equalization cable 40 to equalize the calculation result. That is, the standby control device overwrites the data of the operation result in the own device with the data received via the equalization cable 40. The difference between the communication system 1A of the present embodiment and the conventional redundant control system shown in FIG. 18 is that the network device 200A and the network device 200B perform equalization of the monitoring data. Hereinafter, the network device 200 </ b> A and the network device 200 </ b> B that clearly show the features of the present embodiment will be mainly described. Since the network device 200A and the network device 200B have the same configuration, the following description will be referred to as “network device 200” when it is not necessary to distinguish between them.

In this embodiment, the network device 200 is also distinguished from an active system and a standby system. More specifically, the network device 200 communicates with its own connection destination control device, and determines whether or not the connection destination control device is an active system. The network device 200 behaves as an active network device if the connection destination control device is an active system, and conversely behaves as a standby network device if the connection destination control device is a standby system. That is, in the present embodiment, of the network device 200A and the network device 200B, the one connected to the active control device is the active system, and the one connected to the standby control device is the standby system. When the switching of the active system / standby system occurs for the control device, the network system 200 is also switched between the active system and the standby system depending on the switching. In the present embodiment, the case where the switching to the active / standby system for the network device 200 is subordinate to the switching of the active / standby system for the control device will be described. However, transmission / reception of state data via the equalization cable 400 is described. The other state may be monitored, and the active / standby system may be switched according to the result of the state monitoring independently of the switching of the active / standby system for the control device.

FIG. 2 is a block diagram illustrating 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 abbreviated as “I / F”) unit 220, a second communication I / F unit 230, and a third communication I / F unit. 240, a storage unit 250, and a bus 260 that mediates data exchange between these components.

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 non-volatile storage unit 254 is one of a plurality of components constituting the storage unit 250. Details of processing executed by the control unit 210 in accordance with the relay control program 2542 will be clarified later. Each of the first communication I / F unit 220, the second communication I / F unit 230, and the third communication I / F unit 240 is, for example, a NIC (Network Interface Card). The role of each of these communication I / F units is 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 connection destination IO network and sends data to the connection destination IO network. The first communication I / F unit 220 has a communication buffer that accumulates data received from the IO network to which it is connected. In FIG. 2, the communication buffer is not shown.

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 connection destination control device and transmits data to the connection destination control device. The second communication I / F unit 230 has a communication buffer that accumulates data to be transmitted to the connected control device. In FIG. 2, the communication buffer is not shown.

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

The storage unit 250 includes a volatile storage unit 252 and a non-volatile storage unit 254 as shown in FIG. The volatile storage unit 252 is, for example, a RAM (Random Access Memory). The volatile storage unit 252 is used as a work area for executing the relay control program 2542. The volatile storage unit 252 also serves as a monitoring data buffer 2522 that temporarily accumulates monitoring data to be transmitted to the control device. Further, the volatile storage unit 252 stores an operation / standby flag indicating whether the network device 200 having the volatile storage unit 252 is operating as an active system or a standby system. . The nonvolatile storage unit 254 is, for example, a flash ROM. The non-volatile storage unit 254 stores a relay control program 2542 in advance.

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 turned on or reset, and starts executing the relay control program 2542. In FIG. 2, the power supply of the network device 200 is not shown. The control unit 210 operating in accordance with the relay control program 2542 monitors the operation state of the connected control device and executes a process of setting an operation / standby flag according to the monitoring result, as well as the relay process 2542a. The value processing 2542b is executed. Details of the relay process 2542a and the equalization process 2542b will be made clear in the operation example, but the outline is as follows. The equalization process 2542b is a process for equalizing the monitoring data collected from each of 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. As is apparent from FIG. 3, the processing content of the equalization processing 2542b differs between when operating as an active system and when operating as a standby system. Details of the processing content of the equalization processing 2542b will be made clear 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. In the operation example described below, it is assumed that the control device 100A and the network device 200A are active, and the control device 100B and the network device 200B are standby. In the operation example described below, a case will be described in which the monitoring data buffer 2522 of each of the network device 200A and the network device 200B is empty at the start of the operation.

Each of IO slave devices S1 to Sn samples input signals or output signals such as sensors to generate monitoring data to be transmitted to each of control device 100A and control device 100B, and to each of IO network 30A and IO network 30B. Send. The monitoring data transmitted by the IO slave devices S1 to Sn is provided with a header including information indicating the transmission destination and transmission source of the monitoring data, an identifier uniquely indicating the monitoring data, and the like. Specific examples of the information indicating the transmission destination of the monitoring data include the communication address and node number of the transmission destination device. The same applies to information indicating the transmission source of the monitoring data. The monitoring data transmitted from each of the IO slave devices S1 to Sn is transmitted to each of the network device 200A and the network device 200B via each of the IO network 30A and the IO network 30B. 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”. Although the monitoring data A and the monitoring data B are basically the same data, they may be slightly different depending on the sampling timing shift when sampling each.

When receiving the monitoring data transmitted from the IO network 30A, the first communication I / F unit 220 of the network device 200A writes the received monitoring data in 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 in 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 communication buffer in the first communication I / F unit 220 of the network device 200B is stored in the communication buffer. Monitoring data B is stored.

The control unit 210 of the network device 200A is triggered by the writing of the monitoring data to the communication buffer in the first communication I / F unit 220. In other words, the control unit 210 is triggered by the reception of the monitoring data from the connected IO network 30A. Then, the relay processing 2542a is executed. As shown in FIG. 4, in the relay process 2542a, the control unit 210 reads the monitoring data from the communication buffer in the first communication I / F unit 220 (FIG. 4A: S100), and sends the monitoring data to the monitoring data buffer 2522. The monitoring data is written (FIG. 4A: S110). For this reason, in this operation example, the monitoring data A is stored in the monitoring data buffer 2522 of the network device 200A. Similarly, the network device 200B executes the processing of S100 and S110 (see FIG. 4B), and the monitoring data buffer 2522 stores the monitoring data B. When writing monitoring data to the monitoring data buffer 2522, the control unit 210 sets a first value indicating that equalization has not been performed in a flag indicating whether or not equalization has been performed. Then, a flag having the first value set is added to the monitoring data and written to the monitoring data buffer 2522. A specific example of this first value is 0.

In the network device 200A, the control unit 210 executes the equalization processing 2542b in response to the writing of the monitoring data to which the flag indicating that the equalization has not been performed is written to 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 apparatus is operating as an active system (step SA100). Specifically, the control unit 210 refers to the operation / standby flag stored in the volatile storage unit 252, and if the value of the flag indicates the operation system, the control unit 210 operates as the operation system. It is determined that If the determination result of step SA100 is “Yes”, the control unit 210 executes the process of step SA110. Conversely, if the determination result of step SA100 is “No”, the control unit 210 performs step SA120 and subsequent steps. Execute the process. As described above, in this operation example, the network device 200A operates as an active system. Therefore, in the equalization process 2542b executed by the control unit 210 of the network device 200A, the determination result in step SA100 is “Yes”, and the process in step SA110 is executed.

In step SA110, which is executed when the determination result in step SA100 is “Yes”, the control unit 210 reads monitoring data to which a flag indicating that the equalization has not been performed is added from the monitoring data buffer 2522 (FIG. 4 ( A): S120), the monitoring data is transferred to the connected network device via the third communication I / F unit 240 (FIG. 4A: S130). As described above, the monitoring data buffer 2522 of the network device 200A stores the monitoring data A as monitoring data to which a flag indicating that the equalization has not been performed is added. Therefore, in this operation example, the monitoring data A is transferred 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 processing 2542b when the third communication I / F unit 240 receives data transmitted via the equalization cable 400. In the equalization process 2542b executed by the control unit 210 of the network device 200B, the determination at Step SA100 described above is performed. In this operation example, since the network device 200B operates as a standby system, the determination result in step SA100 of the equalization processing 2542b executed by the control unit 210 of the 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 by the third communication I / F unit 240 from the third communication I / F unit 240 (FIG. 4B: S140), and uses the monitoring data. The corresponding monitoring data stored in the monitoring data buffer 2522 is overwritten (FIG. 4B: S150), and the flag assigned to the monitoring data is rewritten with a second value indicating that the equalization has been performed. . The relevant monitoring data is monitoring data having the same transmission source and the same identifier as the monitoring data acquired in S140 of FIG. 4B. A specific example of the second value is 1. 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, the control unit 210 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 monitoring data flag transferred in S130 of FIG. 4A to the second value, triggered by the reception of the notification. As a result of the above operation, the monitoring data buffer 2522 of each of the network device 200A and the network device 200B stores the monitoring data A, and the monitoring data A is given a flag indicating equalization. It becomes a state.

The control unit 210 of the network device 200A restarts the relay processing 2542a when the flag assigned to the monitoring data stored in the monitoring data buffer 2522 is updated to a value indicating equalization. The processes of S160 and S170 of 4 (A) are executed. In the process of S160, the control unit 210 reads monitoring data to which a flag indicating equalization has been assigned from the monitoring data buffer 2522. In the process of S170, the control unit 210 writes the monitoring data read out in S160 into the communication buffer of the second communication I / F unit 230. Also in the network device 200B, the relay process 2542a is restarted when the notification of equalization completion is transmitted, and the processes of S160 and S170 in FIG. 4B are executed.

The second communication I / F unit 230 of the network device 200A transmits the monitoring data written in the communication buffer as described above to the connection destination control device. Similarly, the second communication I / F unit 230 of the network device 200B transmits the monitoring data written in the communication buffer in the above manner to the control device connected thereto. For this reason, 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. Since the notification can be transmitted and received sufficiently faster than the transmission and reception of monitoring data, the update of the flag in each of the network device 200A and the network device 200B is executed substantially synchronously, and the processes in S160 and S170 are performed. Are also executed almost synchronously. For this reason, 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 almost synchronously.
The above is the operation of this embodiment.

In the conventional redundant control system shown in FIG. 18, since the control device, that is, the control device 10A and the control device 10B perform equalization of the monitoring data, when the data amount of the monitoring data increases, the equalization is performed. As a result, the processing load of the control device increases, and there is a problem in that it hinders high-speed execution of the original calculation. FIG. 5 is a schematic diagram of the communication system 1A of the present embodiment. In the present embodiment, the equalization of the calculation result is executed by the control device 100A and the control device 100B by communication via the equalization cable 40 in FIG. 5, but the equalization of the monitoring data is performed in FIG. It is executed by the network device 200A and the network device 200B by communication via the equalization cable 400. For this reason, even if the amount of monitoring data transferred 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, the control device 100A and the control device 100B are affected. The processing load is not increased by the equalization, and there is no trouble in executing the original calculation.

Further, in the present embodiment, the equalized monitoring data is transferred from the network device 200A to the control device 100A via the communication line LA in FIG. 5, and the equalized monitoring data is transmitted via the communication line LB in FIG. Data is transferred from the network device 200B to the control device 100B. Then, the equalization of the calculation result based on the monitoring data is realized by communication via the equalization cable 40 in FIG. Since the equalized monitoring data is transferred to the control device 100A and the control device 100B, even when the active / standby system is switched due to the stop of the active control device. The control device does not need to wait for the equalization of the monitoring data, and can be switched immediately. That is, according to the present embodiment, the switching speed of the active system / standby system is not reduced.

To summarize the above description, according to the present embodiment, in the control system that collects monitoring data from one or a plurality of devices connected to the first and second networks and performs control based on the monitoring data. The first and second control devices, one of which is the active system and the other is the standby system, the first control device and the first relay device connected to the first network, A second relay device connected to the second control device, a second relay device connected to the second network, an inter-control device communication means that mediates communication between the first control device and the second control device, a first relay device, and a second relay device. And inter-relay device communication means that mediate communication between the two relay devices, and each of the first and second relay devices transfers the monitoring data received from one or more devices to the connection destination control device. And monitoring data Communication for valuation is performed via the inter-relay device communication means, and the one of the first control device and the second control device, which is the active system, receives the monitoring data received from the connected relay device. Provided is a control system characterized in that a calculation for control is performed and the calculation result is transferred to a standby control device via communication means between control devices to equalize the calculation result. Is done. In other words, in the present invention, the one of the first control device and the second control device that is the active system performs the calculation for control using the monitoring data received from the connection destination relay device, and the calculation result Is transferred to the control device serving as a standby system via the inter-control device communication means. Therefore, it is possible to equalize only calculation results that do not include monitoring data between control devices. In addition, only the calculation result can be equalized between the control devices of the present invention. For this reason, according to the present embodiment, in the redundant control system, even if the amount of monitoring data transferred to the control device increases, it does not cause any trouble in the execution of the original operation of the control device and operates. It is possible to prevent the switching speed of the system / standby system from being lowered.

In the conventional redundant control system shown in FIG. 18, the means for mediating data communication between the active system and the standby system is an equalization cable which is a communication means between control devices that mediates communication between control devices. Therefore, when the equalization cable 40 is disconnected, data communication between the active system and the standby system becomes impossible, and communication for monitoring each other's state cannot be performed. For this reason, in the conventional redundant control system, when the equalization cable 40 is disconnected, the active system / standby system cannot be switched anymore, and multiple faults occur such that a fault occurs in the active system control device. Then, there was a problem that the device could not be controlled at all.

On the other hand, in this embodiment, the means for mediating data communication between the active system and the standby system is duplexed by the equalization cable 40 and the equalization cable 400. Even if the disconnection occurs, communication for monitoring each other's state will not be disabled. For example, even when the equalization cable 40 is disconnected at the position indicated by the symbol B in FIG. 6, the control system according to the present embodiment is in a state along the path C1 indicated by the dotted arrow in FIG. Data can be sent and received. Specifically, the control device 100A transmits state data indicating the state of the device itself 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 control device 100B sends the status data indicating the status of its 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. What is necessary is just to make it perform the process to transmit.

In the embodiment described above, one network device is connected to one control device. However, as shown in FIG. 7, a plurality of network devices are connected to one control device. It may be deformed. In the system shown in FIG. 7, two network devices are connected to one control device. In a conventional redundant control system, when a plurality of network devices are connected to a control device, the amount of monitoring data transferred to the control device increases, resulting in problems in the execution of calculations inherent in the control device, This is because problems such as a decrease in the standby system switching speed have occurred, but in the present embodiment, such problems do not occur.

As shown in FIG. 7, even when a plurality of network devices 200 are connected to one control device, the network device 200A and the network device 200B respectively transfer to each of the control device 100A and the control device 100B. The equalization of the monitoring data to be performed is performed by these network devices by communication via the equalization cable 400A, and transferred to each of the control device 100A and the control device 100B via each of the network device 200C and the network device 200D. The equalization of the monitoring data to be performed is executed by these network devices by communication via the equalization cable 400B. For this reason, even if the amount of monitoring data transferred to a control device increases by connecting a plurality of network devices to a single control device, the processing load of the control device is increased by the equalization. It will not be high.

(B: Second embodiment)
In the first embodiment, the case has been described in which the network device 200A and the network device 200B are made to equalize the monitoring data by communication via the equalization cable 400. However, in such an aspect, there is a problem that when the equalization cable 400 is disconnected, the monitoring data cannot be equalized. The network device 200A ′ and the network device 200B ′ of the present embodiment are intended to solve this problem. The network device 200A ′ and the network device 200B ′ of the present embodiment determine whether or not data communication via the equalization cable 400 is possible, and if a determination result indicating that it is possible is obtained The monitoring data is equalized by data communication via the equalization cable 400. On the other hand, when a determination result that it is impossible is obtained, the network device 200A ′ and the network device 200B ′ are monitored by communication via the control device 100A, the equalization cable 40, and the control device 100B. Perform data equalization. Hereinafter, when it is not necessary to distinguish between the network device 200A ′ and the network device 200B ′, the network device 200A ′ is referred to as “network device 200 ′”.

FIG. 8 is a diagram illustrating a configuration example of the network device 200 ′. As apparent from a comparison between FIG. 8 and FIG. 2, the configuration of the network device 200 ′ is that the relay control program 2542 ′ is stored in the nonvolatile storage unit 254 instead of the relay control program 2542. The configuration is different. The relay control program 2542 ′ is a program that causes the control unit 210 to execute the relay process 2542a, the equalization process 2542b ′, and the determination process 2542c. The determination process 2542c is a process of determining whether or not communication via the inter-relay device communication unit, that is, the equalization cable 400 is possible. The equalization processing 2542b ′ determines that communication is not possible while performing communication for equalizing the monitoring data via the inter-relay device communication means when the determination processing 2542c determines that communication is possible. In this case, the communication is performed through the communication device between the control devices, that is, the equalization cable 40. That is, the control unit 210 operating according to the relay control program 2542 ′ includes a relay unit that executes the relay process 2542a, a determination unit that executes the determination process 2542c, and an equalization unit that executes the equalization process 2542b ′. Function as.

FIG. 9 is a diagram illustrating a schematic configuration and an operation example of a control system including the network device 200 ′. In FIG. 9, the network device is abbreviated as “NW device”. In addition, in FIG. 9, it is clearly shown that the network device 200 ′ has a determination unit so that the feature of the present embodiment becomes clear. When the disconnection occurs in the equalization cable 400 at the position indicated by the symbol 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, and equalize the monitoring data. More specifically, the network device 200A ′ uses the monitoring data received from the IO network 30A as a transfer path that solves the communication line LA, the control device 100A, the equalization cable 40, the control device 100B, and the communication line LB in this order. To the network device 200B ′. The network device 200B ′ receives the monitoring data, overwrites the corresponding monitoring data of the own device with the monitoring data, and returns an equalization completion notification. The equalization completion notification sent back from the network device 200B ′ in this way follows the communication line LB, the control device 100B, the equalization cable 40, the control device 100A, and the communication line LA in this order to the network device 200A ′. Is transferred, and the equalization of the monitoring data is completed.

In the present embodiment, the control device 100A and the control device 100B function only as a data transmission path that mediates data communication for equalization, so that these controls are performed as compared with the conventional redundant control system. The processing load on the apparatus can be reduced. As a specific example of the determination process 2542c, a process of transmitting a ping to the partner apparatus via the equalization cable 400, determining that communication is possible if there is a response within a predetermined time, and determining that communication is impossible if there is a response Is mentioned. Note that the transmission / reception of state data between the control device 100A and the control device 100B may be switched according to the availability of data communication via the equalization cable 40. Specifically, if data communication via the equalization cable 40 is possible to each of the control device 100A and the control device 100B, the status data is transmitted to the other control device via the equalization cable 40, If this is not possible, processing for transmitting status data to the other control device via the equalization cable 400 may be executed.

Switching between data communication for equalization of monitoring data via the equalization cable 400 or via the equalization cable 40 depends on whether data communication via the equalization cable 400 is possible. Instead of switching, the mode may be switched according to the processing load of the control device. For example, when the network device 200 ′ measures the processing load of the connected control device, and the measured processing load is less than a predetermined threshold, each control device and equalization cable of the active system and the standby system The monitoring data is equalized by data communication via 40, and when the processing load of the control device is equal to or greater than a predetermined threshold, the monitoring data is equalized by data communication via the equalization cable 400. The control unit of each of the active and standby network devices may be executed. Here, as a specific method for measuring the processing load of the control device, there is an aspect in which the network device 200 executes processing for acquiring data representing the CPU usage rate, the memory usage rate, and the like in the control device from the connected control device. Conceivable. Furthermore, the transfer route of the monitoring data may be switched using both the availability of data communication via the equalization cable 400 and the processing load of the control device. Specifically, when it is determined that the processing load of the control device is equal to or greater than a predetermined threshold and communication via the equalization cable 400 is possible, the monitoring data is transmitted via communication via the equalization cable 400. In other cases, that is, when the processing load of the control device is less than the predetermined threshold value, or the processing load is equal to or higher than the predetermined threshold value, communication via the equalization cable 400 is impossible. In this case, the monitoring data should be equalized by communication via the equalization cable 40.

In addition, for each IO slave device that is the transmission source of the monitoring data, the distribution pattern of whether the monitoring data is equalized on the control device side or on the relay device side, that is, on the network device side is determined in advance, It is also conceivable to distribute the processing load related to the equalization of the 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 monitored on the network device side. This is because the control device 100A stores a distribution pattern table that stores a flag indicating whether the control device side or the network device side equalizes the monitoring data in association with the communication address of each IO slave device. And 100B and network devices 200A ′ and 200B ′. 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 perform control in the distribution table. What is necessary is just to make it equalize about the monitoring data determined to equalize on the apparatus side. Also, a plurality of distribution tables may be prepared in accordance with the processing load of the control device, and the stored content in which the monitoring data to be equalized on the relay device side increases as the table corresponding to the higher processing load. .

(C: Third embodiment)
FIG. 10 is a diagram illustrating a configuration example of a communication system 1C according to the third embodiment of this invention.
This communication system 1C is also a control system laid in an industrial facility. 10, the same elements as those in FIG. 1 are denoted by the same reference numerals. As is clear from a comparison between FIG. 10 and FIG. 1, 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 in place 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. Thirdly, the IO network 30C is connected to the network device 200A ″.

The IO slave devices S1 ′ to Sn ′ are connected to the IO network 30C. The IO network 30C mediates data communication between the IO slave devices S1 ′ to Sn ′ and the network device 200A ″. As described above, the network that transmits the data transmitted from the IO slave devices S1 to Sn to the control device is duplexed by the IO network 30A and the IO network 30B, but is transmitted from the IO slave devices S1 ′ to Sn ′. Such duplication is not applied to the network for transmitting data to the control device. That is, the network device 200A ″ is connected to a duplex network and a non-duplex network. Hereinafter, a network that is not duplicated is referred to as a “single network”.

The network device 200A ″ relays data communication between the IO network 30A and the control device 100A ′ in the same manner as the network device 200A in the first embodiment. Similarly to the network device 200B in the first embodiment, the network device 200B ″ relays data communication between the IO network 30B and the control device 100B ′. Further, the network device 200A ″ and the network device 200B ″ can equalize 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. I do. However, the network device 200A ″ and the network device 200B ″ perform switching between the active system and the standby system by monitoring each other regardless of whether the connection destination control device is the active system or the standby system. Different from the network device 200.

In addition to this, the network device 200A ″ and the network device 200B ″ perform the same processing as the above equalization on the monitoring data received from the IO network 30C. 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 ″ transmits the monitoring data. Is written to the monitoring data buffer. Then, each of the network device 200A ″ and the network device 200B ″ transmits the monitoring data transmitted from the IO network 30C to each connection destination control device.

The control device 100A ′ and the control device 100B ′ are triggered by the reception of data transmitted from the IO slave devices S1 to Sn, and the devices according to the first calculation using the data and the calculation result of the first calculation Execute the control. In addition, the active control device executes a second calculation using the data, triggered by reception of data transmitted from the IO slave devices S1 ′ to Sn ′. That is, the active control device in the present embodiment collects data from the IO slave devices S1 to Sn and performs the first calculation, and collects data from the IO slave devices S1 ′ to Sn ′ and performs the second operation. It also has the role of performing the operation.

If the control device that collects data from the IO slave device via the duplexed network in the redundant control system and performs some operation can also serve as a role to collect data via the single network and execute other operations, There is no need to construct separate systems for the redundant network and single network, and it is expected that the system development and operation costs can be reduced. However, the conventional redundant control system can meet such expectations. was difficult. The reason is as follows.

For example, assume that a single network is connected only to the network device 20A in FIG. In this case, the data received from the single network and the data received from the duplicated network are given from the network device 20A to the control device 10A, while the data received from the duplicated network is received from the network device 20B to the control device 10B. Only the processed data is given. If there is a discrepancy between the data given to the control device 10A and the control device 10B, some redundant control systems determine that there is an error. In such a system, the above connection form cannot be adopted in the first place. .

Even if the above mismatch is not determined to be an error, if the active system / standby system is switched due to a failure of the active system control device or the like in the above connection mode, the active system after the switching Data received from the single network is not given to the control device, and the collection of data transmitted from the single network and the calculation using the data cannot be continued. That is, even if one of the redundant control devices included in the conventional redundant control system can be given data via a single network to perform a predetermined operation, stable operation cannot be guaranteed. .

On the other hand, according to the present embodiment, even if the active / standby switching of the control device occurs, the monitoring data received from the single network is continuously given to the active control device after the switching, The monitoring data can be collected and the calculation can be continued using the data without any problem. For example, even if the active system is switched from the control device 100A ′ to the control device 100B ′ in the communication system 1C shown in FIG. 10, the network device 200A ″ is still an active relay device, and the network device 200B ″ is still This is a standby relay device. Therefore, the monitoring data transmitted from each of the IO slave devices S1 ′ to Sn ′ is, for example, IO network 30C → network device 200A ″ → equalization cable 400 → network device 200B ″ → control device 100B ′. It is transmitted to the control device 100B ′. In other words, according to the present embodiment, data is collected from the IO slave device via the redundant network in the redundant control system, and the control device that performs some computation collects the data via the single network and performs other computations. As a result, the system development cost can be reduced as compared with the case where the duplex network system and the single network system are constructed separately. When switching the active / standby system for a network device is subordinate to switching the active / standby system for a control device, the network device connected to the single network is the active network device. Regardless of whether or not there is, the monitoring data received via the single network is transferred to the other network device via the inter-relay device communication means or the control device communication means, and the monitoring data is equalized. It is sufficient to execute the processing to be executed.

(D: 4th Embodiment)
FIG. 11 is a diagram illustrating a configuration example of a communication system 1D according to the fourth embodiment of the present invention.
This communication system 1D is also a control system laid in an industrial facility. In FIG. 11, the same elements as those in FIG. 1 are denoted by the same reference numerals. FIG. 11 shows a detailed connection mode of the IO slave devices S1 to S3 to the

IO networks

30A and 30B, which is different from FIG. As shown in FIG. 11, each of the IO slave devices Sn (n = 1 to 3) is connected to the IO network 30A via the IO master MAn, and is connected to the IO network 30B via the IO master MBn. . 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 FIG. 1, the detailed connection configuration of the IO slave devices S1 to Sn is omitted, but is the same as that in FIG.

As is clear from a comparison between FIG. 11 and FIG. 1, the communication system 1D is provided with a network device 200A ″ and a network device 200B ″ instead of the network device 200A and the network device 200B in the first embodiment. Is different from the communication system 1A. One of the network device 200A "" and the network device 200B "" according to the present embodiment also behaves as an active system, and the other behaves as a standby system. In the present embodiment, as in the first embodiment described above, of the network device 200A ″ and the network device 200B ″, the one connected to the active control device 100 behaves as an active system. Hereinafter, as in the description of the first embodiment, when it is not necessary to distinguish between the network device 200A ″ and the network device 200B ″, the network device 200A ″ is described as “network device 200 ″”.

In the conventional redundant control system shown in FIG. 18, not only when a failure occurs in the active control device, but also an IO network connected to the active control device via the network device or the IO network is connected to the IO network. Even when some failure occurs in the IO master to which the slave device is connected, it is necessary to switch between the active system and the standby system. This is because, when a failure occurs in the IO network or the IO master, monitoring data via the IO network or the IO master cannot reach the active control device. On the other hand, in this embodiment, even if a failure occurs in the IO network or the IO master by causing the network device 200 ″ to execute processing unique to the present embodiment, switching between the active system and the standby system. It is comprised so that control of a control object apparatus can be continued, without performing this, The feature of this embodiment exists in this point. Hereinafter, the network device 200 ′ ″ that clearly shows the features of the present embodiment will be described.

FIG. 12 is a diagram illustrating a configuration example of the network device 200 ′ ″. In FIG. 12, the same components as those in FIG. 2 are denoted by the same reference numerals. As is clear from comparison between FIG. 12 and FIG. 2, the configuration of the network device 200 ″ ″ is that the relay control program 2542 ″ ″ is stored in the nonvolatile storage unit 254 instead of the relay control program 2542. Different from the configuration of the network device 200. The relay control program 2542 ″ ″ differs from the relay control program 2542 of the first embodiment in that the control unit 210 executes an equalization transmission process 2542 b 1 and an equalization reception process 2542 b 2 instead of the equalization process 2542 b. .

The control unit 210 of the network device 200 ″ ″ is a relay control program 2542 ″ ″ from the nonvolatile storage unit 254 to the volatile storage unit 252 when the power (not shown) of the network device 200 ″ ″ is turned on or reset. And start executing. FIG. 13 is a diagram for explaining an operation executed by the control unit 210 of the network device 200 ″ ″ according to the relay control program 2542 ″ ″. In FIG. 13, the same processes as those in FIG. 4 are denoted by the same reference numerals. The control unit 210 operating according to the relay control program 2542 ″ ″ writes the monitoring data to the communication buffer in the first communication I / F unit 220 in the same manner as the control unit 210 in the first embodiment described above. The relay processing 2542a is executed as a trigger, that is, triggered by reception of monitoring data from the connection destination IO network 30. As described above, in the relay process 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 to the monitoring data buffer 2522 (FIG. 13). : S110). Note that when monitoring data is written to the monitoring data buffer 2522, the first value indicating that the equalization has not been performed is set, a flag is added, and the monitoring data buffer 2522 is written to the first embodiment. It is the same.

As is clear from comparison between FIG. 13 and FIG. 4, the combination of the equalization transmission process 2542b1 and the equalization reception process 2542b2 corresponds to the equalization process 2542b. The execution trigger of the equalization processing 2542b in the first embodiment is different between the active network device and the standby network device. For example, the equalization processing 2542b is executed in response to the writing of the monitoring data to which the flag indicating that the equalization is not completed in the active system to the monitoring data buffer 2522, and the equalization cable 400 is performed in the standby system. The equalization processing 2542b is executed when the monitoring data is received via the network. In contrast, the execution timing of the equalization transmission processing 2542b1 is not different between the active network device and the standby network device, and the execution timing of the equalization reception processing 2542b2 is not different.

More specifically, the control unit 210 of the network device 200 ′ ″ is provided with a monitoring data buffer of monitoring data to which a flag indicating that the equalization has not been performed is assigned regardless of whether or not the network device 200 ″ is operating as an active system. The equalization transmission processing 2542b1 is executed in response to the writing to 2522. In the equalization transmission processing 2542b1, the control unit 210 reads the monitoring data to which the flag indicating that the equalization has not been completed is read from the monitoring data buffer 2522 (FIG. 13: S120), and the monitoring data is transmitted to the third communication I / O. This is given to the F unit 240 (FIG. 13: S130) and transferred to the other network device. Therefore, in this embodiment, the monitoring data A received by the network device 200A ″ from the IO network 30A is transferred to the network device 200B ″ through the equalization cable 400, and the network device 200B ″ is The monitoring data B received from the IO network 30B is also transferred to the network device 200A ″ ′ via the equalization cable 400.

The control unit 210 operating in accordance with the relay control program 2542 ″ ″ receives the monitoring data from the other network device 200 ″ ″ via the equalization cable 400 as an opportunity to receive the equalization reception processing 2542 b 2. Execute. FIG. 14 is a flowchart showing the flow of the equalization reception process 2542b2. As shown in FIG. 14, the control unit 210 can first communicate with the IO slave device that is the transmission source of the monitoring data received from the other network device 200 ″ ″ via the equalization cable 400. It is determined whether or not (step SB100). As a specific determination method for determining whether or not communication with the IO slave device that is the transmission source of the monitoring data is possible, a method using an existing technology such as ping is conceivable.

When the determination result of step SB100 is “No”, that is, when communication is impossible, the control unit 210 receives the monitoring data received from the other network device 200 ″ ″ via the equalization cable 400. Thus, the monitoring data that should have been received via the IO network 30 to which the own device is connected, that is, the monitoring data transmitted to the control device 100 connected to the own device is supplemented (step SB110). Since communication with the IO slave device is impossible, no monitoring data is received from the IO slave device, and step SB110 is a process for compensating for the lack of this monitoring data. More specifically, in step SB110, the control unit 210 provides information indicating the transmission destination of the header portion of the monitoring data received via the equalization cable 400 to the control device 100 connected to the own device. To the monitoring data buffer 2522 with a flag set with a first value indicating that it has not been equalized. Next, the control unit 210 updates the flag of the monitoring data written in the monitoring data buffer 2522 in step SB110 to the second value indicating that the equalization has been completed and notifies the other network device of the completion of equalization ( Step SB150) and the equalization reception processing 2542b2 are completed. Note that when the determination result in step SB100 is “No” as described above, monitoring data is not transferred to the other network device 200 ′ ″ via the equalization cable 400. The other network device may detect the completion of equalization triggered by the reception of the notification and update the flag of the corresponding monitoring data.

On the other hand, if the determination result in step SB100 is “Yes”, that is, if communication is possible, the controller 210 determines whether or not its own device is an active system, as in step SA100 described above. Is determined (step SB120). When the determination result of step SB120 is “Yes”, that is, when the own device is an active system, the control unit 210 receives from the other network device 200 ″ ″ via the equalization cable 400. The monitoring data is discarded (step SB130), and the equalization flag of the monitoring data written in the monitoring data buffer 2522 as corresponding to the monitoring data is updated to the second value (step SB150). The equalization reception process 2542b2 ends. On the other hand, if the determination result in step SB120 is “No”, that is, if the own apparatus is a standby system, the control unit 210 removes the equalization cable 400 in the same manner as the processing in step SA120 described above. The monitoring data received from the other network device 200 "" is replaced with the monitoring data written in the monitoring data buffer 2522 as corresponding to the monitoring data (step SB140), and then the processing of step SB150 is executed. Then, the equalization reception process 2542b2 is completed.
The above is the configuration of the network device 200 ′ ″.

Next, the case where the control device 100A is the active system and the control device 100B is the standby system, that is, the network device 200A ″ is the active system and the network device 200B ″ is the standby system is taken as an example. The operation of the embodiment will be described. The IO master MAn (n = 1 to 3) and the IO master MBn (n = 1 to 3) are all operating smoothly, and a failure such as disconnection occurs in either the IO network 30A or the IO network 30B. If not, the monitoring data An transmitted from the IO slave device Sn (n = 1 to 3) reaches the network device 200A ′ ″ via the IO network 30A, and the monitoring data transmitted from the IO slave device Sn. The data Bn reaches the network device 200B ′ ″ via the IO network 30B.

As described above, in each of the network device 200A ″ and the network device 200B ″, the relay processing 2542a is executed when the monitoring data is received via the first communication I / F unit 220. As a result, as shown in FIG. 15A, the monitoring data An is stored in the monitoring data buffer 2522 of the network device 200A ″, and the monitoring data Bn is stored in the monitoring data buffer 2522 of the network device 200B ″. Stored. Further, the equalization transmission process 2542b1 is executed in the network device 200 ″ when the monitoring data that has not been equalized is written to the monitoring data buffer 2522. As a result, as shown in FIG. 15A, the monitoring data An is transferred from the network device 200A ″ to the network device 200B ″ via the equalization cable 400, and the network device 200B ″ is transferred to the network device 200A ′. Monitoring data Bn is transferred to ″ via the equalization cable 400.

As described above, the control unit 210 of the network device 200 ′ ″ executes the equalization reception process 2542b2 every time monitoring data is received via the third communication I / F unit 240. Specifically, the control unit 210 of the network device 200A ″ ″ 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, the IO master MAn (n = 1 to 3) are all operating soundly, and no failure such as disconnection occurs in the IO network 30A. For this reason, in the equalization reception process 2542b2 executed by the control unit 210 of the network device 200A ″, the determination result in step SB100 is “Yes”, and the processes after step SB120 are executed. Since the network device 200A ″ is an active system, the determination result in step SB120 is “Yes”, and the process in step SB130 is executed. That is, all the 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 reception process 2542b2 is executed every time the monitoring data An is received via the third communication I / F unit 240. Also in the equalization reception processing 2542b2 executed by the control unit 210 of the network device 200B ″, the determination result in step SB100 is “Yes”, and the processing after step SB120 is executed. Since the network device 200B ″ is a standby system, the determination result of step SB120 is “No”, and the process of step SB140 is executed. That is, all the monitoring data Bn stored in the monitoring data buffer 2522 of the network device 200B ″ is replaced with the monitoring data An received from the network device 200A ″ ″ via the third communication I / F unit 240 ( (See FIG. 15B). As a result, the monitoring data An is transferred to the control device 100A via the network device 200A ″, and the monitoring data An is also transferred to the control device 100B via the network device 200B ″.

On the other hand, when any failure occurs in the IO master MA1 and the IO master MB2, as shown in FIG. 16A, the monitoring data A1 that the network device 200A ″ was supposed to receive is missing. However, the monitoring data B2 that the network device 200B ″ was supposed to receive is also lost. Note that NULL in FIG. 16A means that monitoring data is missing. In this case, as shown in FIG. 16A, the monitoring data A2 and A3 are transferred from the network device 200A "" to the network device 200B "" via the equalization cable 400, and from the network device 200B ". The monitoring data B1 and B3 are transferred to the network device 200A ″ ″ via the equalization cable 400.

In the equalization reception processing 2542b2 that is executed in the network device 200A ″ when the monitoring data B1 is received via the third communication I / F unit 240, the determination result in step SB100 is “No”. The process of step SB110 is executed. As a result, as shown in FIG. 16B, the monitoring data A1 that should have been received by the network device 200A ″ ″ is complemented with the monitoring data B1. Similarly, in the equalization reception processing 2542b2 executed by the network device 200B ″ when the monitoring data A2 is received via the third communication I / F unit 240, the determination result in step SB100 is “No”. ", And the process of step SB110 is executed. As a result, as shown in FIG. 16B, the monitoring data B2 that the network device 200B ″ was supposed to receive is supplemented with the monitoring data A2. In this operation example, monitoring data B1, monitoring data A2, and monitoring data A3 are transferred from the network device 200A ″ to the control device 100A as equalized monitoring data, and equalized to the control device 100B. As the monitoring data, monitoring data B1, monitoring data A2, and monitoring data A3 are transferred from the network device 200B ″. In this operation example, the equalized monitoring data is transferred from the network device 200A ″ to the control device 100A, which is the active control device, so that the control of the control target device is continued without any problem. be able to.

As described above, according to the present embodiment, even if a failure occurs in either the IO network connected to the active control device via the network device or a plurality of IO masters connected to the IO network. Thus, there is no need to switch the active / standby system for the control device, and the frequency of occurrence of switching of the active / standby system in the redundant control system can be reduced. Furthermore, according to the present embodiment, a failure occurs in the IO master connected to the IO network connected to the active control device via the network device, and the standby control device passes through the network device. Even if multiple failures occur, such as when a failure also occurs in an IO master connected to the connected IO network, control is not performed unless those IO masters are connected to the same IO device. The control of the target device can be continued, and the effect that the tolerance against multiple failures can be further enhanced as compared with the first embodiment described above is achieved. In this embodiment, the standby network device transfers all the monitoring data received from the IO network to the active network device via the equalization cable 400 between the network devices. Only missing monitoring data may be transferred. Various methods are conceivable for causing the standby network device to detect missing monitoring data in the active system. For example, the active network device transmits a list of identifier information of the received monitoring data to the standby network device via the equalization cable between the active network device, and based on the list What is necessary is just to make the standby network device detect the missing monitoring data in the active system. Further, when the data corresponding to the monitoring data is not received via the equalization cable between the network devices even after a predetermined time has elapsed since the standby network device received the monitoring data via the IO network. The standby network device may determine that the monitoring data in the active system is missing.

Further, in the case where the IO slave devices S1 to S3 include control target devices, the result of the calculation based on the calculation data transmitted from the control device 100 to the control target device, that is, the equalized monitoring data is represented. The data transfer control may be performed in the same manner depending on whether or not the IO master that connects the control target device to the IO network 30 has failed. For example, if each of the IO slave devices S1 to S3 in FIG. 16B is a device to be controlled, the control device 100A → the network device 200A ″ ″ → the equalization cable for the IO slave device S1. Operation data may be transferred along a transmission path such as 400 → network device 200B ″ ″ → IO network 30B. Similarly, arithmetic data may be transferred to the IO slave devices S2 and S3 along a transmission path such as the control device 100A → the network device 200A ″ → the IO network 30A.

In addition, in this embodiment, since the equalization of the monitoring data is performed by the network device 200 ′ ″, the amount of monitoring data transferred to the control device increases as in the first embodiment described above. However, there is an effect that it is possible to prevent any trouble in the execution of the original calculation of the control device and to prevent the switching speed of the active system / standby system from being lowered. Of course.

In the above-described embodiment, a case where a failure occurs in the IO master has been described. However, when a failure such as a disconnection occurs in the IO network 30, or a communication line that connects the IO network 30 and the network device 200 ′ ″. Needless to say, when a failure such as disconnection occurs, the above-described supplementation is performed for all monitoring data that should have been received via the IO network 30. In the above embodiment, only one duplicated IO network is connected to the network device 200 ′ ″. However, as shown in FIG. 17, a plurality of duplicated IO networks may be connected. For example, FIG. 17 illustrates a case where two duplicated IO networks are connected to the network device 200 ′ ″.

Generally, in a redundant control system, it is not preferable that the data transfer path from the IO slave apparatus to the active control apparatus 100 or the transfer path in the reverse direction fluctuate. Therefore, identification information indicating the transmission source determined to be incapable of communication in step SB100 is written in a predetermined storage area of the volatile storage unit 252, and thereafter, from the device in which the identification information is stored in the storage area. The monitoring data is always complemented or replaced by the monitoring data received via the equalization cable 400, and the process of initializing the storage area triggered by the power-off or reset of the own device is controlled by the network device 200 ″. You may make it make the part 210 perform. According to such an aspect, even if the IO master or the like is repaired after the occurrence of the above complementation and the necessity for the complementation or the like is eliminated, the network device 200 ″ ″ is turned off or reset. The data transfer route from the IO slave device to the active control device 100 is not switched to a route that is not supplemented as described above, and the influence caused by the route switching can be avoided.

(E: deformation)
Although the first, second, third, and fourth embodiments of the present invention have been described above, the following modifications may of course be added to these embodiments.
(1) In the first embodiment, the push type in which the monitoring data is transmitted and stored via the equalization cable 400 from the active network device of the

network devices

200A and 200B to the standby network device. The case where the equalization of the monitoring data is realized by the data communication in the above is described. However, the equivalence of the monitoring data is obtained by pull-type data communication that causes the standby network device to execute the process of acquiring the monitoring data from the active network device via the equalization cable 400 and updating the monitoring data of the own device. May be realized. The same applies to other embodiments.

(2) The second embodiment and the third embodiment may be combined. Specifically, each of the network device 200A ″ and the network device 200B ″ determines whether or not data communication via the equalization cable 400 is possible, and, if possible, the other device via the equalization cable 400. If the monitoring data is transmitted to the network device, and if impossible, the process of transmitting the monitoring data to the other network device via the equalization cable 40 may be executed. Similarly, the second embodiment and the fourth embodiment may be combined, and the second, third, and fourth embodiments may be combined.

(3) In each of the above embodiments, the application example of the present invention to the gateway device that transfers the monitoring data collected from the IO slave device to the control device has been described. However, the application target of the present invention is not limited to the gateway device, and may be another type of relay device such as a router, a repeater, or a switching hub. Further, the network connected to the relay device of the present invention is not limited to a control network such as an IO network or a serial bus, but is a general information system that mediates data communication according to a general-purpose communication protocol such as TCP. It may be a network. In short, it is connected to a control device that collects monitoring data and executes operations using the monitoring data, and a network connected to a device that outputs the monitoring data, and controls the data received via the network. The present invention can be applied to any relay device that transfers data to the device.

(4) A mode in which a network device included in the communication system of each of the above embodiments, that is, a relay device is provided alone, that is, a mode in which the relay device is manufactured and sold may be employed. Such a network device is replaced with a network device in a conventional redundancy control system, and the network devices are connected to each other by an equalization cable between relay devices, thereby making the conventional redundancy control system a communication system of each of the above embodiments. This is because it becomes possible to function as.

(5) In each of the above embodiments, the relay processing 2542a and the equalization processing 2542b (in the fourth embodiment, the equalization transmission processing 2542b1 and the equalization reception processing 2542b2) that clearly show the features of the present invention are performed by software. It was realized. However, each of the relay means for executing the relay process 2542a and the equalization means for executing the equalization process 2542b are configured by electronic circuits, and the networks of the first to third embodiments are combined by combining these electronic circuits. An apparatus may be configured. The same applies to the network device 200 ′ ″ of the fourth embodiment. In the above embodiment, the equalization cable is used as the communication device between relay devices. However, a wireless communication device such as a wireless LAN interface may be used as the communication device between relay devices. Further, when the network device 200A and the network device 200B are mounted in one housing, a bus connected to both devices may be used as a communication device between relay devices. The same applies to the inter-control device communication means.

(6) In each of the above embodiments, regardless of whether each of the control device 100A and the control device 100B or each of the control device 100A ′ and the control device 100B ′ is an active system or a standby system, the connection destination In the above description, the case where the calculation for device control is performed using the monitoring data received via the network device, that is, the case where the present invention is applied to a hot standby control system has been described. However, the application target of the present invention is not limited to a hot standby control system, and the present invention may be applied to a warm standby control system. The warm standby control system is the same as the hot standby control system in that one of the redundant control devices becomes the active system and executes the above calculation, and the other becomes the standby system to prepare for failure of the active system. However, a difference is that the above calculation is not executed in the standby control device. In the first to third embodiments, even in the standby network device, the monitoring data received by the first communication I / F unit 220 is written into the monitoring data buffer 2522 (FIG. 4B: S100 and Each process of S110) is executed, but the process may be omitted in the standby network device. This is because the monitoring data written by the monitoring data buffer 2522 by the processes of S100 and S110 in FIG. 4B is overwritten by the process of step SA120 of the equalization process 2542b.

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 ... Nonvolatile storage unit, 2542, 2542 ', 2542 "' ... Relay control program, 2542a ... Relay process, 2542b ... Equalization process, 260 ...

Bus

30A, 30B, 30C ... IO network, 40,400,400A, 400B ... equivalent cable, 50 ... monitoring system, S1 to Sn, S1 'to Sn' ... IO Slave device.

Claims

In a control system that collects monitoring data from one or more devices connected to the first and second networks and performs control based on the monitoring data,
The first and second control devices, one of which is an active system and performing the control, and the other is a standby system;
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;
Inter-relay device communication means for mediating communication between the first relay device and the second relay device;
Communication means between control devices that mediates communication between the first control device and the second control device;
With
The first and second relay devices are
A determination unit that determines whether communication is possible via the inter-relay device communication unit;
Each of the first and second relay devices is
The monitoring data received from the one or more devices is transferred to the connection destination control device, and when it is determined by the determination means that communication is possible, the monitoring data etc. is transmitted by communication via the inter-relay device communication means. On the other hand, when it is determined that communication is impossible by the determination unit, the monitoring data is equalized by communication via the control unit communication unit,
One of the first control device and the second control device, which is an active system, performs the control using monitoring data received from a connection destination relay device.
One of the first and second relay devices is
As processing to equalize the monitoring data, execute processing to transfer the monitoring data received from the connected network to the other relay device,
The other of the first and second relay devices receives the monitoring data received from the connection destination network as the processing corresponding to the monitoring data as the process of equalizing the monitoring data from the one relay device. The control system according to claim 1, wherein a process of replacing with the monitored data is executed.
The first and second control devices are:
It is determined whether or not communication via the inter-control device communication means is possible, and if possible, status data indicating the presence or absence of a failure in the own device is transmitted and received via the inter-control device communication means. The presence or absence of the other failure is monitored, and if it is not possible, the presence or absence of the other failure is monitored by transmitting and receiving the status data via the inter-relay device communication means. Item 3. The control system according to Item 2.
The first and second relay devices receive monitoring data transmitted from each of a plurality of devices,
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 the control device side is predetermined,
Each of the first and second relay devices equalizes monitoring data received from a device that is determined to perform equalization on the relay device side,
Each of the first and second control devices includes monitoring data transmitted from a device that is determined to perform equalization on the control device side among the monitoring data received via the connection destination relay device, etc. The control system according to claim 1, wherein the control system performs valuation.
Each of the first and second relay devices is
First processing means for transferring the monitoring data received from the connection destination network to the other relay device;
It is determined whether or not communication with the device that is the transmission source of the monitoring data received from the other relay device is possible, and the monitoring data that should have been received from the device determined to be unable to communicate is the other relay device. Second processing means for complementing with the monitoring data received from
The control system according to claim 1, comprising:
The second processing means includes
While storing the identification information indicating the device determined to be incapable of communication in the storage device, the device having the identification information stored in the storage device is complemented or replaced by the monitoring data received from the other relay device, The control system according to claim 5, wherein the storage content of the storage device is initialized in response to power-off or reset of the device itself.
The first and second relay devices are
Load measuring means for measuring the processing load applied to the connected control device,
Each of the first and second relay devices is
When the processing load measured by the load measuring means is equal to or greater than a predetermined threshold and the determination means determines that communication is possible, the monitoring data is equalized by communication via the inter-relay device communication means. The control system according to claim 1, wherein in other cases, the monitoring data is equalized by communication via the inter-controller communication means.
The first and second relay devices include load measuring means for measuring a processing load applied to a connection destination control device, and
Whether the monitoring data is equalized on the relay device side so that the monitoring data to be equalized on the relay device side increases as the processing load on the first and second control devices increases, or on the control device side A plurality of distribution patterns are determined according to the processing load,
Each of the first and second relay devices performs equalization of monitoring data that is determined to be equalized on the relay device side in a distribution pattern according to the processing load measured by the load measuring means. Done
Each of the first control device and the second control device performs equalization of monitoring data which is determined to be equalized on the control device side in a distribution pattern according to the processing load of the own device. The control system according to claim 1.
A third network is connected to one of the first and second relay devices,
The relay device connected to the third network collects monitoring data from a device connected to the third network, transfers the collected monitoring data to a control device connected to the own device, and The control system according to claim 1, wherein the control system is transferred to the relay device.
2. The control system according to claim 1, comprising a plurality of relay device pairs including the first relay device and the second relay device that communicate via the inter-relay device communication means.
1st and 2nd control apparatus connected to the communication means between control apparatuses, Comprising: One side becomes an active system and controls, and the other is connected to one of the 1st and 2nd control apparatus which becomes a standby system. And a relay device that is connected to a first network to which one or more devices that transmit monitoring data are connected, and that transfers monitoring data transmitted from the one or more devices to a connected control device,
Connected to inter-relay device communication means that mediates communication between the second network to which the one or more devices are connected and the other relay device connected to the other of the first and second control devices. A communication interface unit,
Relay processing for transferring monitoring data received from the one or more devices via the first network to a connection destination control device, and determination processing for determining whether communication is possible via the inter-relay device communication means. When it is determined that communication is possible in the determination process, communication for equalizing the monitoring data is performed via the inter-relay device communication unit, and when it is determined that communication is impossible, the control is performed. An equalization process for performing the communication via the inter-device communication means;
A relay apparatus comprising: