JPH1188353A - Duplex system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To automatically switch on-line and standby without using a changeover dedicated signal line. SOLUTION: A pair of stations 6a and 6b respectively connected to a common information terminal 8 are connected to the transmission line 5 of a network and applied to this duplex system for which one of the pair of the stations 6a and 6b is turned to on-line for indicating an operation state to the information terminal 8 and the other is turned to standby for indicating a standby state to the information terminal 8. Then, the respective stations 6a and 6b mutually transmit and receive information through the transmission line 5 and the on-line and standby of the stations 6a and 6b are switched based on the transmitted and received information.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of connecting a pair of stations having the same processing function to a transmission line of a network such as a LAN (Local Area Network), and sharing the pair of stations with common information. More particularly, the present invention relates to a duplex system in which one of a pair of stations is an online (operating) station and the other is a standby (standby) station.

[0002]

2. Description of the Related Art In general, in a system in which the operation of the system cannot be stopped or interrupted due to a failure or the like, a plurality of stations (processing devices) for performing the same processing operation are provided, and one of the stations is usually used. The station is designated online (operating system), processing is performed at the station designated online, and the other is designated as standby (standby system). If an error occurs in the online station, the standby station is changed to online,
Move an online station to standby.

FIG. 24 is a schematic diagram showing a schematic configuration of a duplex system having the above-described functions. LAN transmission path 1
A pair of stations 2 having the same processing function
a, 2b and a plurality of other stations 3 are connected. And usually one station (primary)
2a is designated online and the other station (secondary) 2b is designated standby.

Each station 2a, 2b has dedicated signal lines 4a, 4b for switching between online and standby, and the dedicated signal lines 4a, 4b are controlled by the two stations 2a, 2b. And by monitoring, the duplication station is switched between online and standby.

More specifically, each of the stations 2a and 2b has a 1-bit output port and a 1-bit input port for inputting / outputting signals on the dedicated signal lines 4a and 4b, and the state of each port is ON and OFF. Take the two values of The output port of one station 2a (2b) is
The dedicated signal line 4a (4b) is connected to the input port (2a). And the online station 2a
(2b) turns off its own output port when an abnormality of its own station is detected by a self-diagnosis function, for example.

The station 2a (2b) turns on the output port when it is online, and turns it off when it is on standby. Dedicated signal line 4 from the other side
Look at the value of the input port of b (4a),
a (2b) is controlled such that when the partner station 2b (2a) is on standby, the own station 2a (2b) is brought online. Online Station 2
When a (2b) detects an abnormality in its own station 2a (2b), the station a (2b) is demoted to standby, thereby promoting the partner station 2b (2a) online.

A WDT (watch dog timer) method has been implemented as a method for detecting that an abnormality has occurred in the partner station 2b (2a).

That is, each station 2a (2b)
Is a dedicated signal line 4a from its own output port at regular intervals.
A pulse signal or a continuation signal is transmitted to the partner station 2b (2a) via (4b). At the same time, each station 2a (2b) monitors the presence or absence of a signal at the input port of the dedicated signal line 4b (4a) from the partner station 2b (2a), and if no allowable time signal is detected, the partner station 2b (2b) 2a) is determined to be abnormal.

If the abnormal station is online, the abnormal station is shifted to standby, and the standby station is shifted to online.

[0010]

However, FIG.
A dedicated signal line 4 connects between the stations 2a and 2b shown in FIG.
The following problems still need to be solved in the method of connection by a and 4b. That is, since the dedicated signal lines 4a and 4b for switching between online and standby are used, there is an advantage that high reliability can be secured.

However, in order to connect the stations 2a, 2b with each other by the dedicated signal lines 4a, 4b, each station 2a, 2b requires a hardware configuration such as an input port and an output port, and the equipment cost increases. I do. Exclusive signal lines 4a and 4b only for switching other than the transmission path 1.
Laying has a problem that the whole system becomes complicated.

Further, there is a problem that high-level switching control cannot be performed with information of only the dedicated signal lines 4a and 4b.

The present invention has been made in view of such circumstances, and the information transmission between stations is performed by transmitting the information through a network transmission path necessary for the original processing or an information terminal connected to the station. An object of the present invention is to provide a duplex system that can automatically switch between online and standby without using a dedicated switching signal line, and that can perform advanced switching control.

[0014]

According to a first aspect of the present invention, a pair of stations each connected to a common information terminal are connected to a transmission line of a network. In a redundant system in which one is online indicating an operation state for an information terminal and the other is a standby indicating a standby state for an information terminal, each station transmits and receives information to and from each other via a transmission path, and based on the transmitted and received information, The station is switched between online and standby.

According to a second aspect of the present invention, in the duplex system according to the first aspect, each station transmits and receives information to and from each other via a transmission path, and determines a station in which an abnormality has occurred from the transmitted and received information, and determines a determination result. Is switched between on-line and standby of the station.

In the duplex system configured as described above, each station transmits and receives information to and from each other via a transmission line, and determines a station in which an abnormality has occurred from the transmitted and received information. Therefore, a dedicated signal line is not required to separately switch between online and standby, so that the hardware configuration of the entire system can be simplified.

According to a third aspect of the present invention, in the duplex system according to the second aspect of the present invention, information from an online station to a standby station is compared with information from a standby station to an online station, and is transmitted in a short cycle. ing.

In the duplex system configured as described above, the standby station monitors the status of the online station in a shorter cycle,
The occurrence of an abnormality can be detected more quickly, and the reliability of the system can be further improved.

According to a fourth aspect of the present invention, in the duplex system according to the second aspect, when each station detects that both stations are online and standby at the same time based on the transmitted and received information, Only one of the stations specified in is online.

For example, when the system is powered on, both stations are in a standby state. In addition, even in the normal operation state, both stations may be erroneously brought online. In such a case,
Since only one station always goes online, the reliability of the system can be improved.

According to a fifth aspect of the present invention, in the duplex system according to the second aspect, each station transmits and receives information to and from each other via a transmission line at a fixed period, and transmits information over an allowable time set longer than the fixed period. If not received, it is determined that an abnormality has occurred in the partner station.

In the duplex system configured as described above, the WDT (Watch Dog Timer) method is substantially implemented in a software manner via a transmission line, and it is easy to determine that an abnormality has occurred in the station on the other end. Can be detected.

According to a sixth aspect of the present invention, in the duplex system of the second aspect, each station fetches and outputs information output from the common information terminal at a constant period and transmits the information to the other station. The station in which the abnormality has occurred is determined based on the comparison result between the information stored by itself and the information received from the other party.

In the duplex system configured as described above, each station fetches and outputs information output from the common information terminal at a fixed period, and transmits the information to the other station.

In this case, since each station takes in the same information, the information stored by itself and the information received from the other party should be equal. Therefore, if the two are different, it can be determined that an abnormality has occurred.

According to a seventh aspect of the present invention, in the duplex system according to the second aspect, when each station detects that both stations are online and standby at the same time based on the information transmitted and received, The elapsed time is measured and transmitted to the partner station, and only one of the stations determined based on the result of comparison between the elapsed time of itself and the elapsed time received from the partner is kept online. In the redundant system configured as described above, for example, when the system is started,
When one of the stations rises first, this station detects that both stations including itself are in standby at the same time, and starts counting the time elapsed from the detection time.

When the other station rises with a delay from the preceding station, it detects that both stations including itself are in standby at the same time and starts counting the time elapsed from the detection time.

In this case, since a difference in elapsed time occurs between the stations, for example, only the station that has been started up is brought online.

According to an eighth aspect of the present invention, a pair of stations each connected to a plurality of common information terminals are connected to a transmission line of a network, and one of the pair of stations is an on-line indicating the operating state of each information terminal. In a redundant system in which the other is a standby indicating the standby state for each information terminal, each information terminal has a unique importance and each station monitors the operation state of each information terminal, and each station If an abnormality is detected in the operation state, the total importance of each information terminal that can be processed by itself is calculated and transmitted to the partner station, and the total importance of the terminal and the total importance received from the partner side are calculated. Is switched between online and standby on the basis of the result of comparison.

In the duplex system configured as described above, each information terminal has a unique importance. When an abnormality occurs in, for example, one or a plurality of information terminals among the plurality of information terminals, a station capable of processing an important information terminal goes online.

That is, there is a case where an abnormality occurs in some of the information terminals, and a situation occurs in which a plurality of information terminals including a normal information terminal cannot be processed due to the abnormality.
In this case, the information terminals that can be processed by each station differ between the stations. Therefore, the station that can process the important information terminal goes online, and the important information terminal is continuously processed.

According to a ninth aspect of the present invention, a pair of stations each connected to a plurality of common information terminals are connected to a transmission line of a network, and one of the pair of stations is an on-line indicating an operation state for each information terminal. In a redundant system in which the other is a standby indicating the standby state for each information terminal, each information terminal has a unique importance and each station monitors the operation state of each information terminal, and each station When a command to switch the station between online and standby is input from outside, the total importance of each information terminal that can be processed by itself is subtracted from the importance given to the command only when the terminal is online. Calculates the degree and sends it to the station on the other side, and receives the total importance of itself and the received Switching between online and standby station on the basis of a comparison result of a total of importance.

In the duplex system configured as described above, when a command to switch between online and standby of a station is input from outside, the total importance of the online stations is reduced. On the other hand, the total importance of the standby station is not reduced. Therefore, when a switching command is input from the outside, the on-line station becomes a standby with a high probability.

According to a tenth aspect of the present invention, in the duplex system according to the eighth aspect, each station has a unique importance, and in the comparison result, the total importance of the own station and the total importance received from the other party are determined. If they are equal, the station is switched between online and standby based on the importance of each station.

In the duplex system configured as described above, when the total importance of itself is equal to the total importance received from the partner, the important station is automatically brought online. Therefore, the important information terminal and the important station are in the operating state (online).

According to an eleventh aspect of the present invention, in the duplex system of the second aspect, when the station is switched from online to standby based on the determination result, the online station is temporarily shifted to a retreat state, and the standby station is shifted to online. After that, the station in the evacuation state is shifted to the standby state. The evacuation state means that when an on-line station wants to transition to standby, the on-line area is emptied and temporarily saved in another area so that the on-line station can immediately go on-line.

By providing such an evacuation state, conversion between online and standby proceeds smoothly.

According to a twelfth aspect of the present invention, in the duplex system according to the second aspect, the on-line station is forcibly shifted to the evacuation state based on the external command, and the standby station is shifted to the on-line state. Station to standby.

In the duplex system configured as described above, for example, the operator can forcibly shift the on-line station to the standby state via the evacuation state by an operation command.

A thirteenth aspect is the above-mentioned eleventh or first aspect.
In the dual system, when the standby station does not go online within the allowable time after the online station goes into the evacuation state, the evacuation station is restored to the online state.

That is, although the on-line station is shifted to the evacuation state by an external command, an abnormal state in which the on-line station is not shifted to online for some reason is prevented from continuing for a long time.

According to a fourteenth aspect, a pair of stations each connected to a common information terminal is connected to a transmission line of a network, and one of the pair of stations is online indicating an operation state of the information terminal, and the other is information. In a redundant system in which a standby state is indicated for a terminal, the standby station monitors the operation of the online station, and when the operation stops, the station itself takes over the operation of the online station, and, if necessary, the station Switch between online and standby.

In the duplex system configured as described above, since the standby station constantly monitors the operation of the online station, if an abnormality occurs in the online station, the standby station immediately takes over the processing and continues the processing. it can.

According to a fifteenth aspect of the present invention, a pair of online and standby stations each connected to a plurality of common information terminals are connected to a transmission line of a network.
In a duplex system in which a pair of stations share and process a plurality of information terminals, each information terminal has a unique importance, and each station has its own assigned operation state of each information terminal. Monitoring
Each station calculates the total importance of each information terminal to which it is assigned and transmits it to the other station, based on the comparison result of the total importance of itself and the total importance received from the other side. To switch the information terminals among the stations.

In the duplex system configured as described above, the on-line station and the standby station execute the processing for each information terminal assigned respectively.

Each station calculates the total importance of each information terminal assigned to it. Then, for example, the assignment of information terminals is switched between the stations so that the total importance is approximated. That is, the importance of the load applied to each station is leveled.

According to a sixteenth aspect, a pair of stations each connected to a common information terminal are connected to a transmission line of a network, and one of the pair of stations is online indicating an operation state for the information terminal, and the other is an information terminal. In a redundant system that becomes a standby indicating a standby state for a terminal, each station transmits and receives information to and from each other via a common information terminal, and determines a station in which an abnormality has occurred based on the transmitted and received information, based on the determination result. Switches the station between online and standby.

In the duplex system configured as described above, information transmitted and received between stations passes through a common information terminal.

Therefore, the traffic amount on the transmission path of the network is reduced, and the transmission load on the transmission path is reduced.

When a plurality of information terminals are present, when some of the information terminals fail and information cannot be exchanged between the stations, both stations are brought online and each station becomes its own. Processes information terminals that can process the data, thereby increasing the reliability of the system.

According to a seventeenth aspect, in the duplex system according to the second aspect, the station is periodically switched between online and standby in addition to when an abnormality occurs.

With this configuration, it is possible to prevent an abnormality (fault) that cannot be detected unless the system is online from occurring in the standby station or the information terminal to be processed, and preventing the failure from being left for a long time. . Therefore, the reliability of the system is further improved.

According to an eighteenth aspect of the present invention, in the duplex system according to the eighth aspect, when each station has a difference between the total importance of itself and the total importance received from the other party is equal to or larger than a predetermined rule, each station has the Switch between online and standby.

That is, similarly to the duplex system according to the eighth aspect, when an abnormality occurs in some information terminals and a plurality of information terminals including a normal information terminal occur, the information terminals that can be processed by each station are assigned to the station. There are differences between each other. However, if the difference is less than specified. The status quo is maintained without switching between online and standby.

As described above, by providing a dead zone when switching between online and standby, frequent changes of the operating information terminal are suppressed beforehand, and a stable duplex system can be provided.

[0056]

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

(First Embodiment) FIG. 1 is a schematic diagram showing a schematic configuration of a duplex system according to a first embodiment of the present invention.
A pair of stations 6a and 6b having the same function and a plurality of other stations 7 are connected to the LAN transmission line 5. A control target 8 as a common information terminal is connected to the pair of stations 6a and 6b. Each of the stations 6a and 6b executes a predetermined calculation process on the process data output from the control target 8, and sends the calculation processing result to the control target 8 as operation data.

The pair of stations 6a and 6b are respectively given unique names "primary (Sdp)" and "secondary (Sds)". A pair of stations 6
Of the stations a and 6b, the state of the station that performs the main control on the control target 8 is defined as online (operating system), and the state of the station that is not performing the main control is defined as standby (standby system). Usually one is online and the other is standby. This state is automatically switched between the stations 6a and 6b according to the situation.

When each of the stations 6a and 6b is a process control device, the control target 8 is an analog input / output device, and each of the stations 6a and 6b is a LAN.
In the case of a station such as a gateway for connecting to the network, the control target 8 is a LAN.

Between the pair of stations 6a and 6b,
For example, information is transmitted and received at regular intervals via the LAN transmission line 5, and the state of the partner stations 6b and 6a is monitored. The transmitted / received information is mainly information on whether the self is online or on standby and whether there is an abnormal state. Then, it is determined whether the conversion between online and standby is necessary between the stations 6a and 6b based on the information, and the conversion is executed if necessary.

More specifically, when an abnormal situation occurs in an online station, this online station becomes a standby, and the standby station is converted to online.

Even if no abnormality has occurred, various states are switched as described below according to the combination of online and standby.

When the own station 6a (6b) is on-line and the partner station 6b (6a) is on standby, and when the own station 6a (6b) is on standby and the partner station 6b (6a) is online, between the online and standby states State transition does not occur.

When both the self station 6a (6b) and the partner station 6b (6a) are online or both are in standby, one station goes online and the other station changes to standby.

When each of the stations 6a and 6b can take only two types, that is, online (On) and standby (St), respectively, this pair of stations 6a and 6b has four types of combinations as shown in FIG. 5 with the initial state
There are types. FIG. 3 shows a state transition.

As the status of each of the stations 6a and 6b, an abnormal status may be added in addition to the above-mentioned two statuses of online and standby. In this case, the state is 3
The combination of each state described above is 3 × 3
+ 1 = 10, for a total of 10 types.

Next, a specific processing operation will be described.

First, when both stations 6a and 6b are on-line or standby (duplication state collision), the processing for the control target 8 is not normally performed only during that time.
As a method of preventing this (or minimizing the opportunity as much as possible), a method of providing a difference in the monitoring time of the partner between the primary and the secondary is adopted.

(1) That is, both stations 6
When the standby stations a and 6b are in standby, the primary station 6a is immediately promoted to online, but the secondary station 6b is connected to the remote station 6a for two seconds, for example, in consideration of the delay in transmission of the duplex state to the remote station 6a. The station 6a is monitored, and if the other station 6a is still on standby, it is promoted to online.

(2) In a system in which no abnormal state is provided, it is desirable that the time for which the self-station forcibly stays in standby when a failure occurs is twice as long (for example, 4 seconds).

(3) If both stations 6a and 6b are online, the primary station 6
For 2 seconds (the value described above), the state of the partner station 6b is observed. If the partner station 6b is still online, the own station is demoted to standby. The secondary station 6b immediately sends its own station 6
Demote b to standby.

Next, the technical effects of the duplex system of the first embodiment configured as described above will be described.

(1) Switching between online and standby (duplex switching) is possible without using dedicated signal lines 4a and 4b for switching between online and standby as shown in the conventional system.

As described above, the dedicated signal lines 4a, 4a,
4b can realize faster switching, but in a system in which the switching time may be longer than the time taking into account the state transmission time, by adopting the system of the first embodiment, Manufacturing costs can be significantly reduced.

Further, since there is no need to wire the dedicated signal lines 4a and 4b between the stations 6a and 6b, the construction work of the system is simplified.

(2) In the method of creating an abnormal state in addition to online and standby in the state of each station 6a, 6b, (a) the own station is in standby,
When the partner station becomes abnormal, the own station can shorten the time required for promotion from standby to online.

(B) When downgrading from online to standby due to a relatively minor failure, if the partner station is already in an abnormal state, switching is not performed, and as a result, the loss of the online station can be prevented.

(3) By providing a difference in the diagnosis time between the primary and the secondary, the duration of a duplicated state collision in which both stations are online or standby at the same time can be shortened.

(Second Embodiment) A duplex system according to a second embodiment of the present invention will be described with reference to FIG.

In the duplex system of the second embodiment, information such as a diagnostic message transmitted from the online station 6a (6b) to the standby station 6b (6a) in the duplex system of the first embodiment shown in FIG. Is set shorter than the transmission cycle of information transmitted from the standby station 6b (6a) to the online station 6a (6b), as shown in FIG.

When an abnormality (down) of the online station 6a (6b) occurs, it needs to be detected as quickly as possible, and the online station must be immediately switched to the currently standby station. Therefore, when the fixed period of the transmission in the duplex state is used as the abnormality detecting means, the shorter the period is, the shorter the detection delay time becomes. Therefore, the online station 6a (6
The transmission cycle from b) is shortened.

On the other hand, the abnormality (down) of the standby station has no effect until the abnormality (down) of the next online station occurs. The probability that both stations 6a and 6b are abnormal (down) at the same time is low, and it usually takes a long time to recover from the abnormality (down). No need to detect.

As shown in FIG. 4, the transmission cycle of the diagnostic message automatically changes from the short cycle to the long cycle due to the downgrade of the state of the primary station 6a from online to standby.

The transmitting-side station 6a (6b) includes the next transmission diagnostic time (transmission cycle) in the diagnostic message.
The receiving station 6b (6a) diagnoses the partner station 6a (6b) based on the transmission diagnosis time (transmission cycle).

As described above, by making the transmission period of the information of the duplication state different between the online side and the standby side, the load on the CPU of each station 6a, 6b can be reduced, and the transmission path of the LAN transmission line 5 can be reduced. Transmission burden can be reduced.

(Third Embodiment) A duplex system according to a third embodiment of the present invention will be described with reference to FIG.

In the duplex system according to the second embodiment, each station 6a, 6b in the duplex system according to the first embodiment transmits information transmitted from a partner via the LAN transmission line 5 at a constant period. A timer for measuring the time elapsed from the reception time is incorporated. And
If the stations 6a and 6b do not receive information for longer than the predetermined period (for example, three times the transmission period) and for a set allowable time, it determines that an abnormality has occurred in the partner stations 6b and 6a.

When the abnormal occurrence station is an on-line station, switching between on-line and standby is performed. If the station in which the abnormality has occurred is a standby station, the switching between online and standby is not performed, and only a message indicating that the abnormality has occurred is output as a warning.

The abnormal state is treated the same as the abnormal state in the first embodiment. Specifically, as an abnormal state, when the hardware breaks down and the program stops working When the program is defective and the program does not work as expected (including runaway) When the power is turned off There is no problem with the corresponding station, It is assumed that the LAN between the online and standby stations breaks down.

Further, as information to be transmitted to the other party in a fixed cycle, there is tracking information between online and standby. It should be noted that transmission having a shorter cycle than transmission of such duplicated information may be used for diagnosis of an abnormality. When information with a short cycle is used, the switching of duplication can be performed quickly.

In the duplex system of the third embodiment configured as described above, it is determined whether or not there is an abnormality in the station on the partner side by using information transmitted at regular intervals via the transmission line 5 of the LAN. Therefore, it is possible to reliably detect the occurrence of an abnormality in the system and execute the processing quickly.

(Fourth Embodiment) A duplex system according to a fourth embodiment of the present invention will be described with reference to FIG.

In the redundant system according to the fourth embodiment, each of the stations 6a and 6b has raw data memories 9a and 8b for storing raw data output from the control target 8 as a common information terminal at regular intervals. Update counters 10a and 10b are provided. Further, the previous value counter 11 is provided in the online station 6a (6b).
a, a previous standby value counter 12a, and a standby update counter 13a.

The on-line station 6a detects that an abnormality has occurred in each of the stations 6a and 6b in the following procedure.

(1) When one cycle arrives, both stations 6a and 6b take in the raw data sent from the controlled object 8 and write it to the raw data memories 9a and 9b.

(2) For each item of the raw data, the corresponding update counter 10a, 1
Increment the value of 0b.

(3) The standby station 6b transmits the value of the update counter 10b of the self-station 6b to the online station 6a via the transmission line 5 of the LAN. The calculation becomes easier if the transmission cycle is longer than the raw data collection cycle. The online station 6a writes the received value to the standby update counter 13a.

(4) The online station 6a compares the update counter 10a of its own station with the previous value counter 11a and calculates the increment.

(5) The online station 6a compares the received value of the standby update counter 13a with the value of the previous standby value counter 12a and calculates the increment. (6) The on-line station 6a compares the on-line increase with the standby increase.

Since the online and standby modes are not synchronized, there is a time lag in incrementing the update counters 10a and 10b even if the same raw data is received at the same time. Also, since it takes time to transmit the update counter from the standby to the online, a margin is provided in the comparison of the increase.

If, after subtracting this margin, the increase in online is smaller than the increase in standby, the predetermined increase cannot be obtained because the online station 6a could not receive new raw data. It is determined that an abnormality has occurred in the online station 6a.

Then, the online station 6a is switched to standby, and the standby station 6b is switched to online.

Conversely, if the increase in online is larger than the increase in standby and the increase in standby is larger than the allowable value, it is determined that an abnormality has occurred in the station 6b in standby. In this case, only the warning of the occurrence of the abnormality is output without switching between online and standby. (Fifth Embodiment) A duplex system according to a fifth embodiment of the present invention will be described with reference to FIGS.

In the redundant system according to the fifth embodiment, each station 6a, 6b determines that both stations 6a, 6b are online or standby at the same time based on the information received from the partner stations 6b, 6a. Upon detection, the elapsed time from the detection time is counted and transmitted to the partner station, and only one of the stations determined based on the result of comparison between the elapsed time of itself and the elapsed time received from the partner is brought online. I do.

Next, specific detailed methods will be described in order.

Elapsed time (delay time) for diagnosis is 10
Seconds. In addition, the transmission cycle of the elapsed time for transmitting to each other is set to about 1 second, which is sufficiently smaller than the elapsed time (delay time) of 10 seconds. As a result, the transmission is performed about 10 times during the elapsed time of 10 seconds, and if there is no transmission error, the duplex information and the elapsed time (delay time) of the partner station can be received about 10 times.

This elapsed time (delay time) is set to a value of 10 seconds when it becomes necessary to change the state of duplication indicating the relationship between online and standby. As shown in FIG. 7, the value is decremented over time. When the value becomes 0, a dual state indicating the relationship between online and standby is transited. That is, an elapsed time (delay time) of 10 seconds is provided.

During the elapsed time (delay time) of 10 seconds, the elapsed time (delay time) for switching the state of the partner station is also considered.
, The stations 6a and 6b compare the values of the elapsed time (delay time) as shown in FIG. More specifically, the time is compared with a margin of time such as a fluctuation time of a transmission delay for transmitting the duplex state. Here, the time is set to 2 seconds. The elapsed time (10 seconds here) must be sufficiently larger than this time.

When the difference is larger than 2 seconds, the station having the smaller elapsed time value undergoes a state transition, and the elapsed time is set to 0. The station with the larger elapsed time value does not cause a state transition, stays in the previous state, and the other station causes the state transition, and when the collision of the double state is eliminated, the value of the elapsed time (delay time) is set to 0. I do.

When the difference is smaller than 2 seconds, the primary station 6a continues the operation. The secondary station 6b resets the elapsed time (delay time) to 10 seconds. According to this procedure, when the difference is small, the secondary timer is increased, a difference of 2 seconds or more is provided, and the primary station 6s is brought online.

FIGS. 7 and 8 show a specific example at the time of startup of the duplex system according to the fifth embodiment.

FIG. 7 shows a state in which the primary station 6a has risen but the secondary station 6b has not yet risen.

(1) The primary station 6a
When the self station is started up, no duplex information can be obtained from the station 6b on the other side, so that both stations 6a, 6
b are both determined to be in standby. Then, the elapsed time (delay time) of 10 seconds is set in its own timer. Then, thereafter, the elapsed time is decremented.

(2) Since the elapsed magnetic time (delay time) is not input from the partner station 6b until the elapsed time (delay time) reaches 0, the primary time is reached when the elapsed time (delay time) reaches 0. Station 6a switches from standby to online. FIG. 8 shows a state in which the secondary station 6b has risen 10 seconds after the primary station 6a has risen.

(1) When the primary station 6a first rises, the secondary station 6b has not yet risen, so there is no information from the partner station 6b. Therefore, as in FIG. 7, the primary station 6a sets the elapsed time (delay time) of 10 seconds in the timer. Thereafter, the countdown is performed.

(2) The secondary station 6b stands up. The difference is 2 seconds or more. The transmission path delay is less than 1 second.

(3) Duplicate information (standby information) and the current elapsed time (delay time) of the primary station 6a arrive from the primary station 6a to the secondary station 6b. Put in the partner information memory. Thereafter, it is repeated periodically.

(4) Duplicate information (standby information) and the current elapsed time (delay time) of the secondary station 6a arrive from the secondary station 6b to the primary station 6a, and store them in the partner information memory. . Thereafter, it is repeated periodically.

(5) The secondary station 6b
From the partner information memory, it is known that the partner station 6a is in standby and the elapsed time is nine. Since the other party is not online, the procedure for transitioning to online is started. And
The elapsed time (delay time) of 10 seconds is inserted into the timer, and the countdown is performed thereafter. In this case, the difference between the value of the elapsed time of the partner station 6a and the timer of the self-station 6b is 2 seconds or less, and the self-station 6b is secondary, so the timer is returned to 10 seconds. It is only this time that the time is returned to 10 seconds, and thereafter, since the difference becomes 2 seconds or more, the countdown is performed without restarting the timer.

(6) The primary station 6a
From the partner information memory, it is known that the partner station 6b is in standby and the elapsed time (delay time) is 7. Since the other station 6b is not online, the elapsed time (delay time) is not 0, and the value of the own station 6a is smaller than 2 seconds, it is determined that the own station 6a is higher in priority than the other station 6b. Then, the self station 6a is brought online and the timer value is set to 0.

(7) The secondary station 6b
Knowing that the primary station 6a has come online, the timer of the self-station 6b is stopped and the value is set to 0.

In the redundant system configured as described above, in the redundant system according to the fifth embodiment, for example, at the time of starting the system, even if both stations 6a and 6b go online and standby at the same time, the other stations 6b and 6a When sufficient time has been confirmed to check the status of the duplexing and when the status of the other party has been confirmed, the duplexing is quickly switched to shift to a normal relationship between online and standby.

(Sixth Embodiment) A duplex system according to a sixth embodiment of the present invention will be described with reference to FIGS. In the duplex system of the sixth embodiment, a plurality of lower stations 8a, 8b, 8c, 8d as a plurality of information terminals are connected to each station 6a, 6b via a common lower LAN transmission line 14. I have.

As shown in FIG. 10, an I / O 15 having a plurality of cards may be used instead of the plurality of lower stations 8a, 8b, 8c and 8d.

Each of the lower stations 8a to 8d has a unique importance. For example, the lower station 8a is [40] and the lower station 8b is [27]. Note that each importance does not need to be a fixed value. It may vary with time.

At this point, the failure occurs at the position A of the transmission line 14 of the lower LAN, and only the lower station 8a and the secondary station 6
b, the lower stations 8b to 8d are connected and functioning, and the lower station 8a, 8b is connected to the primary station 6a and the lower station 8a, 8b is connected to the primary station 6a. 6
It is assumed that the lower stations 8c and 8d are connected to and function as b.

Each of the stations 6a and 6b periodically calculates the total importance of the lower stations normally connected to itself, and calculates the total importance of the lower stations. 6a. When switching from online to standby is performed only by an online station, the total importance may be transmitted from the standby side to only the online side. The switching state between online and standby is determined by comparing and comparing the total importance of the stations 6a and 6b.

Note that, instead of the total importance, the number of failures of the device or the normal number may be used. In order to know the number of failures, it is necessary to know the number of connected devices in advance. Further, as this value, the above result can be temporarily determined and classified into light failure, medium failure, heavy failure, and the like, and this value can be entered.

Next, a specific procedure for switching between online and standby using the total importance in the redundant system in the state shown in FIG. 9 will be described.

In the redundant system shown in FIG. 9, before a failure occurs at the position A and the position B, the lower station 8a
If all 8d are normal, the online station 6
At the station 6a and the standby station 6b, the total importance is equal to 112.

That is, the online side and the standby side have the same value, no switching occurs, the online remains online, the standby remains the standby, and the same duplex state is maintained.

When the transmission path 14 of the lower LAN is disconnected at the position B and the transmission path 14 of the lower LAN can be used, the total important city on the online side is 67 and the total important city on the standby side is 45. Comparing this, the value on the online side is larger and the primary station 6b
Keep online.

On the other hand, if the transmission line 14 of the lower LAN is disconnected at the position A, the total importance on the online side becomes 40, the total importance on the standby side becomes 72, and the value on the standby side becomes larger. Therefore, the standby secondary station 6b is switched to online, and the online primary station 6a is switched to standby.

In the duplex system according to the sixth embodiment thus configured, a plurality of common lower stations 8a to 8d connected to the stations 6a and 6b.
An abnormality occurs in some of the lower stations 8a to 8d, and the lower stations 8a to 8d that can be processed by the stations 6a and 6b are assigned to the stations 6a to 8d. 6b. Therefore, important lower stations 8a to 8d
Since the stations capable of processing are brought online, the important lower stations 8a to 8d are continuously processed.

(Seventh Embodiment) A duplex system according to a seventh embodiment of the present invention will be described with reference to FIG.

In the redundant system according to the seventh embodiment, in the redundant system according to the sixth embodiment shown in FIG. 9, for example, a switching command (command) inputted from the outside by an operator is also assigned importance. . Then, when each of the stations 6a and 6b receives the switching command, if the station itself is an online station, the calculated total capacity is reduced by the importance of the switching command. That is, when a switching command is input from the outside, the on-line station becomes the standby with a high probability.

FIG. 11 shows a specific example. Assume that the total importance of the online station 6a is 100, and the total importance of the standby station 6b is 50. When receiving the switching command (command) to the standby, the online station 6a subtracts 200 from the total importance at the online station 6a.

This value is set to a value larger than the maximum possible value of the total importance. As a result, the total importance of the on-line station 6a becomes minus 100. If the duplication process functions between the two stations 6a and 6b, the total importance of the standby station 6b becomes larger, so that the conventional standby 6 Station 6
b is newly online.

At this point, the total importance of the online stations is 50, and the total importance of the standby stations is minus 100. In this state, when a command for switching to the standby mode is further sent to the online station, the subtraction of 200 is performed as before. As a result, the total importance of the stations online is minus 150. As a result, the total importance of the standby stations becomes larger, and the duplication is switched.

Even if a switching command is issued to both of the stations 6a and 6b by mistake, the switching is performed in a normal switching procedure, and there is always an online station. In addition, both stations 6a, 6b
Even at the point in time when the command for switching to standby is issued, the determination of the abnormal state is performed, and the station of the enline is switched to the one with less abnormality.

(Eighth Embodiment) A duplex system according to an eighth embodiment of the present invention will be described with reference to FIG.

In the redundant system according to the eighth embodiment, importance is assigned to each of the stations 6a and 6b in the redundant system according to the sixth embodiment shown in FIG. Specifically, as shown in FIG. 12, a bit of [1] is added to the last digit of the total importance calculated by the primary station 6a, and the last digit of the total importance calculated by the secondary station 6b is added. Is added to [0].

The value to which the bit [1] or [0] is added is referred to as a comparison value. As shown, the upper side of the comparison value is the total importance itself. In other words, the least significant bit is a distinction between primary and secondary. As a result, the final comparison value is never the same for the primary and the secondary, but always different.

Therefore, the comparison between the comparison target values simplifies the processing for switching between online and standby.

Incidentally, for example, if the primary is determined to be less than the secondary, the portion must be divided into the primary and the secondary. In this embodiment, the primary or secondary can be determined only by the numerical value.

When the total importance of the user is equal to the total importance received from the other party, the important station is automatically brought online. Therefore, an important control target and an important station are in an operating state.

(Ninth Embodiment) A duplex system according to a ninth embodiment of the present invention will be described with reference to FIG.

In the duplex system according to the ninth embodiment, in the duplex system according to the first embodiment shown in FIG. 1, the states of the stations 6a and 6b are changed to "online", "standby" and "standby" as shown in FIG. In addition to "down (abnormal)", a "evacuation" state can be set.

The evacuation state is different from the evacuation state in which the online station 6a (6b) is set to an empty area so that the standby station 6b (6a) can immediately go online when the station 6a (6b) wants to transition to the standby mode. This is to temporarily save to the area. This evacuation state is also used when demoting from online to standby or by prohibiting going online by a switching command (command) from another station to standby.

For example, if the station 6a (6b) is continuously in the evacuation state due to the evacuation instruction input by the operator, it is forgotten that this evacuation instruction has been issued, and the combination of online and standby is forever. There is a danger that it will not transition to a duplex state consisting of matching. In order to prevent this, a timer is started when the apparatus enters the save state by a save instruction (command), and after a certain period of time, the standby mode is restored.

The specific operation will be described with reference to FIG.

First, it is assumed that the primary station 6a is online and the secondary station 6b is standby.

When a request for switching to the standby mode is sent to the online station, the online, that is, the primary station 6a is temporarily in a retreat state as indicated by a solid arrow. The standby station, that is, the secondary station 6b, is immediately promoted online when the other party is in the waiting state. When the partner station comes online in the standby state, the primary station 6a is restored to the standby state. This transition is indicated by the solid line (1) in FIG.

If the partner station 6b is in the standby state forever, it is returned to the online state by the diagnosis. This is indicated by a broken line in FIG. In addition, the temporary evacuation state for demoting the above-mentioned online station 6a and the corresponding station 6a
The auxiliary state may be used or another state may be created in order to distinguish the online state from the forced evacuation state that prohibits the user from going online.

The forced retreat state is used as a test,
It is used when a failure occurs in an unstable manner and the system is frequently switched between online and standby, causing trouble to the system.
The state can be shifted to the forced retreat state by an operation of the operator.

When a forced evacuation command is issued by an operator, there is a possibility that the command will be forgotten. To prevent this,
Provide a timer. A method for preventing forgetting to release will be described with reference to FIG.

When an operation command (command) for transition to the evacuating state is received and a transition is made to the evacuating state, a timer is started.
This timer initial value may be a fixed value or may be one parameter in the command. When the timer expires, the system automatically shifts from the standby state to the standby state. If a release command arrives before the time expires, it takes precedence. In order to further extend and maintain the retracted state, the command is issued again.

As described above, by adding a new retreat state to the state of each station 6a, 6b, the online station is demoted, and it is possible to quickly switch between online and standby.

By the way, if the demo is simply downgraded from online to standby, the station which has been in the conventional standby mode must enter into arbitration between the two stations, which takes time.

By providing a timer, the on-line station is shifted to the evacuation state by an external command. However, it is possible to prevent the standby station from shifting to the on-line state for any reason and continuing the abnormal state. You.

(Tenth Embodiment) A duplex system according to a tenth embodiment of the present invention will be described with reference to FIG.

The same parts as those of the duplex system of the sixth embodiment shown in FIG. 7 are denoted by the same reference numerals.

The standby station 6b of the duplex system according to the tenth embodiment monitors the operation of the online station 6a via the LAN transmission line 5,
When the operation stops, the own station 6b takes over the operation of the online station 6a, and if necessary, the own station becomes online and continues the online operation.

Next, the specific configuration and operation of each station 6a, 6b will be described.

Each of the lower stations 8a to 8d connected to the transmission line 14 of the lower LAN outputs data to the transmission line 14 at a constant period by a broadcast method. Therefore, each station 6a, 6b can fetch these data by the lower LAN interfaces 16a, 16b under the same conditions.

In each of the stations 6a and 6b, the data received by the lower LAN interfaces 16a and 16b is received by the lower LAN reception processors 17a and 17b, and then temporarily stored in the upstream databases 18a and 18b.

The online station 6a outputs this data to the LAN transmission path 5 via the LAN transmission processing section 19a and the LAN interface section 20a by broadcast communication.

The standby station 6b is connected to the LAN
Online station 6a output to the transmission line 5
From the LAN interface 20b and LA
N receiving unit 21b and temporarily monitor database 22b
To be stored.

The standby station 6b
Is compared by the comparative diagnostic processing unit 23b between the data stored in the upstream database 18b and the data stored and held in the monitoring database 22b. Those not in the monitoring database 22b are monitored for time. For data that exists in the upstream database 18b for a certain period of time and does not exist in the monitoring database 22b, the comparative diagnosis processing unit 23b sends the corresponding data to the LAN transmission processing unit 1
The broadcast is transmitted to the LAN transmission line 5 via the LAN 9b and the LAN interface 20b.

Thus, the online station 6
If a loss occurs in the data reception from the lower stations 8a to 8d in step a, the standby station 6b executes processing for the lost data (broadcast transmission processing for the LAN transmission path 5), so that the entire redundant system Reliability can be improved.

If the above-mentioned data timeout occurs frequently in the standby station 6b, the on-line station 6a is determined to be abnormal, the duplexing is switched, and the existing standby station 6b becomes online. The online station 6a is switched to standby.

In the tenth embodiment of the portable dual system thus constructed, the standby station 6
b) monitors not only the duplex state between online and standby, but also the processing to be processed by the online station 6a, and if the processing is interrupted for a certain time on the online side, the processing is replaced by the standby side. Thus, interruption of online processing is prevented beforehand.

In addition, since the processing time delay is problematic in the above-mentioned shoulder substitution, if the frequency of the shoulder substitution becomes high,
Switch to duplexing assuming that an online station is abnormal (down). In particular, when the online station cannot perform self-diagnosis and cannot find any abnormality on its own, or when the load on the online station increases, such an event occurs. Reliability is further increased.

(Eleventh Embodiment) A duplex system according to an eleventh embodiment of the present invention will be described with reference to FIGS.

In the redundant system according to the eleventh embodiment, a plurality of common control objects 24a to 24d are connected to the stations 6a and 6b, respectively. Each of the control targets 24a to 24d has an individual importance similarly to each of the lower stations 8a to 8d in the system of the sixth embodiment in FIG.

Further, each of the stations 6a and 6b implements a dual control system of online or standby for each of the controlled objects 24a to 24d. That is, for each of the controlled objects 24a to 24d, the online station 6a
(6b) and the standby station 6b (6a) need to be determined according to the situation at that time. When viewed from the stations 6a and 6b, the own station 6a (6
The control targets 24a to 24d for which b) is online and the control targets 24a to 24d for which the own station 6a (6b) is on standby are allocated.

In the system according to the tenth embodiment,
The total importance of each of the controlled objects 24a to 24d, which are assigned online to the stations 6a and 6b, is calculated so as to equalize the total importance between the stations 6a and 6b.

A specific sharing method will be described with reference to the sharing table of FIG.

The names of the devices 1 to 4 are given to the four control objects 24a to 24d, respectively. The device 1, the device 3, and the device 4 are both normal in the primary station 6a and the secondary station 6b, but the device 2 has an abnormality in the primary station 6a. In the device 2, the secondary station 6b has a higher value in the determination of the importance level, so the secondary station 6b is online, and is not a target of the current load distribution.

The targets of the load distribution this time are the primary station 6a and the secondary station 6a.
The devices 1, 3, and 4 have the same value of importance with respect to b. These conditions are that the importance is the same between the primary and the secondary, and whether the device is normal or abnormal is not a condition for load distribution.

It is assumed that the first state is state 1 in the upper part of FIG. As described above, the secondary station 6b is fixed online for the device 2, but the primary station 6b is assumed to be online for the devices 1, 3, and 4.

In the load distribution processing, control is performed as follows.
In other words, only those stations having a difference in importance between the two stations 6a and 6b are subject to load distribution. However, when determining the load distribution, the value of the importance of the device having a difference is also used.

(1) Each station 6a, 6b
Then, based on the information on the duplex state, the total importance of the devices whose own station is online is calculated. Then, the total importance of the own station 6a (6b) is set to S.
s, the total importance of the partner station 6b (6a)) is S
Define o. Note that the importance of each device is the station 6
The values are the same for each of the stations 6a and 6b because they are transmitted and received between the stations 6a and 6b.

(2) Only stations with a high total importance of devices that are online determine load distribution. Conversely, the station with the smaller total importance of the devices going online does not judge the load distribution.

(3) The station for determining the load distribution finds the difference between the online total importance of the two stations 6a and 6b, and calculates this value as D (= | Ss-So |).
And

(4) Search for a device having a degree of importance closest to half the value of D. The search target has the same importance value in the primary and the secondary, and the station is an online device. However, if the importance is not lower than D, there is no corresponding device. Let X be its importance.

(5) The state of the corresponding device is set to standby, and the state of the partner station is set to online. Switching of the duplex state between online and standby for this device is performed in the manner described above.

For example, in state 1, the total online importance is higher at the primary station 6a.
The primary station 6a first determines load distribution. Ss is 320, So is 130, and D is 19
0. The value closest to this half value is 100
It is. Therefore, the duplex state of the device 1 is switched. As a result, a state 2 is set.

In the state 2, the secondary station 6
Since the online total importance of “b” increases, the secondary station 6 b determines the load distribution. Ss
Is 230, So is 220, and D is 10. Since there is no device corresponding to this, the load distribution ends in this state 2.

In the redundant system of the eleventh embodiment configured as described above, each of the control targets 24a to 24a is controlled.
24d each as a primary station 6a
And the secondary station 6b determine the sharing between the online state and the standby state, and automatically adjust the load sharing so that the total importance of the controlled objects that are online becomes substantially uniform.

Therefore, even if a plurality of failures occur in the control target, the operation rate of the system increases, and
Even if there is no failure, the load can be distributed between the dual stations 6a and 6b.

(Twelfth Embodiment) A duplex system according to a twelfth embodiment of the present invention will be described with reference to FIGS. 18, 19 and 20.

In the duplex system according to the twelfth embodiment, a pair of stations 6a and 6b are connected to the LAN transmission path 5, and each station 6a and 6b
An I / O 15 having a plurality of interfaces is connected to b as a common information terminal.

Each station 6a, 6 shown in FIG.
b, instead of exchanging information via the LAN transmission line 5,
I / O 15 as a common information terminal connected to itself
The information is exchanged via the interface cards 15a and 15b.

In the duplex system shown in FIG. 20, a pair of stations 6 is connected to the LAN transmission line 5.
a, 6b are connected, and each station 6a, 6b
Are connected to a plurality of lower stations 8a to 8d as common information terminals via a transmission line 14 of a lower LAN.

Each station 6a, 6 shown in FIG.
b, instead of exchanging information via the LAN transmission line 5,
Information exchange is performed via the transmission path 14 of the lower LNA as a part of a common information terminal.

Hereinafter, a specific configuration and operation will be described.

(1) When the control target is I / O 15 In the case of the configuration as shown in FIG. 18, as shown in FIG.
O15 interface card 15a, 15b or I
Two counters 25 for redundancy control inside the / O card
a. A register or a memory for holding 24b is prepared. This register or memory is stored in both stations 6
a and 6b.

Each station 6a, 6b only increments one counter 25a (25b).
The other counter 25b (25a) merely refers. Online and standby stations 6a, 6
The method for incrementing the two counters 25a and 25b between b is different.

The increment and reference to the counters 25a and 25b are performed at a constant cycle. When the increment of the counter station 6b (6a) with respect to each counter 25a (25b) stops for a certain period of time (for example, three times the increment cycle) with respect to each counter 25a (25b), the corresponding counter station 6b (6a).
Is determined to be a failure.

Then, the standby station 6b
When the failure of the partner station 6a (6b) is detected in (6a), the own station 6b (6a) is switched online.

(2) In the case where the control target is a LAN In the case of the configuration shown in FIG. 20, the exchange of the duplex information performed via the transmission path 5 of the upper LAN is performed via the transmission path 14 of the lower LAN. I do. In this case, the same information as when the transmission path 5 of the upper LAN is used may be transmitted and received via the transmission path 14 of the lower LAN, or the station 6a (6b) of the online station may simply transmit the information to the station 6b (6a) of the standby. ) May only be transmitted with 1-bit information indicating that it is online.

Then, the standby station 6b
If the online information from the online station 6a (6b) is interrupted for a predetermined time (for example, three times the online information transmission cycle) in (6a), an abnormality (failure) occurs in the online station 6a (6b). And the self station 6b (6a) is promoted online.

(3) When there are a plurality of controlled objects Online and standby management is performed for each of a plurality of different controlled objects including the difference between the two controlled objects.

Next, the technical effect of the duplex system of the twelfth embodiment configured as described above will be described.

(1) When there is a device that does not allow online at the same time as a control target When, for example, an output card such as DO or AO is used as an I / O card or when control (sequence) such as an analog input card is required If the control is performed simultaneously from the two stations 6a and 6b, the output may not be stable temporarily or the data may be incorrect. Therefore, the control of these cards needs to be limited to one station, that is, only the online station 6a (6b).

When the transmission / reception of the duplex information is performed only by the transmission path 5 of the upper LAN, as shown in FIG. 18, if the transmission path 5 of the upper LAN fails, each of the stations 6a, 6
In the case b, since the duplex information of the partner stations 6b and 6a cannot be obtained, the two stations 6a and 6b go online at the same time.

However, the duplication information is transmitted to the I / O
When transmission / reception is performed via O15, it is possible to prevent the number of online devices from becoming two when only the transmission line 5 of the upper LAN is broken.

When the control target I / O 15 itself breaks down, there may be two on-line stations 6a and 6b depending on the control method. However, if the control target is faulty in the first place, Even if the number of online stations 6a and 6b is two, there is no problem.

(2) A case where two online stations may exist In the duplex system shown in FIG. 20, when the transmission line 14 of the lower LAN has a failure at the position of the mark X, the transmission line 14 of the lower LAN is If both the right and left positions of the mark can be operated, both the primary station 6a and the secondary station 6b may be online.

That is, the stations 8a,... On the left side of the x mark position can communicate only with the primary station 6a, and the stations 8d,. Therefore, both the primary and secondary stations 6
Even if a and 6b go online at the same time, there is no problem in control.

Conversely, when viewed from the lower stations 8a to 8d, the online stations 6a. This is a desirable state because 6b always exists.

In the above-described duplex control method using the transmission line 5 of the upper LAN, one of the stations 6a (6b) is online. Top L
Only when the transmission line 5 of the AN failed, both stations 6a and 6b went online.

However, when the transmission path 14 of the lower LAN is used and the duplex switching method described above is used, in the case of a failure as shown in FIG. The state becomes the same as the failure of the transmission line 5, and two online stations can be formed. This is because when the transmission line 14 of the lower LAN is disconnected in the middle, the duplex control information from the partner station 6b (6a) is interrupted, so that the partner station 6b (6a) is regarded as a failure and the respective stations 6a, 6b Goes online. The assignment range of the primary station 6a is each lower station 8a,.
And the sharing range of the secondary station 6b is ×
The lower stations 8d,.

It should be noted that this online station has 2 stations.
Such control can be performed through the transmission path 5 of the upper LAN, but the control becomes complicated. That is, in the method using only the transmission line 5 of the upper LAN, the lower stations 8a to 8b of the two stations 6a and 6b are used.
In comparison with the connection status of 8d, it is necessary to control to bring both stations 6a and 6b online only when there is no overlap.

As described above, when there are a plurality of control targets, it is easy to determine online for each control target by the above-described method.

If the primary and secondary stations 6a, 6b have completely different control targets, the two stations 6a, 6b are simultaneously on-line, so that control of each control target can be continued.

Further, since the duplex control information is transmitted and received via the control target, the traffic volume of the transmission path 5 of the upper LNA is reduced, and the transmission load of the transmission path 5 of the upper LNA is reduced.

(Thirteenth Embodiment) A duplex system according to a thirteenth embodiment of the present invention will be described with reference to FIG.

In the redundant system of the thirteenth embodiment, the online station 6a (6b) and the standby station 6b (6a) in the redundant system of the first embodiment shown in FIG. Automatically switch between online and stylus at regular intervals.

This is effective for an information terminal that cannot be accessed unless it is on-Iran. That is, I /
Among the O devices, there is an I / O device in which data is abnormal when accessed from one of the primary station 6a and the secondary station 6b during access. In such an I / O device, only the online station 6a (6b) accesses and the standby station 6b (6b) does not access.

In such an I / O device, an abnormality can be detected because the online station 6a (6b) can access the station, but the standby station 6b (6b) can be accessed.
Since access is not possible in a), there is an abnormality that cannot be detected as long as the same state is maintained.

For example, the standby station 6b
If the access circuit to the same I / O device in (6a) becomes abnormal, the abnormality is determined by the online station 6a.
Until (6b) becomes abnormal and switching between online and standby occurs, it cannot be found. For example, the access circuit for the interface card 15b of the secondary station 6b in FIG.
This corresponds to a failure at the marked position.

In the case where a failure occurs at the position B of the transmission line 14 of the lower LAN in the duplex system of the sixth embodiment shown in FIG. 9 and only one of the stations 6a is on-line, a lower layer capable of communicating with the other station 6b is provided. The stations 8c and 8d do not operate normally until this failure is recovered.

In order to prevent such a situation,
In the duplex system of the thirteenth embodiment, as described above, online and standby are automatically switched at regular intervals.

That is, as shown in FIG. 21, each of the stations 6a and 6b starts a timer when it comes online. When the timer reaches 0, the on-line station 6a (6b) transitions to the waiting state. And finally, it transits to the stainless steel. This timer is activated only when the partner station 6b (6a) is in the standby state. Further, even if there is no abnormality in the online station 6a (6b), the Tasmer does not start when there is an abnormality in the standby station 6b (6a).

In the duplex system of the thirteenth embodiment configured as described above, the online station 6
If there is an abnormality that can only be detected by a (6b), a situation in which the abnormality cannot be detected while the standby station 6b (6a) remains in the standby state forever is prevented.

When an abnormality has occurred in the information terminal to be processed, the online station 6a (6b)
If the information terminals (lower stations 9a to 8d) that can be processed by the and the standby station 6b (6a) are different, more information terminals can move.

(Fourteenth Embodiment) A duplex system according to a fourteenth embodiment of the present invention will be described with reference to FIGS.

In the duplex system according to the fourteenth embodiment, in the duplex system having the same configuration as that of the sixth embodiment shown in FIG. 22, each station 6a, 6b has its own total importance and the total weight received from the partner. The station is switched between online and standby only when the difference from the importance is equal to or greater than a predetermined rule.

Since each of the stations 6a and 6b knows the degree of importance given to each of the lower stations 8a to 8d, the maximum value of the total importance of the entire duplex system is known. The stations 6a and 6b are switched as follows.

(1) Online station 6a (6
b) does nothing if the total importance of the own station is the maximum value.

(2) Online station 6a (6
In b), if the total importance of the own station is smaller than the maximum value, the total importance of the standby station 6b (6a) is checked, and if the value is the maximum value, some abnormality occurs on the self side. , And immediately switches between online and standby.

(3) In cases other than the above, when the difference between the total importance of the on-line station 6a (6b) and the total importance of the standby station 6a (6b) is equal to or greater than a predetermined rule, and Station 6
If b (6a) is larger, switch between online and standby.

When the number to be compared is the number of faults, the number of faults = 0 corresponds to the case where the total importance described above is the maximum value.

Further, in the duplex system according to the fourteenth embodiment, in the above-mentioned switching processes (2) and (3), it takes time until the switching is performed. This time may be a fixed time or a function of the difference.

Next, the technical effects of the duplex system according to the fourteenth embodiment configured as described above will be described.

When an error occurs in the redundant system, the error may be expanded, restored, or fluctuated. When an abnormality is detected in both stations 6a and 6b, especially when the cause is different between the two stations 6a and 6b, and especially when the cause is the same, the detection time between the two stations 6a and 6b is reduced. Due to the difference, the difference in the abnormal number between the two stations 6a and 6b fluctuates, and there is a possibility that the difference between the two stations 6a and 6b is larger.

Then, when switching between online and standby is performed according to the total importance corresponding to the difference,
As shown in FIG. 23, if the difference (difference in total importance) is within a specified range (dead zone), switching is not performed, so that
The instability of the duplex system due to the switching operation is prevented.

When the difference is stable, switching even if the difference is small improves the operability of the entire system.

However, if one of the stations is completely normal,
In other words, when the total importance of one station indicates the maximum value and the other station has a failure,
Only in this case is the switch switched, no matter how small. This is because if one is normal, the normal should be stable, because there is no cause of the anomaly that causes instability. It is better for the system to switch online to a station with no failure. This is because even if the station in which the error has occurred is repeatedly caused and restored, the normal station is not affected.

[0242]

As described above, in the duplex system of the present invention, information transmission between stations is performed via a transmission line of a network necessary for processing and an information terminal connected to the station.

Therefore, online and standby can be automatically switched without using a dedicated switching signal line, and sophisticated switching control can be performed.

[Brief description of the drawings]

FIG. 1 is a schematic diagram showing a schematic configuration of a duplex system according to a first embodiment of the present invention;

FIG. 2 is a diagram for explaining a transition operation of a redundant state of the redundant system according to the first embodiment;

FIG. 3 is a diagram showing each transition state of a redundant state of the redundant system according to the first embodiment;

FIG. 4 is a diagram for explaining a change in an information transmission cycle in the duplex system according to the second embodiment of the present invention;

FIG. 5 is a diagram for explaining an abnormality detection operation for a partner station in the duplex system according to the third embodiment of the present invention;

FIG. 6 is a schematic diagram showing a schematic configuration of a duplex system according to a fourth embodiment of the present invention.

FIG. 7 is a diagram for explaining an abnormality detection operation for an online station in a redundant system according to a fifth embodiment of the present invention;

FIG. 8 is a diagram for explaining an abnormality detection operation for an online station in the redundant system according to the fifth embodiment;

FIG. 9 is a schematic diagram showing a schematic configuration of a duplex system according to a sixth embodiment of the present invention.

FIG. 10 is a schematic diagram showing a schematic configuration of a duplex system according to a sixth embodiment of the present invention.

FIG. 11 is a diagram showing a comparison of total importance between stations in a duplex system according to a seventh embodiment of the present invention;

FIG. 12 is a schematic diagram showing a schematic configuration of a duplex system according to an eighth embodiment of the present invention.

FIG. 13 is a diagram for explaining a state transition relationship between stations to which a save state is added in the redundant system according to the ninth embodiment of the present invention;

FIG. 14 is a diagram for explaining a state transition relationship between stations to which an evacuation state is added in the redundant system according to the ninth embodiment.

FIG. 15 is a schematic diagram showing a schematic configuration of a duplex system according to a tenth embodiment of the present invention.

FIG. 16 is a schematic diagram showing a schematic configuration of a duplex system according to an eleventh embodiment of the present invention.

FIG. 17 is a diagram showing a comparison of the total importance between the stations in the redundant system according to the eleventh embodiment.

FIG. 18 is a schematic diagram showing a schematic configuration of a duplex system according to a twelfth embodiment of the present invention.

FIG. 19 is a diagram for explaining an operation of exchanging information via an information terminal performed by each station in the duplex system of the twelfth embodiment.

FIG. 20 is a schematic diagram showing a schematic configuration of a duplex system according to a twelfth embodiment.

FIG. 21 is a diagram for explaining an operation of switching between online and standby at a constant cycle in a redundant system according to a thirteenth embodiment of the present invention;

FIG. 22 is a schematic diagram showing a schematic configuration of a duplex system according to a fourteenth embodiment of the present invention;

FIG. 23 is a diagram showing a switching state between online and standby when a dead zone is provided in the duplex system according to the fourteenth embodiment of the present invention;

FIG. 24 is a schematic diagram showing a schematic configuration of a conventional duplex system.

[Explanation of symbols]

 5 LAN transmission line 6a, 6b Station 8 Control object 8a, 8b, 8c, 8d Lower station 9a, 9b Raw data memory 10a, 10b Update counter 11a, 11b Previous value memory 12a Previous standby value Counter 13a Standby update counter 14 Lower LAN transmission line 15 I / O 15a, 15b Interface card 16a, 16b Lower LAN interface 17a, 17b Lower LAN reception processing unit 18a, 18b Updatabase 19a, 19b LAN transmission processing unit 20a, 20b LAN interface 21b LAN reception processing unit 22b Monitoring database 23b Comparative diagnosis processing unit 24a to 24d Control target 25a, 25b Counter

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Fumihiko Okaba 1 Toshiba-cho, Fuchu-shi, Tokyo, Japan Inside the Toshiba Fuchu Plant, Inc. 72) Inventor Kazuo Hotta 1 Toshiba-cho, Toshiba-cho, Fuchu-shi, Tokyo (72) Inventor Yoichi Takayanagi 1-futoshiba-cho, Toshiba-cho, Fuchu-shi, Tokyo

Claims (18)

[Claims] 1. A pair of stations each connected to a common information terminal are connected to a transmission line of a network,
In a duplex system in which one of the pair of stations is online indicating an operation state for the information terminal and the other is a standby indicating a standby state for the information terminal, the stations exchange information with each other via the transmission path. A duplex system for transmitting and receiving, and switching the station between online and standby based on the transmitted and received information. 2. The stations transmit and receive information to and from each other via the transmission path, determine a station in which an abnormality has occurred from the transmitted and received information, and switch the station between online and standby based on the determination result. The duplex system according to claim 1. 3. The duplex system according to claim 2, wherein the information from the on-line station to the standby station is transmitted in a short period in comparison with the information from the standby station to the on-line station. 4. When each of the stations detects that both stations are online and standby at the same time based on the transmitted / received information, only one of the stations determined in a predetermined procedure is brought online. 3. The duplex system according to claim 2, wherein: 5. Each of the stations transmits and receives information to and from each other via the transmission line at a fixed period, and if the station does not receive the information for a set time longer than the predetermined period, the station on the other end becomes abnormal. 3. The duplex system according to claim 2, wherein it is determined that the error has occurred. 6. Each of the stations fetches and outputs information output from the common information terminal at regular intervals, stores the information, transmits the information to a station on the other side, and receives the information stored by itself and the information received from the other side. 3. The duplex system according to claim 2, wherein a station in which an abnormality has occurred is determined based on a comparison result with the information. 7. When each of the stations detects that both stations are online and standby at the same time based on the transmitted / received information, each station counts the time elapsed from the detection time and sends the time to the partner station. 3. The duplex system according to claim 2, wherein only one of the stations determined on the basis of a comparison between the elapsed time of the self station and the elapsed time received from the other party is brought online. 8. A pair of stations each connected to a plurality of common information terminals are connected to a transmission line of a network, and one of the pair of stations is online indicating an operation state of each information terminal, and the other is online. In a redundant system which is a standby indicating a standby state for each of the information terminals, each of the information terminals has a unique importance and each of the stations monitors an operation state of each of the information terminals, When an abnormality is detected in the operation state, the total importance of each information terminal that can be processed by itself is calculated and transmitted to the station of the other party, and the total importance of the information terminal and the total received from the other party are calculated. A redundant system that switches between online and standby stations based on the results of comparison with the importance. 9. A pair of stations each connected to a plurality of common information terminals are connected to a transmission line of a network, and one of the pair of stations is online indicating an operation state for each information terminal, and the other is online. In a redundant system which is a standby indicating a standby state for each of the information terminals, each of the information terminals has a unique importance and each of the stations monitors an operation state of each of the information terminals, When a command to switch between online and standby of a station is input from the outside, the sum of the total importance of the information terminals that can be processed by the terminal and the importance given to the relevant command only when the terminal is online is calculated. Calculates the importance and sends it to the other station so that the total Redundant system for switching between online and standby station on the basis of a comparison result between the total degree of importance and trust. 10. Each of the stations has a unique importance, and in the comparison result, if the total importance of itself is equal to the total importance received from the other party, the importance of each station is determined. 9. The duplex system according to claim 8, wherein the on-line state and the standby state of the station are switched based on the station. 11. When a station is switched from online to standby based on the determination result, the online station is temporarily shifted to an evacuation state, the standby station is shifted to online, and then the evacuation station is set to standby. The duplex system according to claim 2, wherein the system is shifted. 12. An evacuation state is forcibly shifted to an on-line station based on an external command, a standby station is shifted to an on-line state, and then the evacuation state station is shifted to a standby state. The duplex system according to claim 2. 13. The evacuation station is restored to online when the standby station does not go online within an allowable time after the online station enters the evacuation state. 13. The duplex system according to 12. 14. A pair of stations each connected to a common information terminal are connected to a transmission line of a network, and one of the pair of stations is online indicating an operation state for the information terminal, and the other is the information terminal. In a redundant system in which the standby station indicates a standby state, the standby station monitors the operation of the online station, and if the operation stops, the station itself takes over the operation of the online station and, if necessary, the station of the station. Redundant system that switches between online and standby. 15. A pair of online and standby stations each connected to a plurality of common information terminals are connected to a transmission line of a network, and the pair of stations share the plurality of information terminals with the plurality of information terminals. In a redundant system that performs processing, each of the information terminals has a unique importance level, and each of the stations monitors an operation state of each of the information terminals assigned to the information terminal. Calculate the total importance of each assigned information terminal and send it to the other station, and the information between each station based on the result of comparing the total importance of itself with the total importance received from the other side Redundant system that switches the sharing of terminals. 16. A pair of stations each connected to a common information terminal are connected to a transmission line of a network, and one of the pair of stations is online indicating an operation state for the information terminal, and the other is an information terminal. In the redundant system that becomes a standby indicating a standby state, the respective stations transmit and receive information to and from each other via the common information terminal, and determine a station in which an abnormality has occurred from the transmitted and received information, based on the determination result. System that switches between online and standby stations. 17. The duplex system according to claim 2, wherein the station is periodically switched between online and standby in addition to the occurrence of the abnormality. 18. The duplexing system according to claim 8, wherein each of the stations switches between online and standby when the difference between the total importance of the station and the total importance received from the other side is equal to or greater than a predetermined rule. system.