JP2002290408A - Active/standby switchover method, active/standby determination method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method that can conduct switchover from a standby system to an active system and determination of active system/standby system stably and swiftly, with a simpler program. SOLUTION: In addition to a state definition representing active system/ standby system, a state of 'active operation preparation token waiting' 35 and a state of 'active operation preparation token holding' 36, which represent a non-stationary state (intermediate state), are defined. For example, if a standby system at a certain node detects that an active system does not transmit a token due to a failure, etc., and the next node reissues the token, the standby system transits to the 'active operation preparation token waiting' 35 state first, then it transits to the 'active operation preparation token holding' 36 state. The standby system transits to the active system (a state of 'active system token waiting') 31 state, if the active system does not transmit a token before the time is up (even after a prescribed time is passed).

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a network control system, and more particularly to a method for switching or determining operation / standby when nodes constituting a network are duplicated in an operation system and a standby system.

[0002]

2. Description of the Related Art In recent years, in the field of control systems, a manufacturing technology center (abbreviation: MSTC) FA has been developed for the purpose of unifying the specifications of a control LAN in the industry. There is a protocol ("FA Link Protocol") defined by the Control Network Task Force.

[0003] Since the specification of the FA link protocol has been made public, it will be briefly described here. First, conventionally, a control network such as a plant control system (hereinafter referred to as a network control system)
Because each company adopted its own method, it was impossible or very difficult for others to modify this network. In the past, a special network had to be constructed for control.

In order to solve the above problem, the FA link protocol enables a network to be realized by a general-purpose LAN such as Ethernet (registered trademark). That is, conventionally, general-purpose LANs such as Ethernet have low reliability because of data collisions and the like, and are unsuitable for control purposes. It can be used for control and has, for example, the following features. (1) The masterless token system is adopted, and even if some nodes fail, the network does not stop. (2) If the token is not transmitted for a fixed time, the next node transmits the token. (3) The operating state of another node can be recognized. Etc. and cyclic transmission for transmitting periodic data, message transmission for transmitting non-periodic data,
And two data communication methods are supported. Note that cyclic transmission is a function that supports periodic data exchange that occurs between nodes.

[0005] The flow of the token is basically determined by the node number assigned to each node in advance.
For example, token rotation is performed in order (in ascending order) from the youngest node number. In this case, the node with the highest node number passes the token to the node with the lowest node number.

Each node has a "token monitoring timer" as a configuration for detecting that the token is not transmitted for the predetermined time in the above (2). This token monitoring timer measures the time since the last token flow on the network. Then, when the token monitoring timer has expired (time-up), the next node reissues the token.

Here, in the field of information processing, the reliability of the system is increased by duplicating the device (node) (operating / standby) like a duplex system or the like.

In the above-mentioned network control system, it is conceivable to improve the reliability of the system by duplicating the nodes as described above. However, at the time of switching from the standby system to the active system, or when the standby / active system is used. In an unstable situation that has not yet been determined, it is desirable to be able to stably and promptly determine one of the above-described duplicated nodes as the active system and the other as the standby system in an appropriate manner.

Further, a program for performing such processing has been complicated. That is, conventionally, in the standby system, variables such as “variable indicating the state of the active system” and “variable indicating the number of times the abnormal state of the active system continues” are prepared, and transition to the active system is performed. When referring to these variables, branch according to their values and perform the processing according to the state,
That was the general approach. However, in this method, since processing is performed by referring to a plurality of variables in one state, a complicated structure with many branches is likely to occur, and processing such as updating of variables tends to be complicated. Also, since only the steady state (active system, standby system) is defined and the unsteady state is not clearly defined, for example, even if the self state is recognized as the standby system, the standby system is now May be in the process of transitioning to the active system (that is, in an unsteady state), so even if it is in a steady state, the judgment processing of "is now an unsteady state?" The amount of program description has increased. Therefore, it is desired to simplify the program.

SUMMARY OF THE INVENTION An object of the present invention is to provide a network control system in which nodes are duplicated, in which the switching between the active system and the standby system, or the determination thereof, can be performed stably and quickly, and the operation / standby mode in which the program configuration is simplified. A switching method and an operation / standby determination method are provided.

[0011]

An operation / standby switching method according to the present invention is directed to a network control system in which part or all of nodes connected to a network are duplicated into an operation system and a standby system. This is an operation / standby switching method, in which, in addition to the state definitions of the standby system and the active system, an unsteady state in the process of transitioning the standby system to the active system is defined as an intermediate state, and the standby system is switched to the active system. In the process, the state is temporarily transitioned to the intermediate state.

As described above, by clearly defining the unsteady state (intermediate state), for example, in an unstable unsteady state where it is unclear whether to switch from the standby system to the active system,
Since the transition to the intermediate state can be made once until it is clear whether or not the transition is made, stable switching can be performed. Further, since the transition to the intermediate state is clearly made in the non-stationary state, it is not necessary to confirm “Is the current state unsteady?” In the stationary state.

Further, for example, the network control system adopts an FA link protocol, each node has a token monitoring timer, and a certain node does not transmit a token for a certain period of time or more using the token monitoring timer. When detecting that, the next node retransmits the token, the standby system of the node that the active system did not transmit the token, when receiving the token in the intermediate state, set a shorter time than the token monitoring timer Using an operation / standby switching timer, it is determined whether or not to transition from the intermediate state to the operation system.

As described above, the present invention mainly targets a network control system employing the FA link protocol. Also, whether or not to switch from the standby system to the active system is determined using the operation / standby switching timer set to a shorter time than the token monitoring timer, so that the token is erroneously reissued from the next node. It can be performed at high speed without any problem. In addition to the definition of the intermediate state, the effect of simplifying the program increases.

Using the above-described definition of the intermediate state and the operation / standby switching timer, not only switching from the standby system to the operation system,
In the determination (or re-determination) of the active system / standby system in various situations (unsteady state) described below, the active system / standby system is determined.
The determination of the standby system can be performed stably and promptly.

In the operation / standby determination method according to the present invention, for example, some or all of the nodes connected to the network are duplicated nodes composed of the A system and the B system, and either one of the A system and the B system is used. Is an operation / standby determination method in a network control system in which the standby system is active and the other is a standby system. When the A / B systems start up at the same time, both are temporarily set to the standby system or intermediate state, and the A / B system is set to the active system by using the operation / standby switching timer with a time difference between the A system and the B system. Determine the standby system.

Further, for example, some or all of the nodes connected to the network are duplicated nodes composed of the A system and the B system, and one of the A system and the B system is an operating system.
The other is an operation / standby determination method in a network control system serving as a standby system, in which, in addition to the state definition of the standby system and the operation system, an unsteady state of a process in which the standby system transitions to the operation system is defined as an intermediate state. In the meantime, the number of token transmissions and receptions in the active system is stored, and when a network including a duplicated node is established and all nodes other than a certain duplicated node subsequently rejoin after leaving, both are temporarily set to the standby system or In the intermediate state, the active system and the standby system are determined using the active / standby switching timer with a time difference according to the number of times of transmission and reception, so that the former active system in the redundant node becomes the active system again. I do.

As described above, by setting the timer up time of the operation / standby switching timer according to the actual number of times of transmission / reception, the formerly active system continues to be the active system and the formerly active system Is maintained as a standby system.

Further, for example, a part or all of the nodes connected to the network are duplicated nodes composed of the A system and the B system, and one of the A system and the B system is an operating system.
The other is an operation / standby determination method in a network control system serving as a standby system, in which, in addition to the state definition of the standby system and the operation system, an unsteady state of a process in which the standby system transitions to the operation system is defined as an intermediate state. In the meantime, when both redundant nodes become active systems, both are temporarily set to the standby system or the intermediate state, and the operating / standby switching timer is provided with a time difference according to the token transmission / reception number stored in each node. Determine the active system and the standby system.

Thus, it is possible to prevent the unstable state such as the operation of both systems from continuing. In addition, for example, in addition to the state definitions of the standby system and the active system, an unsteady state of the process in which the standby system transitions to the active system is defined as an intermediate state, and two nodes to which the same node number is assigned are respectively defined. When the two networks are connected to form a single network from a state connected to another network, the two nodes temporarily transition to both standby and intermediate states, and are stored in each node. An operation system and a standby system are determined using an operation / standby switching timer that determines a time-up time according to the number of received tokens.

[0021]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention provides a network control system in which nodes constituting a network are duplicated. In this configuration, for example, when switching from a standby system to an active system, when starting up a node, When adding new nodes or duplicating a node in the middle,
When an (unstable) non-steady state occurs, it is possible to stably and promptly shift to the steady state in an appropriate form.

In the present invention, the unsteady state is clearly defined as the operation preparation state (intermediate state), and for example, when the standby system is switched to the operation system, the transition to the intermediate state is performed once, so that stable switching can be performed. I can do it. Furthermore, since the steady state and the unsteady state (transition process) can be clearly separated, in each state, it is sufficient to simply describe correspondingly, and the configuration of the program can be simplified.

Hereinafter, embodiments of the present invention will be described with reference to the drawings. Note that a network control system employing the FA link protocol is called an FA control network.

FIG. 1 is a diagram showing an example of the system configuration of the FA control network according to the present embodiment. Although FIG. 1 shows a production system as an example, the invention is not limited to this. The subject of the present invention is control systems in general.

This FA control network 10
Is a robot controller (R
C) 11, programmable controller (PC) 12,
Control is performed by connecting control devices such as a numerical control device (NC) 13 and a control personal computer 14 and the like (hereinafter, these are referred to as “nodes” without distinction) via Ethernet and mutually exchanging data. Network control system to be performed. This FA control network 10 further includes
Via a gateway or the like, it is possible to connect to an information network composed of an EWS, a personal computer, a server, and the like, and it is also possible to connect to an external network.

Each "node" that constitutes the FA control network 10 uses a token passing method (F
A function of performing communication control (using the A-link protocol) is provided (basic data transmission means is realized using UDP / IP, which is widely used on Ethernet), and thereby the above data exchange and the like are performed.

In this example, each of the above "nodes" is duplicated. That is, there are an active system and a standby system. However, not all nodes are duplicated. It is the entire device that is duplicated. For example, when the PCs are duplicated, two PCs having the same node number are connected to the network.

FIG. 2 is a schematic configuration diagram of the node.
Each node 21 includes a buffer (reception buffer, transmission buffer) 22, a memory 23, a processing unit 24, a token monitoring timer 25, an operation / standby switching timer 26, and the like. Is). Buffer 2
2. About the memory 23 and the token monitoring timer 25,
No particular description (for details, refer to the FA link protocol specification). However, the memory 23 may store a “reception count” described later and a basic set value of the timer 26. The processing unit 24 performs various processes described below. The operation / standby switching timer 26 will be described later in detail.

FIGS. 3 (a) to 3 (c) are diagrams schematically showing a state where the above-mentioned nodes are duplicated, and how switching and token transmission are performed when a failure occurs in the operating system. In this figure, each "node" of the PC, RC, NC, personal computer and the like in FIG. 1 is shown in a simplified manner without any particular distinction. Here, it is assumed that all nodes are duplicated, the active node is indicated by a solid line, and the standby node is indicated by a dotted line.

The node number assigned to each node is
# 1, # 2, and # 3. Regarding redundancy, it is assumed that there are a system A and a system B, and in the illustrated example, it is assumed that the node of the system A is on the operating side. Accordingly, in the following description, for example, two nodes of node number # 2 are:
The node of the system A will be described as 2A and the node of the system B will be described as 2B. However, the node numbers are not # 2A and # 2B, and the node number is # 2 for both (that is, operating). The system node and the standby node have the same node number.)

First, FIG. 3A shows a state before a failure occurs. In this state, the token circulates in the order of node 1A → node 2A → node 3A... Node 1A →. The standby nodes 1B, 2B, and 3B monitor the transfer of the token, and determine that the node itself can be the standby system if the token is normally transferred.

Next, in FIG. 3B, the token is not transmitted from the node 2A after the token is passed from the node 1A to the node 2A due to some cause such as a failure of the node 2A. Here is an example. In this case, the node 3A, which is the next node, issues a token again as shown in the figure when the token monitoring timer 25 included in the node 3A times out. At this time, the standby node 2B of the failed node 2 has transitioned to an unsteady state (intermediate state) (this will be described with reference to FIG. 4).

Then, the token circulates again. First, the node 1A receives the circulated token and transmits it to the node 2. (As described above, both the nodes 2A and 2B have the node number # Because it is 2,
The node 1A does not distinguish between the two and passes the token), and the node 2B keeps the node 2
If A does not transmit the token, it transitions from the intermediate state to the active system and transmits the token (details will be described with reference to FIG. 4).

FIG. 4 is a state transition diagram of a node. In the steady state, the active system is between the state of "active system token wait" 31 and the state of "active system token hold" 32, and the standby system is "standby system token wait" 33 and "standby system token hold" 34. State transitions between the states.

More specifically, when the active system receives a token in the state of “active system token wait” 31, the active system transits to the state of “active system token holding” 32. It returns to the state of "waiting for token" 31.

When the standby system detects that the active system has received the token in the state of "standby system token wait" 33,
The state transits to the state of “standby system token holding” 34, and when detecting that the active system has transmitted the token in this state, the state returns to the state of “standby system token waiting” 33.

Further, in this example, a state of "waiting for operation preparation token" 35 and a state of "holding operation preparation token" 36 are defined as an unsteady state (intermediate state). The state transition related to this intermediate state will be described later.

Using the above-described state definitions, each node 21 (particularly, the processing unit 24) executes a process of switching to the active system and a process of determining the active / standby system described below. First, the process of switching to the active system will be described with reference to FIG.

It is assumed that some trouble has occurred in the active system (node 2A in the example of FIG. 3; hereinafter, the parentheses correspond to the example of FIG. 3). As described above, the standby system (node 2B) enters the “standby system token holding” state 34 when the active system receives the token addressed to the own node.
In A), since a failure has occurred, the time has elapsed without transmitting a token, so that the token monitoring timer 25 in the next node is up (time-up). Therefore, the next node (node 3A) reissues the token.

When the standby system (node 2B) observes this token (step S1), it transitions to the "waiting for operation preparation token" 35 (step S2). afterwards,
When a token addressed to the own node is received again (step S
(3, YES), and transition to the state of "operation preparation token holding" 36 (step S4). At this time, the operation / standby switching timer 26 is started (step S5). The set time of the timer 26 is shorter than the token monitoring time. When the timer 26 is up (step S6, YES), it is regarded that the operation system has stopped, and the node (the node 2B) transmits the token. (Step S
7), transit to “waiting for active token” 31 (step S8). If the active system transmits a token before the active / standby switching timer 26 is up (for example, when the active system is restored) (step S9, YES).
Transition to “waiting for standby token” 33 (step S1)
0).

As described above, in this example, when the active system does not transmit the token (that is, when there is a possibility that some abnormality has occurred), the standby system is not immediately switched to the active system, but Once a transition is made to the intermediate state (unsteady state) and the token is received again, the operation / standby switching timer 26 is started, and if the token is not transmitted after waiting for a while, the transition is made to the standby system ( The working system is
It considers a situation where a token was not transmitted only once for some temporary reason, not a failure.)
The time of the operation / standby switching timer 26 is set shorter than the token monitoring time in order to prevent the next node from transmitting a token again.

Next, a method of determining the standby system / active system will be described. In other words, one of the two systems (A system and B system) constituting the above-mentioned duplicated node becomes the active system and the other becomes the standby system, but a situation occurs in which the system has not yet been determined.
The determination method at that time will be described below.

The operation / standby switching timer 26 is also used when determining the standby / operation system. Also, while operating in a state where both the active system and the standby system are subscribed, the active system node stores the number of token receptions in the memory 23 or the like (this number is equal to or greater than a certain rule number). Will not increase).

FIG. 6 is a diagram showing an operation example of the operation / standby switching timer when determining the standby system / operation system. In the figure, the arrow pointing to the right represents the flow of time.

The set time of the operation / standby switching timer 26 is
Set shorter than the token monitoring time. The basic set value of the time-up time of the operation / standby switching timer 26 is set in advance so that there is a difference between the A system and the B system. Fluctuates according to the number of times the token is received. However,
As described above, the number of receptions does not increase beyond a certain prescribed number of times.

FIG. 6 shows, as an example, the time-up timing of the operation / standby switching timer 26 of the nodes A and B when the number of token receptions is 0 (“0 times A
System "," 0 times B system position ", and the time-up timing of the operation / standby switching timer 26 of the nodes of the A system and B system when the number of token receptions is the maximum (the specified number of times). (The positions marked as “specified times A system” and “specified times B system”).

As described above, since the time difference is provided between the A system and the B system, for example, as in the first example described below,
If the number of tokens received is 0 for both the A and B systems,
In the illustrated example, the operation / standby switching timer 26 of the node A
Since the time-up occurs earlier, the node of the A-system becomes the active system, and there is no possibility that both the systems become the active systems by mistake. Also, the node of the A system does not always become the active system.
In the case where the number of tokens received by the B-system node is the specified number of times, as shown in FIG.
Since the time of the standby switching timer 26 expires earlier, the node of the B system becomes the active system.

Based on the above description, the standby system /
A first example and a second example of a method of determining an active system will be described. First, the first example is a method of determining the standby system / active system when the A system / B system simultaneously starts up.

When the A / B systems start up at the same time,
Once both are in the operation ready state (or the standby system), the operation system and the standby system are determined by using the operation / standby switching timer 26 having a time difference between the A system and the B system as described above. As a result, even if the A-system / B-system starts up at the same time, it is possible to prevent a situation in which both systems become the active systems by mistake.

This will be described in more detail with reference to FIG. When the A-system / B-system start up at the same time, both nodes temporarily enter the state of "waiting for operation preparation token" 35 (step S11). After that, the process transits to “hold operation preparation token” 36 (step S12), sets a time-up time of the operation / standby switching timer 26, and starts (step S13). Then, whether to become the standby system or the active system is determined depending on whether or not the own operation / standby switching timer 26 times out before the other party (step S14).

As the set value of the time-up time of the operation / standby switching timer 26, a different basic set value is registered in advance between the A-system / B-system, and a value which is changed from this basic set value in accordance with the number of tokens received. (Set value = basic set value−token reception count × α; α is an arbitrary coefficient).

In this case, since the A system and the B system have just been started up, the token reception count of both is “0”.
Therefore, in the example of FIG. 6, the basic setting value is registered so that the operation / standby switching timer 26 of the A-system node is timed out earlier.
After transmitting the token (step S15), the state transitions to the active system (step S16). The node of the system B transitions to the standby system by detecting the token transmission (step S1).
7).

Next, a second example will be described. The second example is a method of determining a standby / active system when all nodes other than a certain redundant node have left the network and another node has joined again.

First, when all nodes other than a certain duplicated node leave the network, the duplicated node does not transmit a token. Thereafter, when another node joins again, the network is constructed again.

The processing contents at this time are basically the same as those in the first example (FIG. 7). In other words, both of the redundant nodes first transition to the state of “waiting for operation preparation token” 35. Then, the process transits to "hold operation preparation token" 36, sets the time-up time of the operation / standby switching timer 26, and starts. As described above, the time-up time of the operation / standby switching timer 26 for each node is shortened in accordance with the “number of receptions” (stored in the memory 23 or the like of the node). There is a very high possibility that the time will elapse earlier. For example, in the example of FIG. 6, if it is assumed that the “number of receptions” of the A-system node has reached 0 and the “number of receptions” of the B-system node has reached the specified number of times, The time of the standby switching timer 26 is up earlier. In this case, the node of the system B transitions to the active system after transmitting the token. The node of the A system transitions to the standby system by detecting this token transmission.

As described above, with a very high probability, the node that was the active system before the reconfiguration of the network can be made the active system, and the node that was the standby system can be made the standby system. That is, the consistency of the state in which the active system continues to be the active system and the standby system continues to be the standby system is maintained.

In the network control system of this embodiment, even if both the A system and the B system become active systems due to a malfunction or the like, it is possible to quickly and appropriately shift to the normal state. Malfunctions are more likely to occur in an unsteady state than in a steady state. Although there are various situations in which a malfunction is likely to occur, an example will be described below.

One example of a situation in which a malfunction is likely to occur is, for example, a case where a node that has not been duplicated is duplicated. For example, in FIG. 3, it is assumed that initially only the node 1A has joined the network and the node 1B has not joined. In this state, the node 1A naturally transmits and receives the token as the active system. Then, when the node 1B later joins, since both have the node number # 1 as described above, both may become active due to malfunction or the like.

In this case, both nodes 1A and 1B
When it is detected that there are two units in the active system, the state temporarily transitions to the state of “waiting for operation preparation token” 35. Thereafter, the state transits to the state of "operation preparation token holding" 36, and the operation / standby switching timer 26 is started. In such a case, as described in the second example, basically, the one who was in the active system first (node 1A) times out first, so that the node 1A transitions to the active system after transmitting the token. I do. The node 1B joined later detects this token transmission and transitions to the standby system.

Next, referring to FIG. 8, the A system and the B system have joined each other to transmit and receive tokens, and then the two networks have been combined to form one network. The case will be described.

Conventionally, the network type of the LAN is a bus type, but a star topology is the main type at present. In particular, a mode using a switching HUB is generally used. The form used is shown as an example.

In the example of FIG. 8, a first network in which the nodes 1A, 2 and 3 are connected to the HUB 41, and a second network in which the nodes 1B, 4 and 5 are connected to the HUB 42 are provided. And exist separately. Nodes are not duplicated in either network.

In such a configuration, in the first network, node 1A → node 2 → node 3 → node 1A →
The token circulates as follows, and in the second network, node 1B → node 4 → node 5 → node 1B →
... the token is circling. However, since both the node 1A and the node 1B have the node number # 1, each node recognizes that "node 1" exists.

In such a state, as shown by the dotted line in the figure, when the HUB 41 and the HUB 42 are connected to form the two networks into one network, for example, node 5 → node 1B (node 3 → node 1A) When the token is transmitted, the node 1A and the node 1B are not distinguished as the node 1A / node 1B, but are recognized as the “node 1” as described above. Tokens such as node 1A → node 2 and node 1B → node 4 are sent out, respectively.
Then, both the node 1A and the node 1B recognize the token issued by the partner station.
Exists, and this node is currently the active node. "
In the A-link protocol, all tokens are transmitted by broadcast. That is, each node recognizes the existence of all tokens flowing on the network. Then, when the "destination node number" in the data as the token matches the node number of the own station, it is determined that the self-addressed token is received (transmission right is acquired).

As described above, when it is detected that there are two nodes having the same node number in the active system, each node executes the processing described below. This process is basically the same as the process described in the first example.

First, both the nodes 1A and 1B temporarily transition to the state of "waiting for operation preparation token" 35. Thereafter, the state transits to the state of "operation preparation token holding" 36, and the operation / standby switching timer 26 is set and started.

Before the connection between the HUB 41 and the HUB 42, since both the node 1A and the node 1B were operating as active systems, when it is considered that the “number of receptions” has reached the specified number, In the example of (1), the node 1A times out first, and after transmitting the token, transitions to the active system. The node 1B detects this token transmission and makes a transition to the standby system.

As described above, in this example, for some reason,
Even if two nodes having the same node number are both active, using the operation / standby switching timer 26,
Since the active / standby system can be quickly determined, it is possible to avoid a long-lasting unstable state in which both the A system and the B system become active systems.

[0069]

As described above in detail, according to the operation / standby switching method and the operation / standby determination method in the network control system of the present invention, the definition of the conventional steady state (operation system, standby system) In addition, since the unsteady state is clearly defined (operation ready state), the steady state and the unsteady state can be distinguished, stable switching can be performed, and the configuration of the program is simplified.

Further, by providing an operation / standby switching timer and using this operation / standby switching timer for operation / standby switching or operation / standby determination, the operation system / standby system is determined quickly, and both systems are operated. Continuation of an unstable state such as Also, by changing the timer up time of the operation / standby switching timer according to various conditions, the former operation system continues to be the operation system, and the former system continues to be the standby system. State consistency is maintained.

[Brief description of the drawings]

FIG. 1 is a diagram showing an example of a system configuration of an FA control network according to the present embodiment.

FIG. 2 is a schematic configuration diagram of a node.

FIGS. 3 (a) to 3 (c) are diagrams showing a simplified state in which the nodes are duplicated, and also show how switching and token transmission are performed when a failure occurs in the operating system.

FIG. 4 is a state transition diagram of a node.

FIG. 5 is a flowchart illustrating an example of a process of switching from a standby system to an active system.

FIG. 6 is a diagram illustrating an operation example of an operation / standby switching timer when a standby system / operation system is determined.

FIG. 7: Standby system / A system / B system start up at the same time
It is a flowchart figure for demonstrating the determination process of an active system.

FIG. 8 is a diagram for describing a case where two networks are combined to form one network.

[Explanation of symbols]

 Reference Signs List 10 FA control network 11 Robot controller (RC) 12 Programmable controller (PC) 13 Numerical controller (NC) 14 Control personal computer 21 Node 22 Buffer (reception buffer, transmission buffer) 23 Memory 24 Processing unit 25 Token monitoring timer 26 Operation / Standby switching timer 31 “waiting for active token” (state) 32 “holding active token” (state) 33 “waiting for standby token” (state) 34 “holding standby token” (state) 35 “waiting for operational token” (State) 36 "Operation preparation token holding" (State) 41 HUB 42 HUB

Continued on the front page F term (reference) 5B034 BB02 CC01 5H209 AA07 CC09 CC13 GG04 JJ09 SS01 SS07 5K032 AA06 BA03 CA17 EA03 EA06 EB03 EB06 5K033 AA06 BA03 BA08 CA15 EA03 EA04 EA07 EB06

Claims (6)

[Claims] An operation / standby switching method for each duplicated node in a network control system in which a part or all of nodes connected to a network are duplicated into an active system and a standby system. In addition to the state definition, the unsteady state of the process in which the standby system transitions to the active system is defined as an intermediate state, and the process transitions to the intermediate state once in the process of switching the standby system to the active system. Operating / standby switching method. 2. The network control system according to claim 2, wherein
The link protocol is adopted, and each node has a token monitoring timer, and when the node detects that a certain node does not transmit a token for a certain period of time using the token monitoring timer, the next node retransmits the token. When the standby system of the node to which the active system has not transmitted the token receives the token in the intermediate state, the standby system which has been set to a time shorter than the token monitoring timer is activated.
2. The operation / standby switching method according to claim 1, wherein it is determined whether or not the transition from the intermediate state to the active system is performed using a standby switching timer. 3. A part or all of nodes connected to a network are duplicated nodes composed of an A system and a B system, and one of the A system and the B system is an active system and the other is a standby system. An operation / standby determination method in a network control system, wherein an unsteady state of a process in which a standby system transitions to an operation system is defined as an intermediate state in addition to a standby system and an operation system state definition. When the system B starts up at the same time, both are temporarily set to the standby system or the intermediate state, and the operation system and the standby system are determined using the operation / standby switching timer having a time difference between the system A and the system B. Operation / standby decision method. 4. A part or all of the nodes connected to the network are duplicated nodes composed of an A system and a B system, and one of the A system and the B system is an active system and the other is a standby system. An operation / standby determination method in a network control system, in which, in addition to the state definitions of the standby system and the active system, the unsteady state of the process in which the standby system transitions to the active system is defined as an intermediate state. When a network including a redundant node is established, and all nodes other than a certain redundant node subsequently rejoin after leaving, the both are temporarily set to a standby system or an intermediate state, and the token transmission / reception is performed. The active / standby system is determined using the operation / standby switching timer with a time difference according to the number of times, and the former active system in the redundant node is made the active system again. Operation / standby determination method according to claim. 5. A part or all of nodes connected to a network are duplicated nodes composed of an A system and a B system, and one of the A system and the B system is an active system and the other is a standby system. An operation / standby determination method in a network control system, in which, in addition to the state definitions of the standby system and the active system, an unsteady state in a process in which the standby system transitions to the active system is defined as an intermediate state. When both become active systems, both are once set to the standby system or the intermediate state, and the active system and the standby system are switched by using the operation / standby switching timer which has a time difference according to the token transmission / reception number stored in each node. The operation / standby determination method to be determined. 6. In addition to defining the states of the standby system and the active system, an unsteady state in which the standby system transitions to the active system is defined as an intermediate state, and two nodes to which the same node number is assigned are defined. When the two networks are connected to each other from a state connected to another network to form a single network, the two nodes temporarily transition to both standby and intermediate states, and are stored in each node. An operation / standby determination method for determining an active system and a standby system using an operation / standby switching timer whose time-up time is determined according to the number of received tokens.