JPH10198618A - System and method for distributed communication control - Google Patents

Abstract

PROBLEM TO BE SOLVED: To easily and speedily detect communication abnormality by confirming whether a communication function is recovered or not at every prescribed time, updating the relevant part of table into established state when the recovery is confirmed, and performing communication while alternately using duplexed communication routes. SOLUTION: Each controller 3 transmits the table of communication enable/ disable state to an operator station 1 periodically while using the normal communication route. The operator station 1 displays the table of communication enable/disable state sent from each controller 3 in the table of matrix with a communicating party and presents the part, where the occurrence of any trouble is judged, from the matrix to an operator. Each controller 3 tries communication through the disabled route to the communicating party in disabled state on each route for confirming whether the communication function is recovered or not at every prescribed time. As a result, when communication is made successful, the route is returned to the enabled state and concerning following communication, communication is performed while alternately using the duplexed routes.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a distributed communication control system and a distributed communication control method which are required to have high reliability such as nuclear power, thermal power, and chemistry and are applied to a plant.

[0002]

2. Description of the Related Art FIG. 4 is a diagram showing a network configuration of a conventional distributed communication control system of this kind. A plurality of control devices 3 that perform control calculations and an operator station 1 that collects data from the control devices 3 and displays the status of machines and plants to inform the operator are connected to the network. In many cases, the input / output device 4 is hierarchically connected to the control device 3, but FIG. 1 shows an example of a system in which the input / output device 4 itself is directly connected to a network in order to provide flexibility in configuration. Generally, in this type of system, several control devices 3 and several tens of input / output devices 4
Is connected. In the following, when the input / output device and the control device are referred to without distinction, they are referred to as communication nodes.

[0003] In such a distributed communication control system, duplicating the communication medium has been conventionally employed as a means for improving reliability. The generally employed method is generally as follows.

(1) The same communication contents are simultaneously communicated on a duplicated communication path. Therefore, even if one system fails,
Communication can be continued with the other system. (2) One of the redundant communication paths is always used. When it is detected that the used path is out of order, the path is switched to the other path to continue the communication. (3) Duplicate communication paths are used alternately. For this reason,
If one system fails, the other system can continue communication.

[0005]

In the above (1), since communication is always performed simultaneously on two routes, there is a problem that the processing load in the communication mode is increased as compared with the case where only one route is used. Therefore, when a high-speed communication cycle is required, it is an issue to reduce the processing load of communication as much as possible.

In the above (2), it is necessary to always check the soundness of the other unused path. Otherwise, if the other path is also faulty, one of the paths in use will fail, and when trying to switch, the failure of the other path will be detected for the first time. There's a problem.

For the reasons described above, the method (3) of alternately using the communication paths is often employed. the above
In the method of (3), since both paths are always used, a failure can be detected quickly, and only one of the communication paths is used in each communication. It does not have to be expensive compared to the method.

As a method of detecting a failure in the duplex system and displaying the failure on the operator station as described in the above (3), test communication is periodically performed to determine whether the operator station can communicate with all communication nodes. A method for doing so is generally considered.

As described above, if the operator station periodically performs test communication for communication check, an extra communication load is applied to the operator station and the network. In particular, when the distribution of communication nodes is remarkable, for example, if a communication test is to be performed on both communication paths for 100 communication partners in a one-second cycle, the operator station will be turned off every 5 ms (200 times per second).
Communication tests have to be performed, and the processing load on the operator station and the traffic on the network are very high. Further, if a test is performed several times a second to reduce the load, a problem occurs that a large amount of time is required until a failure is detected.

On the other hand, without performing the test communication,
When the operator station performs communication for data collection, a method may be considered in which if communication fails, it is regarded as a failure. In this way, no extra load is added only for the test communication. However, the operator station does not collect data unnecessary for display and logging for reasons such as reducing the communication load, and does not always communicate with all communication nodes at all times. Therefore, there is a problem that a communication abnormality with a communication node that is not communicating cannot be detected.

An object of the present invention is to provide a distributed communication control system and a distributed communication control method capable of easily and quickly detecting a communication abnormality without imposing an extra communication load.

[0012]

In order to solve the above-mentioned problems and achieve the object, a distributed communication control system and a distributed communication control method according to the present invention are configured as follows. (1) A distributed communication control system according to the present invention is a distributed communication control system for controlling data communication in a network in which a plurality of control devices and at least one operator station are connected, wherein each of the control devices is duplicated. A table showing, for each communication path, a communication success / failure state with each control device that is a communication partner on the communication path, and whether the communication function has been restored at predetermined time intervals with respect to the communication partner in the negative state in the table. Means for trying to communicate on a corresponding communication path in order to confirm whether or not, when recovery of the communication function is confirmed by this means, means for updating a corresponding part of the table to a successful state, When communicating with the communication partner, communication is performed on the communication path that is in the established state in the table, and both of the duplexed communication paths are in the established state. If it is, and means for communicating using said redundant communication paths alternately, the operator station comprises means for displaying the information of the communication success state received from the controller. (2) The distributed communication control method according to the present invention is a distributed communication control method for controlling data communication in a network in which a plurality of control devices and at least one operator station are connected, wherein each of the control devices is duplicated. In the table showing the communication success / failure status with each control device, which is the communication partner on the communication path, for each communication path, check whether the communication function has been restored at predetermined time intervals with respect to the communication partner with the status of No. In order to perform the communication on the corresponding communication path, and when the recovery of the communication function is confirmed, the corresponding portion of the table is updated to a satisfactory state, and when communicating with the communication partner, the table is updated. When the communication is performed on the communication path that is in the established state and both of the duplicated communication paths are in the established state, the duplicated communication path is used alternately. Performs communication, the operator station displays the information of the communication success state received from the controller.

As a result of taking the above-described measures, the following effects are produced. (1) In the distributed communication control system according to the present invention, each of the control devices may determine whether or not the communication is successful with each of the control devices as communication partners on the duplexed communication path in a table indicating the success or failure of each communication path. When the recovery of the communication function with respect to the communication partner in the state is confirmed, the corresponding part of the table is updated to the state of the communication, the communication is performed on the communication path in the state of the table in the table, and the duplex is performed. When both communication paths are in a successful state, communication is performed using the duplicated communication paths alternately.Therefore, by having the table, a communication path capable of communication can be immediately selected, and communication failure can be prevented. After the first communication to be detected, no time for performing the detection is required. Further, since the communication success / failure state is checked by the control communication without performing the test communication, the load related to the communication and the processing load thereof are not increased.

Further, all communication nodes on the network utilize the fact that they always communicate with any control device,
The table of the controller can be sent to the operator station to indicate the detection status. Also, in this case, the number of control devices is much smaller than the number of input / output devices, so that the load on the transmission of the table can be much smaller than in the case of performing test communication.

In addition, the table is updated sufficiently quickly in a cycle of communication by the control device, and the operator station transmits a table indicating a communication success / failure state sent from each control device to a matrix table with a communication partner (control device). In addition to displaying on the display, the place where it is determined from the matrix that there is a communication failure is presented to the operator,
It is possible to detect abnormalities much faster and more easily than by a method of detecting the time by transmitting the data to the operator station appropriately and detecting it by test communication.

[0016]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The network configuration of a distributed communication control system according to an embodiment of the present invention is the same as that shown in FIG. A plurality of control devices 3, a plurality of input / output devices 4, and one operator station 1 are connected to the network shown in FIG. 4 by a bus-type connection of a token-passing communication network. Each control device 3 is connected to communication paths 2A and 2B, which are two duplex communication media. Hereinafter, the communication paths 2A and 2B are referred to as an A system and a B system, respectively. Each input / output device 4 and operator station 1 are also connected to the A system and the B system similarly to the control device 3. Note that the device that performs communication may be divided into a control device that performs control calculations, an input device that captures sensor signals, an output device that drives an actuator, and the like.In this embodiment, for simplicity, the devices are collectively referred to as a control device. ing.

FIG. 1 is a diagram showing an internal configuration common to the communication nodes 1, 3, and 4. A-system communication circuit 10 and B
The communication circuit 11 of the system performs reception and transmission of the token passing method. A control circuit 12 using a microprocessor performs calculations and input / output processing necessary for plant control. The communication circuits 10 and 11 and the control circuit 12
The data connected by the computer bus 13 and received by the communication circuit 10 or 11 is passed to the control circuit 12, and the data transmitted from the control circuit 12 is conversely transmitted to the communication circuit 10 or 1.
Send from 1. Each of the communication nodes 1, 3, and 4 is assigned a number for identification in communication, and specifies the number of the partner communication node from its own communication node and performs one-to-one communication.

FIG. 2 is a diagram showing a communication state success / failure table stored in a storage circuit (not shown) built in the control circuit 12. This table shows the communication status of the A system and the B system. For example, three control devices 3 are connected in the configuration shown in FIG.
It is assumed that numbers 22 and 23 are assigned. Then, the control circuit 1 in each control device 3 (21, 22, 23)
2 is provided with the table. The view of the table is as follows.

FIG. 2 shows the state of communication from the own control device 3 (23) to the partner control device 3 (21 or 22), and shows the state of each of the A system and the B system. “○” indicates that communication is successful (communication is possible), “×” indicates that communication is unsuccessful (communication is not possible), and “−” indicates that communication is not possible.

In this example, the communication from 23 to 21 is A
System and B system succeed, and communication from 23 to 22 is B
This indicates that only the system was successful and the system A was faulty (that is, not normal). Further, since communication from 23 to 23 is not performed, "-" indicates that the communication is not performed.

The above table can store the states of the maximum number of communication nodes connected to one network. In the present embodiment, numbers indicating communication partners are prepared from 1 to 255 on the table. Also, it is assumed that "-" (out of communication target) is indicated at the number of the communication node that is not connected.

The operation procedure of the distributed communication control system will be described below in (1) to (5). (1) Each communication node uses one of the duplicated communication paths in the first communication. In the second communication,
Use the other system. Thereafter, similarly, the path is switched each time communication is performed. (2) The control circuit 12 of each communication node, when trying to perform communication through any of the routes, if the communication cannot be performed normally, changes the success / failure status of the communication partner in the table shown in FIG. To Then, the subsequent communication is continued by using only the path in the “completion” state in which normal communication is possible.

2-1) The control circuit 12 checks the table in FIG. 2 to determine whether a communication path different from the previous communication path is available. That is, the communication success / failure state corresponding to the communication partner number of the communication system (A system or B system) in FIG. 2 is checked.

2-2) If communication is possible in the above 2-1) ("o" is attached), transmission is performed through the different communication paths. For example, if the transmission was previously performed by the A system, the transmission is performed by the B system this time. Data to be transmitted in the B system is passed from the control circuit 12 to the communication circuit 11 and transmitted. On the other hand, if communication is not possible ("x" or "-" is attached), transmission is performed in the same system as the previous time. (3) The control circuit 12 of each communication node checks “No” (“×”) with the communication partner in the “No” state on each path to check whether the communication function has been restored at predetermined time intervals. Attempt communication on the route in the state of ")". As a result, if the communication is successful, the state is returned to "completion"("o"), and in the subsequent communication, communication is performed by using the duplicated paths alternately as described above. If the communication is not successful, the communication function has not been recovered and the state has not been changed, so that the path of “No” is not used.

As described above, the control circuit 12 checks the table of FIG. 2 at regular intervals (for example, one second), finds a location marked with “x”, and indicates that communication is normal (communicable state).
Test whether it has been restored.

3-1) When the transmission is performed, the communication circuit determines whether the communication has failed or succeeded.
The result is sent to the control circuit 12. When the communication fails, the control circuit 12 records the state of “x” in the corresponding column of the table.

3-2) Further, the control circuit 12 checks the above-mentioned table, checks the location of the state of "x", and takes out the number of the other party with the "x" and the communication path. If the "x" status is found, execute the following 3-3). If not found, the following 3-3)
Does not execute.

3-3) The control circuit 12 attempts transmission using a combination of the communication number and the other party number in the “x” state. When the transmission is successful, the control circuit 12 updates the corresponding column of the table to ““ ”, and does not update to“ ○ ”when the communication fails. It should be noted that if all the communication in the “x” state is confirmed every period, the load of the communication processing may increase. Therefore, the load is distributed by checking one by one in one cycle. As described above, since the table is updated also as communication necessary for control, the load related to communication does not need to be increased as compared with a case where test communication is performed for abnormality detection. (4) Each control device 3 transmits to the operator station 1 a communication status success / failure table which is constantly updated by the methods (1) to (3). On the other hand, the control device 3 sends and receives input / output data through communication with the input / output device 4 or another control device 3. Therefore, since any input / output device 4 always communicates with any control device 3, the table transmitted to the operator station 1 reflects the communication state of all communication nodes.

Each control device 3 transmits the table updated as described above to the operator station 1 periodically, for example, every 0.5 seconds. Since the number of the control devices 3 is as small as about several as compared with the total number of nodes, it is not necessary to greatly increase network traffic by transmitting the table. The operator station 1 displays the received table in a matrix as shown in FIG. (5) The operator station 1 displays the communication status success / failure table received from each control device 3 in a matrix on a display device (not shown). As described above, the correspondence between the communication states of all the communication nodes and the respective control devices 3 is displayed in a matrix, so that the location where the communication abnormality has occurred can be accurately presented to the operator.

FIG. 3 is a diagram showing a display example of a communication state. In FIG. 3, “CPU” indicates the control device 3,
“I / O” indicates the input / output device 4. The control devices are placed along the horizontal axis and all the control devices are placed along the vertical axis, and the corresponding communication states are displayed. If the status of the communication success / failure state table is "O", "O"
K ”and“ × ”indicates“ ERR (ERROR
In the case of "R)" or "-", "-" is displayed. "Net number" is an identification number assigned to the network, and "Host number" is an identification number assigned to each communication node.

All communication nodes on the network always communicate with any control device 3 (any control device 3
If you don't communicate with, you're not using it at all.)
Therefore, the status is checked in the horizontal axis direction, and if there is at least one "ERROR", the fact that there is a communication error is displayed in the "communication state" column. The communication node where the A system and the B system have “ERROR” in both cases may be abnormal in the communication node itself, not in the communication system.
"Abnormal" is displayed in the column. By looking at this matrix table, the operator can know whether or not there is an abnormal communication node and which part of the communication system has a failure.

For example, if the control unit 3 communicates in 0.5 seconds, the above table is updated every 0.5 seconds. Furthermore, if the transmission is performed to the operator station 1 at a 0.5 second cycle, the failure detection display can be performed in about 1 second, which is many times different from the conventional method of thinning out the test communication and detecting it. Is obvious.

As described above, in the distributed communication control system shown in the present embodiment, a plurality of control devices 3 are connected by a network, and control is performed by exchanging data necessary for control by network communication. This is a distributed communication control system in which the status of a machine or a plant is monitored by the operator station (monitoring terminal) 1 above. The communication hardware is duplicated, and each communication is performed by each control device 3 that performs communication. Communication system that alternately uses the communication paths that have been used, when a single failure occurs, quickly detects the presence or absence of the failure and displays the location of the communication failure to the operator. Sex control system.

Each of the control devices 3 has a table indicating a communication success / failure state with a control device of a communication partner on each of the duplicated paths. If communication cannot be performed normally, each control device 3
Sets the success / failure status of the communication partner to be negative. Then, the subsequent communication is continued by using only the route that can be normally communicated.

First, each control device 3 periodically transmits the communication success / failure state table to the operator station 1 using a normal communication path. Operator station 1
Displays a table of communication success / failure status sent from each control device 3 as a matrix table with the communication partner (control device 3), and displays a portion where it is determined from the matrix that a communication failure has occurred. Present to the operator.

Each control device 3 attempts to communicate with the communication partner in the negative state on each path via the negative path in order to confirm whether the communication function has been restored at predetermined time intervals. As a result, if the communication is successful, the state is returned to a normal state, and in the subsequent communication, communication is performed by using the duplicated paths alternately.

It should be noted that the present invention is not limited to only the above-described embodiment, and can be implemented with appropriate modifications without departing from the scope of the invention. In the above embodiment, the communication of the token passing method has been described as an example, but the present invention is not limited to this method and can be applied. The present invention is also applicable to distributed control devices in fields other than nuclear power, thermal power, and chemistry.

[0038]

According to the present invention, it is possible to provide a distributed communication control system and a distributed communication control method capable of easily and quickly detecting a communication abnormality without imposing an extra communication load.

[Brief description of the drawings]

FIG. 1 is a diagram showing an internal configuration common to each communication node according to an embodiment of the present invention.

FIG. 2 is a diagram showing a communication state success / failure table according to the embodiment of the present invention.

FIG. 3 is a diagram showing a display example of a communication state according to the embodiment of the present invention.

FIG. 4 is a diagram showing a network configuration of a distributed communication control system according to an embodiment of the present invention and a conventional example.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Operator station (monitoring device, communication node) 2A ... Communication path (A system) 2B ... Communication path (B system) 3 ... Control device (communication node) 4 ... Input / output device (communication node) 10 ... Communication circuit (A 11) Communication circuit (for B system) 12 ... Control circuit 13 ... Computer bus

Claims (2)

[Claims] 1. A distributed communication control system for controlling data communication in a network in which a plurality of control devices and at least one operator station are connected, wherein each of the control devices is a communication partner on a duplicated communication path. A table showing the communication success / failure state with each control device for each communication path, and for the communication partner in the no state in the table, to confirm whether the communication function has been restored every predetermined time,
Means for attempting communication on a corresponding communication path; means for updating a corresponding part of the table to a satisfactory state when the recovery of the communication function is confirmed by the means; and for performing communication with the communication partner. Means for performing communication on a communication path that is in the established state in the table, and when both of the duplicated communication paths are in the established state, communicating using the duplicated communication path alternately; A distributed communication control system, wherein the operator station includes means for displaying information on a communication success / failure state received from each of the control devices. 2. A distributed communication control method for controlling data communication in a network in which a plurality of control devices and at least one operator station are connected, wherein each of the control devices is a communication partner on a duplicated communication path. In a table showing the communication success / failure state with each control device for each communication path, the communication path corresponding to the communication path corresponding to the failure state is checked at predetermined time intervals to check whether the communication function has been restored. When the communication function is recovered and the recovery of the communication function is confirmed, the corresponding part of the table is updated to a successful state, and when performing communication with the communication partner, the communication path is in the successful state in the table. When the communication is performed, and both of the duplicated communication paths are in a successful state, the communication is performed by using the duplicated communication paths alternately, Operator stations distributed communications control method characterized by displaying the information of the communication success state received from the controller.