JP3385928B2 - Redundant distributed controller - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a distributed control device having a redundant communication system, and more particularly to a distributed control device having an improved self-diagnosis method for the communication system.

[0002]

2. Description of the Related Art A conventional distributed control system comprises a master station control system installed in a control room or the like and a plurality of slave station control systems distributed in a field or the like. The respective control devices are connected to each other by a communication system such as a communication cable and perform data communication and the like to control the plant and the like.

However, if any trouble occurs in the communication system, communication between the control devices becomes impossible, and control of the plant becomes impossible.

For this reason, in the conventional distributed control apparatus, in order to improve the reliability, the communication system is made redundant such as duplicated.

FIG. 5 is a block diagram showing an example of such a conventional redundant distributed control device. In FIG. 5, 1a and 1b are control devices of the master station, 2a, 2b, 3a and 3
b, 5a, 5b, 6a and 6b are communication cards, 4a and 4b are slave station control devices, and 100 and 101 are communication cables such as coaxial cables.

Communication cards 2a and 3a are mounted on the master station control device 1a, and communication cards 2b and 3b are mounted on the master station control device 1b.

On the other hand, communication cards 5a and 6a are mounted on the control device 4a of the slave station, and communication cards 5b and 6b are mounted on the control device 4b of the slave station.

The communication cards 2a, 2b, 5a and 5b are sequentially connected by a communication cable 100, and the communication card 3
A, 3b, 6a and 6b are sequentially connected by a communication cable 101.

Further, two "communication buses A" and "communication buses B" are formed by the communication cables 100 and 101, respectively.

The operation of the redundant distributed control device shown in FIG. 5 will be described with reference to FIGS. 6 and 7. FIG. 6 is an explanatory diagram for explaining the load distribution and redundancy configuration, and FIG. 7 is an explanatory diagram for explaining the communication system self-diagnosis method. In addition, FIG.
Further, the reference numerals in FIG. 7 are the same as those in FIG.

The master station controller 1a uses the communication card 2a to communicate with a communication card connected to the "communication bus A", while the master station controller 1b uses the communication card 2b to "communicate". It communicates with the communication card connected to the bus B ″.

Therefore, the communication load from the master station control devices 1a and 1b is distributed to the "communication bus A" and the "communication bus B".

On the other hand, when the control device 1a of the master station fails in the communication on the "communication bus A", the control device 1a immediately retries the communication on the "communication bus B" using the communication card 3a.

Similarly, when the control device 1b of the master station fails in communication on the "communication bus B", the control device 1b immediately uses the communication card 2b to retry the communication on the "communication bus A".

For example, as shown in FIG. 6, when the master station controller 1a communicates with the slave station controller 4a, in the normal state, in other words, when the "communication bus A" is normal, the controller 1a. Performs communication with the control device 4a via the communication cards 2a and 5a, as indicated by "a" in FIG.

On the other hand, when a failure occurs in the "communication bus A", the control unit 1a communicates with the control unit 4a via the communication cards 3a and 6a as shown by "B" in FIG.

Similarly, when the control device 1b of the master station communicates with the control device 4a of the slave station, in the normal state, in other words, when the "communication bus B" is normal, the control device 1b is operated as shown in FIG.
Communication with the control device 4a is performed via the communication cards 3b and 6a as indicated by the middle "c".

On the other hand, if a failure occurs in the "communication bus B", the control device 1b communicates with the control device 4a via the communication cards 2b and 5a, as indicated by "d" in FIG.

As a result, if the communication fails on one of the "communication bus A" and the "communication bus B", the communication can be retried on the other communication bus, so that the communication system is made redundant. It becomes possible to plan.

Further, in order to prevent wasteful communication with the communication buses incapable of communication in the master station control devices 1a and 1b, self-diagnosis of the communication system is periodically performed.

As a self-diagnosis method, the control device 1 of the master station
a performs test communication using both "communication bus A" and "communication bus B", and if there is no response from the slave station controller, connect to the communication bus with no response from the slave station controller. The determined communication card is defective.

As the test communication, the return communication is performed by the communication card of the slave station so as not to affect other communication as much as possible.

For example, as shown by "a" and "b" in FIG. 7, the controller 1a of the master station uses the communication cards 2a and 3a to perform test communication with the controller 4a of the slave station.

If the communication cards 5a and 6a mounted on the control device 4a are normal, "c" and "d" in FIG.
As shown in, the return response from the communication cards 5a and 6a is returned.

Similarly, as shown by "e" and "f" in FIG. 7, the controller 1a of the master station performs test communication with the controller 4b of the slave station using the communication cards 2a and 3a.

Here, since the communication card 6b is normal, there is a return response as shown by "G" in FIG. 7, but if the communication card 5b mounted on the control device 4b has a failure. In this case, there is no return response from the communication card 5b.

Therefore, the control unit 1a judges that the "communication bus A" has a fault and immediately uses the "communication bus B".

As a result, the control devices 1a and 1b of the master station can periodically carry out self-diagnosis of the communication system.

[0029]

However, the communication of a general application is not communication with the communication card of the slave station but communication with the control device of the slave station. For example, communication is generally performed such that a control device of a master station accesses a memory that stores data in a control device of a slave station.

On the other hand, as described above, the conventional self-diagnosis method of the communication system performs the return communication with the communication card of the slave station so as not to affect other communication as much as possible.

Therefore, in the case where there is a failure in the interface portion of the slave station communication card to the slave station control device, the communication communication card returns the test communication, but the slave station control device does not. I can't access it.

FIG. 8 is an explanatory view for explaining an example of such a failure, and the reference numerals in FIG. 8 are the same as those in FIG.

For example, the communication card 5 shown in "A" in FIG.
Even if a failure occurs in the interface part with the control device 4a of a, the test communication indicated by "b" in FIG. 8 is normally returned, so that the "communication bus A" is normal in the control device 1a of the master station. I will judge.

Therefore, the control device 1a of the master station is shown in FIG.
Accession to the data in the controller 4a of the slave station, as shown in C "
If the communication to be accessed is performed using the "communication bus A", a communication error will occur due to a failure at the portion "A" in FIG.

For this reason, the control unit 1a has the "communication bus B".
There is a problem that the communication must be retried as shown by "d" in FIG. 8 by using, and the communication system failure may not be found by the conventional communication system self-diagnosis. there were. Therefore, the problem to be solved by the present invention is to realize a redundant distributed control device capable of surely performing self-diagnosis of a communication system.

[0036]

In order to achieve such a object, according to the first aspect of the present invention, in a redundant distributed control device in which a communication system is made redundant, two communication cards are mounted. One control device and two communication cards are attached, and as a self-diagnosis of the communication system, the memory in the first control device is accessed through the communication card of the first control device and stored in advance in this memory. And a second control device for performing test communication for reading the test pattern, and two communication cables for connecting two communication cards respectively mounted on the first and second control devices to form two communication buses.
And one of the communication buses for self-diagnosis of the communication system.
A second test to a memory in the first controller using
Pattern is written and the other side of the communication bus is used.
Test pass to read the second test pattern.
It is characterized by performing trust .

In order to achieve such a subject, in the second aspect of the present invention, in the first aspect of the present invention, when the reading of the second test pattern fails as a self-diagnosis of the communication system, the first aspect of the present invention is used. It is characterized in that test communication is performed to read out the test pattern previously stored in the memory in the control device.

In order to achieve such a subject, in the third aspect of the present invention, in the second aspect of the present invention, when the reading of the test pattern fails as a self-diagnosis of the communication system, two communication cards are used. It is characterized in that the communication is performed back.

[0039]

[0040]

[0041]

[0042]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention will be described in detail below with reference to the drawings. FIG. 1 is a configuration block diagram showing an embodiment of a redundant distributed control apparatus according to the present invention.

In FIG. 1, 2a, 2b, 3a, 3b, 4
a, 4b, 5a, 5b, 6a, 6b, 100 and 101
Are denoted by the same reference numerals as those in FIG. 5, and 7a and 7b are control devices of the master station.

The connection relationship is almost the same as that of the conventional example shown in FIG. 5, except that the control devices 1a and 1b are replaced by the control devices 7a and 7b.

The operation of the embodiment shown in FIG. 1 will now be described with reference to FIG.
This will be described with reference to FIGS. 3 and 4. 2, 3 and 4 are explanatory views for explaining the self-diagnosis method of the communication system.

However, since the basic operation is the same as the conventional example shown in FIG. 5, only the communication system self-diagnosis method will be described.

First, a fixed test pattern is stored in advance in a memory in the control device 4a shown by "a" in FIG. For example, the test pattern is “555
Hexadecimal numbers such as 5 "," AAAAA "and" FFFF "are stored.

The controller 7a (not shown in FIG. 2), which is the master station, uses the communication cards 2a and 3a (not shown in FIG. 2) to control the controller 4a of the slave station. The test pattern is read as test communication.

If there is no failure in the interface portion of the communication cards 5a and 6a with the control device 4a, for example, as shown by "b" in FIG. 2, a test pattern stored in the memory of "a" in FIG. It is possible to access.

That is, the control device 7a (not shown in FIG. 2) of the master station can determine that the communication card has no abnormality if the reading of the test pattern is successful.

On the other hand, if there is a failure in the interface part of the communication card 5a with the control device 4a as shown by "C" in FIG. 2, the test pattern stored in the memory of "A" in FIG. 2 is accessed. It cannot be done and an error occurs as shown by "D" in FIG.

That is, since the communication with the communication card 5a results in an error, the master station controller 7a (not shown in FIG. 2).
Can detect the failure of the communication card 5a.

Therefore, the controller 7a of the master station (not shown in FIG. 2) is stored in the memory of the controller 4a of the slave station using "communication bus A" and "communication bus B". Communication is performed to read the test pattern, and if the reading on the "communication bus A" fails, the communication card 5a is regarded as abnormal, and if the reading on the "communication bus B" fails, the communication card 6a is regarded as abnormal.

As a result, by performing the test communication for reading the test pattern stored in advance in the memory in the control device of the slave station, the interface portion of the communication card of the slave station to the control device of the slave station is broken. Even if there is, it is possible to detect an abnormality.

However, in the above self-diagnosis of the communication system,
If the reading of the test pattern fails on both the "communication bus A" and the "communication bus B" as indicated by "a" and "b" in FIG. 3, is the control device 4a of the slave station a failure?
It cannot be determined whether or not the communication cards 5a and 6a mounted are out of order.

In this case, as shown by "C" and "D" in FIG. 3, the return communication is performed by the communication cards 5a and 6a of the slave station as the test communication.

If the communication cards 5a and 6a have a failure, the return response will not be returned. If the control device 4a has a failure, the communication card itself is normal, and a reply is returned.

That is, "communication bus A" and "communication bus B"
If the reading of the test pattern fails in both cases, the communication cards 5a and 6a perform return communication, and if the return response is returned, the control device 4a considers it to be abnormal, and if the return response is not returned, communication is performed. Card 5a
And 6a are considered abnormal.

As a result, when the reading of the test pattern fails on both the communication buses, it is possible to judge which of the control device and the communication card has a failure by performing the return communication with the communication card.

Another self-diagnosis method for the communication system shown in FIG. 4 will be described. The master station controller 7a (not shown in FIG. 4) uses the communication cards 2a and 3a (not shown in FIG. 4) to identify the slave station controller 4a as a test communication. Write or read the test pattern.

For example, as shown by "a" in FIG. 4, a specific test pattern shown by "c" in FIG. 4 is written in the memory in the control device 4a shown by "b" in FIG. 4 through the communication card 5a. , The written test pattern is read out via the communication card 6a as indicated by "d" in FIG.

If there is no failure in the interface part of the communication cards 5a and 6a with the control device 4a, the specific test pattern written via the communication card 5a can be accurately read out via the communication card 6a.

Here, if there is a failure in the interface portion of the communication card 5a or 6a with the control device 4a, the test pattern cannot be read accurately.

That is, if the reading of the test pattern indicated by "d" in FIG. 4 fails, the control device 4a or the communication card 6a is abnormal.

In this case, as shown in FIG.
Test communication for reading another test pattern stored in advance in the memory in a is performed to the communication card 5a, and if the reading of the other test pattern is successful, it is considered that the communication card 6a is abnormal.

If the reading of the other test pattern fails, it means that the control device 4a or the communication card 5a has an abnormality.

Further, in this case, as shown in FIG. 3, the return communication is performed by the communication cards 5a and 6a as the test communication, and if the return response is returned, the control device 4a is returned.
Is regarded as abnormal, and if the return response is not returned, the communication cards 5a and 6a are regarded as abnormal.

On the other hand, if the test pattern read via the communication card 6a does not match the test pattern written via the communication card 5a as indicated by "d" in FIG. 4, the communication card 5a has an abnormality. become.

As a result, by writing and reading the test pattern as the test communication on the "communication bus A" and the "communication bus B", the failure of the control device and the communication card can be specified.

In the description of FIGS. 2 to 4, the periphery of the slave station control device 4a is illustrated for simplification, but the same self-diagnosis is performed for the other slave station control devices.

Further, the controller 7a is used as the controller of the master station.
Similarly, the control device 7b illustrated in FIG.

Although two communication buses are illustrated for the sake of simplicity of description, two or more communication buses may be used. Accordingly, the number of communication cards mounted on each control device may be two or more.

Although the test pattern is stored in the memory in the slave station controller 4a in the description of FIG. 2, the test pattern may be stored in a specific file.

In the description of FIG. 4, the test pattern is written via the communication card 5a and the test pattern is read out via the communication card 6a, but the reverse is also possible.

Further, in the description of FIG. 4, when the reading of the test pattern by the communication card 6a fails, the test pattern is written through the communication card 6a and the test pattern is read through the communication card 5a. You can go.

In this case, if the communication card 6a is abnormal, the test pattern read by the communication card 5a does not match the written test pattern.

If the reading of the test pattern from the communication card 5a also fails at this time, either the communication cards 5a and 6a or the control device 4a is abnormal, and the abnormal device is detected by the method shown in FIG. Can be specified.

[0078]

As is apparent from the above description,
The present invention has the following effects. Via communication card
Then, access the memory in the control device of the slave station and use this memo.
By testing communication for reading pre-stored test pattern Li, the communication system redundant distributed control system which can reliably perform a self-diagnosis of can be achieved.

[Brief description of drawings]

FIG. 1 is a configuration block diagram showing an embodiment of a redundant distributed control device according to the present invention.

FIG. 2 is an explanatory diagram illustrating a communication system self-diagnosis method.

FIG. 3 is an explanatory diagram illustrating a self-diagnosis method of a communication system.

FIG. 4 is an explanatory diagram illustrating a communication system self-diagnosis method.

FIG. 5 is a configuration block diagram showing an example of a conventional redundant distributed control device.

FIG. 6 is an explanatory diagram illustrating a load distribution and redundancy configuration.

FIG. 7 is an explanatory diagram illustrating a communication system self-diagnosis method.

FIG. 8 is an explanatory diagram illustrating an example of a failure.

[Explanation of symbols]

1a, 1b, 4a, 4b, 7a, 7b Control device 2a, 2b, 3a, 3b, 5a, 5b, 6a, 6b Communication card 100, 101 Communication cable

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Claims (3)

(57) [Claims] 1. A redundant distributed control device having a redundant communication system, wherein a first control device having two communication cards and two communication cards are installed as a self-diagnosis for the communication system. A second control device for performing test communication for accessing a memory in the first control device via a communication card of the first control device and reading a test pattern stored in advance in the memory; Two communication cables connected to two communication cards respectively mounted on the two control devices to form two communication buses are provided, and one of the communication buses is used for self-diagnosis of a communication system.
Note Second test pattern for memory in first controller
Is written to the second bus using the other of the communication buses.
The test communication is performed to read the test pattern of
And a redundant distributed control device. 2. As a self-diagnosis of a communication system, when the reading of the second test pattern fails, test communication for reading the test pattern previously stored in the memory in the first control device is performed. According to claim 1,
Redundant distributed control device. 3. The redundant communication according to claim 2 , wherein when the reading of the test pattern fails, the return communication is performed by the two communication cards as a self-diagnosis of a communication system.
Lengthening distributed control device.