JP2003140709A - Process controller - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent the influence of any failure caused by a specific operation timing at the time of judging the control arithmetic results of at least three controllers operating in parallel by majority, and performing process control. SOLUTION: This process controller is provided with N (N is a natural number which is 3 or more) pieces of controllers 20 arranged between a network interface 10 and a process equipment interface 30 for respectively operating according to individual clocks, and for executing the processing of a request from the network interface in a processing timing instructed by processing timing information added to the request among processing timings synchronizing with a common processing timing signal. The request distributing part of the network interface 10 adds the processing timing information for instructing the timing in which the processing of the request received from a monitoring device 2 should be executed by the controller 20 to the request, and for notifying each controller 20 of the request. A response comparing part judges a response from each controller 20 to the request by majority, and decides one response to be transmitted to the monitoring device 2.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a process control device, and more particularly to a process control device having a redundant configuration.

[0002]

2. Description of the Related Art Conventionally, a process control device used for process control of a plant or the like has been used which has a redundant structure in which a plurality of controllers for performing control calculations are provided when high reliability is required. A conventional process control device having such a redundant structure generally has two controllers, a master system and a slave system, and when an abnormality occurs in the master controller, a redundant standby redundancy system is generally used in which the standby controller switches to the standby controller. is there.

However, in such a redundant standby redundancy system process control device, when the controller switches from the master system to the slave system, the slave system, which has been waiting, starts processing after detecting the stop of the master system. There is a problem in that it cannot be used for process control with a short control cycle of the process because of a control blank time. For this reason, there has been a demand for a process control device in which a control blank time does not occur even when an abnormality occurs in the operating controller.

On the other hand, a method is conceivable in which three or more controllers having the same structure are operated in parallel, a majority decision is made on the control outputs of these controllers, and the result of the decision is used for process control. Normally, in a process control device, a processing request from an upper monitoring device and a control for a lower process device are processed by time sharing, so that different control calculation processes are performed in a short time. Therefore, in order to obtain a desired control calculation result by the above method, it is necessary to obtain a control calculation result for the same control calculation process from each controller.

[0005]

However, in a controller that performs various control arithmetic processing by executing a program by a microprocessor such as a CPU, each controller executes a specific control arithmetic processing. If there is an input from the upper monitoring device or the lower process device at a specific timing, a malfunction such as a calculation error may occur.

In order to solve such a problem, a configuration may be considered in which an operation clock is input from the outside to completely synchronize the operation of each controller, but this configuration requires separate dedicated hardware. There was a problem that it became an expensive system. Even if the controllers having the same configuration are operated in perfect synchronization based on a common operation clock, the above-mentioned inconvenience occurs due to a specific operation timing. Even if the controllers are operated in parallel, all calculation results will be different, and this problem cannot be avoided.

Further, if the requests to each controller are overloaded, the response delay occurs only in one of the controllers, and it is not possible to guarantee the identity of processing. Furthermore, if it is determined that such a timing shift is abnormal, the system will be stopped unnecessarily, an extra load will be applied to the equipment, and the entire plant will be greatly damaged. The present invention is intended to solve such a problem and operates in parallel.
An object of the present invention is to provide a process control device capable of obtaining stable control calculation results from each controller at the same time when performing a process control by making a majority decision on the control calculation results of one or more controllers.

[0008]

In order to solve the above-mentioned problems, a process control device according to the present invention provides a controller for performing a control operation for process control and a request received from a host device via a network. A network interface for notifying the controller and transmitting a response from the controller to the higher-level device to the request, and transmitting control data to the process equipment connected to the IO bus based on the control calculation in the controller, and the process equipment And a process device interface for receiving measurement data from the controller, the controller performs control calculation based on a request received via the network interface, and transmits the obtained control data to the process control device via the process device interface. And by controlling the process equipment, and output to the network interface measurement data obtained from the process control device as a response from the controller,
A process control device that sends a response from a network interface to a host device. It is provided as a controller between the network interface and the process equipment interface in parallel, and uses the processing timing information added to the request from the network interface. The request delivery unit of the network interface is provided with N (N is a natural number of 3 or more) controllers that execute the processing corresponding to the request at the instructed processing timing, and the request received from the host device via the network is The processing timing information that indicates the timing at which the controller should execute the processing corresponding to the request is added and notified to each controller, and the response comparison unit reports the response from each controller to the request. 1 the number determined decision to send to the host device
It decides one response.

Regarding the processing timing, the request distribution unit selects the processing timing for processing the newly received request based on the processing status of the request transmitted to each controller, and outputs the processing timing information indicating the processing timing. It may be added to the request.

The load check unit of the network interface judges whether or not the newly received request can be accepted based on the processing status of the request transmitted to each controller, and only when the request is acceptable, the request is passed to the request distribution unit. You may do it. At this time,
When the load check unit determines that the request cannot be accepted, the host device may be notified that the request cannot be executed.

[0011]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a block diagram showing a configuration of a process control device according to a first exemplary embodiment of the present invention. In the figure, the process control device 1 is
It is provided with one network interface 10, three controllers 20 (controller A, controller B, controller C) having the same configuration and one process equipment interface 30.

The network interface 10 and the three controllers 20 are connected to an internal LAN (Local Area Network).
k) connected to 40 and configured to be able to communicate with each other. The process device interface 30 is provided separately from the three controllers 20 by a USB (Universal Serial Bus).
Are connected by a data communication path 50, and one-to-one communication with these is possible. In addition, the network interface 10 and the three controllers 20
The process equipment interface 30 is connected to a bus (not shown). Further, the network interface 10 is an external control LAN 3 to which the monitoring device 2 is connected.
The process device interface 30 is connected to the (network), and is connected to the external IO bus 5 to which the process device 4 is connected.

In such a configuration, in the network interface 10 of the process control device 1, the control LA
3 requests from the monitoring device 2 received via N3
L is given to each of the three controllers 20 and one response among the responses from the three controllers 20 to this request is determined by the majority decision.
It outputs to AN3 and responds to the monitoring device 2. In each of the three controllers 20, the network interface 1
The request given from 0 is processed, the response to the request is output to the network interface 10, the process control operation is performed, and the operation result is output as control data to the process equipment interface 30.

In the process equipment interface 30, 3
From the control data output from each of the two controllers 20, one control data determined by majority decision
Output to the bus 5 to control the process equipment 4. Therefore, even if one of the controllers 20 has an abnormality and outputs a response or control data different from the other two, a normal response or control data is output to the monitoring device 2 or the process equipment 4 without interruption. can do.

Next, the network interface 10 will be described in detail with reference to FIG. FIG. 2 is a functional block diagram of the network interface 10. As shown in FIG. 2, the network interface 10 is
Response / request transmission / reception unit 11, load check unit 12,
Request distribution unit 13, response reception unit 14, response comparison unit 1
5 and an abnormality notification unit 16.

The request output from the monitoring device 2 to the control LAN 3 is received by the response / request transmission / reception section 11,
It is sent to the load check unit 12. Load check unit 12
Checks the request processing status (processing load) of each controller 20, and checks all the operating controllers 2
When 0 is in a state in which the request sent can be accepted, the request sent from the response / request transmission / reception unit 11 is transferred to the request delivery unit 13, and when there is a controller in operation and in an unacceptable state, a response is sent. / Notifies the request transmitting / receiving unit 11 that the request cannot be accepted and deletes the request.

In this case, the load check unit 12 determines that the next request can be accepted when the number of requests being executed by the controller 20 is less than or equal to a predetermined number. The number of requests being executed is obtained by subtracting the number of responses from the number of transferred requests, for example. The number of responses is input from the response receiving unit 14 described later. Response / request transceiver 1
When notified that the request cannot be accepted, 1 notifies the request source that the request cannot be executed.

The request distribution unit 13 adds processing timing information indicating the timing to be processed to the request transferred from the load check unit 12, and then the internal LAN 4
Broadcast to three controllers 20 via 0. In this case, the processing timing information is a 3-bit code indicating the processing timing in one control cycle, and the request delivery unit 13 uses the process equipment interface 3 described later.
0 refers to the current value of the 3-bit processing timing signal 103 output in parallel on the bus (not shown), and sets the value of the processing timing signal generated in the future as the timing of executing the request. At this time, the timing of executing the newly received request or the timing of transmitting the request response is selected based on the processing status of the request transmitted to each controller. As for the processing status of the request, the one managed by the load check unit 12 may be used.

On the other hand, when a response to the request is transmitted from each of the three controllers 20, the response receiving unit 14 receives the response, sends it to the response comparing unit 15, and notifies the load check unit 12 of the controller that has returned the response. . In this case, the response receiving unit 14 temporarily holds the received response, and sends it to the response comparing unit 15 after the responses from the three controllers 20 are gathered. When there is no response from one of the three controllers 20 within the predetermined time, the controller 20 is notified of the controller 20 and
For example, predetermined specific data such as null data is sent to the response comparing unit 15 as the response of the controller 20 together with the other two responses.

Here, when there is no response within a predetermined time, the load check unit 12 is notified of the unresponsive controller 20 because the load check unit 12 does not process the unprocessed request of the unresponsive controller 20. By remaining, the number of running requests exceeds the predetermined number,
This is to prevent the two controllers in operation from being unable to execute the request.

The response comparing section 15 compares the responses from the three controllers 20 sent from the response receiving section 14, and sends the response / request transmitting / receiving section 11 of the content only when there are two or more responses having the same content. Send one reply. However, if the matched content is predetermined specific data such as null data, the response is not transmitted. The response sent to the response / request transmission / reception unit 11 is the control LA.
The data is output to N3 and transmitted to the monitoring device 2 that made the request. In addition, the response comparison unit 15 notifies the abnormality notification unit 16 of the controller that has returned a response having a different content from the other. The abnormality notification unit 16 transmits the abnormality notification to the controller notified from the response comparison unit 15 via the internal LAN 40.

The network interface 10 is
LAN interface for control LAN3 and internal LAN
A LAN interface for 40, a digital input interface for inputting the processing timing signal 103, a non-volatile semiconductor memory storing a program that realizes the function of the network interface 10, and a program stored in the non-volatile semiconductor memory. It is composed of an arithmetic processing unit (CPU), a RAM used for temporary storage when a program is executed, and a bus connecting these.

Next, the controller 20 will be described in detail with reference to FIG. FIG. 3 is a functional block diagram of the controller 20. As shown in FIG. 3, the controller 20 includes a request processing unit 21, a database 22, an arithmetic processing unit 23, an input / output processing unit 24, and an abnormality processing unit 25.
The database 22 stores set values of process control conditions, present values of measurement data, and control data for controlling process equipment. In this case, the internal L
The request output to the AN 40 is received by the request processing unit 21, the content of the request is analyzed, and the processing according to the request is executed based on the processing timing information added to the request.

For example, if the request is a change in the process control condition, the set value of the specified control condition in the database 22 is rewritten to the set value instructed by the request,
The rewritten set value is read from the database 22 and used as the response content. If the request is a request for the current value of the process condition, the current value of the specified process condition is read from the database 22 and used as the response content. Such a response is sent by the request processing unit 21 to the internal LAN.
It is output to 40 and is transmitted to the network interface 10. In this case, the request processing is performed by the processing timing signal 10 output from the process equipment interface 30.
3 is executed, and the processing is executed when the information indicated by this signal matches the processing timing information added to the request.

The arithmetic processing unit 23 reads a set value of the process control condition and the current value of the process condition from the database 22 at a predetermined timing, and performs a control operation for calculating a control amount required to match the current value with the set value. Then, the calculation result is written in the database 22 as control data. The input / output processing unit 24 uses the database 2 at a predetermined timing.
The control data is read from 2 and transmitted to the process equipment interface 30. In addition, the process device transmits a command requesting transmission of the process data measured by the process device to the process device interface 30, receives the process data measured by the process device transmitted from the process device interface 30, and stores the current value in the database 22. Write.

Further, the request processing unit 21 receives the abnormality notification transmitted from the abnormality notification unit 16 of the network interface 10 in the same manner as the request, and the abnormality processing unit 2
Notify 5. The input / output processing unit 24 confirms whether or not the information transmitted from the process device interface 30 includes an abnormality notification, and when the information is included,
The abnormality processing unit 25 is notified. The abnormality processing unit 25 stops the processing of the controller 20 when receiving the abnormality notification.

The controller 20 has an internal LAN 40.
LAN interface for communication, a communication interface for the data communication path 50, a digital input interface for inputting the processing timing signal 103, and a controller 20
A non-volatile semiconductor memory that stores a program that realizes the functions of the above, an arithmetic processing unit (CPU) that executes the program stored in the non-volatile semiconductor memory, a storage area of the database 22 and a temporary storage area when the program is executed. It is composed of a RAM used and a bus connecting them. In addition, this controller 20 can be hot-plugged and unplugged so that one of the three controllers 20 can be used.
When one of them fails, it can be replaced while continuing the process control.

Next, the process equipment interface 30 will be described in detail with reference to FIG. FIG. 4 is a functional block diagram of the process equipment interface 30. As shown in FIG. 4, the process equipment interface 30 is
Controller communication processing unit 31, data comparison unit 32, IO
A bus input / output processing unit 33, an abnormality notification unit 34, and a processing timing signal generation unit 35 are provided.

The commands and control data transmitted by each controller 20 via the respective data communication paths 50 are received by the controller communication processing section 31, and the data comparison section 3
Sent to 2. In this case, the controller communication processing unit 31
Receives the received data temporarily and sends the data to the data comparison unit 32 after the received data from the three controllers 20 are gathered. When the received data from the three controllers 20 is not completed within a predetermined time, predetermined specific data such as null data is set as the received data of the unreceived controller 20, and the received data is sent to the data comparison unit 32 together with other received data. send.

The data comparison unit 32 compares the three received data sent from the controller communication processing unit 31, and outputs the contents to the IO bus input / output processing unit 33 only when there are two or more received data whose contents match. Input one matching received data. However, if the matched content is predetermined specific data such as null data, it is not transmitted.
The data sent to the IO bus input / output processing unit 33 is output to the IO bus 5 and sent to the process equipment 4. Also,
The data comparison unit 32 notifies the abnormality notification unit 34 of the controller that has transmitted data different from the other data. Abnormality notification section 34
Transmits an abnormality notification to the controller 20 notified from the data comparison unit 32 via the controller communication processing unit 31.

On the other hand, the data output from the process equipment 4 to the IO bus 5 is received by the IO bus input / output processing unit 33 and sent to the controller communication processing unit 31. The controller communication processing unit 31 outputs the sent data to each of the three data communication paths 50 and sends the data to each controller 20. The processing timing signal generation unit 35 generates the processing timing signal 103, and the network interface 10
And output to the bus connected to the three controllers 20 and the process equipment interface 30.

Here, the processing timing signal 103 is, for example, a 3-bit parallel signal, and eight processing timings can be obtained by taking eight states obtained from a combination of 3 bits in sequence during one control cycle of the process control device. It is provided. The processing timing signal 103
Is not limited to 3 bits, but may be changed to another number of bits according to the type of processing executed in one control cycle and the processing speed of the controller 20.

This process equipment interface 30 is
A communication interface for the three data communication paths 50 and I
Interface for O bus 5 and processing timing signal 10
A digital output interface for three outputs, a non-volatile semiconductor memory that stores a program that realizes the functions of the process equipment interface 30, an arithmetic processing unit (CPU) that executes the program stored in the non-volatile semiconductor memory, and a program It is composed of a RAM used for temporary storage during execution and a bus connecting these.

Next, the operation of this process control device will be described. First, the operation when there is no request from the monitoring device will be described. FIG. 5 is a sequence diagram illustrating the operation of the process control device according to the first embodiment,
It shows the operation when there is no request from the monitoring device. As shown in FIG. 5, in this process control device, three controllers (controller A, controller B, and controller C) execute the same processing in parallel.

When the control cycle of cycle n (n is a natural number) is started, each controller sends a command for requesting measurement data to the process equipment interface when the processing timing signal reaches a predetermined timing. To do. The process equipment interface takes the majority vote of the commands sent from each controller, sends the command on the majority side to the process equipment, receives the measurement data sent from the process equipment that received this command, and sends the command to each controller. Send to. In this case, the majority decision is made by comparing the commands transmitted from the respective controllers and, if the commands from the two or more controllers match, the matching command is decided as the multiple command.

Each controller updates the current value of the database when it receives the measurement data, and when the predetermined processing timing is reached, performs a control operation of inputting the set value and the current value of the database to calculate the control data of the database. The result is updated, and this control data is transmitted to the process equipment interface when a predetermined processing timing is reached. The process equipment interface controls the process equipment by taking the majority decision of the control data transmitted from each controller and transmitting the control data on the majority side to the process equipment. Also in this case, the majority decision is made by comparing the control data transmitted from the respective controllers, and when the control data from two or more controllers match, the matching control data is decided as the multiple control data.

Next, the operation when a request is made from the monitoring device will be described. FIG. 6 is a sequence diagram illustrating the operation of the process control device according to the first embodiment,
The operation when a request for the current value of the measurement data is made from the monitoring device is shown. As shown in FIG. 6, when the three controllers (controller A, controller B, and controller C) execute the same processing in parallel in the control cycle of cycle n (n is a natural number), the network interface receives the request. Then, the network interface checks the loads of the three controllers.

As a result of the load check, if all three controllers can execute the request, the processing timing information is added to the request and the request is transmitted to the three controllers. In this case, the network interface adds, as the processing timing information, information designating the timing of executing the request, but allocates the processing timing to which the processing is not allocated to the timing of executing the request. Upon receiving the requests, the three controllers execute the requests at the processing timing specified by the processing timing information.

In this case, each of the three controllers accesses each database at a processing timing after updating the current value of the database, reads the current value, and sends it to the network interface as a response to the request. The network interface receives the responses sent from the respective controllers, compares the contents (current values) thereof, and outputs one of the two or more responses having the same contents to the control LAN, Send to monitoring device. In this case, since the three response contents are the same, the three controllers perform the same operation as that described with reference to FIG. 5 thereafter. Here, the processing operation at processing timings other than the request processing of the three controllers and the operation of the process equipment interface are the same as those described with reference to FIG.

Next, the operation when the network interface detects a mismatch of responses will be described. FIG. 7 is a sequence diagram illustrating the operation of the process control apparatus according to the first embodiment, and shows the operation when the network interface detects a mismatch in the responses from the three controllers. In FIG. 7, the description is the same as the description in FIG. 6 until the three controllers execute the request at the processing timing specified by the processing timing information added to the request and send the response to the network interface. Is omitted.

After the network interface receives the response transmitted from each controller, these contents (current values) are compared, and it is detected that the response contents of the controller A do not match the response contents of the other two controllers. Then, the network interface outputs the response of the controller B and the controller C having the matched contents to the control LAN as a response to the request, transmits the response to the monitoring device, and transmits the abnormality notification to the controller A.

Upon receiving the abnormality notification, the controller A executes the abnormality processing and disconnects it from the control calculation processing. On the other hand, the controller B and the controller C perform the same operation as that described in FIG. 5 thereafter. Even after the controller A is disconnected, the network interface and the process equipment interface perform the same operation as before as long as the response and control data of the controller B and the controller C match, and the process control device as a whole has no interruption. Continue control.

Next, the operation when the process equipment interface detects a mismatch in command and control data among the three controllers will be described. FIG. 8 is a sequence diagram for explaining the operation of the process control apparatus according to the first embodiment, and shows the operation when the process equipment interface detects a mismatch in commands and control data among the three controllers. In FIG. 8, the description is the same as the description in FIG. 5 until the three controllers execute the designated control operation at predetermined processing timings and send the control data of the operation result to the process equipment interface. Omit it.

After the process equipment interface receives the command and control data transmitted from each controller, the contents of these are compared, and when it is detected that the contents of the controller C do not match the contents of the other two controllers, The process equipment interface outputs the commands and control data of the controller A and the controller B whose contents match with each other to the IO bus and sends them to the process equipment and also sends an abnormality notification to the controller C.

Upon receiving the abnormality notification, the controller C executes the abnormality processing and disconnects it from the control calculation processing. On the other hand, the controller A and the controller B perform the same operation as described with reference to FIG. 5 thereafter. Even after the controller C is disconnected, the network interface and the process equipment interface perform the same operation as before as long as the response and control data of the controller A and the controller B match, and the process control device as a whole has no interruption. Continue control.

As described above, in the process control device of this embodiment, three controllers that perform control arithmetic processing are operated in parallel, and the data output from these are compared, and two or more match. Since the operation is continued for a while, even if an abnormality occurs in one of the controllers and the controller is disconnected from the control calculation processing, the process control can be continued without interruption. In this embodiment, three controllers are operated in parallel, but the number is not limited to three and may be three or more. As the number of controllers to be operated in parallel is increased from 3 or more, the number of controller abnormalities allowed to continue the process control without interruption can be increased.
Therefore, the optimum number may be selected based on the reliability required for the process control device and the reliability of the controller.

Further, since the controller for performing the control calculation process has a redundant configuration by parallel execution, by ensuring the reliability of the network interface and the process equipment interface, the entire process control apparatus can be provided without requiring the controller to have high reliability. The reliability of can be secured. Therefore, a low-priced commercial product can be used for the controller, and the cost can be reduced while ensuring reliability. In addition, since it is possible to use a commercial product with a rapid generation change, it is possible to improve the processing capacity by improving the semiconductor technology in a timely manner and shorten the product development period.

Further, since the output of the controller is always confirmed to be normal by the network interface and the process equipment interface, it is possible to secure sufficient reliability as a process control device, so that an error occurs in the memory system used by the controller. It is not necessary to provide a correction function, and it is possible to deal with a multi-bit error that is considered to be caused by a cosmic ray that cannot be corrected by the error correction function, and it is possible to further reduce the cost.

Next, with reference to FIGS. 9 and 10, a configuration for synchronizing the processing timing in each controller 20 operating in parallel will be described. FIG. 9 is an explanatory diagram showing processing timing signals supplied to the controller.
FIG. 10 is a timing chart showing a configuration example of the processing timing signal. As shown in FIG. 9, each controller 2
0 is supplied with the processing timing signal 103 in parallel from the processing timing signal generator 35 (see FIG. 4) of the process equipment interface 30 via the timing signal bus 51. The request processing unit 21, the arithmetic processing unit 23, and the input / output processing unit 24 (see FIG. 3) of each controller 20 determine the processing content based on the content of the processing timing signal 103.

As shown in FIG. 10, the processing timing signal 103 is composed of a 3-bit parallel signal, that is, processing timing signals 103A to 103C, and a code which circulates every control cycle (for example, 100 ms) is output. Here, eight processing timings t1 to t8 are provided corresponding to the value of the code for each control cycle.
Each controller 20 identifies a processing timing based on the value of the code, and executes a preset processing for each processing timing, for example, a processing request from an upper monitoring device or control for lower processing equipment. To do.

As described above, the processing timing signal 103 is supplied in parallel to each controller 20, and each controller 20 determines the content to be processed based on the processing timing signal 103. It is possible to execute the processing of the same contents almost in synchronization with each other. As a result, unlike the conventional case, it is not necessary to completely synchronize the processing in the microprocessor using the common operation clock in each controller 20, and it is possible to use the individual operation clocks.

Therefore, even if each controller has a problem caused by a specific operation timing, the probability of a problem occurring simultaneously in a plurality of controllers becomes extremely low, and the majority of the outputs / responses of these controllers are judged. By doing so, it is possible to avoid the influence on the entire process control device 1, and to realize stable control operation. In addition, an expensive circuit configuration for synchronizing the operations of the controllers using the common clock is not required, and the product cost can be significantly reduced. Further, it is not necessary to use a device having the completely same configuration as the controller, and flexibility can be obtained as the system configuration.

As the code used for the processing timing signal 103, a general binary number may be used. At this time, since a plurality of bits change at the same time, if the bit detection in the controller 20 varies, it may be recognized as a different code instantaneously. In this embodiment, a gray code as shown in FIG. 10 is used as the processing timing signal 103. The Gray code is a code in which only one bit changes when transitioning from any value to the next value. Therefore, when the processing timing changes, it is possible to avoid erroneous recognition of a code due to variations in bit detection, and each controller 20 can realize stable processing timing synchronization.

Next, the controller management processing by the network interface 10 will be described with reference to FIGS. 11 and 12. FIG. 11 is a configuration example of a request (message) transmitted from the network interface 10 to each controller 20. FIG. 12 is an example of a processing schedule in each controller. As described above, in the network interface 10, when instructing each controller 20 to perform processing, the request distribution unit 13
A request is transmitted from (see FIG. 2) via the internal LAN 40.

This request, as shown in FIG.
This is one of the packets used in Ethernet (registered trademark), and is composed of a header 41 that stores information about the packet such as the destination and source of the packet and the packet type, and a data section 42 that stores information indicating the content of the request. Has been done. The data section 42 stores a request ID 43 for identifying the request, a request content 44 in which the content of the request is coded, and processing timing information 45 indicating the timing of executing the request. For example, in the case of a request to instruct each controller 20 to change the setting value, the request content 44 includes a point ID 44A indicating a process device to be processed, that is, a control point, a process type 44B indicating a type of process, and its process. And the processing data 44C used for are set. In the processing timing information 45, the gray code defined by the processing timing signal 103 is set.

In each controller 20, the request processing unit 21 receives such a request, analyzes the content, and executes the request. At this time, the processing content is determined from the request content 44, and the processing timing is determined from the processing timing information 45. In the example of the request 46 of FIG. 11, since the processing type 44B indicates “update set value”,
The request processing unit 21 takes out the “DB setting value” of the processing data 44C and writes it in the database 22 as a new setting value corresponding to the point ID 44A. Also,
This processing is executed when the gray code of the processing timing signal 103 from the process equipment interface 30 indicates "011", that is, the processing timing t3. As a result, in each controller 20, new setting values are written all at once in synchronization with the next processing timing t3.

In the example of the request 47 shown in FIG. 11,
Since the processing type 44A indicates “current value read”,
The request processing unit 21 reads out the current value obtained from the process device stored in the database 22,
Notify the network interface 10. Further, this processing is executed when the gray code of the processing timing signal 103 from the process equipment interface 30 indicates "101", that is, the processing timing t5. As a result, the current value is read out all at once from each controller 20 in synchronization with the next processing timing t5. The read current value is notified from the controller 20 to the network interface 10 by a response. At this time, the request ID of the corresponding request
Also, by notifying by that response, it may be possible to identify which request each response corresponds to,
It can also handle the case where multiple requests are issued in a multiplexed manner.

As described above, the processing timing signal 103 is supplied in parallel to each controller 20, and each controller 20 determines the contents to be processed based on the processing timing signal 103. Since the timing to execute the requested process is specified by the request to the controller 20, it is possible to execute the same process among the controllers 20 almost in synchronization, and the output / response of the controller can be accurately performed. You can often judge by majority.
Further, unlike the conventional case, it is not necessary to completely synchronize the processing in the microprocessor by using a common operation clock in each controller 20, and it becomes possible to use each individual operation clock.

Therefore, even if each controller has a malfunction that occurs due to a specific operation timing, the probability that a plurality of controllers will simultaneously fail is extremely low, and stable control operation can be realized.
In addition, an expensive circuit configuration for synchronizing the operations of the controllers using the common clock is not required, and the product cost can be significantly reduced. Further, it is not necessary to use a device having the completely same configuration as the controller, and flexibility can be obtained as the system configuration.

In this way, each controller 20 performs the preset processing at each processing timing. In the sequence of FIG. 6 described above, as shown in FIG. 12, first, the “measurement data request” process to the process equipment is performed at the process timing t1, and the process timing t2.
Then, the "request reception" process is performed. Further, at the processing timing t3, the “DB current value update” processing of storing the measurement data obtained from the process equipment in the database 22 is performed, and at the processing timing t4, the “DB current value update” based on the request is performed.
The "current value read" process is performed. Then, after the processing timing t5 in which the processing is not set, the "control calculation" processing for calculating the control data to the process equipment is performed at the processing timing t6, and the calculation result is stored in the database 22 at the processing timing t7. The "DB control data update" processing is performed, and the "control data transmission" processing to the process device is performed at the processing timing t8.

The scheduling of such processing is managed by the load check unit 12 of the network interface 10, and when requesting a new processing, the processing timing not set is specified and the request is issued. To do. At this time, when requesting a new process from the controller 20 based on the request from the monitoring device 2, the load check unit 12 determines acceptance / rejection based on the above scheduling. If the load cannot be accepted due to overload, the monitor device 2 is notified of the non-acceptance. As a result, overload on the controller 20 can be avoided and stable process control can be realized.

The processing at each processing timing may be designated to the controller 20 from the network interface 10 side, but the routine processing performed by each controller 20, for example, "measurement data request",
Regarding the processing related to the control of the process equipment, such as “DB current value update”, “control calculation”, “DB control data update”, “control data transmission”, the processing timing may be fixedly assigned in advance. The request processing in the network interface 10 can be omitted.

Next, a second embodiment of the present invention will be described. The process control device of this embodiment is different from that of the first embodiment in that it has a self-diagnosis function for confirming whether or not the databases of the three controllers are correct. This self-diagnosis function issues a request to the response / request transmission / reception unit 11 of the network interface 10 shown in FIG. 2 to transmit the data of the database 22 shown in FIG. This can be realized by providing a function of discarding the data sent to the response / request transmission / reception unit 11 in response to the request. That is, the program realizing the self-diagnosis function may be added to the nonvolatile semiconductor memory storing the program realizing the function of the network interface 10.

In this case, the response / request transmission / reception section 11
The request for the self-diagnosis function issued by is transmitted to the three controllers 20 only when the load of the controllers 20 is light due to the operation of the load check unit 12. The request transmitted to the controller 20 is executed by the request processing unit at a predetermined timing, the data in the database 22 is read in a predetermined unit, and is sequentially transmitted to the network interface 10. The data of the database 22 transmitted from the three controllers 20 are compared by the response comparison unit 15, and the controller in which the mismatch is detected is notified to the abnormality notification unit 16. As a result, the abnormality notification unit 16 transmits the abnormality notification to the controller, and the controller that receives the abnormality notification executes the abnormality processing and disconnects it from the control calculation processing.

According to this embodiment, by comparing the data in the databases 22 of the three controllers 20 in the background, it is possible to detect an error in the RAM storing the data in the databases 22. Therefore, it is possible to detect an error that has occurred in an area that is not frequently used, and it is possible to remove the controller 20 in which an abnormality has occurred.

Next, the third embodiment of the present invention will be described with reference to FIG. FIG. 13 is a block diagram showing a third embodiment according to the process control device of the present invention. The process control device 6 of this embodiment is the first
Is different from the embodiment described above in that the network interface 10, the process equipment interface 30, the internal LAN
40 and the data communication path 50 have a redundant configuration. In FIG. 13, this process control device 6
Are two network interfaces 10 of the same configuration.
(Network interface A, network interface B) and three controllers 20 having the same configuration
(Controller A, Controller B, Controller C)
And two process equipment interfaces 30 having the same configuration
(Process device interface A, process device interface B).

Two network interfaces 10
Is an internal LAN 40 of a different system (A system internal LAN, B
It is connected to three controllers 20 via a system internal LAN), and is configured to be able to mutually communicate with the three controllers 20. In this case, the network interface A is connected to the three controllers 20 via the A system internal LAN and the network interface B is connected to the B system internal LAN.

Two process equipment interfaces 30
Are individually connected to the three controllers 20 by the data communication paths 50, and one-to-one communication is possible between them. In addition, a control signal line 60 is connected between the two process equipment interfaces 30 so that control signals can be mutually transmitted.
Further, the two process device interfaces 30 are connected to the two network interfaces 10 and the three controllers 20 via buses (not shown) having different systems.

The two network interfaces 10 are control LANs 3 (A system control LAN,
It is connected to the monitoring device 2 via the B-system control LAN) and is configured to be able to mutually communicate with the monitoring device 2. In this case, the network interface A is connected to the monitoring device 2 via the A system control LAN, and the network interface B is connected to the B system control LAN. Two
The two process equipment interfaces 30 each include two external IO buses 5 (A system I) to which the process equipment 4 is connected.
O bus, B system IO bus).

In this process control device 6, two network interfaces 10 and three controllers 20 operate in parallel, and two process equipment interfaces 30 are provided.
One of them always operates as a master (active system), and the other is on standby as a slave (standby system). The two network interfaces 10 separately give the requests of the monitoring device 2 received via the control LANs 3 having different systems to the three controllers 20 respectively, and in response to the requests from the three controllers 20 respectively. 1 to output to the control LAN 3 to which each response is connected, which is determined by a majority decision, and responds to the monitoring device 2.

The two network interfaces 10 differ from those described in the first or second embodiment in that they have two digital input interfaces for inputting processing timing signals, and have a master and a slave. That is, when the processing timing signals output from both process device interfaces 30 are input and the processing timing signals on the master side are not input, the processing is continued based on the processing timing signals on the slave side. .

Of the same requests given from the two network interfaces 10, each of the three controllers 20 processes only the previously given request and outputs a response to this request to the two network interfaces 10. In addition, command generation and process control calculations for the process equipment 4 are performed.
The generated commands and calculation results are output to the two process equipment interfaces 30 as control data.

Here, of the same requests given from the two network interfaces 10, only the request given first can be processed because the requests transmitted by the monitoring device are the same in the A system and the B system. Response / request transmission / reception unit 1 because it has a message header
This is because when 1 receives the same message, it determines that the message received later is the same as the message received earlier and ignores it.

The three controllers 20 differ from those described in the first embodiment or the second embodiment in that the LAN interface for the internal LAN 40, the communication interface for the data communication path 50, and the processing timing. The response / request transmission / reception unit 11 has two systems each including a digital input interface for inputting the signal 103.
Is transmitting and receiving via the two internal LANs 40,
The input / output processing unit 24 performs transmission / reception via the two data communication paths 50, the processing timing signals output from both the master and slave process device interfaces 30 are input, and the processing timing signals on the master side are input. That is, the processing is continued based on the processing timing signal on the slave side when the processing is stopped.

The process equipment interface 30 controls the process equipment 4 by outputting, to the two IO buses 5, one control data determined by the majority decision from the control data output from each of the three controllers 20 on the master side. The slave side performs a standby operation for confirming the operation of the master side via the control signal line 60. The process device interface 30 on the slave side switches to the master when detecting the operation stop on the master side. Further, the two process device interfaces 30, regardless of the master side or the slave side, output processing timing signals to a bus (not shown) connected to each.

The two process equipment interfaces 30 differ from those described in the first or second embodiment in that they have two interfaces for the IO bus 5 and control data are stored in the two IO buses. 5 and the digital signal input / output interface for the control signal line 60 and the master / slave switching. For master / slave switching, for example, in the case of a master, the signal indicating the operation is always output to the digital input / output interface, and in the case of the slave, the signal input to the digital input / output interface is constantly monitored, and the signal input is This can be performed by storing a program for switching itself to the master when the interruption occurs in the nonvolatile semiconductor memory and allowing the CPU to execute this program.

With the above configuration, the process control device of this embodiment has the network interface 1
0, the control LAN 3 and the internal LAN 40 have an abnormality, the communication with the monitoring device 2 is not interrupted, so that the processing can be continued normally. Further, even when an abnormality occurs in the operating process device interface 30, the process can be continued by the waiting process device interface 30. As described above, the process control device according to the present embodiment is not only capable of continuing the process control without interruption even if one of the controllers 20 becomes abnormal and is disconnected from the control calculation process, but also has three The process can be continued even when an abnormality occurs in the interface part connected to the controller 20. Therefore, the reliability can be further improved as compared with the first embodiment.

In this embodiment, all those connected to the three controllers 20 have a redundant configuration, but not all need to have a redundant configuration. Reliability required as a process control device and three controllers 2
The required reliability can be obtained with a minimum increase in cost by providing a redundant configuration only in a necessary portion in consideration of the reliability of each of those connected to 0. For example,
The process control device includes two network interfaces 10 having the same configuration (network interface A, network interface B), three controllers 20 having the same configuration (controller A, controller B, controller C), and one process equipment interface 3.
0, or one network interface 10 and three controllers 20 (controller A, controller B, controller C) having the same configuration,
It may be configured with two process device interfaces 30 (process device interface A, process device interface B) having the same configuration.

Next, with reference to FIG. 14, a configuration for synchronizing the processing timing in each controller 20 operating in parallel will be described. FIG. 14 is an explanatory diagram showing processing timing signals supplied to the controller. As shown in FIG. 14, the processing timing signal 103 is supplied in parallel to each controller 20 from the processing timing signal generator 35 (see FIG. 4) of the process equipment interface 30 via the timing signal bus 51. The request processing unit 21, the arithmetic processing unit 23, and the input / output processing unit 24 (see FIG. 3) of each controller 20 determine the processing content based on the content of the processing timing signal 103.

As shown in FIG. 10, the processing timing signal 103 is composed of a 3-bit parallel signal, that is, processing timing signals 103A to 103C, and a code that circulates every one control cycle (for example, 100 ms) is output. Here, eight processing timings t1 to t8 are provided corresponding to the value of the code for each control cycle.
Each controller 20 identifies a processing timing based on the value of the code, and executes a preset processing for each processing timing, for example, a processing request from an upper monitoring device or control for lower processing equipment. To do.

In this embodiment, the processing timing signal 103 is individually supplied to each controller 20 and each network interface 10 from the two process equipment interfaces 30. Each controller 2
0 and each network interface 10, the processing timing signal on the master side is selected from the processing timing signals 103 supplied from the two process equipment interfaces 30 and used to determine the processing timing. As a selection method, it may be determined which side is the master side by communicating with the process equipment interface 30, or the master side may be predetermined by default and the processing timing signal from the master side may stop. If detected, it may be switched to the other processing timing signal.

In this way, when the process equipment interface 30 is duplicated, the processing timing signal 103 from each process equipment interface 30 is individually supplied to each controller 20 and each network interface 10, and each controller 20 and each network interface 10 is supplied. In the network interface 10, one of the processing timing signals 103 supplied from the two process equipment interfaces 30 is selected and used, so that each controller 20 can achieve stable synchronization of processing timing. Can be realized.

[0083]

As described above, the present invention is provided as a controller in parallel between the network interface and the process equipment interface, and is instructed by the processing timing information added to the request from the network interface. N (N is 3) that executes the processing corresponding to the request at the processing timing
The request distribution unit of the network interface adds processing timing information indicating the timing at which the controller should execute the processing corresponding to the request, to the request received from the host device via the network. Then, each controller 20 is notified, and the response comparison unit decides one response to be sent to the higher-level device by making a majority decision on the response from each controller in response to the request. Therefore, it is possible to execute the processing of the same content, and it is possible to determine the majority of the outputs / responses of the controller with high accuracy.

Further, unlike the conventional case, it is not necessary to completely synchronize the processing in the microprocessor by using the common operation clock in each controller, and it becomes possible to use each individual operation clock. Therefore, even if each controller has a problem that occurs due to a specific operation timing, the probability that problems will occur simultaneously in multiple controllers will be extremely low,
A stable control operation can be realized.

[Brief description of drawings]

FIG. 1 is a block diagram showing a configuration of a process control device according to a first exemplary embodiment of the present invention.

FIG. 2 is a functional block diagram of the network interface of FIG.

FIG. 3 is a functional block diagram of the controller of FIG.

4 is a functional block diagram of the process equipment interface of FIG. 1. FIG.

FIG. 5 is a sequence diagram illustrating an operation of the process control device according to the first embodiment.

FIG. 6 is a sequence diagram illustrating another operation of the process control device according to the first embodiment.

FIG. 7 is a sequence diagram illustrating another operation of the process control device according to the first embodiment.

FIG. 8 is a sequence diagram illustrating another operation of the process control device according to the first embodiment.

FIG. 9 is an explanatory diagram showing processing timing signals supplied to a controller.

FIG. 10 is a timing chart showing a configuration example of a processing timing signal.

FIG. 11 is a configuration example of a request (message).

FIG. 12 is an example of a processing schedule in each controller.

FIG. 13 is a block diagram showing a configuration of a process control device according to a third exemplary embodiment of the present invention.

FIG. 14 is another explanatory diagram showing a processing timing signal supplied to the controller.

[Explanation of symbols]

1, 6 ... Process control device, 2 ... Monitoring device, 3 ... Control L
AN, 4 ... Process device, 5 ... IO bus, 10 ... Network interface, 11 ... Response / request transmission / reception unit, 12 ... Load check unit, 13 ... Request distribution unit,
14 ... Response receiving section, 15 ... Response comparing section, 16, 34 ... Abnormality notifying section, 20 ... Controller, 21 ... Request processing section, 22 ... Database, 23 ... Arithmetic processing section, 24 ... Input / output processing section, 25 ... Abnormality Processing unit, 30 ... Process device interface, 31 ... Controller communication processing unit, 32 ...
Data comparison unit, 33 ... IO bus input / output processing unit, 35 ... Processing timing signal generation unit, 40 ... Internal LAN, 50 ... Data communication path, 51 ... Timing signal bus, 60 ... Control signal line, 103 ... Processing timing signal.

Claims (4)

[Claims] 1. A controller that performs control calculation for process control and a request received from a host device via a network are notified to the controller, and a response to the request from the controller is sent to the host device. A network interface and a process device interface for transmitting control data to a process device connected to an IO bus based on control calculation in the controller and receiving measurement data from the process device. Control processing is performed by the controller based on the request received via, and the process equipment is controlled by transmitting the obtained control data to the process control equipment via the process equipment interface, A process control device that outputs measured data obtained from a process control device to the network interface as a response from the controller, and transmits as a response from the network interface to the host device, wherein the network interface and the controller are used as the controller. N pieces (N is 3 or more) that are provided in parallel with the process equipment interface and execute the processing corresponding to the request at the processing timing indicated by the processing timing information added to the request from the network interface. Natural number) of the controller, the network interface should execute a process corresponding to the request received from the higher-level device via the network. A request distribution unit for notifying to said each controller by adding processing timing information indicating a timing,
A process control device, comprising: a response comparison unit that makes a majority decision on the response from each controller to the request and determines one response to be transmitted to the host device. 2. The process control device according to claim 1, wherein the request delivery unit selects a processing timing for processing a newly received request based on a processing status of a request transmitted to each controller, and A process control device characterized in that process timing information indicating a process timing is added to the request. 3. The process control device according to claim 1, wherein the network interface determines whether to accept a newly received request based on a processing status of a request transmitted to each controller. However, the process control device has a load check unit that passes the request to the request delivery unit only when the request is acceptable. 4. The process control device according to claim 3, wherein the load check unit notifies the upper-level device that the request cannot be executed when it is determined that the request cannot be accepted. Process control equipment.