JP3706332B2 - Process control device - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a process control apparatus, and more particularly to a process control apparatus having a redundant configuration.
[0002]
[Prior art]
2. Description of the Related Art Conventionally, a process control apparatus used for process control of a plant or the like has a redundant structure provided with a plurality of controllers that perform control computation when high reliability is required.
A conventional process control apparatus having such a redundant structure generally includes a dual standby redundancy system that includes two controllers, a main system and a sub system, and switches to a standby sub controller when an abnormality occurs in the main system controller. is there.
[0003]
However, in such a redundant standby redundancy type process control device, when the controller switches from the primary system to the secondary system, the standby system starts processing after detecting the stop of the primary system. Therefore, there is a problem that it cannot be used for process control with a short process control cycle.
For this reason, there has been a demand for a process control apparatus that does not cause a control blank time even when an abnormality occurs in an operating controller.
[0004]
On the other hand, a system is conceivable in which three or more controllers having the same configuration are operated in parallel, a majority decision is made on the control outputs of these controllers, and process control is performed using the decision result.
Usually, in a process control device, processing requests from a higher-level monitoring device and control for lower-level process devices 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]
[Problems to be solved by the invention]
However, in a controller that performs various types of control arithmetic processing by executing a program with a microprocessor such as a CPU, a high-level monitoring device is used when each controller is executing specific control arithmetic processing. If there is an input from a lower-level process device at a specific timing, a malfunction such as a calculation error may occur.
[0006]
In order to solve such problems, a configuration is also conceivable in which an operation clock is input from the outside and the operation of each controller is completely synchronized. According to this configuration, however, a dedicated hardware is required and an expensive system is required. There was a problem of becoming. Even if the controllers having the same configuration are operated in complete synchronization based on a common operation clock in this way, the above-described problem occurs due to specific operation timing, so that three or more Even if the controller is operated in parallel, all the calculation results are different, and the problem cannot be avoided.
[0007]
In addition, when a request to each controller is overloaded, a response delay occurs only in one of the controllers, and it is not possible to guarantee the same processing.
Furthermore, if it is determined that such a timing shift is abnormal, the system is stopped unnecessarily, an excessive load is applied to the equipment, and the entire plant is seriously damaged.
The present invention is to solve such a problem, and when controlling a process by deciding a majority of control calculation results of three or more controllers operating in parallel, the control calculation results from each controller can be stabilized at the same time. It is an object to provide a process control apparatus that can be obtained.
[0008]
[Means for Solving the Problems]
In order to solve the above-described problems, a process control device according to the present invention notifies a controller that performs a control operation for process control, a request received from a host device via a network, and responds to the request. A network interface that sends a response from the controller to the host device, and a process equipment interface that sends control data to the process equipment connected to the IO bus and receives measurement data from the process equipment based on the control calculation in the controller Control the process based on the request received via the network interface, and control the process equipment by transmitting the obtained control data to the process control equipment via the process equipment interface. A process control device that outputs measurement data obtained from a process control device as a response from a controller to a network interface, and transmits the response from the network interface to a host device as a response, between the network interface and the process device interface as a controller. And N controllers (N is a natural number of 3 or more) that execute processing corresponding to the request at the processing timing indicated by the processing timing information added to the request from the network interface. In the request distribution unit of the network interface, a processing type for instructing the timing at which the controller should execute the processing corresponding to the request in response to the request received from the host device via the network. Notifies each controller by adding ring information, the response comparing unit, in which so as to determine a majority decision to the one to be transmitted to the host device in response to a response from the controller for the request.
[0009]
Regarding the processing timing, the request distribution unit selects the processing timing for processing a newly received request based on the processing status of the request transmitted to each controller, and adds processing timing information indicating the processing timing to the request. You may make it do.
[0010]
The load check unit of the network interface determines whether or not the newly received request can be accepted based on the processing status of the request sent to each controller, and passes the request to the request distribution unit only when the request is acceptable. Also good.
At this time, if the load check unit determines that the request cannot be accepted, the host device may be notified that the request cannot be executed.
[0011]
DETAILED DESCRIPTION OF THE INVENTION
Next, embodiments of the present invention will be described with reference to the drawings.
FIG. 1 is a block diagram showing the configuration of the process control apparatus according to the first embodiment of the present invention. In FIG. 1, the process control apparatus 1 includes one network interface 10, three controllers 20 (controller A, controller B, controller C) having the same configuration, and one process equipment interface 30.
[0012]
The network interface 10 and the three controllers 20 are connected to an internal LAN (Local Area Network) 40 and configured to be able to communicate with each other. The process device interface 30 is individually connected to the three controllers 20 via a data communication path 50 such as a USB (Universal Serial Bus), and is configured to be capable of one-to-one communication with them. The network interface 10, the three controllers 20, and the process equipment interface 30 are connected to a bus (not shown). Further, the network interface 10 is connected to an external control LAN 3 (network) to which the monitoring device 2 is connected, and the process equipment interface 30 is connected to an external IO bus 5 to which the process equipment 4 is connected. .
[0013]
In such a configuration, the network interface 10 of the process control device 1 gives a request from the monitoring device 2 received via the control LAN 3 to each of the three controllers 20 and from each of the three controllers 20 for this request. One response determined by majority vote is output to the control LAN 3 and returned to the monitoring device 2.
Each of the three controllers 20 processes a request given from the network interface 10, outputs a response to the request to the network interface 10, performs process control calculations, and uses the calculation results as control data. Output to.
[0014]
The process equipment interface 30 controls the process equipment 4 by outputting, to the IO bus 5, one control data determined by majority from among the control data outputted from each of the three controllers 20.
For this reason, even when an abnormality occurs in one of the controllers 20 and a response or control data different from the other two is output, a normal response or control data is output to the monitoring device 2 or the process equipment 4 without interruption. can do.
[0015]
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 includes a response / request transmission / reception unit 11, a load check unit 12, a request distribution unit 13, a response reception unit 14, a response comparison unit 15, and an abnormality notification unit 16.
[0016]
The request output from the monitoring device 2 to the control LAN 3 is received by the response / request transmission / reception unit 11 and sent to the load check unit 12. The load check unit 12 checks the request processing status (processing load) for each controller 20, and when all the operating controllers 20 are in a state in which the sent request can be accepted, the response / request transmission / reception unit 11 The transmitted request is transferred to the request distribution unit 13, and when there is a controller that is in operation and cannot be accepted, the response / request transmission / reception unit 11 is notified that the request cannot be accepted and the request is deleted.
[0017]
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 equal to or less than 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 a response receiver 14 described later. When the response / request transmission / reception unit 11 is notified that the request cannot be accepted, the response / request transmission / reception unit 11 notifies the request source that the request cannot be executed.
[0018]
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 broadcasts the request to the three controllers 20 via the internal LAN 40. In this case, the processing timing information is a 3-bit code indicating the processing timing in one control cycle, and the request distribution unit 13 indicates the current status of the 3-bit processing timing signal 103 that is output in parallel on a bus (not shown) by the process device interface 30 described later. The value of the processing timing signal generated in the future is set as the timing for executing the request with reference to the value. At this time, the timing for executing the newly received request and the timing for transmitting the request response are selected based on the processing status of the request transmitted to each controller. The request processing status may be that managed by the load check unit 12.
[0019]
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 and sends the response 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 reception unit 14 temporarily holds the received response, and sends the response to the response comparison unit 15 after the responses from the three controllers 20 are prepared. When there is no response from one of the three controllers 20 within a predetermined time, the controller 20 is notified to the load check unit 12 and predetermined specific data such as null data is transmitted to the controller 20. The response is sent to the response comparison unit 15 together with the other two responses.
[0020]
Here, when there is no response within a predetermined time, the controller 20 that does not respond is notified to the load check unit 12 because the unprocessed request of the controller 20 that does not respond is left unprocessed in the load check unit 12. This is to prevent the number of requests being executed from exceeding a predetermined number and preventing the two operating controllers from executing the requests.
[0021]
The response comparison unit 15 compares the responses from the three controllers 20 sent from the response reception unit 14, and sends the response of this content to the response / request transmission / reception unit 11 only when there are two or more responses with the same content. Send one. 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 output to the control LAN 3 and transmitted to the request source monitoring device 2. In addition, the response comparison unit 15 notifies the abnormality notification unit 16 of the controller that has returned a response having a content different from the others. The abnormality notification unit 16 transmits an abnormality notification to the controller notified from the response comparison unit 15 via the internal LAN 40.
[0022]
The network interface 10 includes a LAN interface for the control LAN 3, a LAN interface for the internal LAN 40, a digital input interface for processing timing signal 103 input, and a nonvolatile semiconductor memory storing a program for realizing the functions of the network interface 10. And an arithmetic processing unit (CPU) for executing a program stored in the nonvolatile semiconductor memory, a RAM used for temporary storage during execution of the program, and a bus for connecting them.
[0023]
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 includes setting values for process control conditions, Stores current values of measurement data and control data for controlling process equipment. In this case, the request output to the internal LAN 40 is received by the request processing unit 21, the request content is analyzed, and processing according to the request is executed based on processing timing information added to the request.
[0024]
For example, if the request is a process control condition change, the setting value of the specified control condition in the database 22 is rewritten to the setting value specified by the request, and the rewritten setting 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 output to the internal LAN 40 by the request processing unit 21 and transmitted to the network interface 10. In this case, the request processing is executed when the processing timing signal 103 output from the process device interface 30 is referenced and the information indicated by this signal matches the processing timing information added to the request.
[0025]
The arithmetic processing unit 23 reads the 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 calculation to calculate a control amount necessary for matching the current value to the set value. The result is written in the database 22 as control data. The input / output processing unit 24 reads the control data from the database 22 at a predetermined timing and transmits it to the process equipment interface 30. In addition, a command requesting transmission of process data measured by the process device is transmitted to the process device interface 30, and the process data measured by the process device transmitted from the process device interface 30 is received and stored in the database 22 as a current value. Write.
[0026]
Further, the request processing unit 21 receives the abnormality notification transmitted by the abnormality notification unit 16 of the network interface 10 in the same manner as the request, and notifies the abnormality processing unit 25 of the abnormality notification. The input / output processing unit 24 checks whether or not an abnormality notification is included in the information transmitted from the process device interface 30, and notifies the abnormality processing unit 25 when the abnormality notification is included. When receiving the abnormality notification, the abnormality processing unit 25 stops the processing of the controller 20.
[0027]
The controller 20 includes a LAN interface for the internal LAN 40, a communication interface for the data communication path 50, a digital input interface for inputting the processing timing signal 103, and a nonvolatile semiconductor memory storing a program for realizing the function of the controller 20 And an arithmetic processing unit (CPU) for executing a program stored in the nonvolatile semiconductor memory, a RAM used as a storage area of the database 22 and a temporary storage area at the time of program execution, and a bus connecting them. Has been. The controller 20 is configured to be hot-pluggable and replaceable when one of the three controllers 20 fails, while continuing the process control.
[0028]
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 illustrated in FIG. 4, the process device interface 30 includes a controller communication processing unit 31, a data comparison unit 32, an IO bus input / output processing unit 33, an abnormality notification unit 34, and a processing timing signal generation unit 35.
[0029]
Commands and control data transmitted by each controller 20 via the respective data communication paths 50 are received by the controller communication processing unit 31 and sent to the data comparison unit 32. In this case, the controller communication processing unit 31 temporarily stores the reception data, and sends the data to the data comparison unit 32 after the reception data from the three controllers 20 are prepared. If the received data from the three controllers 20 are not prepared within a predetermined time, for example, predetermined specific data such as null data is set as the received data of the non-received controller 20, and the data comparing unit 32 together with other received data. send.
[0030]
The data comparison unit 32 compares the three reception data sent from the controller communication processing unit 31, and only when there are two or more reception data with the same content, reception with the same content to the IO bus input / output processing unit 33. Enter one piece of 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 device 4. Further, the data comparison unit 32 notifies the abnormality notification unit 34 of the controller that transmitted data different from the others. The abnormality notification unit 34 transmits an abnormality notification to the controller 20 notified from the data comparison unit 32 via the controller communication processing unit 31.
[0031]
On the other hand, the data output from the process device 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 transmitted data to the three data communication paths 50 and transmits them to each controller 20. The processing timing signal generator 35 generates the processing timing signal 103 and outputs it to a bus connected to the network interface 10, the three controllers 20, and the process equipment interface 30.
[0032]
Here, the processing timing signal 103 is, for example, a 3-bit parallel signal, and eight processing timings are provided by sequentially taking eight states obtained from a combination of 3 bits during one control cycle of the process control apparatus. is there. Note that the processing timing signal 103 is not limited to 3 bits, and 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.
[0033]
The process equipment interface 30 stores a communication interface for three data communication paths 50, an IO bus 5 interface, a digital output interface for processing timing signal 103 output, and a program for realizing the functions of the process equipment interface 30. Non-volatile semiconductor memory, an arithmetic processing unit (CPU) that executes a program stored in the non-volatile semiconductor memory, a RAM that is used for temporary storage during program execution, and a bus that connects them. Yes.
[0034]
Next, the operation of this process control apparatus will be described. First, the operation when there is no request from the monitoring device will be described. FIG. 5 is a sequence diagram for explaining the operation of the process control apparatus according to the first embodiment, and shows the operation when there is no request from the monitoring apparatus. As shown in FIG. 5, in this process control apparatus, three controllers (controller A, controller B, and controller C) execute the same processing in parallel.
[0035]
Here, when the control cycle of the cycle n (n is a natural number) is started, each controller transmits a measurement data request command to the process device interface when the processing timing signal reaches a predetermined timing. The process equipment interface takes a majority vote of commands sent from each controller, sends a command on the majority side to the process equipment, and receives measurement data sent from the process equipment that has received this command. Send to. In this case, the majority decision is made by comparing the commands transmitted from the respective controllers and determining that the matched command is a large number of commands when the commands from two or more controllers match.
[0036]
Each controller updates the current value of the database when it receives the measurement data, performs a control calculation with the database setting value and the current value as input when the predetermined processing timing is reached, and updates the control data of the database with the calculation result When the predetermined processing timing comes, this control data is transmitted to the process equipment interface. The process equipment interface controls the process equipment by taking the majority of the control data sent from each controller and transmitting the control data on the majority side to the process equipment. In this case as well, the majority decision is made by comparing the control data transmitted from each controller and determining the matched control data as a large number of control data when the control data from two or more controllers match.
[0037]
Next, the operation when a request is made from the monitoring device will be described. FIG. 6 is a sequence diagram for explaining the operation of the process control apparatus according to the first embodiment, and shows the operation when a request for requesting the current value of measurement data is made from the monitoring apparatus. As shown in FIG. 6, the network interface receives a request when three controllers (controller A, controller B, controller C) execute the same processing in parallel in the control cycle of cycle n (n is a natural number). Then, the network interface performs load checks on the three controllers.
[0038]
If the three controllers can execute the request as a result of the load check, processing timing information is added to the request and transmitted to the three controllers. In this case, the network interface adds information specifying the timing for executing the request as processing timing information, but assigns a processing timing to which processing is not assigned to the timing for executing the request. When each of the three controllers receives a request, the three controllers execute the request at the processing timing specified by the processing timing information.
[0039]
In this case, each of the three controllers accesses each database at the processing timing after updating the current value of the database, reads the current value, and transmits it to the network interface as a response to the request. The network interface receives the response transmitted from each controller, compares the contents (current values), and outputs one of two or more responses with matching contents to the control LAN. Send to monitoring device. In this case, since all three response contents match, the three controllers continue to perform the same operation as described with reference to FIG. Here, the processing operation at the processing timing other than the request processing of the three controllers and the operation of the process device interface are the same as those described with reference to FIG.
[0040]
Next, an operation when the network interface detects a response mismatch will be described. FIG. 7 is a sequence diagram for explaining 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, since the three controllers execute the request at the processing timing specified by the processing timing information added to the request and transmit a response to the network interface, the description is the same as the description in FIG. Is omitted.
[0041]
After the network interface receives the responses transmitted from the respective controllers, the contents (current values) are compared, and if the response contents of the controller A do not match the response contents of the other two controllers, the network interface The interface outputs the responses of the controllers B and C whose contents are the same as a response to the request to the control LAN, transmits the response to the monitoring device, and transmits an abnormality notification to the controller A.
[0042]
When the controller A receives the abnormality notification, the controller A executes the abnormality process and disconnects from the control calculation process. On the other hand, the controller B and the controller C continue to perform the same operation as described in FIG. 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 responses and control data of the controller B and the controller C coincide with each other. Continue control.
[0043]
Next, the operation when the process equipment interface detects a mismatch in commands and control data between 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 between commands and control data among the three controllers. In FIG. 8, since the three controllers execute the control calculation designated at a predetermined processing timing and transmit the control data of the calculation result to the process equipment interface, the description is the same as the description in FIG. Omitted.
[0044]
After the process equipment interface receives the command and control data transmitted from each controller, the process equipment interface compares the contents and detects that the contents of the controller C do not match the contents of the other two controllers. Outputs the command and control data of the controller A and the controller B whose contents are the same to the IO bus, transmits them to the process equipment, and transmits an abnormality notification to the controller C.
[0045]
When the controller C receives the abnormality notification, the controller C executes the abnormality process and disconnects from the control calculation process. On the other hand, the controller A and the controller B continue to perform the same operation as described in FIG. 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 responses and control data of the controller A and the controller B match. Continue control.
[0046]
As described above, the process control apparatus according to this embodiment operates three controllers that perform control arithmetic processing in parallel, compares these output data, and operates while two or more of them match. Therefore, even if an abnormality occurs in one of the controllers and the control calculation process is disconnected, the process control can be continued without interruption. In this embodiment, the three controllers are described as operating in parallel. However, 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, the number of controller abnormalities that are allowed to continue uninterrupted process control can be increased. Therefore, an optimal number may be selected based on the reliability required for the process control device and the reliability of the controller.
[0047]
In addition, since the controller that performs control operation processing has a redundant configuration by parallel execution, ensuring the reliability of the network interface and the process equipment interface ensures the reliability of the entire process control device without requiring high reliability in the controller. Can be secured. For this reason, a low-price commercial product can be used for the controller, and the cost can be reduced while ensuring reliability. In addition, since it becomes possible to use commercially available products with early generation changes, it is possible to improve the processing capability in a timely manner by improving semiconductor technology, and to shorten the product development period.
[0048]
In addition, since the network interface and process equipment interface constantly check that the controller output is normal, sufficient reliability can be secured as a process control device, so the memory system used by the controller has an error correction function. It is not necessary to provide a multi-bit error that may be caused by a cosmic ray that cannot be corrected by the error correction function, thereby further reducing the cost.
[0049]
Next, with reference to FIG. 9 and FIG. 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, the processing timing signal 103 is supplied in parallel to each controller 20 from the processing timing signal generation unit 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.
[0050]
As shown in FIG. 10, the processing timing signal 103 includes 3-bit parallel signals, that is, processing timing signals 103A to 103C, and a code that circulates every control cycle (for example, 100 ms) is output. Here, for each control cycle, eight processing timings t1 to t8 are provided corresponding to the code value, and each controller 20 identifies the processing timing based on the code value with respect to each processing timing. For example, a processing request from a higher-level monitoring device or control for a lower-level process device is executed.
[0051]
As described above, the processing timing signal 103 is supplied to each controller 20 in parallel, and the contents to be processed are determined based on the processing timing signal 103 in each controller 20. It is possible to execute processing of the same content in synchronization.
As a result, it is not necessary to completely synchronize the processing in the microprocessor using a common operation clock in each controller 20 as in the prior art, and individual operation clocks can be used.
[0052]
Therefore, even if each controller has a malfunction that occurs due to a specific operation timing, the probability of the malfunction occurring simultaneously in a plurality of controllers is extremely low, and the majority of the outputs / responses of these controllers are determined. The influence on the entire process control apparatus 1 can be avoided, and a stable control operation can be realized.
In addition, an expensive circuit configuration for synchronizing the operations of the controllers using the common clock is unnecessary, and the product cost can be greatly reduced. Furthermore, it is not necessary to use a device having the same configuration as the controller, and the system configuration is flexible.
[0053]
As a 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, when variations occur in the bit detection in the controller 20, it may be recognized that the codes are instantaneously recognized as different codes.
In the present embodiment, a gray code as shown in FIG. 10 is used as the processing timing signal 103. This gray code is a code in which only one bit changes when transitioning from an arbitrary value to the next value. Therefore, when the processing timing changes, it is possible to avoid misidentification of codes due to variations in bit detection, and each controller 20 can realize stable synchronization of processing timing.
[0054]
Next, 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 shows an example of a processing schedule in each controller.
As described above, the network interface 10 transmits a request from the request distribution unit 13 (see FIG. 2) via the internal LAN 40 when instructing each controller 20 to perform processing.
[0055]
As shown in FIG. 11, this request is one of the packets used in Ethernet (registered trademark), and includes a header 41 for storing information on the packet such as the packet transmission destination, transmission source, packet type, and the content of the request. The data section 42 stores information to be shown.
The data part 42 stores a request ID 43 for identifying the request, a request content 44 in which the request content is encoded, and processing timing information 45 indicating the timing for executing the request. For example, in the case of a request for instructing each controller 20 to change a setting value, the request content 44 is a process device to be processed, that is, a point ID 44A indicating a control point, a processing type 44B indicating a processing type, and its processing The processing data 44C used in the above is set. Further, the processing timing information 45 is set with a gray code defined by the processing timing signal 103.
[0056]
In each controller 20, such a request is received by the request processing unit 21, and the content is analyzed and executed. 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 in FIG. 11, since the processing type 44B indicates “setting value update”, the request processing unit 21 extracts the “DB setting value” of the processing data 44C and sets a new setting corresponding to the point ID 44A. Write to the database 22 as a value. This processing is executed when the gray code of the processing timing signal 103 from the process device interface 30 indicates “011”, that is, the processing timing t3. Thereby, in each controller 20, a new set value is written simultaneously in synchronization with the next processing timing t3.
[0057]
Further, in the example of the request 47 in FIG. 11, since the processing type 44A indicates “read current value”, the request processing unit 21 reads the current value obtained from the process device stored in the database 22, Notify the network interface 10. This processing is executed when the gray code of the processing timing signal 103 from the process device interface 30 indicates “101”, that is, processing timing t5. As a result, the current values are simultaneously read from the respective controllers 20 in synchronization with the next processing timing t5.
The read current value is notified from the controller 20 to the network interface 10 as a response. At this time, the request ID of the corresponding request is also notified by the response, so that it is possible to identify which request each response corresponds to. it can.
[0058]
In this way, the processing timing signal 103 is supplied to each controller 20 in parallel, and each controller 20 determines the contents to be processed based on the processing timing signal 103, and is sent from the network interface 10 to each controller 20. In this request, the timing for executing the requested processing is designated, so that the processing of the same contents can be executed almost synchronously between the controllers 20, and the output / response of the controller can be determined with a majority decision with high accuracy. can do.
Further, unlike the prior art, it is not necessary to completely synchronize the processing in the microprocessor using the operation clock common to the controllers 20, and it is possible to use individual operation clocks.
[0059]
Therefore, even when each controller has a malfunction that occurs due to the specific operation timing, the probability of the malfunction occurring simultaneously in a plurality of controllers is extremely low, and a stable control operation can be realized.
In addition, an expensive circuit configuration for synchronizing the operations of the controllers using the common clock is unnecessary, and the product cost can be greatly reduced. Furthermore, it is not necessary to use a device having the same configuration as the controller, and the system configuration is flexible.
[0060]
In each controller 20, a preset process is performed at each processing timing in this way. In the sequence of FIG. 6 described above, as shown in FIG. 12, the “measurement data request” process to the process device is first performed at the processing timing t1, and the “request acceptance” process is performed at the processing timing t2. Further, “DB current value update” processing for storing the measurement data obtained from the process equipment in the database 22 at the processing timing t3 is performed, and “DB current value reading” processing based on the request is performed at the processing timing t4. Then, after processing timing t5 in which processing is not set, “control calculation” processing for calculating control data for the process equipment is performed at processing timing t6, and the calculation result is stored in the database 22 at processing timing t7. “DB control data update” processing is performed, and “control data transmission” processing to the process device is performed at processing timing t8.
[0061]
Such processing scheduling is managed by the load check unit 12 of the network interface 10, and when a new process is requested, a request is issued by designating a process timing at which no process is set.
At this time, when a new process is requested to the controller 20 based on the request from the monitoring device 2, the load check unit 12 determines whether it is acceptable based on the scheduling as described above. If it is overloaded and cannot be accepted, the monitoring device 2 is notified of the unacceptability. Thereby, an overload to the controller 20 can be avoided in advance, and stable process control can be realized.
[0062]
All processing at each processing timing may be specified to the controller 20 from the network interface 10 side. However, routine processing performed by each controller 20, for example, “measurement data request”, “DB current value” For processing related to process device control such as “update”, “control calculation”, “DB control data update”, “control data transmission”, the processing timing may be fixedly assigned in advance. Request processing at can be omitted.
[0063]
Next, a second embodiment of the present invention will be described. The process control apparatus of this embodiment is different from 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 data sent to the response / request transmission / reception unit 11 in response to a request. That is, a program for realizing the self-diagnosis function may be added to the nonvolatile semiconductor memory storing the program for realizing the function of the network interface 10.
[0064]
In this case, the request for the self-diagnosis function issued by the response / request transmission / reception unit 11 is transmitted to the three controllers 20 only when the load on the controller 20 is light by the action of the load check unit 12. The request transmitted to the controller 20 is executed by the request processing unit at a predetermined timing, and the data in the database 22 is read for each predetermined unit and sequentially transmitted to the network interface 10. Data in the database 22 transmitted from the three controllers 20 are compared by the response comparison unit 15, and the abnormality notification unit 16 is notified of the controller in which the mismatch is detected. As a result, the abnormality notification unit 16 transmits an abnormality notification to the controller, and the controller that has received the abnormality notification executes abnormality processing and disconnects from the control calculation processing.
[0065]
According to this embodiment, by comparing the data of the databases 22 of the three controllers 20 in the background, it is possible to detect errors in the RAM that stores the data of the databases 22. For this reason, it is possible to detect an error that has occurred in an area that is not frequently used, and to remove the controller 20 in which an abnormality has occurred.
[0066]
Next, a third embodiment of the present invention will be described with reference to FIG. FIG. 13 is a block diagram showing a third embodiment of the process control apparatus of the present invention.
The process control device 6 of this embodiment is different from the first embodiment in that the network interface 10, the process equipment interface 30, the internal LAN 40, and the data communication path 50 are configured redundantly. In FIG. 13, the process control device 6 includes two network interfaces 10 (network interface A, network interface B) having the same configuration, three controllers 20 (controller A, controller B, controller C) having the same configuration, and 2 Two process device interfaces 30 (process device interface A and process device interface B) having the same configuration are provided.
[0067]
The two network interfaces 10 are connected to the three controllers 20 via different internal LANs 40 (A-system internal LAN, B-system internal LAN), and are configured to be able to communicate with the three controllers 20, respectively. . 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 three controllers 20 via the B-system internal LAN.
[0068]
The two process equipment interfaces 30 are individually connected to the three controllers 20 via the data communication path 50, and are configured to be capable of one-to-one communication with them. In addition, a control signal line 60 is connected between the two process equipment interfaces 30 so that control signals can be transmitted to each other.
Further, the two process equipment interfaces 30 are connected to the two network interfaces 10 and the three controllers 20 via buses (not shown) of different systems.
[0069]
The two network interfaces 10 are connected to the monitoring device 2 via control LANs 3 (A-system control LAN and B-system control LAN) of different systems, and are configured to be able to communicate with the monitoring device 2 respectively. . 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 monitoring device 2 via the B-system control LAN. Each of the two process device interfaces 30 is connected to two external IO buses 5 (A system IO bus and B system IO bus) to which the process device 4 is connected.
[0070]
In this process control device 6, two network interfaces 10 and three controllers 20 operate in parallel, one of the two process device interfaces 30 always operates as a master (active system), and the other operates as a slave (standby system). Waiting. The two network interfaces 10 separately give the requests of the monitoring device 2 received via the control LANs 3 of different systems to each of the three controllers 20, and in the response from each of the three controllers 20 to this request A response determined by majority decision is output to the control LAN 3 to which each is connected, and the response is sent to the monitoring device 2.
[0071]
The two network interfaces 10 are different from those described in the first embodiment or the second embodiment in that there are two digital input interfaces for processing timing signal input, and both master and slave processes. That is, when the processing timing signal output from the device interface 30 is input and the master processing timing signal is not input, the processing is continued based on the processing timing signal on the slave side.
[0072]
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. Further, command generation and process control operations are performed on the process device 4, and the generated commands and operation results are output to the two process device interfaces 30 as control data.
[0073]
Here, of the same requests given from the two network interfaces 10, only the request given first can be processed because the requests sent by the monitoring device have the same message header in the A system and the B system. Therefore, when the response / request transmission / reception unit 11 receives the same message, it determines that the message received later is the same as the message received earlier and ignores it.
[0074]
The three controllers 20 are different from those described in the first embodiment or the second embodiment in that a LAN interface for the internal LAN 40, a communication interface for the data communication path 50, and a processing timing signal 103 input. The response / request transmission / reception unit 11 performs transmission / reception via the two internal LANs 40, and the input / output processing unit 24 performs transmission / reception via the two data communication paths 50. When the processing timing signal output from both the master and slave process device interfaces 30 is input and the master processing timing signal is not input, processing is performed based on the slave processing timing signal. It was to continue.
[0075]
The process equipment interface 30 controls the process equipment 4 by outputting one control data determined by majority decision from the control data outputted from each of the three controllers 20 to the two IO buses 5 on the master side, and controlled by the slave side. A standby operation for confirming the operation on the master side is performed via the signal line 60. The slave-side process device interface 30 switches to the master when detecting the stop of the master-side operation. Further, the two process equipment interfaces 30 output processing timing signals to buses (not shown) to which the process equipment interfaces 30 are connected, regardless of the master side or the slave side.
[0076]
The two process device interfaces 30 are different from those described in the first embodiment or the second embodiment in that they have two interfaces for the IO bus 5 and output control data to the two IO buses 5. It is configured to be possible, and it has a digital input / output interface for the control signal line 60 and is configured to be switchable between master and slave. Master / slave switching, for example, outputs a signal indicating that it is operating to the digital input / output interface at all times when it is a master, and monitors the signal input to the digital input / output interface at all times when it is a slave. When the interruption occurs, a program for switching itself to the master is stored in the nonvolatile semiconductor memory, and the CPU can execute the program.
[0077]
With this configuration, the process control apparatus according to this embodiment is disconnected from the monitoring apparatus 2 even when an abnormality occurs in any of the network interface 10, the control LAN 3, and the internal LAN 40. Since there is no, processing can be continued normally. Further, even if an abnormality occurs in the operating process device interface 30, the process can be continued by the standby process device interface 30. As described above, the process control apparatus according to this embodiment not only can continue the process control without instantaneous interruption even if an abnormality occurs in one of the controllers 20 and is disconnected from the control arithmetic processing, The process can be continued even when an abnormality occurs in the interface portion connected to the controller 20. For this reason, the reliability can be further improved as compared with the first embodiment.
[0078]
In this embodiment, all the devices connected to the three controllers 20 have a redundant configuration, but not all of them need to have a redundant configuration. By taking into account the reliability required as a process control device and the individual reliability of those connected to the three controllers 20, the required reliability is minimized by adopting a redundant configuration only at necessary locations. It can be obtained with an increase in cost. For example, the process control apparatus includes two network interfaces 10 (network interface A, network interface B) having the same configuration, three controllers 20 (controller A, controller B, controller C) having the same configuration, and one process equipment interface 30. One network interface 10, three identically configured controllers 20 (controller A, controller B, controller C), and two identically configured process equipment interfaces 30 (process equipment interface A, And a process equipment interface B).
[0079]
Next, with reference to FIG. 14, a configuration for synchronizing processing timings in the controllers 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 generation unit 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.
[0080]
As shown in FIG. 10, the processing timing signal 103 includes 3-bit parallel signals, that is, processing timing signals 103A to 103C, and a code that circulates every control cycle (for example, 100 ms) is output. Here, for each control cycle, eight processing timings t1 to t8 are provided corresponding to the code value, and each controller 20 identifies the processing timing based on the code value with respect to each processing timing. For example, a processing request from a higher-level monitoring device or control for a lower-level process device is executed.
[0081]
In the present embodiment, processing timing signals 103 are individually supplied from the two process device interfaces 30 to each controller 20 and each network interface 10. In each controller 20 and each network interface 10, one of the processing timing signals on the master side is selected from the processing timing signals 103 supplied from the two process device interfaces 30 and used to determine the processing timing. As a selection method, it may be determined which is the master side by communication with the process equipment interface 30, or the master side is determined in advance by default, and the processing timing signal from the master side is stopped. When it is detected, it may be switched to the other processing timing signal.
[0082]
As described above, when the process device interface 30 is duplicated, the processing timing signal 103 from each process device interface 30 is supplied to each controller 20 and each network interface 10 individually, and each controller 20 and each network interface 10 is supplied. Then, since one of the processing timing signals 103 supplied from the two process device interfaces 30 is selected and used, each controller 20 can achieve stable processing timing synchronization. .
[0083]
【The invention's effect】
As described above, the present invention is provided as a controller in parallel between the network interface and the process equipment interface, and is performed at the processing timing indicated by the processing timing information added to the request from the network interface. Provided with N (N is a natural number greater than or equal to 3) controllers that execute processing corresponding to the request, the request distribution unit of the network interface performs processing corresponding to the request on the request received from the host device via the network. Processing timing information for instructing the timing to be executed by the controller is added and notified to each controller, and the response comparison unit determines a majority of responses from each controller in response to the request and determines one response to be transmitted to the host device. I will do it Having to, it is possible to perform the processing of the same contents substantially synchronized between the controllers 20, an output / response of the controller can be accurately majority decision.
[0084]
Further, unlike the prior art, it is not necessary to completely synchronize the processing in the microprocessor using an operation clock common to the controllers, and it is possible to use individual operation clocks.
Therefore, even when each controller has a malfunction that occurs due to the specific operation timing, the probability of the malfunction occurring simultaneously in a plurality of controllers is extremely low, and a stable control operation can be realized.
[Brief description of the drawings]
FIG. 1 is a block diagram showing a configuration of a process control apparatus according to a first embodiment of the present invention.
FIG. 2 is a functional block diagram of the network interface of FIG. 1;
FIG. 3 is a functional block diagram of the controller of FIG. 1;
4 is a functional block diagram of the process equipment interface of FIG. 1. FIG.
FIG. 5 is a sequence diagram for explaining the operation of the process control apparatus according to the first embodiment;
FIG. 6 is a sequence diagram illustrating another operation of the process control apparatus according to the first embodiment.
FIG. 7 is a sequence diagram illustrating another operation of the process control apparatus according to the first embodiment.
FIG. 8 is a sequence diagram illustrating another operation of the process control apparatus according to the first embodiment.
FIG. 9 is an explanatory diagram showing a processing timing signal supplied to a controller.
FIG. 10 is a timing chart illustrating 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 apparatus according to a third embodiment of the present invention.
FIG. 14 is another explanatory diagram showing a processing timing signal supplied to the controller.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1,6 ... Process control apparatus, 2 ... Monitoring apparatus, 3 ... Control LAN, 4 ... Process equipment, 5 ... IO bus, 10 ... Network interface, 11 ... Response / request transmission / reception part, 12 ... Load check part, 13 ... Request Distribution unit, 14 ... Response reception unit, 15 ... Response comparison unit, 16, 34 ... Abnormality notification unit, 20 ... Controller, 21 ... Request processing unit, 22 ... Database, 23 ... Calculation processing unit, 24 ... Input / output processing unit, 25 ... Abnormal 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)

A controller for performing a control operation for process control, a network interface for notifying the controller of a request received from a host device via a network, and transmitting a response from the controller to the request to the host device; A process device interface for transmitting control data to a process device connected to the IO bus based on a control operation in the controller and receiving measurement data from the process device, and received via the network interface The process control is performed by the controller based on the request, and the process equipment is controlled by transmitting the obtained control data to the process control equipment via the process equipment interface, and the process control The measurement data obtained from the vessel was output to the network interface as a response from the controller, a process control device that transmits as a response from the network interface to the host system,
The controller is provided in parallel between the network interface and the process equipment interface, and performs processing corresponding to the request at the processing timing indicated by the processing timing information added to the request from the network interface. N controllers to execute (N is a natural number of 3 or more)
The network interface adds a processing timing information indicating the timing at which the controller should execute processing corresponding to the request to the request received from the host device via the network, and notifies the controller of the request. A process control device comprising: a distribution unit; and a response comparison unit that determines a response to be sent to the host device by determining majority responses from the controllers in response to the request. The process control apparatus according to claim 1, wherein
The request delivery unit selects processing timing for processing a newly received request based on the processing status of the request transmitted to each controller, and adds processing timing information indicating the processing timing to the request. Feature process control device. In the process control device according to claim 1 or 2,
The network interface determines whether or not to accept a newly received request based on the processing status of the request transmitted to each of the controllers, and a load check unit that passes the request to the request distribution unit only when the request is acceptable A process control apparatus comprising: The process control apparatus according to claim 3, wherein
The process control device, wherein the load check unit notifies the host device that the request cannot be executed when it is determined that the request cannot be accepted.

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