JP2008250936A - Redundant control device and its tracking method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a redundant control device capable of shortening a control cycle while facilitating a reliability check of control data subjected to tracking processing with no restrictions on an installation distance between control devices of the redundant control device. <P>SOLUTION: The redundant control device includes a control data memory which has three memories 13a and memory control circuits 13b controlled by the instructions of a control program execution circuit. The respective memories are sequentially switched in time series into a memory in a first state of carrying out writing and reading of control data for performing control operation in this control cycle, into a memory in a second state of copying and storing the contents of the memory in the first state, and into a memory in a third state of storing control data in the preceding control cycle transferred to a stand-by control device in this control cycle, to attain parallel processing of control operation processing and tracking processing of the control program. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a redundant control device in which control devices used in a factory automation field such as a steel plant and a papermaking plant and a process automation field such as a chemical plant are made redundant.

  2. Description of the Related Art Conventionally, in a control device that controls an important plant, it is known that a redundant control device of standby redundancy type is used to prevent an abnormal state in which the control device itself fails and the plant becomes uncontrollable.

  This standby redundant type redundant control device is equipped with two sets of control devices consisting of two systems, an active system control device and a standby system control device, in the event that a failure such as a power failure or failure occurs in the active system control device. The control right is switched from the active control device to the standby control device to continue the control.

  FIG. 7 shows a schematic configuration of such a conventional duplex control apparatus. The control device 21a and the control device 21b of the conventional duplex control device each have input / output data exchanged between a control program memory 122 storing a control program and an input / output device (not shown) via the I / O interface 114. Control data memory 123 for storing control data including control data and control variables during control calculation execution, and control program execution circuit 121 for reading input data and executing control calculation for each control cycle Become.

  In addition, the control data memory is stored in units of control cycles, and is configured by a tracking circuit 116 of the active system control device 21a that transmits the data to other standby system control devices 21b in units of control cycles.

  FIG. 8 shows the relationship between the method of using the control data memory 123 and the control cycle in the redundant control device having such a configuration.

  As shown in FIG. 8, in the conventional duplex control device, the control program execution circuit 121 executes control calculation using control variables such as input data and setting data in the control data memory 123 in units of control cycles. To do.

  When the control program execution circuit 121 executes the control calculation, the control program execution circuit 121 transfers the control variable including the output data of the calculation result to the standby system control device 21b via the tracking circuit 116, and the control control device 21b (not shown) By making the contents of the data memory 123 the same as the contents of the control data memory 123 of the active system control device 21a (referred to as equalization), the standby system control device 21b always operates when the active system control device 21a fails. Make sure that the control program can be executed. Equalizing the contents of the control data memory 123 is called tracking processing.

  In order to shorten the control cycle time, even if two sets of control data memories 123a and 123b are prepared as shown in FIG. 9, the contents of one control data memory used in the control calculation are transferred to another control data memory. Since the contents of the original control data memory cannot be changed during this period, the control data memory 123b can be used for the control calculation only after the control calculation is completed.

  Therefore, in such a duplex control device, it is necessary to set the control cycle to a time longer than the sum of the control calculation processing time and the tracking processing time, so it is difficult to shorten the control cycle to a time shorter than this. It was.

In order to shorten the control cycle of such a conventional dual control device, the control data memory is composed of a pair of dual port memories, and the dual port memories are connected to each other via a memory bus, so that one control arithmetic CPU can A technique is disclosed in which control data is simultaneously written in the own tracking memory and the tracking memory of the other control device, so that a separate tracking process is not performed after the control calculation, and the control cycle is shortened. (For example, refer to Patent Document 1).
Japanese Unexamined Patent Publication No. 4-158457 (first page, FIG. 1)

  In the transfer method disclosed in Patent Document 1, the active system control device and the standby system control device are directly connected by a memory bus, and are executed at the same speed at which data is simultaneously written to the control data memory of the own system and the other system.

  However, the control data memory consisting of the dual port memory writes all the control variables during the execution of control calculations simultaneously to the control data memory used by itself and other systems at the same speed, so no dedicated time is required for tracking transmission processing. However, if an error occurs in this transfer, the system cannot be rewritten. Therefore, there is a problem that the reliability of the transferred control data is lowered.

  In this case, if an error check is performed on the control data to be tracked, the control operation program executes the next instruction after confirming that the control data transfer has been normally completed after the execution of the control operation instruction. Therefore, there is a problem that not only the program becomes complicated but also the control cycle is prevented from being shortened.

  The present invention has been made in order to solve the above-described problems, and duplex control that makes it easy to check the reliability of control data that is tracked between the control devices of the duplex control device and that can also shorten the control cycle. An object is to provide an apparatus.

  In order to achieve the above object, a duplex control device according to the present invention includes an input / output device that processes input data and output data between control targets, and an active system control device and a standby system control for the input / output device. Two sets of control devices, and the operating system control device reads input data from the control target for each control cycle, executes control arithmetic processing according to a pre-stored control program, and controls the control target Output data to the system, and transfer control data including the input data, the output data, and control variables used for execution of the control program to the standby system control device, and the active system control device and the standby system control device A tracking process for equalizing the control data is executed, and when the active control device fails, the standby control device is switched to the standby control device to execute control. A long duplex control device, wherein the control device is an input / output means for processing the input data and the output data with the input / output device, a control program memory for storing the control program, A control data memory for storing control data; a control program calculation circuit for executing the control calculation process according to the control program for each control cycle; and from the active system control device to the standby system control device for each control cycle. A tracking circuit for executing the tracking process for transferring the control data; and a status transmission circuit for notifying the partner system whether or not the operation state of the own system control device is normal. Three memories capable of writing and reading independently, and a memory control circuit controlled by a command from the control program execution circuit The control program execution circuit includes three memories, a memory in a first state in which the control data for performing the control arithmetic processing in the current control cycle is written and read, and the control data Control data in the previous control cycle to be transferred to the standby control device in the current control cycle via the tracking circuit and the second state memory for copying and storing the contents of the memory in the first state The control operation process and the tracking process are processed in parallel by sequentially switching to the three states of the memory in the third state to be stored in time series.

  In order to achieve the above object, a tracking processing method for a duplex control apparatus according to the present invention includes an input / output device that processes input data and output data between control targets, and an active system control device for the input / output device. And two sets of control devices of a standby control device, the active control device reads input data from the control target for each control cycle, and executes control arithmetic processing according to a pre-stored control program, Obtaining output data to the controlled object, transferring control data including control data used for execution of the input data, the output data, and the control program to the standby system control device, and the active system control device and the A tracking process for equalizing the control data of the standby control device is executed, and when the active control device fails, the control right is switched to the standby control device. In this case, the control data memory has three memories that can be independently written to and read from, respectively, in the current control cycle. A first step of executing the control calculation process; a second step of copying and storing the control data processed in the first step; and the control data of the previous control period in the current control period. A third step of transferring to the standby control device, and the memory used in the first step to the third step is time-sequentially in units of the control period with respect to the three memories. The control calculation process and the tracking process are processed in parallel, and the control calculation process and the tracking process are processed in parallel.

  According to the present invention, it is possible to provide a duplex control device and a tracking method thereof that can easily check the reliability of control data to be tracked between the control devices of the duplex control device and can shorten the control cycle. it can.

  Embodiments of the present invention will be described below with reference to the drawings.

  A duplex control apparatus according to a first embodiment of the present invention will be described with reference to FIGS. The configuration of the duplex control device 1 is shown in FIG.

  The duplex control device includes an active system control device 1a and a standby system control device 1b that are initially set as an active system or a standby system at the start of operation of the device, an input / output device 2 that controls input / output signals to and from the control target, The input / output bus 3 connects the active system control device 1a and the standby system control device 1b to the input / output device 2.

  Next, the structure of each part of a pair of active system control apparatus 1a and standby system control apparatus 1b is demonstrated. The control device 1 includes an input / output control circuit 14 that processes input data from a control target (not shown) and output data to the control target, and a control program memory 12 that stores a control program. Control data memory 13 for storing control data including data, output data and control variables used for control program execution, control program calculation circuit 11 for executing the control program for each control cycle, and operation system for each control cycle A tracking circuit 16 for transferring control data to the standby control device 1b, a status transmission circuit 17 for notifying the partner system whether or not the operation status of the own system is normal, and a control device 1 for connecting these circuits. And a bus 18.

  Next, the detailed configuration of the control data memory 13 will be described with reference to FIG. The control data memory 13 is provided between the memory 13 composed of three memories 13a1 to 13a3 that can be independently written and read, and between these memories 13 and the bus 18, and the control program execution circuit 11 commands. And a memory control circuit 13b controlled by.

  The memory control circuit 13b also includes bidirectional buffers 13b1 to 13b6 that control the flow of control data between the bus 18 and the memories 13a1 to 13a3, write / read signals from the control program execution circuit 11, and memory It comprises a command control circuit 13b7 which receives the selection signal and controls reading and writing of each of the memories 13a1 to 13a3.

  Specifically, in the memory control circuit 13b, one of the bidirectional buffer 13b1 is connected to the bus 18 and the other is connected to the memory 13a1, and control data is exchanged. Similarly, one of the bidirectional buffer 13b2 is connected to the bus 18 and the other to the memory 13a2, and the bidirectional buffer 13b3 is connected to the bus 18 and the other to the memory 13a3, and control data is transferred.

  Further, a bidirectional buffer 13b4 is provided between the memory 13a1 and the memory 13a2, a bidirectional buffer 1354 is provided between the memory 13a2 and the memory 13a3, and a bidirectional buffer 13b6 is provided between the memory 13a3 and the memory 13a1. Each is connected by bus.

  Further, the output of the bidirectional buffer 13b4 is between the memory 13a1 and the memory 13a2, the output of the bidirectional buffer 13b5 is between the memory 13a2 and the memory 13a3, and the output of the bidirectional buffer 13b6 is the memory 13a3 and the memory 13a1. Are connected to each other by bus.

  The memories 13a1 to 13a3 are controlled by the command control circuit 13b7 so that they can be read and written independently, and two adjacent memories 13 can be written simultaneously.

  Next, the control data control operation of the duplex control apparatus configured as described above will be described with reference to FIGS.

  FIG. 3 is a diagram for explaining the operating states of the three memories 13a1 to 13a3. For example, FIG. 3A shows the operating state of the three memories 13 whose control cycle is n-th scan. Similarly, FIG. 3B shows the operation state of each of the three memories 13 in which the control cycle is the n + 1th scan, and FIG. 3C is the control cycle in the n + 2th scan.

  The three operating states are: the input data is read (R) from the input / output control circuit 14 in the current control cycle (R), the control program is executed and the operation output is written (W), the memory in the first state, the control In the previous control cycle that is transferred to the standby control device 1b in the current control cycle via the tracking circuit 16 and the second state memory that duplicates and stores the control data of the first state memory that has completed the computation. The memory control circuit 13b receives the memory selection signal and the read / write signal from the control program execution circuit 11, and the memory in these three states is stored in the three states. Control is performed so that the memories 13a1 to 13a3 are sequentially switched in time series.

  FIG. 3A shows that in the n-th scan, the memory 13a1 is in the first state, the memory 13a2 is in the second state, and the memory 13a3 is in the third state.

  FIG. 3B shows that at the (n + 1) th scan, the memory 13a1 has transitioned to the third state, the memory 13a2 has transitioned to the first state, and the memory 13a3 has transitioned to the second state.

  FIG. 3C shows that the memory 13a1 is in the second state, the memory 13a2 is in the third state, and the memory 13a3 is in the first state at the n21st scan.

  Thus, the three memories 13a1 to 13a3 are provided, and the control calculation process and the tracking process are processed in parallel using different memories by sequentially switching and controlling the states of the respective memories.

  Next, the operation of the tracking process will be described with reference to FIG. FIG. 4 shows the flow of control data transferred from the active control device 1a to the standby control device 1b.

  Assuming that the control cycle is at the nth scan, the memory 13a1 (denoted as M1 in FIG. 4) is in the first state, and the memory 13a2 (M2) is written to the memory 13a1 at the timing when the control calculation is completed. The last state of the control data is in a second state where it is copied and stored.

  The control data tracked at the nth scan stores the control data at the (n-1) th scan and is transferred from the memory 13a3 in the third state to the tracking circuit 16 of the active system control device 1a. The control data is transferred to the memory 13a3 (M3) of the standby control device 1b via the tracking circuit 16 of the standby control device 1b.

  That is, the transferred control data is transferred to the standby control device 1b with a delay of one scan.

  At this time, the control cycle is set according to the control calculation processing time (read / write time to the memory) in the first state and the second state and the control data from the memory in the third state to the tracking circuit 16 of the own system. (Writing time) The transfer time may be set longer than the longer transfer time, and the control data transfer time between the tracking circuits 16 of both systems does not affect the control calculation of the next control cycle.

  Next, with reference to FIG. 5, the tracking processing operation when an abnormality occurs in the duplex control device will be described. FIG. 5 illustrates the control operation when a failure occurs in the active control device 1a at the nth scan, and the failure is notified to the standby control device 1b via the status transmission circuit 17.

  When a failure is detected in the standby control device 1b after the control data has been transferred from the memory 13a3 (M3) to the tracking circuit 16 in the first state in the memory 13a1 (M1), the standby control device 1b operates. Switch to the system control device 1a, transfer the control right, and start the control using the memory 13a3 (M3) control data of the (n-1) th scan.

  In the case where the memory 13a1 (M1) is in the first state and the standby system controller 1b detects a failure before the control data is completely transferred from the memory 13a3 (M3) to the tracking circuit 16, the standby system controller 1b Switching to the active control device 1a, the control right is transferred, and control is started using the control data in the memory 13a1 (M2) of the n-2th scan.

  When it is notified that the failure of the control device that has shifted to the standby control device 1b has been recovered at the n + i scan, the control data from the n + i + 1 scan to the standby control device 1b is sent from the active control device 1a. Start transferring.

  As described above, according to the present embodiment, the control data to be transferred becomes a response with a delay of one scan, but the transfer between the tracking circuits 16 is independent of the control arithmetic operation of the control program execution circuit 11. Since transfer control is possible, the setting of the control cycle can be shortened.

  In the case of the dual port memory method described in Patent Document 1, since all the data that is being subjected to the control calculation is subjected to tracking processing, when the same control data is repeatedly used, useless time is generated, When an error check is performed in order to improve the reliability of control data to be tracked, the error check process becomes complicated and further time is required, so the control cycle needs to be increased accordingly.

  In addition, for an error during transfer, it is impossible to re-execute the same instruction, so that correct data cannot be rewritten.

  In addition, since the write processing speed of the dual port memory method usually requires a nanosecond level speed, the distance between the control devices cannot be extended, so that the installation location between the control devices is limited. There's a problem.

  However, according to this method, it is possible to generate and transmit error codes of control data in a lump, so that the receiving side can also check. Therefore, it is possible to resend the control data to be tracked, and not only can the reliability of the control data be efficiently performed, but also the distance between the active control device 1a and the standby control device 1b can be extended. There is also an effect that there is no restriction on the installation location of the apparatus.

  Hereinafter, Example 2 will be described with reference to FIG. About each part of Example 2, the same part as the control apparatus 1 of Example 1 is shown with the same code | symbol, and the description is abbreviate | omitted.

  The difference between the second embodiment and the first embodiment is that the control data memory 13 is provided in each control device 1 in the first embodiment, but in the second embodiment, the shared memory 113 of two sets of control devices is configured. By switching the control states of the three memories 113a1 to 113a3, the control data tracking process as in the first embodiment is not required.

  The control data memory 113 includes three memories 113a1 to 113a3 and a tracking memory instruction flag 113a4 for writing whether or not these memories are in a trackable state every time the control calculation is completed. Each is coupled to a bus 18 so as to be accessible from the device 1.

  After the control calculation, the contents of the two memories used for writing are compared to confirm that there is no error in the memory operation or writing operation, and then the tracking memory instruction flag 113a4 is set. Correct data can be reliably transmitted to the standby system control device 1b.

  Since the two sets of control devices 1 can mutually monitor the operating state by the status transmission circuit 17, when the active control device 1a fails and the status is notified, the standby control device 1b The control right is switched to the system, and control is started using the control data of the memory 113 indicated by the tracking memory instruction flag 113a4.

  Therefore, according to the second embodiment, the distance between the control devices cannot be extended and the reliability of the control data cannot be improved, but the control cycle can be shortened compared to the first embodiment. .

  The present invention is not limited to the above-described embodiment, and the control data memory of the control device 1 is composed of at least three or more independently readable / writable memories, and includes control calculation processing, tracking processing, However, the present invention can be implemented in various modifications without departing from the gist of the present invention.

The block diagram of the duplication control apparatus of Example 1 of this invention. The block diagram of the control data memory of the duplication control apparatus of this invention. Explanatory drawing of control operation | movement of the control data memory of this invention. Explanatory drawing of control operation | movement of the tracking process of the duplication control apparatus of this invention. Explanatory drawing of the control operation of the tracking process of the duplex control device of the present invention The block diagram of the duplication control apparatus of Example 2 of this invention. The block diagram of the conventional duplication control apparatus. Explanatory drawing of the control action for the setting of the conventional control period. Explanatory drawing of operation | movement of the tracking process of the conventional duplication control apparatus.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Control apparatus 1a Active system control apparatus 1b Standby system control apparatus 2 Input / output apparatus 3 Input / output bus 11 Control program execution circuit 12 Control program memory 13 Control data memory 13 Memory 13a1 Memory (M1)
13a2 memory (M2)
13a3 memory (M3)
13b Memory control circuit 13b1 to 13b6 Bidirectional buffer 13b7 Command control circuit 14 Input / output control circuit 16 Tracking circuit 17 Status transmission circuit 18 Bus 113 Control data memory 113a1 to 113a3 Memory 113a4 Tracking memory instruction flag 21a Active system control device 21b Standby system control Device 121 Control program execution circuit 122 Control program memory 123 Control data memory 114 I / O interface 116 Tracking circuit

Claims (3)

An input / output device that processes input data and output data to and from the controlled object, and two sets of control devices, an operating system control device and a standby system control device, for the input / output device, the operating system control device Reads out the input data from the control target for each control cycle, executes control arithmetic processing according to a pre-stored control program, obtains output data to the controlled target, the input data, the output data and the Transferring control data including control variables used for execution of the control program to the standby system control device, executing a tracking process for equalizing the control data of the active system control device and the standby system control device, and When the active system control device fails, it is a standby redundant type redundant control device that executes control by switching the control right to the standby system control device,
The control device comprises: input / output means for processing the input data and the output data with the input / output device;
A control program memory for storing the control program;
A control data memory for storing the control data;
A control program calculation circuit for executing the control calculation process according to the control program for each control cycle;
A tracking circuit for executing the tracking process for transferring the control data from the active system control device to the standby system control device for each control cycle;
A status transmission circuit for notifying the partner system whether or not the operation state of the own system control device is normal,
The control data memory has three memories capable of independently writing and reading, and a memory control circuit controlled by a command from the control program execution circuit,
The control program execution circuit includes three memories, a first state memory that executes writing and reading of the control data for performing the control calculation processing in the current control cycle, and the first state. A second state memory for copying and storing the contents of the second memory, and a third storage for storing control data in the previous control cycle transferred to the standby control device in the current control cycle via the tracking circuit. Switch sequentially to three states with the state memory, in time series,
The duplex control apparatus, wherein the control calculation process and the tracking process are processed in parallel. The control data memory is configured as a shared memory of two sets of the control devices,
The control data memory further includes a tracking memory instruction flag that indicates which of the three memories is in a state where the tracking process is possible,
The control program execution circuit confirms that the contents of the two memories used for writing are the same after the completion of the control calculation process, and writes the completion to the tracking instruction flag. The duplex control device according to claim 1, characterized in that: An input / output device that processes input data and output data to and from the controlled object, and two sets of control devices of an active system control device and a standby system control device for the input / output device, the active system control device Reads out the input data from the control target for each control cycle, executes control arithmetic processing according to a pre-stored control program, obtains output data to the controlled target, the input data, the output data and the Transferring control data including a control variable used for execution of the control program to the standby system control device, executing a tracking process for equalizing the control data of the active system control device and the standby system control device, and A tracking processing method of a redundant redundant control device of standby redundancy type in which control is performed by switching the control right to the standby control device when an active control device fails.
The control data memory has three memories that can be independently written and read,
A first step of executing the control calculation process in the current control cycle;
A second step of copying and storing the control data processed in the first step;
A third step of transferring the control data of the previous control cycle to the standby control device in the current control cycle;
For the three memories, the memory used in the first step to the third step is sequentially switched in time series in units of the control cycle, and the control calculation process and the tracking process are used. A tracking method for a duplex control apparatus, characterized in that processing is performed in parallel.

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