JPH09198266A - Process control system - Google Patents

Abstract

(57) [Summary] [PROBLEMS] To provide a process input / output device having high reliability, maintainability, and visibility. An object of the present invention is to provide a process input / output device with reduced wiring man-hours, wiring mistakes, and inspection man-hours in the manufacturing process. A process input / output device 3 and the like are realized by a microprocessor 301 and software in place of a conventional relay circuit. The software is stored in the non-volatile rewritable memory element 302. The software can be rewritten by the maintenance monitoring device 6. Further, a limit value is set for the number of times of rewriting, and rewriting is not performed when the number of rewritings is equal to or more than the limit value. Also, to prevent accidental rewriting,
Provide a rewrite enable / disable switch.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a process input / output device of a process controller having a process operation end protection / driving circuit.

[0002]

2. Description of the Related Art A process control system operates a plant by operating an operating end (process operating end) of the plant. The process operation end protection / end drive circuit that constitutes a part of this process control system has conventionally been constituted by a relay circuit or the like. Further, the software required for control is stored in a non-volatile fixed memory device. This is because it is necessary to continue the operation even when the process control device is stopped, the recovery from the power failure of the process control device is performed in a short time, and the possibility of erroneous circuit mixing is eliminated.

[0003]

However, the circuit conventionally used has poor maintainability. For example,
When the circuit is changed, the wiring needs to be changed in the relay circuit. Further, in a nonvolatile fixed memory element, it is necessary to rewrite the contents and replace the memory element itself.

Further, since the operation state of such a circuit is poor in visibility, it is difficult to grasp the state and investigate the cause when the plant is abnormal. For example, to check the signals in the circuit, the actual wiring, timer, and relay operations had to be followed.

Further, the number of wiring steps is large in the manufacturing process of such a circuit, and there is a high possibility that wrong wiring may be mixed. There is no choice but to increase the number of inspection steps to prevent incorrect wiring.

In order to facilitate the modification and confirmation of the operating state of the software stored in the non-volatile fixed memory device, the software may be stored in the non-volatile rewritable memory device. However, such a memory device has a problem in reliability. For example, data may be lost due to electrical stress during rewriting.

According to the present invention, while ensuring operation reliability and non-volatility, the operation state visibility, the easiness of circuit change, and the maintainability are improved, and the number of wiring steps and the number of inspection steps for circuit production are reduced. An object is to provide a process input / output device of a process control device.

[0008]

According to the present invention, the basic circuit, which is conventionally composed of a relay circuit, is made into software and the software is stored in a nonvolatile rewritable memory element. While this software can be changed by a maintenance management tool as needed, it has a rewrite permission switch to prevent erasure by mistake and ensures safety.

The structure of the present invention will be described in more detail below.

According to a first aspect of the present invention, in a process control system for operating a plant by operating an operating end of the plant, an input process for receiving input of state information indicating the state of the plant, and a separate process. A process input / output device for performing output processing for instructing the determined operation content of the operation end to the operation end, and a process control device for determining the operation content based on the status information received by the process input / output device Wherein the process input / output device includes a nonvolatile rewritable memory device in which an input / output program defining at least the contents of the input processing and the output processing is stored, and an arithmetic unit for executing the input / output program. A process control system is provided which is characterized by including the following.

It is preferable to further include a maintenance monitoring device which is directly or indirectly connected to the process input / output device and which performs a reading process and a rewriting process of stored contents of the nonvolatile rewritable memory element.

The nonvolatile rewritable memory device includes:
Further, a rewrite count value indicating the number of times the rewrite process has been performed is stored so far, and the maintenance monitoring device confirms the rewrite count when performing the rewrite, and as a result of the confirmation, The above rewriting process may be performed and the rewriting frequency value may be updated only when the rewriting frequency value is less than or equal to the separately defined number of times.

The process input / output device may output a predetermined operation content to the operation end while the rewriting process is being performed.

The process input / output device is provided with a control permission condition separately determined for each operation terminal, and the operation content is operated only when the operation content input from the process control device satisfies the control permission condition. It is preferable to output to the end.

At least one of the maintenance monitoring device and the process input / output device is preferably provided with a limiting mechanism for limiting the execution of the rewriting process.

The operation will be described.

The process input / output device receives an input of state information indicating the state of the plant. The process control device determines the operation content based on the status information received by the process input / output device. The process input / output device indicates to the operating end the operation content of the determined operating end. In this case, if the process input / output device outputs the operation content to the operation end only when the operation content input from the process control device satisfies the control permission condition, the process control device can handle the abnormality.

Such input / output processing performed by the process input / output device can be realized by the arithmetic unit executing an input / output program. If the input / output program is stored in the non-volatile rewritable memory device, the maintenance monitoring device can read the contents and confirm the operating state of the input / output device. In addition, it can be rewritten if necessary.

When the input / output program is rewritten, the maintenance monitoring device first confirms the number of rewrites up to that time stored in the nonvolatile rewritable memory element. As a result of the confirmation, the rewriting process is performed only when the rewriting number value at that time is less than or equal to the separately set limit number,
Update the rewrite count value. By doing so, the reliability of data retention can be ensured.

While the rewriting process is being performed, the process input / output device can prevent the plant state from being disturbed by outputting the predetermined operation content to the operating end.

Depending on the specific program and circuit configuration, input / output from the process control device to / from the process input / output device may be stopped, and status information and the like may be changed from the operating end immediately before rewriting. If the entered contents are retained, reliability and safety can be further ensured.

A situation in which rewriting processing is erroneously performed can be prevented by providing a limiting mechanism.

[0023]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to the drawings.

As shown in FIG. 1, the process control system according to the present embodiment includes a process control device 1, a bus 2 and a process control device 1.
Alternatively, it is composed of two or more process input / output devices 3 and a maintenance / monitoring device 6. The process operation end s itself is included in the process itself to be controlled.

The process operating end s is an operating end of an auxiliary machine (for example, a one-way rotating auxiliary machine, a motor-operated valve, a solenoid valve, etc.) required for operating the plant, and is assigned to each auxiliary machine. . The process operation end s can change the state of the auxiliary machine according to the operation command from the process input / output device 3. At the same time, the operating state of the auxiliary machine is output to the process input / output device 3.

[Process control device 1] The process control device 1 is a device which collectively manages the operation of the process operating end s. The process control device 1, as shown in FIG.
It is configured to include a PU 101, a volatile rewritable memory element 102, a bus 103 connecting these elements, and the like. The operation management program software (process control program 7) executed by the CPU 101 is stored in the volatile rewritable memory element 102.

During plant operation, the process control device 1
Outputs an operation command to each process input / output device 3 by executing the process control program 7. Various information necessary for determining the operation command is input as state information from the process input / output device 3 to which the process operation end s to be controlled is assigned.

[Process Input / Output Device 3] The process input / output device 3 is located between the process control device 1 and the process operating end s and performs input / output processing of various control signals. The process input / output device 3 is provided for each process operation terminal s. The process input / output device 3 is functionally provided with a normal drive condition processing circuit 30, a protection drive condition processing circuit 31, and an operating end drive circuit 32 (see FIG. 4).

The normal driving condition processing circuit 30 generates a driving condition (driving permission condition) for the auxiliary machine required for normal operation of the plant and determines whether or not the driving permission condition is satisfied. To do.

The protection drive condition processing circuit 31 is for driving the process operation end s in order to protect the main equipment of the plant when some abnormality occurs. When an abnormality occurs, the protection drive condition processing circuit 31 ignores the above-mentioned drive permission condition and forcibly issues a drive instruction to the operating end drive circuit 32.

The operation end drive circuit 32 is a circuit for outputting a drive signal to the process operation end s of the auxiliary machine. The operation end drive circuit 32 normally outputs a drive signal when the drive condition is satisfied as a result of the determination by the normal drive condition processing circuit 30. However, when some abnormality occurs, a drive signal is output in accordance with a drive instruction from the protection drive condition processing circuit 31 described later.

As shown in FIG. 2, the process input / output device 3 of the present embodiment specifically comprises an MPU 301, a non-volatile rewritable memory element 302, a bus 303, and an operating end drive circuit 32. The normal drive condition processing circuit 30 and the protection drive condition processing circuit 31 described above are realized by the MPU 301 executing the process input / output program 8 stored in the nonvolatile rewritable memory element 302. As a result of taking such a configuration, in the present embodiment,
The change in the state of the main equipment is constantly monitored, and when any abnormality occurs, the state of the main equipment can be prevented from being damaged or burned, and the state can be promptly shifted to a safe direction.

The process input / output program 8 is
The maintenance / monitoring device 6 is configured to be able to rewrite and monitor. The storage form of the process input / output program 8 in the non-volatile rewritable memory element 302 is in consideration of the rewriting. This point will be described later in detail with reference to FIG.

The procedure of process control by the process control device 1 and the process input / output device 3 will be described below with reference to FIGS. 3 and 4.

A state signal 11a indicating the state of the process operating end s is input to the process input / output device 3 from the process operating end s. The process input / output device 3 outputs the status signal 11a as it is as the condition signal 9 to the process control device 1 (see FIG. 4). The condition signal 9 is a signal that is used as a judgment factor for the process control device 1 to analyze the state of the plant, and is output from all the process input / output devices 3 to the process control device 1.

In addition to this, the operation end drive permission signal 11b is also input to the process input / output device 3 from the process operation end s. The operation end drive permission signal 11b serves as a reference and a condition for the operation end control signal 10 described later to determine whether or not the process operation end s can be normally operated. Actual operation end drive permission signal 11b
Is, for example, an operation state of another related process operation end s, a plant state signal, and the like. The process input / output device 3 takes in the operation end drive permission signal 11b and stores it in the nonvolatile rewritable memory element 4.

The process control device 1 analyzes the state of the plant based on the contents of the condition signal 9 and the like. As a result of the analysis,
Process operation end s that needs to perform some operation
In response to this, the operation end control signal 10 is output to the process input / output device 3 associated with the process operation end s.

The process input / output device 3 temporarily stores the input operating-end control signal 10 in the nonvolatile rewritable memory element 302. Then, the normal drive condition processing unit 30
Determines whether the content of the operation end control signal 10 input at this time satisfies the criteria and conditions indicated by the operation end drive permission signal 11b. If the result of this determination is that the criteria are met, the operating end control signal 10 is output to the operating end drive circuit 32. The operation end drive circuit 32 drives the process operation end s based on the operation end control signal 10.
The operation end drive signal 12 is output to the process operation end s.

[Maintenance / Monitoring Device 6] Maintenance / Monitoring Device 6
Is for maintenance and monitoring of the process input / output device 3. The maintenance / monitoring device 6, as shown in FIG.
PU 601, memory 602, bus 603, monitor 605
It has. It is connected to the process control device 1 and / or the process input / output device 3. CPU6
01 executes various programs stored in the memory 602 to realize various functions for maintenance and monitoring. For example, the maintenance / monitoring device 6 is directly (or
Process input / output device 3 (via process control device 1)
By accessing the memory, the nonvolatile memory device 302 has a function of rewriting the program and data stored in the non-volatile rewritable memory element 302. In addition, the program stored in the non-volatile rewritable memory element 302 and the information about the operating state of the process input / output device 3 are acquired and monitored 60.
5 has the function of displaying. Further, the nonvolatile rewritable memory element 302 is provided with a rewrite frequency management circuit 26 that counts the number of times of rewriting. The rewrite frequency management circuit 26 is actually the CPU 601 as well as other functions.
Is realized by executing a program stored in advance in the memory 602.

The operation of the maintenance / monitoring device 6 will be described below with reference to FIGS.
This will be described with reference to FIG. Here, the contents of the operation will be described separately.

(1) Display of operating state of process input / output device 3 The maintenance / monitoring device 6 acquires information indicating the operating state of the process input / output device 3 and displays it on the monitor 605 as a control logic diagram. . The information is as shown in FIG.
Via the process control device 1 (operating state signal 14),
Alternatively, the (operation status signal 16) is directly obtained from the process input / output device 3.

(2) Updating the process input / output program 8 The rewriting program 22 which is a new process input / output program is stored in advance in the memory 602 of the maintenance / monitoring device 6. As shown in FIG. 6, the rewriting program 22 is divided into N groups (group 22-1 to group 22-N). Further, the maintenance / monitoring device 6 includes a rewriting frequency management circuit 26 that counts the number of times rewriting processing is performed.

On the other hand, the nonvolatile rewritable memory device 30
As shown in FIG. 6, the area 2 is divided into a memory area 17 for storing a program and a rewrite frequency count area 21 for holding the rewrite frequency. Memory area 17
Is further divided into N small areas (area 17-1 to area 17-N). The above-mentioned rewriting program 22 is written in each area in units of groups. In other words, the group 22-1 is in the area 17-1, and the group 2 is in the area 17-2.
2-2 is stored.

The program is rewritten by shifting the process input / output device 3 to the rewrite mode and then transferring a new program to the non-volatile rewritable memory 302.

That is, the maintenance / monitoring device 6 outputs the program rewriting command 13 (or rewriting command 15) to the process input / output device 3 (see FIG. 5). The process input / output device 3 to which the program rewriting command signal 13 (15) is input shifts to the rewriting mode. After that, the transfer of a new program to be subsequently performed is basically performed in group units.

When the process input / output program 8 is partially rewritten, the maintenance / monitoring device 6 stores only the group containing the portion of the rewriting program 22 which is the rewriting target, in that group. Transfer to the area that should. Hereinafter, a detailed description will be given with reference to FIGS. 6 to 7.

When the maintenance / monitoring device 6 starts the rewriting process, as shown in FIG. 7, first, the rewriting frequency count area 21 of the nonvolatile rewritable memory 302 is accessed,
Check the number of rewrites until then. After checking the number of rewrites,
Start the program transfer. In this case, first, it is determined for each group whether or not it is a rewriting target. The determination is performed by determining whether or not the user has previously designated it as a target of the rewriting process. If it is not the target of rewriting, the process directly proceeds to the determination for the next group. If it has been rewritten,
Transfer the group to the corresponding area. 6 and 7
In the above example, only the group 22-2 is rewritten.

Upon completion of the determinations for all groups, the rewrite frequency management circuit 26 increments the rewrite frequency by 1. Then, this new rewrite count is
It is stored in the rewrite count area 21.

When the entire process input / output program 8 is rewritten, the same processing is performed to sequentially transfer all the groups constituting the rewriting program 22 (see FIGS. 8 and 9). That is, the maintenance / monitoring device 6 first transfers the group 22-1 of the rewriting program 22 to the area 17-1 of the nonvolatile rewritable memory element 302. When the transfer of the group 22-1 is completed, the group 22-2 is transferred to the area 17-2. Similarly, the remaining groups 22-3 to 22-N are sequentially transferred to the memory areas 17-3 to 17-N.

The same applies to counting the number of rewrites and updating the rewrite count area 21 by the rewrite count management circuit 26.

As a result of checking the number of times of rewriting, if the number of times of rewriting exceeds the separately determined number of times (1000 times in this embodiment), the rewriting is performed by the process input / output program 8
Maintain that fact regardless of whether it is a whole or a part of
The rewriting is stopped by displaying it on the monitor 605 of the monitoring device 6. By setting such a limit on the number of times of rewriting, it is possible to maintain the reliability of the stored contents of the nonvolatile rewritable memory element 302. The limited number of times is determined according to the failure rate of the memory used as the non-volatile rewritable memory element 302, and is stored in the memory 602 of the maintenance monitoring device 6.

While the program is being transferred (or the rewriting permission switch, which will be described later, is writing-permitted), regardless of whether the rewriting is the whole or part of the process input / output program 8, the process controller 1 and the process I / O device 3
Input / output of data between and is suspended. Further, the input from the process operation terminal s to the process input / output device 3 is also stopped. On the other hand, the process input / output device 3 holds the operating end drive signal 12 at the value (or a predetermined value) immediately before the start of the writing process. As a result, the influence of rewriting on the plant can be suppressed.

Although not particularly mentioned in the above description,
In this embodiment, a rewrite permission switch is provided so that the process input / output program 8 or the like is not lost due to an erroneous operation. The rewrite permission switch can be realized by either hardware or software. An example of each is shown in FIG.

The rewrite permission switch 28 provided in the main body of the process input / output device 3 is composed of hardware.
Normally, the rewrite permission switch 28 is set to the "non-permission" position. In this state, the maintenance / monitoring device 6 sends a rewrite command 1
3 (15) comes, non-volatile rewritable memory 302
Cannot rewrite the data in. When rewriting the programs and data in the non-volatile rewritable memory 302, the rewriting permission switch 28 is manually switched to the "permission" position before sending the rewriting command 13 (15).

The rewrite permission switch 27 provided in the maintenance / monitoring device 6 is realized by software. The rewrite permission switch 27 limits the function of the maintenance / monitoring device 6 unless a separately determined keyword is input. Here, the rewriting program or the like to the process input / output device 3 cannot be transmitted unless this keyword is input.

In the example of FIG. 10, the rewrite permission switch 28 (hard switch) and the rewrite permission switch 27 (soft switch) are used together for the sake of more certainty. Therefore, if either one of them is not unlocked, the data in the non-volatile rewritable memory element 302 cannot be rewritten.

In the process control system of the embodiment described above, the circuit is made into software, so that the relay circuit and the like are not required, and the process input / output device and the entire process control system can be downsized.

By reading the operation signal of the process input / output device or the like, the operation state can be easily confirmed. The improvement in the visibility of the plant control operation leads to the improvement of the plant monitorability and the quicker response to the plant abnormality.

Since the non-volatile rewritable memory element is used, the software can be rewritten corresponding to the circuit change, and the maintainability is high. Further, since the software is not lost even when the power fails, there is no need to rewrite the software after the power failure. If the number of times of rewriting is small, the possibility of error occurrence at the time of writing becomes small, and therefore the reliability becomes high. By setting a limit on the number of rewrites, the reliability of software retention is further enhanced.

Since the write permission / prohibition switch is provided, the software is not inadvertently changed, so that the process control is highly safe.

Since the immediately preceding value is output during the software update process, the plant is not disturbed even during the update and the safety is high. In the above-described embodiment, the process input / output device 3 is used. Among the functions (circuits) included in the above, only the normal drive condition processing circuit 30 and the protection drive condition processing circuit 31 are made into software. However, the operating end drive circuit 32 may also be software.

Further, the operating end control signal 10 to be described later determines whether or not the process operating end s can be normally operated. The criteria and conditions are the operating end drive input from the process operating end s. The permission signal 11b was used. However, these criteria and conditions may be separately input to the process input / output device in advance.

The "operating end" referred to in the claims corresponds to the process operating end s in the above embodiment. "Status information" means status signal 11a (condition signal 9)
Corresponds to the content contained in. The “operation content” corresponds to the content of the operation end control signal 10. The “input / output program” corresponds to the process input / output bypass gram 8.
The “non-volatile rewritable memory element” corresponds to the non-volatile rewritable memory element 302. "Arithmetic unit"
Corresponds to the MPU 301. What is "rewrite count value"?
This corresponds to the value stored in the rewrite count area 21. “Control permission condition” means the operation end drive permission signal 11
Non-volatile rewritable memory element 3 defined according to b
It corresponds to the criteria and conditions stored in 02. The "limitation mechanism" corresponds to a rewrite permission switch.

[0064]

As described above, according to the present invention, a process input / output device having high reliability, maintainability and visibility can be obtained. In addition, the number of wiring steps, wiring mistakes, and inspection steps in the manufacturing process can be reduced.

[Brief description of drawings]

FIG. 1 is a process input / output device 3 according to an embodiment of the present invention.
It is a figure which shows the whole structure of the process control system containing.

FIG. 2 is a process input / output device 3, a process control device 1,
3 is a diagram showing an internal configuration of a maintenance / monitoring device 6. FIG.

FIG. 3 is a diagram showing signals transmitted and received between respective units.

FIG. 4 is a diagram showing an outline of processing of a process input / output device 3 based on a signal flow.

5 is a diagram showing a signal flow in a protection / monitoring operation by the protection / monitoring device 6. FIG.

FIG. 6 is a diagram showing how a part of the memory area 17 is rewritten.

FIG. 7 is a diagram showing a procedure of rewriting a part of a memory area 17.

FIG. 8 is a diagram showing how the entire memory area 17 is rewritten.

FIG. 9 is a diagram showing a procedure for rewriting the entire memory area 17.

FIG. 10 is a diagram showing the rewrite permission switches 27 and 28 of the nonvolatile rewritable memory element 302.

[Explanation of symbols]

1 ... Process control device, 2 ... Bus, 3 ... Process input / output device, 6 ... Maintenance / monitoring device, 7 ... Process control program, 8 ... Process input / output program, 9 ... Condition signal, 10 ... Operating end control signal , 11a ... Status signal, 11b
... operation end drive permission signal, 12 ... operation end drive signal, 13 ...
Program rewriting command, 14 ... Operating state signal, 15 ... Program rewriting command, 16 ... Operating state signal, 17 ... Memory area, 21 ... Rewriting count area, 22 ... Rewriting program, 27 ... Rewriting permission switch, 28 ... Rewriting permission switch , 30 ... Normal drive condition processing circuit, 31 ... Protective drive condition processing circuit, 32 ... Operating end drive circuit, 101 ... CPU,
102 ... Volatile rewritable memory device, 103 ... Bus,
301 ... CPU, 302 ... Non-volatile rewritable memory device, 303 ... Bus, 601 ... CPU, 602 ... Memory,
603 ... Bus, 605 ... Monitor, s ... Process operation end

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Yasuhiro Asahi 5-2-1 Omika-cho, Hitachi-shi, Ibaraki Hitachi Ltd. Omika factory

Claims (6)

[Claims] 1. A process control system for operating a plant by operating the operating end of the plant, input processing for receiving input of status information indicating the state of the plant, and operation of the operating end determined separately. The process input / output device includes a process input / output device for performing an output process of instructing contents to the operation terminal, and a process control device for determining the operation contents based on the state information received by the process input / output device. The device is configured to include at least a nonvolatile rewritable memory device storing an input / output program defining the contents of the input process and the output process, and an arithmetic unit for executing the input / output program. A process control system characterized by: 2. A maintenance monitoring device, which is directly or indirectly connected to the process input / output device and which performs a reading process and a rewriting process of the stored contents of the nonvolatile rewritable memory device, further comprising: The process control system according to claim 1. 3. The non-volatile rewritable memory element comprises:
Further, a rewrite count value indicating the number of times the rewrite processing has been performed is stored so far, and the maintenance monitoring device confirms the rewrite count value when performing the rewrite, and as a result of the confirmation, 3. The process control system according to claim 2, wherein the rewriting process is performed and the rewriting number value is updated only when the rewriting number value is less than or equal to a separately set limit number. 4. The process input / output device outputs predetermined operation contents to the operation end while the rewriting process is being performed. Process control system. 5. The process input / output device is provided with a control permission condition separately determined for each operation end, and the operation content is input only when the operation content input from the process control device satisfies the control permission condition. It outputs to the said operation end, The process control system of Claim 4 characterized by these. 6. The process control system according to claim 5, wherein at least one of the maintenance monitoring device and the process input / output device comprises a limiting mechanism for limiting execution of the rewriting process.