JPS60229106A - Real time correction type programmable logic controller - Google Patents

Abstract

PURPOSE:To correct a sequence program contained in a programmable logic controller during on-line control without giving an evil effect to a plant, by adding a buffer memory which stores and correct programs. CONSTITUTION:Programs 111-11N so far executed are stored in an SPM11. When the program 112 is corrected, an area of the program 112 or a key instruction word is designated. Then a CPU in a programmable logic controller PLC copies the program 112 to a buffer memory 15 for correction and produces a new program 151. This program 151 is corrected on the memory 15 and in an idle period after execution of programs 111-11N. In this case, a program group of the SMP11 including the program 112 is used to control a plant. When the correction of the program 151 is over, this program is executed with operation of a switch 36 set on a setting device 3.

Description

[Detailed Description of the Invention] [Field of Application of the Invention] This invention relates to a plant that operates online using a programmable logic controller (hereinafter abbreviated as PLC) as a control device, especially a plant where sequence programs in the relevant PLc are frequently modified or changed. Regarding PLO that controls.

[Background of the invention]

In an online control system using a PLO as a control device, when modifying the sequence program in the PLC, if the program is modified while in the online control state,
It is possible that this may have an adverse effect on the plant to be controlled.

An adverse effect is, for example, the target plant going out of control or, conversely, stopping.

Therefore, conventionally, modifying a currently running program while online means changing the settings of timers, counters, etc., or replacing one command word with another. It was limited to about. Changing a set value or rewriting only one instruction word can relatively easily determine the impact on the plant, and the internal process of rewriting the memory that stores the set value and instruction word can be done instantly. Because it is done. Furthermore, since the modification does not increase or decrease the program size, there is no need to move each instruction word (details will be described later).

Generally, modifying a program often involves making minor changes to the program, and it is difficult to understand the impact it will have on the plant. Furthermore, if there is an increase or decrease in the number of command words in the modified program, each command word in the program following the modified program must be moved. If the program is executed during the move, the state of the program is incomplete, so it is inevitable that it will not adversely affect the plant or the like. For this reason, when modifying a general program, the plant operation has been temporarily halted to make the modification. The problem with the conventional method is that it is impossible to modify the program while online control is being executed. Another way to correct the program is to cohesively transfer the program you want to modify to another PLC that is not in online control, and after making the modifications, use Simulation Depack to confirm that the modified program is normal. , the PLC in online control state
One possible method would be to restart the embedded plant in a short period of time. This method requires another PLC, and the problem that the plant operation must be stopped once the modified program is incorporated into the PLC under online control remains unsolved.

[Purpose of the invention]

An object of the present invention is to solve such problems and to make it possible to modify a sequence program currently in operation in a PLC during online control without adversely affecting the plant.

[Summary of the invention]

In the present invention, when modifying a program during execution of online control, the part to be modified is temporarily saved in a modification save area, and the program can be modified there. Until the modification of the program is completed, the CPU continues to execute the program before modification without stopping online control. After modifying the saved program and checking its operation, run the CPU.
This provides a means to instantly change from a program before modification to a program after modification. If there is a problem with the modified program or an abnormality occurs in the plant, it is possible to instantly switch back to executing the original program.

[Embodiments of the invention]

(1) Conventional example Figure 1 shows a conventional PLC and programming device (hereinafter referred to as
This figure shows the rough configuration of the PSE (abbreviated as PSE).

PLClooI is a processing device (hereinafter abbreviated as CPU) 8
, a process input/output control device (hereinafter abbreviated as PIOCE) 9, and a process input/output device (hereinafter abbreviated as PI3) 1
0, Sequence program storage memory (hereinafter referred to as 8PM
) 11, a data bus 12, an address bus 13, and a data transmitting/receiving device 7. Also, PIO
The CE9 has a built-in buffer memory 90, which can be accessed from the CPU8.

This memory 90 is connected to the plant 40 to be controlled and the PIOI
It can be connected via PSElooO and used to exchange input/output data between the plant 40 and PIClooO, or it can be disconnected from the plant and used to transfer input/output data from the plant directly from PSElooO. It is also possible to input. The data input by humans here can also be used as plant pseudo input data for simulation debugging of sequence programs.

Furthermore, this memory is used for temporary storage of various input/output data within the CPUB.

Now, P8E1000 connected to PLClooI via communication line 13 includes firmware 1, data transmitter/receiver 9t2, setting device 3, CR'r4, and display work memory 14.
, a data bus 5, and an address bus 6. The setting device 3 also includes processing mode switching buttons 31 for the sequence program, such as circuit creation correction mode A311, circuit readout mode 33312, input/output setting mode C313, simulation debugging mode D314, output state change display mode E315, etc. A branch button 32 that specifies a branch, which is a command word of a sequence program, a contact button 33 that specifies whether it is a contact or a coil, a contact number button 34 that specifies a contact number, and a contact difference button 35 that sets the on/off state of the contact. , has been installed. Further, the firmware 1 includes software that operates as shown in the flowchart of FIG. 2 in the form of a ROM.

A method for modifying a sequence program in a conventional PLC will be explained. PLClool as shown in Figure 1 is
Assume that you are performing online control of a specific plant. Assume that it becomes necessary to modify the sequence program in SPMII. In this case, the operator first
From among the processing mode switching buttons 31 on the setting device 3 of the E1000, select and press the program creation/correction button A311. Then, the software in the firmware 1 looks at the plant control status of PLClooI, and if online control is in progress, it will not be able to accept any program modification operations. This is as shown in Figure 2. For this reason, operators must
The operation must be stopped, the connection between PIOCE9 and PIOIO must be disconnected, and the online control state of PLClooI must be released, as shown in FIG. After the release, the program can be modified. After that, when you have finished modifying the program, press the simulation button 314 of the mode switching button 31 on the setting device 3, and only after confirming that the modified program is normal.
Connect PIOCE9 and PIOIO, restart the plant, and start online control of the plant by PLClooI.

A major problem is raised here. In other words, when modifying a 7-can program that is currently in operation, the plant must be stopped during the modification operation. This can be dealt with if the plant's operation is temporarily stopped, but conventional methods cannot deal with plants that are intangible and constantly in operation all year round. Also, even if the plant is temporarily shut down,
Interactive program modification and simulation debugging usually require several minutes to several hours, and only in plants where there is sufficient time for this.
This means that it can be handled using conventional methods.

The present invention was made to solve this problem.

Here, for ease of explanation, the types of plants to be controlled by PLO will be defined. First, let Pl be plants that are intangible and always in operation all year round. Next, plants may be stopped temporarily, but the stoppage time is not long enough to make program corrections possible.
Let it be P2. Finally, let P3 be a plant whose stop time is sufficient to modify the program. When categorized in this way, plants whose programs can be modified using the conventional method are limited to those belonging to P3. The present invention applies not only to plants belonging to P3, but also to plants belonging to P3.
The purpose is to make it possible to modify the sequence program that controls the plants belonging to P1 and P2, in other words, to make it possible to modify the program during online control.

As a means for that purpose, in the present invention, as shown in FIG. A PS having an execution changeover switch 36 for switching the execution of
Use E.

Further, the buffer memory 15 for program correction can be expanded.

(2) Examples of the present invention The present invention will now be described in detail by way of examples. Fifth
The figure shows how the program modification buffer memory 15 and the execution changeover switch 36 are used. 8PM11 has programs 111 to 11N that have already been created and have been executed up to that point, and one of them is currently running.
Suppose that 12 programs need to be modified. In that case, program 1 that the operator would like to modify using PSE
If you specify the 12 areas or representative command words,
The CPU 8 of PLClooI copies 112 to the correction buffer memory 15 and creates a new program 151. Modification of the copied program 151 can then be started on the modification buffer memory 15. Processing such as copy correction can be performed in the free time until the CPU 8 finishes executing the programs 111 to 11Nt in the SPMII (that is, finishes one scan process) and starts the next scan cycle (usually when the PLC is running). Scan cycle activation is every 10 msec to 100 msec). Alternatively, it is also possible to provide a separate processing device exclusively for correction.

While the program 151 is being modified on the modification backup memory 15, the plant is controlled by a group of programs in the SPMII including the program 112 before the modification. Therefore, when modifying the program 151 interactively, there is no time limit at all. However, in the firmware 1 of PSElooo, the circuit creation/modification mode cannot be selected during online control (FIG. 2), but in the present invention, such an operation check must be eliminated.

After the modification of the program 151 is completed, the execution changeover switch 36 on the setting device 3 of the PSE 1000 is used to switch from execution of the program 112 before modification to execution of the program 151 after modification.

(Rotate from 36'ea to b in Figure 5). As a result, the program 111 that is controlling online
When the process reaches 112 in the execution of steps 11N to 11N, the modified program 151 is executed instead of 112. This process will be described next.

When the CPU 8 finishes processing the program 111, the above modification can be executed simply by setting the start address of the modified program 151 in the program counter. As a result, when the CPU 8 finishes processing the program 111, it jumps to the program 151 and continues processing. When the program 151 has been executed to the end, the program counter is operated in the same manner again to return the process to SPMII program execution. In the example of FIG. 5, program 113 will be executed. In this way, it is possible to transfer the execution of processing from the program 112 before modification to the program 151 after modification. Possible methods of operating the program counter include using a jump instruction, jump destination address, and return destination address storage memory.

If there is a problem with the modified program and even the slightest abnormality is observed in the plant, immediately return the execution selector switch 36 to its original state (from b to a in Figure 5) to correct the plant control. This is done in the previous program. In FIG. 5, the execution is not transferred to the modified program 151 on the modification buffer memory 15, but control is performed using the original programs 111 to IIN. The modified program 151 that has a problem can be modified again. In this way, program modification and debugging can proceed at the same time.

- If you want to avoid instantaneous abnormalities in the controlled object, install a new PIOCE 16 (Fig. 6), set the execution selector switch 36 of the setting device to "simulation" mode C, and process pseudo input data. Enter and perform all simulation debugging.

All of these processes are performed during the idle time of the online control process of the CPU 8. Simulation debugging is finished,
After it is confirmed that the modified program is normal, if the execution changeover switch 36 is set to the "modified program execution" mode b, the modified program 151 as described above is executed and this control is started. In this way, the program can be modified during online control, and
A transition to control by the modified program is made.

Next, the movement process will be described. Program 11 before modification
2 (Figure 5) was not well received, 82M1
1 and the area is wasted.

In order to eliminate this, 151 programs on the correction buffer memory 15 that are newly executed are replaced with 8 programs that are no longer needed.
It is necessary to move to the area of 112 programs on M11. However, if the capacity of the program before modification and the program after modification are different, and there is a difference in the storage area size, it is necessary to move the existing program (FIG. 7). If the capacity of the modified program 115 increases by R18 due to modification of the program 112,
Existing programs 113-11N must be moved by R later. Since the program cannot be executed during this moving process, it is necessary to temporarily stop the operation of the plant (required time = θ~several seconds). Plants with temporary downtime P2. Regarding P3, movement processing can be performed during the stop time.

The movement process is performed by adding a program with a processing flow as shown in FIG. 8 to the firmware 1 shown in FIG. Specifically, it is inserted after the processing block E in FIG. Additionally, F3161 is newly provided in the mode switching button of the setting device 3 (FIG. 9), and movement processing is started by pressing this button.

This results in siblants P2. P3 can be dealt with.

For plants P1 that are always in operation, this moving process is not performed, and the modified programs 151 are left in the modification buffer memory 15 (mode d of "modified program fixed execution" in FIG. 5). A jump instruction is set at the beginning of the program 112 before modification, and the CPU
When the process always reaches that address, the modified program 151 is executed (FIG. 10). Thereafter, even if the execution switch is switched to the "normal execution" mode shown in FIG. 5a, the modified program 151 is executed unconditionally because the jump instruction has been inserted. If it becomes necessary to modify another program, the modification can be made in the same manner as described above using the empty area of the modification buffer memory 15. If this type of program modification is performed and the modification buffer memory 15 becomes full, more memory may be added.

〔Effect of the invention〕

By providing a PLO that allows modification of the control program during online control, it is possible to avoid stopping the operation of the controlled object.

[Brief explanation of the drawing]

Figures 1 and 3 show the conventional PLO and PSEk, Figure 2 shows the operation of the firmware in the PSE, Figure 4 shows the configuration of the PLC and PSE of the present invention, and Figure 5 shows the program. Figure 6 shows the modification and execution process, Figure 7 shows the process for moving the modified program, Figure 8 shows the additions to the PSE firmware, and Figure 9 shows how to debug the modified program. 1 is a diagram showing a setting device, and FIG. 10 is a diagram showing specifications for fixed execution of a modification program. 1000...PSE, 1001...PLC, 1...
・Firmware, 2...Data transmitting/receiving device, 3...
- Setting device, 36... Execution selector switch, 15...
-Buffer memory for correction. Agent Patent Attorney Akio Takahashi No. 7 Condolences and Diagram Q

Claims (1)

[Claims] 1. A CPU that processes a process sequence, an input/output device for the process, a buffer memory provided between these for storing input/output data of the sequence, and a program for the sequence. What is claimed is: 1. A real-time modification programmable logic controller comprising a memory for storing programs, the programmable logic controller having a buffer memory for storing and modifying programs.