JPS62162106A - Program changing method for programmable controller - Google Patents

Abstract

PURPOSE:To improve general useability and versatility of a PC by making partial change of a user program while continuing controlling without interrupting operation of the PC. CONSTITUTION:A new changed program consisting of four words is prepared in a memory 3, and information to the effect that the program of four words is replaced by one word instruction a of existing program is inputted. No operation instruction is added to the end of the existing program in a memory 5, and the position of NOP instruction is shifted little by little to lower address. The specified position is behind an instruction a of changed position. The valve of increased number of words n is subtracted by 1, and when it does not become zero, one NOP instruction is added further, and the NOP instruction is shifted successively to lower address, and placed behind preceding NOP instruction. Above-mentioned processes are repeated until it becomes n=0, and consequently, three NOP instructions are placed behind the instruction a of changed part of the existing program.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a programmable controller (hereinafter referred to as a PC), and particularly relates to a method for partially changing a user program without interrupting the execution of the program.

(Prior art) In a PC, by repeatedly executing a user program,
The new logic of the control output signal group is determined according to the logic changes and history of the control input/output signal group. The shorter the repetition period of the user program execution process, the higher the tolerance between control input and output signals, and the better control can be performed.

In addition to executing user programs, it also connects to peripheral devices such as programming consoles, printers, and display devices, and performs signal processing such as processing given commands and exchanging data. It also handles system monitoring such as resetting watchdog timers and checking memory and buses. Furthermore, depending on the model,
Some PCs exchange data with other PCs.

As shown in FIG. 3, a general PC is configured to repeat user program execution processing, service processing, and other processing in order at high speed. 1 of all of these
The scanning time (TI + T2 + 3) is called the scanning time. The execution cycle of the user program, which determines control responsiveness, is determined by this scan time. Therefore, the time T2 for service processing and other processing time T3
By shortening 1, the gap time will be shortened and control responsiveness will be improved.

In normal operation, the allotted time 2 for service processing 1-2 is determined by a timer to the minimum necessary short constant time. For commands that cannot be completed in one service process, the service process is repeated several times.

In a PC with the above-mentioned @conditions, when changing the program while a user program is being executed, the program in the execution area must be changed in one service process.

If a program is gradually rewritten through multiple service processes, a program that is not being rewritten (the logic does not match or the flow of logic is interrupted) will be executed, and as a result, the program that is not intended to be controlled will be executed. This could lead to an operating condition that could be extremely dangerous.

(Problem to be Solved by the Invention) In a conventional PC, the process of creating a program to change to a free area of memory cannot be performed by time-sharing processing that intermittently repeats the above service process within the allocated time. can. However, a problem arises when incorporating (rewriting) the modified program prepared in this way into an existing program that is currently being executed.

For example, as shown in FIG. 4 (Δ), a problem occurs when a one-word instruction a in an existing program is replaced with a four-word modified program. This change causes an increase of 3 edicts, but all programs after instruction a must be moved by 3 words accordingly. The process of moving a large number of instruction words on memory in this way takes a lot of time. This process takes considerably longer than the allotted time for one service process.

Therefore, in the past, in many cases it was not possible to change the program in parallel with the execution of the user program, and when changing the program, even if it was a simple partial change, the execution of the user program was temporarily changed. had to be interrupted. In other words, I had to temporarily stop running my PC.

This invention was made in view of the above-mentioned conventional problems, and its purpose is to provide a program that allows partial modification of a program without interrupting the execution of the user program.
The purpose of this invention is to provide a method for changing C programs.

(Means for Solving the Problems) Therefore, in the present invention, a change program is prepared in an empty area of memory by time-sharing processing that intermittently repeats the above V-vis processing within the allocated time, and this change program is Add no-operation instructions corresponding to the increase in the number of instruction words caused by incorporating them into the existing program being executed to the end of the existing program and move them to the embedding position, and then execute the above-mentioned service processing once to add the no-operation instructions to the end of the existing program. The method was to rewrite the part containing the above using the above modification program.

(Example) As shown in FIG. 1, a PC according to the present invention has a CPU (
arithmetic processing unit) 1, system program memory 2, system working memory 3, programming console 4, user program memory 5, and data memory 6
, an input circuit 7, an output circuit 8, and a timer 9.

A number of control human signal sources are connected to the input circuit 7. The output circuit 8 has a large number of control output signal relays, to which devices to be controlled are connected. The control output signal V given to the input circuit 7; the important thing is that it is once taken into the data meter 6 and sent to the performer)
The data memory 61. : Output the generated control output signal 8T from the output circuit 8 to the outside. By repeatedly executing the user program stored in the memory 5, the CPU 1 determines a new logical change in the control output group according to the logical change in the control output signal group and the history.

FIG. 2(A) shows the overall operation of a PC to which the present invention is applied. Steps 201-2 in FIG. 2 (A>
04 is the execution process of the user program described above. In step 201, the control input signal from the input circuit 7 is taken into the data memory 6.

In step 202, one instruction of the user program is executed, and in step 203, each instruction is sequentially executed until the END instruction set at the end of the user program is detected. When the user program runs one line up to the END command, the control output signal of the data memory 6 is transferred to the output circuit 8 in step 204.

When the above user program execution process is completed once, the timer 9 is started in step 205, and the process moves to the service process in step 206. The above-mentioned timer 9 defines the allotted time for service processing. When timer 9 times out, a timer interrupt is generated as shown in step 207, and the service processing is interrupted at this point. ) is saved in the system working memory 3 in step 208, and the process moves to user program execution processing in steps 201 to 204.

In this way, user program execution processing and service! l! l PI! are repeated in order.

In the service process 206, the programming console 4
Processes commands given from . Work that cannot be processed in one time allotted time specified by the timer 9 is divided into several service processes and executed, as has already been repeatedly explained.

When changing a program, the user first operates the keyboard of the programming console 4 to create a new changed program in an empty area of the system working memory 3, and inputs which part of the existing program the changed program is to be incorporated into.

In the example of FIG. 4A, input is made to create a new change program consisting of four words in the memory 3 and to replace this four-word program with the one-word instruction a of the existing program. This input is accepted by service process 206.

After the above operation, a command to start changing the program is given on the console 4. Then, the process shown in FIG. 2(B) is executed as the service process 206 in FIG. 2(A).

First, in step 301, it is determined whether the number of command words will increase as a result of the program change to be performed from now on. If the number of books increases, the increased number n of books is calculated in step 302. In the example of FIG. 4(A), n=3.

Next, in step 303, as shown in FIG. 4(B), a no-operation instruction (an instruction that does virtually nothing, hereinafter referred to as a NOP instruction) is added to the end of the existing program (currently being executed) in the program 5. ) is added. next step 30
In step 4, the position of the NOP instruction is sequentially moved to smaller addresses little by little. In the next step 305, N
It is determined whether the OP command has reached the predetermined position, and if it has not reached the predetermined position, the process returns to step 304. The predetermined position is as shown in Figure 4 (B
), this is after the changed instruction a.

Next, in step 306, the value of the increased number of words n is decreased by 1,
In step 307, it is determined whether the subtraction result is a leak. If it is not an empty mouth, return to step 303 and add a NOP command of 1 ([!ll), and
Move the P instruction to the younger address one by one, and move the previous NOP
After the command.

The above process is repeated until n=o. As a result, in the example of FIG. 4, as shown in (C), three NOP instructions are placed after the instruction a at the changed location in the existing program.

The processing up to this point is executed by time-sharing processing using the timer 9. Therefore, the user program (existing program) containing the NOP instruction is executed, but N O
) command has no effect on control, so there is no problem.

If YES is determined in step 307, interrupts by timer 9 are prohibited in step 308, and step 30
Proceed to 9 and write the command a and the 3 flW (7) N Ol) command for a total of 4 words! Rewrite with the provided modification program. After that, the scheduler 310 cancels the prohibition of timer interrupts.

The fact that the program rewriting routine 309 is executed with timer interrupts disabled does not mean that this process takes time. Since the word lengths of the changed part and the changed program are aligned in advance, routine 309 can be performed in a short time. However, if timer interrupts are not prohibited, there is a possibility that a timer interrupt will occur during the processing of routine 309, depending on the midpoint of the previous processing. To eliminate this possibility, timer interrupts are prohibited.

(Effects of the Invention) As explained in detail above, according to the present invention, the operation of the PC can be continued without interrupting the operation of the PC, and while the side listening operation is continued.
Since it is possible to partially change the user program, l) C
further improves its versatility and flexibility.

[Brief explanation of drawings]

Figure 1 is a block diagram of a PC according to the present invention, and Figure 2 (A
), (B) is a flowchart A7-chart showing the operation of the above PC,
Figure 3 shows the operation of a general PC, Figure 4 (A),
(B) and (C) are explanatory diagrams of examples of program changes. 1...CPLJ, 3...System working memory, 4...Programming console, 5...User program memory, 9...Timer. Patent Applicant Tateishi Electric Co., Ltd. Agent Patent Attorney Iwa Hyakuji (1 other person) 4th Zuhi [4) B Riram

Claims (1)

[Claims] (1) In a programmable controller that repeats user program execution processing and service processing that processes commands from a programming console in sequence at high speed, free memory is created by time-sharing processing that intermittently repeats the above service processing within the allocated time. Prepare a modified program in the area, add no-operation instructions to the end of the existing program corresponding to the increase in the number of command words caused by incorporating this modified program into the existing program being executed, and move it to the embedding position. A method for changing a program in a programmable controller, characterized in that the portion including the no-operation instruction is then rewritten by the changing program by executing the service process once.