JPH01169504A - Programmable controller - Google Patents

Abstract

PURPOSE:To start the execution of a program from the leading address of a stopped circuit by calculating the leading address of an instruction at a stopped step based on a step number obtained at the time of stopping the program execution and a changed program. CONSTITUTION:A PC processor 1 has a CPU 1A, a ROM 1B, a RAM 1C, etc., and executes control relating to PC and a programming device 2 executes programming while forming a rudder graphic displayed on a display part 2A by an input through a key 2B. The change of a program is stored in the RAM 1C and the step number at the time of stopping program execution is stored. The leading address of the instruction at the stopped step is calculated based on the step number at the time of stopping the program execution and the changed program. When the contents of a program counter are rewritten based on the calculated leading address, program execution can be started from the leading address of the stopped circuit.

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 specifically relates to continuous execution processing of a PC program.

[Conventional technology] Conventionally, functions of created user programs and PC
It is known to perform test execution of a user program in order to know the operating state of the program. In such a case, it may become necessary to depack the program, and a continuous execution process may be performed in which program execution is stopped midway or restarted from midway.

FIG. 4 is a flowchart showing a conventional example of the above-described continuous execution process. As is clear from the figure, step 5
In step S31, it is determined whether to continue or start execution of the user program, and if the determination is affirmative, the process advances to step S32, where the instruction at the address indicated by the program counter is executed.

Note that settings for continuing or starting program execution are made manually during programming, etc., and if there is human effort to stop the execution, the process advances to step 533 and the execution of the program is stopped.

[Problems to be solved by the invention] However, when program execution is stopped midway, the program is changed by depacking, etc., and then execution is started from the middle of the program, the instruction at the address indicated by the program counter is not executed. The command may be different from the one given when the machine was stopped. As a result, there is a problem that execution starts from a step, that is, from the middle of the circuit on the ladder diagram, making the operation of the circuit uncertain.

FIG. 5 is a ladder diagram for explaining the above-mentioned problem. In detail, FIG. show. As shown in FIG.
Suppose you stop execution with .゛After that, if the two contacts Bl and B2 of the fifth circuit are deleted by changing the program, when the program execution is restarted and the instruction at the address indicated by the program counter is tried to be executed, the same result as shown in the same figure (B)
As shown in the figure, program execution is restarted from the instruction at the third address of the 100th circuit.

As is clear from the above, there is a problem in that execution is not restarted from the instruction whose execution has been stopped.

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to solve the above-mentioned conventional problems and provide a programmable controller that can execute instructions from the start address of the circuit, rather than from the middle of the circuit, even if the user program is changed. It is in.

[Means for Solving the Problems] To this end, the present invention provides a programmable controller in which program execution is performed by sequentially executing steps consisting of a group of instructions, in which a change in the program is detected. A change record jQ means for storing, a step number recorder for storing the step number when the program execution is stopped, a 0 means, and a change memory means for recording the change in the program when the program is stopped. A start address calculation means for calculating the start address of the instruction in the stopped step based on the step number and the program after the change, and a rewriting means for rewriting the contents of the program counter based on the calculation result of the start address calculation means. It is characterized by

[Operation] According to the above configuration, when program execution on the PC is stopped and program execution is restarted, execution is started from the instruction at the top address of the circuit where the program was stopped.

[Example] Hereinafter, an example of the present invention will be described in detail with reference to the drawings.

FIG. 1 is a block diagram showing the configuration of a PC according to an embodiment of the present invention. In the figure, 1 is a processor of the PC, which includes a CPUIA, ROMIB, RAMIC, etc., and controls the PC. The RO old B stores processing procedures etc. which will be described later in FIG. 2, and the RAMIC has an area where a user program is written and a work area which functions as a circuit counter and an instruction counter which will be described later.

Reference numeral 2 denotes a programming device, which includes a display section 2A and keys 2B, and performs programming while creating a ladder diagram displayed on the display section 2A by human power using the keys 2B. Further, the programming device 2 manually controls the stopping and starting of the PC operation using the key 2B. Reference numeral 3 denotes an input/output device, which is located between various devices connected to the PC and the processor 1 and controls data input/output.

FIGS. 2(A) and 2(B) are flowcharts of continuous execution processing according to an embodiment of the present invention, and this processing is started to check the functions of the created user program and to know the operating status of the PC. It is processing.

In FIG. 2 (8), in step 51, it is determined by a flag whether or not there has been a change in the user program;
If the determination is affirmative, the process proceeds to step S2, where circuit start address calculation processing is performed, and in step S3, the program counter is rewritten based on the above calculation result, and after the above flag is lowered, the process proceeds to step S4. Also, if the determination in step 51 is negative, the process proceeds to step S4.

In step S4, it is determined whether to continue or start execution of the user program.

That is, it is determined whether or not the command to stop execution has been manually issued, and if the determination is affirmative, the process proceeds to step S5.
Executes the instruction at the address indicated by the program counter.

In the case of a negative determination in step S4, the process proceeds to step S6, where the program execution is stopped, and the number of the circuit that was stopped is stored in the RAMIC in step S7, and this process is ended.

FIG. 2(B) is a flowchart showing the details of the circuit start address calculation process described above, and FIG. 3 is a ladder diagram for explaining the aspect of program counter rewriting.

Details of the circuit start address calculation process shown in FIG. 2(B) will be explained with reference to FIG. 3. First, step S21
Then, the contents of the circuit counter indicating the circuit number and the instruction counter indicating the address of the instruction are set to 1 and O, respectively. By the way, this 1 indicates the first circuit, and 0 indicates the RAM.
Indicates the first address of the instruction stored in the IC. Also,
Among the instructions stored in the RAMIC, the last instruction of each circuit has predetermined information indicating that it is the final instruction, for example, the logic of a predetermined bit is "1".

Next, in step S22, it is determined whether the contents of the circuit counter match the stopped circuit number, and in the case of a negative determination, the process advances to step S23, where the instruction at the address indicated by the instruction counter is read from the RAMIC, and the step S
In step 24, it is determined whether the read instruction is the final instruction of the circuit. If the determination is negative, the contents of the instruction counter are incremented by 1, and if the determination is affirmative, the contents of the instruction counter and the circuit counter are incremented by 1 and the process returns to step S22.In step 522,
If the contents of the circuit counter match the number of the stopped circuit, this process ends.

Through the above-described processing, even if the second instruction of the fifth circuit is deleted due to a change in the user program as shown in FIG. 3, the contents of the instruction counter will indicate the starting address of the stopped 100th circuit. As a result, if the contents of the program counter are rewritten based on the contents of the instruction counter, when program execution is restarted, the instruction will be executed starting from the instruction at the top address of the stopped circuit.

[Effects of the Invention] As is clear from the above explanation, according to the present invention, the PC
When program execution is stopped and program execution is started again, execution starts from the instruction at the top address of the stopped circuit.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing the configuration of a PC according to an embodiment of the present invention, FIGS. 2A and 2B are flowcharts showing continuous execution processing according to an embodiment of the present invention, and FIG. FIG. 4 is a flowchart showing a conventional continuous execution process; FIG. 5 is a ladder diagram showing an example of a conventional continuous execution operation. 1...processor, IA...cpu. 1B...ROM1 1C...RAM. 2... Programming device, 2A... Display unit, 2B... Key, 3... Input/output device. To '7 and 47y1j -), -1 pro PC configuration request,
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Claims (1)

[Claims] In a programmable controller in which a program is executed by sequentially executing steps consisting of a group of instructions, a change storage means for storing a change in the program; step number storage means for storing a step number at the time of the stop; and when the change storage means stores a change in the program, the step number at the time of the stop is determined based on the step number at the time of the stop and the program after the change; A programmable controller comprising: a start address calculation means for calculating the start address of the instruction; and a rewrite means for rewriting the contents of a program counter based on the calculation result of the start address calculation means.