JPH07210403A - Task switching system - Google Patents

Abstract

PURPOSE:To provide a task switching system capable of shortening time required for task switching processing. CONSTITUTION:When execution right is applied from an operating system(OS) to a task T1, the task T1 executes a programmed instruction. After the lapse of 2ms from the application of the execution right to the task T1, the OS sets up a passage flag. When the flag is set up, the task T1 continues the execution of the instruction being executed, and at the time of ending the execution of the instruction, saves information obtained at the time of stopping the execution to a RAM 3 and stops the task execution. After the end of the saving of the information, the OS applies the execution right to a succeeding task T2. Since an instruction in executing is not stopped on the way and information to be saved to the memory can be reduced, time required for task switching can be shortened.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a task switching system for a programmable controller operating in a dedicated BASIC language.

[0002]

2. Description of the Related Art In the case of performing task processing in a programmable controller operating in a conventional BASIC language, an operating system OS sequentially gives execution rights to tasks T ₁ ... (Arrow a) as shown in FIG. Together with a task T ₁ being executed after a certain period of time (for example, 2 ms)
A command to stop the execution is given to (...) (arrow b), and the execution is stopped, and the information at that time is stored in the operating system OS.
Is saved in the memory (arrow c), and the execution right is forcibly transferred to the next task. In this way, from the first task T ₁ to the final task Tm, the execution right is sequentially and cyclically transferred under the control of the operating system OS, the respective tasks are executed, and the task whose execution right is returned is stored in the memory. The saved information is read and the continuation is executed.

[0003]

All of the above task switching is managed by the operating system OS, which is generally called a time slice method, but is executed in each task T ₁ . Since this is stopped for a certain period of time, the amount of information to be saved in the memory becomes large, and the process for saving the information takes time, resulting in a problem that the entire program takes time.

The inventions of claims 1 and 2 are made in view of the above problems, and an object of the invention is to provide a task switching system capable of shortening the time required for the task switching processing. is there.

[0005]

In order to achieve the above object, in the invention of claim 1, there are a plurality of tasks to be executed by the arithmetic processing device, and the execution right of each task is sequentially given to the arithmetic processing device. In a task switching system consisting of an operating system that executes each task in sequence,
In the operating system, a flag is set when a certain period of time has passed after the task execution right is given, and in the task that is executed with the execution right given, if there is an instruction that is being executed when the above flag is set, the task is executed after the instruction is completed Stop the task execution by yourself, save the information at that time to the memory,
The operating system is characterized in that the execution right is transferred to the next task after this saving is completed.

According to another aspect of the present invention, there is a plurality of tasks executed by the arithmetic processing unit, and task switching including an operating system for sequentially giving the execution right of each task to the arithmetic processing unit to sequentially execute each task. In the system, the task to be executed by giving the execution right stops the tax execution by itself when the execution of one instruction is completed and saves the information at that time in the memory. It is characterized by transferring the execution right to.

[0007]

According to the first aspect of the present invention, the operating system sets a flag when a certain period of time elapses after the task execution right is given, and the task which is executed with the execution right given is sometimes executed when the flag is set. If there is an instruction in the middle, the task itself stops task execution after the instruction is completed and the information at that time is saved in the memory, and the operating system transfers the execution right to the next task after this saving is completed. Since instructions are not stopped midway and the amount of information saved in the memory is reduced accordingly, the time required for task switching is shortened and the execution time of the entire program can be shortened.

According to the second aspect of the present invention, in the task executed by giving the execution right, when the execution of one instruction is completed, the task itself stops the tax execution and saves the information at that time in the memory. Since the system transfers the execution right to the next task after this saving is completed, the number of accesses to the task from the operating system is reduced, and the task is stopped when the execution of one instruction is completed. The amount of information saved in the memory is smaller than that in the case where the program is stopped in the middle of execution, the time required for the switching of the result task is shortened, and the execution time of the entire program can be shortened.

[0009]

FIG. 5 shows a basic configuration of a programmable controller using the present invention. This programmable controller is an arithmetic processing unit that performs arithmetic processing and control processing of the programmable controller based on an operating system and a user program. An RO that includes a CPU 1 and stores an operating system of a programmable controller and a system program.
It comprises an M2, a RAM 3 for storing a user program and securing a stack area and a work area, and an I / O interface 4 for connecting an external input / output device. The user program is written in a dedicated BASIC language, and the user program is divided into a plurality of tasks and processed by the operating system for multitasking. The present invention is a task switching system related to this multi-task processing, and the present invention will be described below with reference to embodiments.

(Embodiment 1) This embodiment corresponds to the invention of claim 1. FIG. 1 shows the concept of the task switching processing of this embodiment, and this embodiment will be described based on this FIG. First, in the present embodiment, when the program controller starts the program execution operation, the CPU 1 executes the user program under the control of the operating system OS. However, when the operating system OS performs multitask processing, each task is executed. To execute each task by giving execution right to
It has a function of setting a progress flag for a fixed time (for example, 2 ms has elapsed) after giving the execution right to the task. On the other hand, each of the tasks T _{1 to} Tm executes the programmed instruction if the execution right is given. When the elapsed flag is set, if there is an instruction being executed at that time, the task execution is continued until the instruction execution is completed, and after the instruction is completed, the task itself has a function of stopping the task execution.

When the execution right is given from the operating system OS (arrow a), the task to which the execution right is given, for example, the instruction programmed in T ₁ is executed. The operating system OS sets a progress flag at 2 ms after the execution right is given to the task T ₁ (arrow b ′). When this progress flag is set,
In the task T ₁ , if the instruction is being executed, the instruction is continued to be executed, and the information at the time of the stop is RA at the end of the execution of the instruction.
The task is saved in the stack area of M3 and the task execution is stopped (arrow c).

If no instruction is executed when the elapsed flag is set, task execution is stopped in task T _{1 and} the information at the time of stop is saved in RAM 3 (c). After the information saving is completed, the operating system OS gives the execution right to the next task T ₂ and sets a progress flag at the time point when 2 ms has elapsed, as described above. Task T ₂
In the same way as above, if the execution right is given, the programmed instruction is executed, and if there is an instruction being executed at the time when the above progress flag is set, the instruction execution is continued, and when the instruction execution is completed The information at that time is saved in the RAM 3. Of course, if the instruction is not executed when the elapsed flag is set, the task T ₁ saves the information at that time in the RAM 3 and stops the task execution. In this way, the above processing is repeated until the execution of the first task T ₁ to the final task Tm is completed, and when the execution of the final task Tm is completed, the entire program is not completed in the operating system OS. In this case, the execution right is returned to the first task T ₁ and the above processing is repeated. Here, in the task whose execution right has returned, the information saved in the RAM 3 at the end of execution of the previous task is read and the instruction next to the instruction executed the previous time is executed.

The above process is repeated until the entire program is completed. FIG. 2 shows a flowchart in which the CPU 1 performs the above-mentioned task processing. When the program execution is started, the CPU _{1 first} activates the task T _{1 and} the information from the stake of the task T ₁ (set in the RAM 3). To execute the instruction in the task T ₁ , and if there is an instruction that is still executing after 2 ms, execute the instruction and save the information to the stack of the task T ₁ when the execution of the instruction is completed. Then, the processing of task T ₁ is completed.

After that, the above processing is repeated until the final task Tm is completed. When the final task Tm is completed, it is judged whether or not the entire program is completed. Is returned to the first task T ₁ and repeated. As described above, in this embodiment,
2m set up by operating system OS
The task itself manages the timing of stopping the task execution based on the flag indicating the passage of s, and if there is an executing instruction, the task is not stopped until the execution of the instruction is completed.
The amount of information saved in AM3 can be reduced.

(Second Embodiment) In the first embodiment, the number of accesses to the task of the operating system OS is the same as the conventional example, but in the present embodiment, the number of accesses is also reduced. FIG. 3 shows the concept of the task switching processing of this embodiment, and this embodiment will be described based on this FIG.

First, in this embodiment, when the program controller starts the program execution operation as in the first embodiment, the CPU 1 executes the user program under the control of the operating system OS. When performing a task process, an execution right is given to each task to execute each task, and only an access to give the execution right to the task is performed. On the other hand, each task T _{1 to} Tm has a function of executing _one programmed instruction when the execution right is given and stopping the task execution itself when the instruction execution is completed.

When the execution right is given from the operating system OS (arrow a), _{one of} the programmed instructions is executed in the task to which the execution right is given, for example, T ₁ , and the execution of the instruction is executed. At the time of the end, the information at the time of the stop is saved in the RAM 3 and the task execution is stopped (arrow c). Operating system OS
Gives the execution right to the next task T ₂ after the information is saved. In task task T ₂ , one of the programmed instructions is executed when the execution right is given in the same manner as described above.
RAM at the time when the instruction execution is completed
Evacuate to 3. In this way, the above processing is repeated until the execution of the first task T ₁ to the final task Tm is completed, and when the instruction execution in the final task Tm is completed, the entire program is completed in the operating system OS. If not, the execution right is returned to the first task T ₁ and the above processing is repeated. Here, the task whose execution right is returned reads the information saved in the RAM 3 at the end of execution of the previous task, and executes the instruction next to the instruction executed the previous time.

The above processing is repeated until the entire program is completed. FIG. 4 shows a flowchart in which the CPU 1 performs the above-mentioned task processing. When the program execution is started, the CPU _{1 first} activates the task T _{1 and} the information from the stack of the task T ₁ (set in the RAM 3). the read and executed by one instruction instruction in the task T _1, that when the execution is completed instructions by removing all information to the stack of the task T _1, and ends the processing of task T _1.

Thereafter, the above processing is repeated until the final task Tm is completed, and when the final task Tm is completed, it is judged whether or not the entire program is completed. If it is not completed, the above task processing is executed. Is returned to the first task T ₁ and repeated. As described above, in this embodiment,
Access to the task T ₁ ... From the operating system OS only gives the execution right, and therefore the number of times of access can be reduced, and the task itself manages the timing of stopping the task execution, and each time the execution of one instruction is completed. Since the task is stopped, the task is not stopped during the execution of the instruction, and the amount of information saved in the RAM 3 can be reduced.

[0020]

According to the first aspect of the present invention, the operating system sets a flag when a certain time has elapsed after the task execution right is given, and the task executed with the execution right given is sometimes executed when the flag is set. If there is an instruction in the middle, the task itself stops task execution after the instruction is completed and the information at that time is saved in the memory, and the operating system transfers the execution right to the next task after this saving is completed. Since instructions are not stopped midway and the amount of information saved in the memory is reduced accordingly, the time required for task switching is shortened and the execution time of the entire program can be shortened.

According to the second aspect of the present invention, in the task to be executed by giving the execution right, when the execution of one instruction is completed, the task itself stops the tax execution and saves the information at that time in the memory. Since the system transfers the execution right to the next task after this saving is completed, the number of accesses to the task from the operating system is reduced, and the task is stopped when the execution of one instruction is completed. There is an effect that the amount of information saved in the memory is smaller than that in the case where the program is stopped in the middle of execution, the time required for switching the result task is shortened, and the execution time of the entire program can be shortened. .

[Brief description of drawings]

FIG. 1 is a flowchart showing a concept of a tax switching process according to a first embodiment of the invention of claim 1;

FIG. 2 is a flowchart showing an operation of a tax switching process in the CPU of the above.

FIG. 3 is a flowchart showing the concept of a tax switching process according to the first embodiment of the invention of claim 2;

FIG. 4 is a flowchart showing an operation of a tax switching process in the CPU of the above.

FIG. 5 is a basic circuit configuration diagram of a program controller using claims 1 and 2.

FIG. 6 is a flowchart showing the concept of a conventional tax switching process.

[Explanation of symbols]

T ₁ ... Task OS Operating system

─────────────────────────────────────────────────── ───

[Procedure amendment]

[Submission date] May 23, 1994

[Procedure Amendment 1]

[Document name to be amended] Statement

[Correction target item name] 0011

[Correction method] Change

[Correction content]

When the execution right is given from the operating system OS (arrow a), the task to which the execution right is given, for example, the instruction programmed in T ₁ is executed. The operating system OS sets a progress flag at 2 ms after the execution right is given to the task T ₁ (arrow b ′). When this progress flag is set,
In the task T ₁ , if the instruction is being executed, the instruction is continued to be executed, and the information at the time of the stop is RA at the end of the execution of the instruction.
The task is saved in the stack area of M3 and the task execution is stopped (arrow c ' ).

[Procedure Amendment 2]

[Document name to be amended] Statement

[Correction target item name] 0012

[Correction method] Change

[Correction content]

If no instruction is executed when the elapsed flag is set, task execution is stopped in task T _{1 and} the information at the time of stop is saved in RAM 3 ( c ' ). After the information saving is completed, the operating system OS gives the execution right to the next task T ₂ and sets a progress flag at the time point when 2 ms has elapsed, as described above. Task T
_{In 2} , the programmed instruction is executed when the execution right is given in the same manner as above, and if there is an instruction being executed at the time when the above progress flag is set, the instruction execution is continued, and when the instruction execution ends Then, the information at that time is saved in the RAM 3. Of course, if the instruction is not executed when the elapsed flag is set, the task T ₁ saves the information at that time in the RAM 3 and stops the task execution. In this way, the above processing is repeated until the execution of the first task T ₁ to the final task Tm is completed, and when the execution of the final task Tm is completed, the entire program is not completed in the operating system OS. In this case, the execution right is returned to the first task T ₁ and the above processing is repeated. Here, the task whose execution right is returned reads the information saved in the RAM 3 at the end of execution of the previous task, and executes the instruction next to the instruction executed the previous time.

Claims (2)

[Claims] 1. A task switching system comprising an operating system that has a plurality of tasks executed by an arithmetic processing unit, and sequentially gives the execution right of each task to the arithmetic processing unit to sequentially execute each task. Then, a flag is set when a certain time has elapsed after the task execution right is given, and if there is an instruction currently being executed when the above flag is set and the task is executed at the time when the execution right is given, the task itself A task switching system that stops task execution and saves the information at that time in memory, and the operating system transfers the execution right to the next task after this saving is completed. 2. A task switching system comprising an operating system in which there are a plurality of tasks executed by an arithmetic processing unit, and the execution right of each task is sequentially given to the arithmetic processing unit to execute each task sequentially. In the task to be executed with the given value, when the execution of one instruction is completed, the task itself stops the task execution and saves the information at that time in memory, and the operating system transfers the execution right to the next task A task switching system characterized by: