JP2737796B2 - How to handle multitasking - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a time slice type multitask processing method.

[Prior Art] As is well known, a time-slicing multitasking processing method divides the use time (hereinafter, CPU time) of a data processing device (hereinafter, CPU) such as a computer into fixed time intervals. Then, the divided times are distributed to a plurality of tasks in a specific order, and the data processing of each task is executed.

Using such a multitask processing method, an actuator driven by a motor M as shown in FIG.
When the actuator ACT is moved from the point A to the point B and the actuator ACT comes into contact with the limit switch LSW installed at the point B, the driving of the motor M is stopped and the time until the actuator ACT reaches the point B. There is a system that performs data processing required for other control by utilizing the data processing. In such a system, the actuator
If it is assumed that there are roughly three types of data processing required for other control in addition to the processing for moving the ACT, for example, as shown in FIGS. It consists of two tasks TSK1 to TSK4, and each task is executed while being time-sliced in order from the task TSK1. Then, a process for moving the actuator ACT is assigned to, for example, the task TSK1, and when the start condition of the mode M is satisfied in the execution time zone of the task TSK1, the motor drive signal MD is turned on as shown in FIG. When the stop condition of the motor M is satisfied in the k-th task cycle cyk thereafter, the motor drive signal MD is turned off. Accordingly, the processing of the task TSK1 is illustrated as shown in steps 30 to 32 of the flowchart of FIG.

[Problems to be Solved by the Invention] However, in the above multitask processing method, after the task TSK1 starts the motor M, the CPU time is occupied only immediately before the actuator ACT reaches the point B, and What is necessary is just to determine whether the switch LSW is turned on. That is, if the average value of the time for the actuator ACT to reach the point B is, for example, 100 ms, the motor M
After starting, do nothing for 90ms, for example,
It is sufficient to determine whether or not the limit switch LSW has been turned ON after the elapse of ms, and the determination processing before that time is unnecessary. However, in the above-described conventional method, the CPU time is allocated to the task TSK1 all the way to the point B, so that the CPU time allocated to the task TSK1 during this time is wasted.

On the other hand, when the actuator ACT reaches the point B, it is necessary to immediately determine that by the condition determination process of the task TSK1, but when the actuator ACT reaches the point B, the CPU time allocated to the task TSK1 must be determined. They do not always match. Therefore, immediately after the CPU time of the task TSK1 has passed under the worst conditions (time t in FIG. 5), the limit switch
When LSW is turned ON, this limit switch
N is determined in the next task cycle cy (k + 1), and the determination of the satisfaction of the condition is delayed by one task cycle, and the motor M cannot be turned off immediately upon reaching point B. The motor M is turned off with a delay of cy (k + 1) as shown by the broken line in FIG. 5 (e).

In other words, there is a problem that it is not possible to immediately cope with the establishment of the external condition, and it is not possible to execute the process with high synchronism with the external condition. This means that after executing task TSK1, the other tasks TSK will continue until actuator ACT reaches point B.
The problem can be solved by prohibiting the allocation of CPU time to 2 to TSK4 and distributing CPU time only to task TSK1, but in this case, after the limit switch LSW is turned ON, O
Since the other tasks TSK2 to TSK4 are not executed during the period from ON to OFF until the FF is performed, the task TSK1 is a task that only causes the CPU to wait the time between the ON and OFF during the ON and OFF (that is, C
Tasks that do not let the PU do other work, in other words, tasks that cause the CPU to do useless work). Therefore, there is a disadvantage that the function of the CPU is wasted during this time.

The present invention has been made in order to solve such a problem, and is a multitasking process capable of effectively utilizing a CPU function and CPU time and executing a highly simultaneous process with respect to external conditions. The aim is to provide a method.

[Means for Solving the Problems] The multitask processing method according to the present invention divides the use time of a data processing device into fixed time intervals, distributes each divided time to a plurality of tasks in a specific order, In the time slice type multitask processing method for performing data processing of a task, the use time of the data processing device is allocated at a shorter time interval than each of the tasks (TSK1 to TSK4), and the task is performed by one of the tasks. A short-period task (TSK0) for executing the determination process regarding the satisfaction of the condition of the control target, and the one task (TSK1)
Has a function for requesting the short-period task to execute a determination process regarding the satisfaction of the condition, and after requesting the short-period task to execute, the one task has the condition satisfied by the short-period task. The use time of the data processing device is not allocated until the confirmation is made.

[Operation] When the task (TSK1) that needs to determine whether the condition is satisfied is determined, the short cycle task (TSK0) is determined to determine whether the condition is satisfied instead of the invoking task (TSK1). Then, when the condition is satisfied, the processing by the short-period task (TSK0) that has performed the predetermined processing (such as turning off the motor) is stopped, and the CPU time is redistributed to the original task (TSK1).

Therefore, the CPU time of the short-period task (TSK0) is, for example, 5 ms.
With a cycle, external conditions can be dealt with with a delay of 5 ms at the worst, and highly synchronous processing can be performed.
If the CPU time is distributed to the short-cycle task (TSK0), the CP of the task (TSK1) that has requested the determination
Since U time is not allocated, it is possible to eliminate wasted CPU time. Furthermore, since the tasks (TSK2 to TSK4) that do not request the short-period task (TSK0) to determine whether the condition is satisfied are allocated the CPU time as usual, the function of the CPU is not wasted.

[Embodiment] Hereinafter, a case where the present invention is applied to the system described in the conventional example will be described as an example.

First, the task TSK1 for turning on the motor M in the present invention.
As shown in the flow chart of FIG. 1, this process comprises a step 20 for "motor ON" and a step 21 for calling a subroutine for judging the satisfaction of the condition. The determination as to whether the limit switch LSW is turned on or not is made in a subroutine as shown in the flowchart of FIG. In this subroutine, it is determined in step 10 whether or not the limit switch has been turned on. If the limit switch has been turned on, the motor M is turned off in step 11, and the status information S is turned on in the next step 12.
The TS is set to “STS = OK”, and when the condition in step 10 is not satisfied, the status information STS is set to “STS = NG”, and the process returns to the task TSK1 that called the subroutine. Then, as shown in the time chart of FIG. 3, this subroutine is executed by a short-period task TSK0 having a period much shorter than the tasks TSK1 to TSK4 (for example, a 5-ms period). This short-period task TSK0 is executed by the subroutine calling process after the task TSK1 turns on the motor M.
Triggered by time allocation and status information
It ends when STS becomes STS = OK or STS = NG.
When TS = OK, the condition is satisfied and the motor M is turned off, so that the task TSK1 is not restarted until called again. However, when STS = NG, the condition is not satisfied, so the operation is restarted after 5 ms. On the other hand, the task TSK1 is not assigned CPU time while TSK0 is activated. Therefore, during this time, the task TSK1 is in the idle period as shown.

Here, the method in which the task TSK1 calls the subroutine in step 21 is different from the normal subroutine call, in that the multitask monitor intervenes to suspend the task TSK1 and
Including processing to start TSK0. Also, the status information STS of the task TSK0 indicates that the multitask monitor
Restart task 0 or suspend task TSK0 and task TSK1
Is used to control whether to operate again.

In this way, the judgment of condition satisfaction is shorter than other tasks
5 ms at worst against external conditions (ON / OFF of limit switch LSW) by performing task TSK0 of 5 ms
, It is possible to perform processing with high synchronization.

While the short-period task TSL0 is activated,
Since no CPU time is allocated to TSK1, it is possible to eliminate the waste of CPU time that simply waits for the passage of time as in the related art. Further, since the CPU time is allocated to the tasks TSK2 to TSK4 in the same manner as usual except for the startup time of the short-period task TSK0, the allocation of the CPU time to TSK2 to TSK4 is prohibited, and the determination of the satisfaction of the condition only by TSK1 is prohibited. It is possible to prevent the CPU function from being wasted as in the case where the execution is performed. That is, in the above embodiment, the allocation of the CPU time to the tasks TSK2 to TSK4 remains the same as the conventional time slice method, and the time from when the limit switch LSW is turned on to when the limit switch LSW is turned off.
By allocating the determination processing of the short-period task TSK0 between to OFF to the CPU, it is possible to eliminate the task TSK1 that does not allow the CPU to perform other work (or causes the CPU to perform useless work). As a result, effective use of the CPU can be achieved, and processing with high synchronism with external conditions can be performed.

In the above embodiment, for the sake of simplicity, the case where the ON / OFF of the limit switch LSW is determined as the content of the satisfaction of the condition has been described. It goes without saying that the present invention can be applied to a case where it is determined whether various external conditions relating to the target are satisfied.

[Effects of the Invention] As described above, in the present invention, a short-period task in which CPU time is allocated in a shorter cycle than a normal task is provided, and whether or not an external condition is satisfied is determined by this short-period task. Is the CPU for the task that requested the condition judgment
By not allocating time, processing can be performed with high concurrency for external conditions.
It is possible to prevent wasteful use of functions and perform efficient processing.

[Brief description of the drawings]

FIG. 1 shows a task TS according to the multitask processing method of the present invention.
FIG. 2 is a flowchart showing an embodiment of the processing contents of K1, FIG. 2 is a flowchart showing an embodiment of the processing contents of the short-period task TSK0, and FIG. 3 shows an example of CPU time distribution by the multitask processing method according to the present invention. Time chart, 4th
FIG. 5 is a block diagram showing an example of a system using multitasking, FIG. 5 is a time chart showing an example of CPU time distribution according to a conventional multitasking processing method, and FIG. 6 shows processing contents of task TSK1 in FIG. It is a flowchart shown. M: Motor, ACT: Actuator, LSW: Limit switch, TSK1 to TSK4: Task, TSK0: Short-period task.

Claims (1)

(57) [Claims] 1. A time slice type multi-task processing for dividing a use time of a data processing device into fixed time intervals, distributing each divided time to a plurality of tasks in a specific order, and performing data processing of each task. In the method, a use period of the data processing device is allocated at a shorter time interval than each of the tasks, and a short-period task for performing a determination process regarding satisfaction of a control target condition performed by one of the tasks is provided. Together, the one task has a function for requesting the short-period task to execute a determination process regarding the satisfaction of the condition, and after requesting the short-period task to execute, the one task has the A multitask processing method, wherein a use time of a data processing device is not allocated until a condition is confirmed in a short cycle task.