JPH0461378B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a method for starting a fixed periodic interrupt program, such as an application program of a programmable controller, which is executed by interrupt processing at fixed time intervals.

[Conventional technology]

When starting a fixed cycle program, a fixed cycle table is used in which the cycle T of each program is set. FIG. 3 shows an example of a periodic table. As shown in the figure, this fixed period table contains the fixed period interrupt program number (No.) and the period T (T ₁ , T ₂ . . .
...) are stored.

FIG. 4 shows the procedure for creating a periodic table. That is, at the initial time, each program is searched (reference), then a fixed cycle table is created (reference), the cycle of each program is set in this table, and the process is completed (reference).

Based on the fixed-period table thus created, each program is executed according to the procedure shown in FIG.

First, it is determined whether the number of registered programs is zero (see). Normally, it is not zero, so by interrupt processing by the timer, the period (count value corresponding to the period) of all registered periodic programs is
are counted down one by one (see).
Next, all activation flags of programs whose cycles have become zero are set (see), and thereafter processing is performed according to these flags and the priority (interrupt) level of the program (see, ). That is, among the programs whose cycle has become zero, the cycle of the program with the highest interrupt level is preset (see), program startup processing is performed (see), and the program is executed (see). When this process is finished, check whether there is a startup flag that has been set again.
If so, the procedure of referring to the one with the higher interrupt level is repeated until there are no more activation flags set. At this time, if there are multiple programs with the same interrupt level and the same cycle, they will be started at the same time and will be executed sequentially according to the registered priority within the level.

[Problem that the invention seeks to solve]

However, with this method, there is a problem in that if there is variation in the processing time of the first program to be executed at the same interrupt level, there will be a shift in the cycle of the second and subsequent programs.

FIG. 6 specifically shows this point. This means that there are two programs with the same interrupt level and the same cycle, such as A and B, and program B.
A has a higher registration priority than program A, and the processing time when program A is executed at time t ₀ after a certain period (T) has elapsed from the start time t _S of the interrupt processing program shown in FIG. An example is shown in which t ₂ is the processing time after a certain period (T) has elapsed from time t _{1 and time t 0} , and the period of program _B at this time is T±(t ₂ - _{t 1} ), A constant cycle cannot be secured due to the influence of the processing time of program A.

Therefore, the present invention eliminates the deviation in the period T due to the difference in processing time of the programs with the same interrupt level and the same cycle as described above, and executes the programs with the same interrupt level and the same cycle at a constant cycle. The purpose is to make it possible.

[Means for solving problems]

For each of multiple fixed-cycle interrupt programs that have the same interrupt level and are executed at the same cycle, set the operating cycle and start-up delay time from the reference time in a table, and start the program after the start-up delay time has elapsed. They are activated sequentially at a fixed cycle based on the operating cycle of.

[Effect]

By setting a startup delay time for each fixed-cycle interrupt program, programs with the same interrupt level and the same cycle can be prevented from being affected by the execution time of other programs with the same level, and can always be executed at a constant cycle. improve stability and reliability.

〔Example〕

FIG. 1 is a flow chart for explaining an embodiment of the present invention, and FIG. 2 is a time chart for explaining the operation of the present invention.

First, a number is assigned to each program, and the operating period T and startup delay time T _i from the start of the program are defined in advance by a certain special instruction (for example, the Prog instruction), and the initial At times, the startup delay time T _i is set in a fixed periodic table similar to that shown in FIG. 3 using the procedure shown in FIG. After that, as in the conventional case, T _i is counted down by 1, and when it reaches zero, the corresponding program is executed, and at the same time, the period T is set in the fixed period table, so that the corresponding program is executed at the period T. to be done. Note that the above program number is given to each program in consideration of the interrupt level, priority, etc.

FIG. 2 shows the above situation. This example shows a case where there are two programs A and B that have the same interrupt level and are executed at the same cycle T, and the startup delay times of programs A and B are set to T ₁₀ and T ₂₀ , respectively. has been done.

In this way, by making it possible to set the startup delay time for the fixed-cycle interrupt program of the program controller, programs with the same interrupt level and the same period T can always be executed regardless of variations in the execution time of other programs at the same level. It will be executed exactly in period T.

〔Effect of the invention〕

According to this invention, for each of a plurality of fixed-cycle interrupt programs that have the same interrupt level and are executed at the same cycle, the operation cycle and startup delay time from a reference time are respectively set in a table. Therefore, it is not only possible to eliminate cycle deviations due to processing time of programs with the same interrupt level and the same cycle, and to execute them at a constant cycle, but also to change the cycle and phase of each program, or to add new processing. The advantage is that there are no changes to the program, making it easier to work with.

[Brief explanation of the drawing]

FIG. 1 is a flow chart for explaining an embodiment of the present invention, FIG. 2 is a time chart for explaining the operation of the present invention, FIG. 3 is a schematic diagram showing a fixed period table, and FIG. FIG. 5 is a flowchart for explaining the periodic table creation procedure, FIG. 5 is a flowchart for explaining the interrupt processing procedure, and FIG. 6 is a time chart showing an example of operation by the conventional fixed-period program starting method. Symbol explanation, T, T ₁ , T ₂ ...period, T _i , T ₁₀ ,
T ₂₀ ...Startup delay time, t ₁ , t ₂ ...Processing time.

Claims (1)

[Claims] 1. In a plurality of fixed-period interrupt programs having the same interrupt level and executed in the same cycle, for each of the fixed-period interrupt programs, the operating cycle and startup delay time from a reference time are defined. A method for starting a fixed-cycle interrupt program, characterized in that the programs are set in a table, and the program is sequentially started at a constant cycle based on the operation cycle, starting from the program for which the start-up delay time has elapsed.