Chapter 5. Power Supply / CPU
5-17
(3) Processing delay time
The following factors influence on the processing delay of task program, consider the characteristics, importance and
urgency of the program.
• Task detection delay (Refer to the detailed description of each task)
• Execution delay due to the execution of prior task programs
• Delay due to the execution of higher priority task programs white executing task programs
(4) Relationship of task program to initialization or scan program
• User defined tasks will not start while the initialization task program is being executed.
• As scan program has the lowest priority, if a task is invoked the scan program will be stopped and the task
programs will be processed prior to them. Therefore, if tasks are invoked many times or concentrated sometimes
the scan time may be extended abnormally. Be cautious when setting task conditions.
(5) Protection of the programs under execution from task programs
• If problems can be occur in case that program lose its execution continuousness by the task programs which have
higher proprieties, the execution of task programs can be partly perverted For program protection, use the Dl
function (Task program start-up disable) or El function (task program start-up enable)
• Use ‘DI’ function where program needs protection and ‘EI’ function where program needs cancellation. After the
scan program ends of the running program, automatically it becomes permissible. Initialization program doesn’t get
influences from ‘DI and EI.’
3) Time driven task program processing method
The followings explain the processing method of a task program when its task condition (start-up condition) has been
set to drive by time.
(1) Settings that have to be set for the task
• Set the task execution cycle and its priority, which are used as start-up conditions for the task programs to be
executed. Priority number will be task number.
(2) Time driven task processing
• The corresponding time driven interrupt task program will be executed every setting time internal (execution cycle).
(3) Precautions for using the time driven task program
• While a time driven task program is being executed or ready for its execution, if a same priority task program has
been invoked to be executed the newly invoked task will be ignored, the representative task collision warning flag
(TASKERR) will be set to ON, the detailed system error flag (JC BMAP[n] will be set to ON at its corresponding
location and occurrence time of the time driven tasks whose execution requests have been ignored will be written at
its corresponding location of the flag TC_CNT[n].
• The timer that invokes the execution request for time driven task programs will be incremented only when the
operation mode is in the RUN mode
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