Chapter 5. Program Configuration and Operation Method
5-13
(3) Task type
Task type and function is as follows.
Cycle time task
(Interval task)
I/O task
(Interrupt task)
Internal device task
(Single task)
Max. Task
number
8
8 8
Start condition
(setting up to max.
4,294,967.295 sec. by
Rising or falling edge of
main unit’s contact
(%IX0.0.0~%IX0.0.7)
Internal device
execution condition
Detection and
execution
Cyclic execution per
setting time
the edge of main unit’s
contact
Retrieve the condition
and execute after
completing Scan
Program
Detection delay
time
Max. 1 ms delay Max. 0.05 ms delay
Delay as much as max.
scan time
Execution
priority
2~7 level setting
(2 level is highest in
priority)
2~7 level setting
(2 level is highest in
priority)
2~7 level setting
(2 level is highest in
priority)
Task no.
without user
With 8~15 range without
user duplication
Within 16~23 range
without user duplication
(4) Processing methods of task program
Here describes common processing method and notices for Task program.
(a) Feature of task program
1) Task Program is executed only when execution condition occurs without every scan repeat processing.
When preparing Task Program, please consider this point.
2) For example, if a timer and counter were used in cyclic task program of 10 second cycle, this timer occurs
the tolerance of max. 10 seconds and the counter and the timer and as the counter checks the input status of
counter per 10 seconds, the input changed within 10 seconds is not counted up.
(b) Execution priority
1) In case that several tasks to be executed are waiting, execute from the highest Task Program in priority.
When the same priority tasks are waiting, execute from the order occurred.
2) In case Cycle time task and external I/O task is occurred concurrently, execute from the highest task program.
(In sequence of XG5000 setting)
3) The task program priority should be set considering the program features, importance and the emergency
when the execution requested.
(c) Processing delay time
There are some causes for Task Program processing delay as below. Please consider this when task setting or
program preparation.
1) Task detection delay (Refer to detailed description of each task.)
2) Program proceeding delay caused by Priority Task Program proceeding
(d) Relationship of initialize, Scan Program and Task Program
1) ser identification task does not start while performing Initialization Task Program.
2) As Scan Program is set as lowest priority, if task occurs, stop Scan Program and process Task Program in
advance. Accordingly, if task occurs frequently during 1 scan or concentrates intermittently, scan time may
extend abnormally. Cares should be taken in case of task condition setting.
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