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Chapter 5 Programming Concepts
XBC E-Type Main Unit
5-10
Ver. 1
c. Processing delay time
i. There are some causes for Task Program processing delay as shown below.
Please consider this when writing the program and setting task priority.
I.
Task detection delay (Refer to detailed description of each task.)
II. Program process delay caused by Priority Task Program process.
III. Input/output data refresh of expansion special module and using PUT,
GET instruction.
d. Relationship of initialize, Scan Program and Task Program
i. The identification task does not start while performing Initialization Task
Program.
ii. As Scan Program is set as lowest priority, if task occurs, Scan Program stops
and processes Task Program. Accordingly, if task occurs frequently during 1
scan or concentrates intermittently, scan time may be excessively extended.
Consideration should be given when setting task condition.
e. Protection of Program in execution from Task Program
i. If the continuity of program execution is interrupted by high priority Task
Program during program execution, it is possible to prohibit the execution of
Task Program. In this case, it is possible to perform the program protection by
‘DI (Task Program Start Disabled) and ‘EI (Task Program Start Enabled)’
application instruction.
ii. Insert ‘DI’ application instruction in the start position of the program requiring the
protection and insert ‘EI’ application instruction in the position to enable.
Initialization Task is not influenced by ‘DI’, ‘EI’ application instruction.
iii. If interrupt occurs while ‘CALLP’ instruction executing, the interrupt program is
executed after ‘CALLP’ instruction is executed.
5. Cyclic task program processing method
Below describes the processing method when the task (start condition) of Task program is set
as Cycle time.
a. Items to be set in Task
i. Set the execution cycle and priority which are the start condition of Task
program to be executed. Check the task number to manage the task.
Summary of Contents for XBC-DN10E
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