Omron CP - PROGRAMMING MANUAL 05-2007 - Basic CPU Unit Operation

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Programming with Tasks Section 2-1
2-1-3 Basic CPU Unit Operation
The CPU Unit will execute cyclic tasks starting at the task with the lowest
number. It will also interrupt cyclic task execution to execute an interrupt task
if an interrupt occurs.
Note All Condition Flags (ER, CY, Equals, AER, etc.) and instruction conditions
(interlock ON, etc.) will be cleared at the beginning of a task. Therefore Condi-
tion Flags cannot be read nor can INTERLOCK/INTERLOCK CLEAR (IL/ILC)
instructions, JUMP/JUMP END (JMP/JME) instructions, or SUBROUTINE
CALL/SUBROUTINE ENTRY (SBS/SBN) instructions be split between two
tasks.
Interrupt task can be executed as cyclic tasks by starting them with TKON.
These are called “extra cyclic tasks.” Extra cyclic tasks (interrupt task numbers
0 to 255) are executed starting at the lowest task number after execution of
the normal cyclic task (celiac task numbers 0 to 31) has been completed.
Executed in order starting
at the lowest number.
Cyclic task 0
Cyclic task 1
Interrupt task 5
Interrupt
occurs.
Cyclic task n
I/O refresh
Peripheral processing