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Task Features Section 4-1
4-1-3 Basic CPU Unit Operation
The CPU Unit will execute cyclic tasks (including extra cyclic tasks, CS1-H,
CJ1-H, or CJ1M CPU Unit only) starting at the lowest number. It will also inter-
rupt 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.
With a CS1-H, CJ1-H, or CJ1M CPU Unit, 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.
Cyclic task 0
Executed in order starting
at the lowest number.
Cyclic task 1
Cyclic task n
I/O refresh
Peripheral processing
*2: END for the final task. Clears ER, Equals,
and N Flags, and then refreshes I/O.
*1: END other than that for the final
task. Clears ER, Equals, and N Flags.
Interrupt
occurs.
Interrupt task 5
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