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1 PROGRAM EXECUTION
1.4 Execution Type of Program
23
1
Action when the execution condition is satisfied
Performs the following action.
■If the execution condition is satisfied before the interrupt is enabled by the EI instruction
The program enters the waiting status and is executed when the interrupt is enabled. Note that if the execution condition for
this fixed scan execution type program is satisfied more than once during the waiting status, the program is executed only
once when the interrupt is enabled.
■When there are two or more fixed scan execution type programs
When the specified time intervals expire in the same timing, the programs are executed in order according to the priority (I31
> I30 > I29 > I28) of the periodic interrupt pointer.
■If another or the same execution condition is satisfied while the fixed scan execution type
program is being executed
Operates according to the fixed scan execution mode setting.
■If the execution condition is satisfied while the interrupt is disabled by the system
Operates according to the fixed scan execution mode setting.
■When an interrupt is generated during a standby while executing constant scan
Executes the fixed scan execution type program.
*1 If processing does not finish during the waiting time, the scan time is extended.
■If another interrupt occurs while the fixed scan execution type program is being executed
If an interrupt program is triggered while the fixed scan execution type program is being executed, the program operates in
accordance with the interrupt priority.
Processing when the fixed scan execution type program starts
The same processing as when the interrupt program starts. (Page 34 Processing at startup of interrupt program)
Fixed scan execution mode
If execution condition for a fixed scan execution type program and fixed cycle interrupt (I28 to I31) based on the internal timer
of the CPU module is satisfied while interruption is disabled, the operation of the program execution after interruption
becomes allowed is specified. However, if execution condition is satisfied while interruption is set to be disabled because of a
DI instruction or the like, this is out of the scope of the fixed scan execution mode.
"Interrupts disabled" refers to the following:
• A program having an interrupt priority higher than or the same as the corresponding program is currently
being executed.
• The corresponding program is currently being executed.
• Program execution is currently at a part in which interrupts are disabled by the system.
Fixed scan interval
END processing
Scan execution type program
Fixed scan execution type program
Condition
established
Constant scan
*1
Waiting time