Mitsubishi Electric FX5 User Manual page 28

Processing when the fixed scan execution type program starts
The same processing as when the interrupt program starts. (Page 38 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.
■Operation in the fixed scan execution mode
This section describes the operation which can be performed in the fixed scan execution mode.
• Execution Count Takes Priority
The program is executed for all the pending number of executions so that it can be executed the same number of times as
execution condition was satisfied.
Cycle interval of TEISYU
"TEISYU"
(Fixed scan execution type program)
• Precede Fixed Scan
When the waiting for execution , one execution is made when interrupt becomes allowed. Even if execution condition was
satisfied twice or more, only one execution is performed.
Cycle interval of TEISYU
"TEISYU"
(Fixed scan execution type program)
1 PROGRAM EXECUTION
26
1.4 Execution Type of Program
Section where interruptions
are disabled
Section where interruptions
are disabled
[1]
All pending executions are executed and the
number of executions of the fixed scan is
guaranteed. (In the chart, three executions are
made immediately after interruption becomes
allowed [1]).
Delay behind the cycle
The program is executed once, and the fixed period
execution of the program is maintained. (Even if
execution condition was satisfied twice or more, only
one execution is made.)
Execution condition satisfied:
6 times
Number of executions:
6 times
Execution condition satisfied:
6 times
Number of executions:
4 times