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Chapter 5 Power Supply / CPU
5 -14
5.4 Program
5.4.1 Classifications of Program
All functional elements need to execute a certain control process are called as a ‘program’. In MASTER-K120 series, a
program is stored in the EEPROM mounted on a CPU module or flash memory of a external memory module. The following
table shows the classification of the program.
Program type Description
Scan program The scan program is executed regularly in every scan
Time-driven interrupt
program (TDI)
The TDI programs are executed with a constant time interval specified with parameter settin
g
.
Process driven interrupt
program (PDI)
The PDI programs are executed when external interrupt input is applied and the corresponding
interrupt routine is enabled by EI instruction.
High speed counter driven
interrupt program(HSCDI)
This interrupt programs are executed when comparison task signal is applied.
(Standard Type only)
Subroutine program
The subroutine programs are executed when they are called by the scan program with a CALL
instruction.
5.4.2 Program Execution Procedure
The following diagram shows that how the CPU module process programs when the CPU module is powered on or switched to
RUN mode.
Start
p
rocessin
g
Scan program
END
p
rocessin
g
Subroutine program
PDI program
TDI program
HSCDI program