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CHAPTER 2 APPLICATION OF PROGRAMMING
2
2.3 Scan Time Structure
2.3.2 Refresh processing of input/output modules or intelligent function modules
2.3.2 Refresh processing of input/output modules or intelligent
function modules
The CPU module performs the following before program operations.
• On/off data input from the input module or intelligent function module to the CPU module
• On/off data output from the CPU module to the output module or intelligent function module
For details on refreshing processing, refer to Page 48, Section 2.6.
2.3.3 Program operation
A main routine program repeatedly executes its operation from the step 0 to the END or FEND instruction. This
program is executed from the step 0 for every scan.
A main routine program can be divided to main routine and subroutine programs. A subroutine program is from a
pointer(P) to the RET instruction, and is created between the FEND and END instructions. This program is executed
only when it is called by a subroutine program call instruction (such as CALL(P), FCALL(P)) from a main routine
program.
*1 Pointer numbers do not need to be specified in ascending order.
END/FEND
instructions
END/FEND
1 scan (After completion
of END processing,
an operation is repeated
starting from step 0.)
Step 0
Program
execution
END processing
Main routine program
Subroutine
program 1
Subroutine
program 2
Subroutine
program 3
Pointer*
1
Program A
Main routine program
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