Precautions - Mitsubishi Electric MELSEC iQ-R Series Programming Manual

3.4

Precautions

When a function is used
■ Global pointer/local pointer/pointer type global labels
Global pointer, local pointer, and pointer type global labels cannot be used as labels indicating program steps in the function
program.
When a function block is used
■ Global pointer/local pointer/pointer type global labels
Global pointer, local pointer, and pointer type global labels cannot be used as labels indicating program steps in the function
block program.
■ When the index register is used
When the index register is used in the function block program, ladder programs for saving and returning the index register
values are required to protect the values.
Setting the index register data to 0 when saving can prevent an error that could be caused by an index modification validity
check. (Whether the device number exceeds the device range or not is checked.)
Ex.
A program that saves the values in the index register Z1 and Z2 before the program execution and returns the saved values
after the program execution
·
Program execution
Before the program execution,
save the index register values in
index_reg_tmp.
Set 0 to the index register areas.
·
After the program execution, return
the values saved in index_reg_tmp
to the index register.
3 PROGRAM ORGANIZATION UNITS
3.4 Precautions
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