Check Structures - Siemens Sinumerik 840D sl Programming Manual

Flexible NC programming

1.12 Check structures

1.12 Check structures
Function
The control processes the NC blocks as standard in the programmed sequence.
This sequence can be variable by programming alternative program blocks and program
loops. These check structures are programmed using the check structure elements (key
words) IF...ELSE, LOOP, FOR, WHILE and REPEAT.
Check structures may only be inserted in the statement section of a program. Definitions in
the program header may not be executed conditionally or repeatedly.
It is not permissible to superimpose macros on keywords for check structures or on branch
destinations. No such check is made when the macro is defined.
Effectiveness
Check structures apply locally within programs.
Nesting depth
A nesting depth of up to 16 check structures can be set up on each subprogram level.
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CAUTION
Programming Manual, 02/2011, 6FC5398-2BP40-1BA0
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