Siemens SINUMERIK 840D sl Programming Manual page 475

Nesting depth
A nesting depth of up to 16 check structures can be set up on each subprogram level.
Runtime response
In interpreter mode (active as standard), it is possible to shorten program processing times
more effectively by using program branches than can be obtained with check structures.
There is no difference between program branches and check structures in precompiled cycles.
Current block display for program loops
If only selected blocks are executed within a program loop, the last main run block before the
program loop is shown in the current block display.
So that the processed selected blocks are also visible in the current block display, e.g. for
diagnostic purposes, the decoding single block SBL2 must be activated.
Grinding without main run block
If, within a program loop, no main run block has been programmed, then the loop is pre-
processed until the loop condition is satisfied.
As a consequence, a high level of utilization can occur and this can have a negative impact on
the display.
The STOPRE command or a dwell time G04 of 0 seconds can be inserted in the loop as
countermeasure.
NC programming
Programming Manual, 12/2019, 6FC5398-2EP40-0BA0
Main program
PROC SUBPROG
LOOP
WHILE
IF
ENDIF
WHILE
SUBPROG
ENDWHILE
ENDWHILE
ENDLOOP
Subprogram
REPEAT
FOR
FOR
WHILE
ENDWHILE
WHILE
ENDWHILE
ENDFOR
ENDFOR
UNTIL
Work preparation
3.1 Flexible NC programming
475