Boundary Conditions; Function-Specific Boundary Conditions; Continue Machining Within Subroutines; Continue Machining Within Program Loops - Siemens SINUMERIK 840D sl Function Manual

TE7: Continue machining - retrace support

15.9 Boundary conditions

15.9 Boundary conditions
15.9.1

Function-specific boundary conditions

15.9.1.1

Continue machining within subroutines

Subroutine call outside or inside a program loop
Clear retrace support within subroutines depends on whether the subroutine call is made
outside or inside a program loop:
• Outside
Clear retrace support is possible if a subroutine is called outside a program loop.
• Inside
Clear retrace support may not be possible if a subroutine is called inside a program loop
(refer to Continue machining within program loops [Page 640]).
Number of passes P
Subroutine repetitions using number of passes P are taken into account for retrace support.
This means that retrace support is performed in the part program with the correct reference to
the part program block and number of passes P to the program continuation point of the
contour.
15.9.1.2

Continue machining within program loops

In NC high-level language, program loops can be programmed using:
• LOOP
• FOR
• WHILE
• REPEAT
• CASE/IF-ELSE-ENDIF in conjunction with GOTOB
If retrace support is performed within program loops, the retrace support is always effective in
the first loop run.
If the machining continuation point on the programmed contour is the result of a loop run not
equal to the first loop run, there can be considerable contour deviations in the further course
of the machining under certain circumstances, which pose a threat to man and machine.
640
ENDLOOP
ENDFOR
ENDWHILE
UNTIL
WARNING
Function Manual, 09/2011, 6FC5397-2BP40-2BA0
Special Functions