Siemens SINUMERIK 840Di Function Manual page 652

Detailed Description
2.8 Single block
2.8.1 Decoding single block SBL2 with implicit preprocessing stop
Asynchronicity
As a result of preprocessing of part program blocks, the reference between the current block
display relative to the main run status of the NCK and the variable values displayed on the
HMI can be lost. The operator display then shows implausible variable values.
Preprocessing stop for each block
With channel-specific setting data SD42200 $SC_SINGLEBLOCK2_STOPRE, a
preprocessing stop is executed on every block when SBL2 is active. This suppresses
preprocessing of part program blocks and maintains the relationship between the current
block display and the variable values display.
Note
This variant of SBL2 does not maintain an accurate contour. In other words, as a result of
the preprocessing stop, a different contour may be generated from the one created without
single-block mode or with SBL1.
Application: Debug mode for testing part programs.
2.8.2 Single-block stop: Suppression using SBLOF
Single block off
Programs identified by the language command SBLOF are executed completely in one block
as with every type of single block.
SBLOF is also valid in subroutines, which are called.
SBLOF
Example for subroutine without stop in single block:
PROC EXAMPLE SBLOF
G1 X10
RET
At the return command, the decision is made whether to stop at the end of the subprogram:
Return jump with M17
Return jump with RET
2-116
Stop at the end of the subprogram
No stop at the end of the subprogram
Mode Group, Channel, Program Operation, Reset Response (K1)
Function Manual, 08/2005 Edition, 6FC5397-0BP10-0BA0