Siemens SINUMERIK 828D Function Manual page 529

Case B:
No repositioning block of a currently active REPOS operation is contained in the main run.
Each future REPOS operation wishing to reapproach the current main program block is controlled by the level of
interface signal:
DB21, ... DBX31.0-31.2 (REPOSPATHMODE0 till 2)
and
DB31, ... DBX10.0 (REPOSDELAY).
Note
In the running ASUB affects the NST:
DB21, ... DBX31.4 (REPOSMODEEDGE)
does not affect the final REPOS, unless this signal applies to the REPOS blocks.
In Case A, the signal is only allowed in the stopped state.
Response to RESET:
NCK has acknowledged the PLC signal
If the level of the signals:
DB21, ... DBX31.4 (REPOSMODEEDGE) = 1
and
DB21, ... DBX319.0 (REPOSMODEEDGEACKN) = 1
and
a RESET occurs in this situation, then the interface signal of the NCK:
DB21, ... DBX319.1–319.3 (Repos Path Mode Ackn0 to 2)
is deleted.
NCK has not yet acknowledged the PLC signal:
If the level of the signals:
DB21, ... DBX31. (REPOSMODEEDGE 4) = 1
and
DB21, ... DBX319.0 (REPOSMODEEDGEACKN) = 0
and a RESET occurs in this situation, the NCK cancels interface signal:
DB21, ... DBX319.0 (REPOSMODEEDGEACKN) = 0
and
DB21, ... DBX319.1–319.3 (Repos Path Mode Ackn0 to 2)
.
Basic Functions
Function Manual, 09/2011, 6FC5397-0BP40-2BA0
K1: Mode group, channel, program operation, reset response
9.8 Block search Type 5 SERUPRO
529