Siemens SINUMERIK 840D sl Programming Manual page 729

Program interruption using an asynchronous subprogram ASUB
ASUB start:
Modal and static motion-synchronous actions remain active and are also operative in the
asynchronous subprogram.
ASUB end:
If the asynchronous subprogram is not resumed with REPOS, the modal and static motion-
synchronous actions that were modified in the asynchronous subprogram will remain active
in the main program.
Repositioning (REPOS)
After repositioning (REPOS), the synchronized actions effective in the interrupted block
become active again. Modal synchronized actions changed from the asynchronous
subprogram are no longer effective after REPOS when processing the remainder of the
block.
Polynomial coefficients programmed with FCTDEF are not affected by asynchronous
subprograms and REPOS. Regardless of where they were programmed, they can be used
at any time in the asynchronous subprogram and in the main program, even after execution
of REPOS.
Response to alarms
Axis and spindle motions started by means of synchronized actions are decelerated in
response to an alarm involving a motion stop. All other actions (e.g. Set output) continue to
be executed.
If a synchronized action itself triggers an alarm, processing will be interrupted and the
subsequent actions in this synchronized action will not be executed. If the synchronized
action is modal, it is not processed any further in the next interpolation cycle; i.e. the alarm is
output only once. Processing of all other synchronized actions continues as normal.
Alarms generating an interpreter stop only take effect once the precoded blocks have been
processed.
If a technology cycle generates an alarm with motion stop, then processing of the relevant
cycle will cease.
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Programming Manual, 06/2009, 6FC5398-2BP20-0BA0
Motion synchronous actions
10.7 Control behavior in specific operating states
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