Siemens SINUMERIK 840D sl Function Manual page 442

M3: Coupled axes
8.5 Generic coupling
Writing variable $AA_COUP_CORR
System variable $AA_COUP_CORR is only written from the part program or synchronized
actions when a generic machine coupling has been activated for the corresponding axis/
spindle at least once.
Correction value
If the correction value $AA_COUP_CORR is being written via a part program/synchronized
action, as well as being determined due to the "track the deviation from synchronism" function
being activated (DB31, ... DBX31.6 = 1), the most recent event to occur is always the one that
takes effect.
Resetting synchronism correction
Writing correction value $AA_COUP_CORR (via a part program or synchronized action or
when performing a calculation) has no effect when synchronism correction is being reset.
Response to channel/mode group reset
Synchronism correction is not reset in the event of a channel/mode group reset, it is retained
instead.
Response to search for reference and zero mark synchronization
If a search for reference or zero mark synchronization procedure is performed for spindles,
synchronism correction is reset automatically.
The system variable $AA_COUP_CORR must not be set during the search for reference/zero
mark synchronization and, as a result, no measurement may be taken for the deviation from
synchronism either.
Furthermore, the synchronism correction must have been implemented in full before the search
for reference/zero mark synchronization is started.
Response to an interruption
If an interruption occurs (e.g. emergency stop), synchronism correction is reset automatically,
the existing synchronism correction is transferred to the setpoint position, and the NC/PLC
interface signal DB31, ... DBX99.2 (synchronism correction implemented) is set.
If, once the interruption has been dealt with, the generic machine coupling remains active and
the NC/PLC interface signal DB31, ... DBX31.6 (track synchronism) is set, the following applies:
● If the signal is level-triggered (MD30455 $MA_MISC_FUNCTION_MASK, bit 7 = 0), the
deviation from synchronism is measured and written to $AA_COUP_CORR; the setpoints
are corrected accordingly.
● If the signal is edge-triggered (MD30455 $MA_MISC_FUNCTION_MASK, bit 7 = 1) and
the deviation from synchronism is to be measured, a new rising edge of the NC/PLC
interface signal DB31, ... DBX31.6 (track synchronism) needs to be executed.
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Function Manual, 01/2015, 6FC5397-2BP40-5BA2
Special functions