Siemens SINUMERIK 840D sl Function Manual page 909

Delete distance to go/Spindle Reset (DB31, ... DBX2.2)
When Spindle reset is set for the LS in synchronous operation, the LS is decelerated to
standstill at the selected acceleration rate. The FS and LS continue to operate in
synchronous mode. The overlaid motion (except with COUP...) is terminated as quickly as
possible.
Spindle stop (Feed stop) (DB31, ... DBX4.3)
When "Spindle stop" is set for the FS or LS, both coupled spindles are decelerated to
standstill via a ramp, but continue to operate in synchronous mode.
As soon as IS "Spindle STOP" is no longer active for any of the spindles in the coupling, it is
accelerated back up to the previous speed setpoint.
Application
"Spindle stop" can halt the synchronous spindle pair without offset since the servo loop
position control remains operative.
Example
When the protective door is opened with an active synchronous spindle coupling, the FS and
LS must be stopped without the coupling relationship being altered. This can be achieved by
applying IS "Spindle stop" to halt the FS and LS (IS "Axis/spindle stationary" (DB31, ...
DBX61.4) = 1). "Servo enable" can then be canceled for both spindles.
Delete S value (DB31, ... DBX16.7)
The S value programmed for the LS is deleted and the LS decelerated down to zero speed
via a ramp. The FS and LS continue to operate in synchronous mode.
On the other hand, IS "Delete S value" has no affect on the FS in synchronous operation.
Resynchronize spindle 1/2 (DB31, ... DBX16.4 and 16.5)
It is also possible to synchronize the spindle (LS) with its positioning measuring system when
it is operating in synchronous mode. It is however recommended that the leading spindle
only be re-synchronized when synchronous mode is not active.
Re-synchronization (DB31, ... DBX31.4)
If the following and leading spindles have fallen out of synchronism, or failed to synchronize
at all, the programmed offset can be restored using the following interface signal:
IS "Re-synchronization" (DB31, ... DBX31.4).
When the low-high edge of the VDI signal is detected, resynchronization is started for the
following spindle in question and acknowledged by the NC with the following interface signal
for the following spindle:
IS "Synchronization running" (DB31, ... DBX99.4) acknowledged for the following spindle.
Extended Functions
Function Manual, 09/2009, 6FC5397-1BP20-0BA0
S3: Synchronous spindle
14.4 Special features of synchronous mode
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