Siemens SINUMERIK 840D sl Function Manual page 908

S3: Synchronous spindle
14.4 Special features of synchronous mode
Servo enable (DB31, ... DBX2.1)
Cancellation of "Servo enable" for LS (either via PLC interface or internally in the control in
the event of faults):
If the servo enable signal of the LS is set to "0" during synchronous operation and a setpoint
coupling is active, a switchover to actual-value coupling is executed in the control. If the LS
is in motion at this instant, it is decelerated to a standstill and an alarm message is
generated. Synchronous operation remains active.
Cancellation of "Servo enable" for FS in synchronous operation (either via PLC interface or
internally in the control in the event of faults):
If the "Servo enable" signal is not set for either of the spindles before synchronous operation
is selected, synchronous operation is still activated when the coupling is switched on. The LS
and FS however remain at a standstill until the servo enable signal is set for both of them.
Set "servo enable" for FS and LS:
When the signal edge of IS "Servo enable" = 1, the spindle either moves back to the old
position (position on cancellation of servo enable) following the IS "Follow-up mode" (signal
status = 0: Stop active) or the current positions (position offset) are used again (signal status
= 1: Follow-up active).
Note
If the "servo enable" signal is canceled for the FS after Spindle STOP without the coupling
being deactivated beforehand, then any synchronism error resulting from external
intervention (e.g. manual rotation) will not be compensated when the "servo enable" signal is
activated again.
This may result in the loss of the defined angular reference between the FS and LS for
special applications. The programmed offset can be reproduced with the following interface
signal:
IS "New synchronization" (DB31, ... DBX31.4).
Follow-up mode (DB31, ... DBX1.4)
The interface signal "Follow-up mode" is only relevant if the "servo enable" for the drive is
canceled. Depending on the IS "follow-up mode," when "servo enable" is set for the FS and
LS, either the spindle will return to the position recorded on cancellation of the servo enable
signal (signal state = 0: Stop active) or the current positions will be used again (signal status
= 1: Follow-up active).
Position measuring system 1/2 (DB31, ... DBX1.5 and 1.6)
Switchover between the position measuring systems for the FS and LS is not locked out in
synchronous operation. The coupling is retained. It is however recommended that the
measuring systems only be switched when synchronous mode is not active.
If "Park" status is selected for the FS or LS in synchronous operation, then the system
responds as if "servo enable" had been canceled.
908
Function Manual, 09/2009, 6FC5397-1BP20-0BA0
Extended Functions