Siemens SINUMERIK Series Function Manual page 735

LS and FS: Setting the "Controller enable"
The position assumed by a spindle with setting the "controller enable" depends on DB31, ...
DBX1.4 == <value> (follow-up operation):
<value> Assumed spindle position
Note
It is recommended for synchronous spindles during a block search, to write the DB31, ...
DBX2.1 interface signal (controller enable) always together for FS and LS. If this is not done,
the block search, for example, stops after a FS machining because the controller enable of
the LS is not pending.
Note
Synchronism error
If the DB31, ... DBX2.1 interface signal (controller enable) is canceled for the FS after
Spindle Stop without the coupling being deactivated beforehand, then any synchronism error
resulting from external intervention will not be compensated when the "controller enable" is
activated again. This causes any programmed angular relationship between FS and LS to be
lost.
The angular relationship can be restored by resynchronizing: DB31, ... DBX31.4 = 1
(resynchronization)
Follow-up mode (DB31, ... DBX1.4)
For follow-up operation, the set position is regularly set to the current actual position:
DB31, ... DBX1.4 == 1 (follow-up operation) AND DB31, ... DBX2.1 == 0 (controller enable)
⇒ Cyclic: Set position = actual position
Note
DB31, ... DBX1.4 (follow-up operation) is relevant only for DB31, ... DBX2.1 == 0 (controller
enable)
Extended Functions
Function Manual, 03/2013, 6FC5397-1BP40-3BA1
0 Position when controller enable is canceled
1 Current position
S3: Synchronous spindle
13.4 Points to note
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