Siemens SINAMICS S120 Function Manual page 142

Servo control
3.15 Dynamic Servo Control (DSC)
When dynamic servo control is activated, you check the position controller gain KPC in the
master. It may be necessary to correct the setting.
Note
KPC when DSC is activated
After activating dynamic servo control, check the position controller gain KPC in the master.
It may be necessary to correct the setting.
Channel p1155 for speed setpoint 1, as well as channel r1119 for the extended setpoint, are
disconnected when DSC is active.
When DSC is activated, p1160 for speed setpoint 2 and p1430 for the speed precontrol are
added to the speed setpoint from the DSC, see function diagram 5030.
Deactivation
If the interconnection is removed at the connector input for KPC or XERR (p1191 = 0 or
p1190 = 0), the DSC structure is dissolved and the "DSC" function deactivated. The sum
from r1119 and p1155 is then added to the values from p1160 and p1430 from the speed
precontrol.
Since it is possible to set higher gain factors using DSC, the control loop can become
unstable when DSC is disabled. For this reason, before deselecting DSC, the value for KPC
in the master must be reduced.
Speed setpoint filter
A speed setpoint filter for smoothing the speed setpoint steps is not required when DSC is
active.
When using the "DSC" function, it only makes sense to use speed setpoint filter 1 to support
the position controller, e.g. to suppress resonance effects.
External encoder systems (except motor encoder)
If, with DSC active, an external encoder is to be used, this requires the selection of a
telegram with additional actual encoder values: Telegram 6, 106, 116, 118, 138 or free
telegrams.
For optimum control in the DSC mode, the same encoder(s) (encoder 2 and/or encoder 3)
must be selected for the control (master) and the drive via parameter p1192 "DSC encoder
selection".
Since the motor encoder (encoder 1) is no longer used in this case, the adaptation factor for
the conversion of the selected encoder system into the motor encoder system is determined
using parameter p1193 "DCS encoder adaptation factor". The factor represents the ratio of
the pulse difference between the motor encoder and the used encoder for the same
reference distance.
The effect of the parameters p1192 and p1193 is illustrated in function diagram 3090.
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Function Manual, (FH1), 01/2013, 6SL3097-4AB00-0BP3
Drive functions