Dsc (Dynamic Servo Control) - Siemens SINUMERIK 840D sl Commissioning Manual

NCK start-up
10.5 Parameterize axis data
10.5.3

DSC (Dynamic Servo Control)

The DSC function eliminates the deadtime that necessarily exists at the speed-setpoint
interface normally used between the NCK and drive due to relocation of the position
controller into the drive.
That results in the following advantages for an axis operated with DSC:
● Considerably improved fault response/stability of the position control loop
● Improved command behavior (contour precision) if the loop gain (K
● A reduction of the cyclic communication load on the PROFIBUS, if the position controller
Note
The speed feedforward control can be used in conjunction with DSC.
Requirements
Before you can activate DSC mode, the following preconditions must be fulfilled:
● DSC-capable drive
● A DSC-capable message frame type has been parameterized in the S7 project for the
Switch ON/OFF
The DSC function is switched ON/OFF via the axis-specific NCK machine data
● MD32640 STIFFNESS_CONTROL_ENABLE (dyn. stiffness control).
If DSC operation is switched ON or OFF, it might be necessary to adjust the following
machine data:
● MD32200 POSCRTL_GAIN (K
● MD32610 VELO_FFW_WEIGHT (feedforward control factor)
● MD32810 EQUIV_SPEEDCTRL_TIME (substitute time const. of the closed speed control
Speed setpoint filter
If you use DSC, a speed setpoint filter for rounding the speed setpoint steps is no longer
necessary. The speed setpoint filter is then only of any use with differential connection to
support the position controller, for example, to suppress resonance.
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set higher in conjunction with DSC is used.
cycle/PROFIBUS cycle is reduced by adjusting the above parameters, even if the control
loop performance is the same.
drive.
loop).
NOTICE
Before you can switch off DSC operation you might have to adapt (reduce) the K
of the axis. Otherwise, instability of the position control loop might result.
factor)
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Commissioning Manual, 07/2007, 6FC5397-2AP10-3BA0
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IBN CNC: NCK, PLC, drive