Dsc (Dynamic Servo Control) (Sw 2.1 And Higher) - Siemens SINUMERIK 840Di Manual

06.03
10.5.8

DSC (Dynamic Servo Control) (SW 2.1 and higher)

Prerequisites
Switch ON/OFF
 Siemens AG, 2003. All rights reserved
SINUMERIK 840Di Manual (HBI) – 06.03 Edition
The DSC function eliminates the deadtime that necessarily exist at the speed
setpoint interface normally used between the NC and drive due to relocation of
the position controller into the drive.
That results in the following advantages for an axis operated with DSC:
S
Considerably improved fault response/stability of the position control loop
S
Improved control behavior (contour precision) if the higher servo gain
(KV factor) that can be set in conjunction with DSC is used.
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A reduction of the cyclic communication load on the PROFIBUS, if the posi-
tion controller cycle/PROFIBUS cycle is reduced by adjusting the above
parameters even if the control loop performance is the same.
Note
The speed feedforward control can be used in conjunction with DSC.
Before you can activate DSC mode, the following preconditions must be fulfilled:
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DSC-capable drive, e.g.:
– SIMODRIVE 611 universal
– SIMODRIVE POSMO CD/CA
– SIMODRIVE POSMO SI
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A DSC-capable message frame type has been parameterized in the S7 proj-
ect for the drive (see Subsection 7.3.7, page 7-233).
The DSC function is switched ON in the axis-spec. NC machine data
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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:
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MD32200: POSCRTL_GAIN (KV factor)
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MD32610: VELO_FFW_WEIGHT (feedforward control factor)
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MD32810: EQUIV_SPEEDCTRL_TIME (substitute time const. of the closed
speed control loop).
Notice
Before you can switch off DSC operation you might have to adapt (reduce) the
KV factor of the axis. Otherwise, instability of the position control loop might
result.
10 NC Start-Up with HMI Advanced
10.5 Axes and spindles
10-325