Optimization Of The Control Data - Siemens PROFIBUS PA SIPART PS2 Manual

4.7

Optimization of the control data

13 Pulse length up
14 Pulse length down
17 Short step zone up
18 Short step zone down
34 Prediction up
35 Prediction down
It is recommended that the firstly an automatic initialization is performed and only thereafter that
the positioner parameters are matched to any special requirements.
TIP: So as to have a fixed reference value, it is advantageous for special control optimization
to set a fixed value for the dead zone (parameter DEBA) instead of "Auto".
The above parameters are usually selected from the diagnostics menu and activated for
general adjustment by pressing the increment or decrement key. Any adjustment to a
parameter will be immediately effective. This means the effect of the new values on the control
results can be immediately tested.
On leaving the diagnostic menu the activation of the parameter for adjustment will be deacti-
vated again.
SIPART PS2 PA Manual
A5E00127926-03
The data automatically determined during initialization for control qual-
ity are optimized for short duration commands with small overshoots. In
special cases (e.g. extremely small and specially quick actuators or
when operating with boosters) it can however occur that these data
need to be revised to achieve quick responses or heavy damping. The
following six parameters are available for this purpose:
This determines for any sense of actuation the smallest drive move-
ment pulse length. The optimum value is dependent particularly on the
volume of the drive. Small values will lead to small actuation incre-
ments and frequent control drive activations. Note that if the value is
too small no movement will result. If drive volumes are large, then it is
better to use larger actuation increments. Note also that large actuation
increments will still lead to large movements for small drives.
The short step zone is the range in which the control variation between
the fast step zone and the dead band. In this zone the drive is activa-
ted in pulses.
If the value is small, even small changes of setpoint will evoke relatively
large positioning speeds and can thus lead to overshoots. If the value
is large, the overshoots will be reduced, particularly on large changes
of setpoint but will lead to slow positioning speeds, particularly as the
target setpoint is approached closely.
These parameters operate on the damping factor and have the effect of
adjusting the control dynamics.
If the value is small, responses will be quick but with overshoots. If the
value is large, response will be slow but without overshoots.
Operation
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