Siemens SIPART DR21, Manual

Page: 94 / 242

3 Functional description of the structure switches
3.6 Controller output structures (S2, S49 to S55)
Manual
94
SIPART DR21
C73000-B7476-C143-08
D
Bumpless switching to automatic mode
If there is no automatic operation (manual-, tracking, safety- or active blocking operation) the
I-part or the operating point yo (only at Yo = Auto) is tracked so that the switching to auto-
matic operation is bumpless. Any still active D-part is set to zero.
D
P-PI-switching
With the control signal P = 1, the controller is switched from PI-to P-behavior, at Yo = Auto,
the switching is bumpless.
3.6 Controller output structures (S2, S49 to S55)
The controller structures follow four different controller output structures depending on structure
switch S2.
S2=0 K-controller
S2=1 Two-position controller with 2 S-outputs heating/cooling, optionally one K-output
S2=2 S-controller with internal feedback
S2=3 S-controller with external feedback
D
S2=0: continuous (K) controller (figure 3-22, page 96 and figure 3-23, page 97)
To control proportional active actuators (e.g. pneumatic actuators or I/P-transformers) or as
command controllers in cascades.
actuating time tP,tM (onPA)
The setting speed of the automatic manipulated variable is set with the parameters tP and
tM. In the oFF position, no limiting takes place, in positions 1 to 1000 s the minimum
actuating time for 0 to 100 % manipulated variable is preset. Whereby tP acts during in-
crease and tM during decrease of the manipulated variable. The P-, I- and D-part as well as
the disturbance variable z is limited in the rise speed.
This setting speed limit is used:
- to avoid integral saturations in the actuating times of the following actuator>1 s
- to avoid hard output surges of the P-, D- and z-part.
In this case it must be taken into account that the control time is greater.