Siemens SIPART DR21 User Manual

3 Functional description of the structure switches
3.4 Controller types (S1, S42 to S45)
Manual
56
SIPART DR21
C73000-B7476-C143-08
safe
Setpoint
external
Setpoint
w
E
Δw
t
tw
α
SH
w
t
w
=
tan
α =
100 %
tS
Δw
tw
Δw·tS
100 %
=
Figure 3-4 Setpoint switching with ramp
The setpoint change/setpoint ramp can be stopped with the control signal tSH. The setpoint
change continues when the signal is reset.
D Setpoint limits SA, SE
With the parameters SA and SE (oFPA) the effective setpoint w can be limited to minimum
value (SA) and maximum value (SE) in the range from -10 to 110 %.
Exception: Ratio controller (S1 = 3)
D T racking of the ineffective setpoint to the active setpoint (S45)
Normally the ineffective setpoint is tracked to the effective setpoint so that the setpoint
switching is bumpless. The internal setpoint (wi) and the external setpoint can be tracked via
the SES (w
ES
). The safety setpoint SH cannot be tracked.
The external setpoint w
EA
through the analog inputs is only indirectly trackable by tracking
the feeding instrument to the internal setpoint.
At S45 = 1 the tracking is suppressed. This switch setting is always required especially in
follow-up controllers if the internal setpoint represents a kind of safety function or if multiple
setpoint operation is to be run in the fixed setpoint controller (S1 = 0).
D x-tracking (S43)
With the structure switch S43 = 1, x-tracking (ratio controller xv-tracking) can be switched
on. This means that the setpoint is tracked to the actual value or the nominal ratio is tracked
to the actual ratio and therefore a control difference xd is reset to 0. The tracking always
takes place when there is no automatic operation (A
). This is the case in manual mode (H),
tracking mode (N), DDC-mode and in operation with safety manipulated variable (Si):
A
=H∨N∨Si
x-tracking in direction-dependent blocking operation is not possible because the P-step pro-
duced by resetting the driving control error to blocking direction would immediately cancel
the blocking.
x-tracking takes place without the set setpoint ramp tS. By tracking the setpoint to the actual
value (nominal ratio to actual ratio), the control difference xd = 0 and automatic operation
starts absolutely bumplessly. Since it can normally be assumed that, especially in manual
operation and in DDC-operation, the actual value has been driven to the desired value dur-
ing manual- or DDC-operation, the tracked setpoint then corresponds to the rated value.

Siemens SIPART DR21 Specifications

General

Brand	Siemens
Model	SIPART DR21
Category	Controller
Language	English