West Control Solutions KS98-1 - Manual (Page 262)

Controlling the setpoint
The digital input rstart reacts to a positive signal slope and sets the effective setpoint to the process value. The
new goal is started on the basis of the controlled variable xeff. Such a ramp can only be started with activated gra-
dient function ( Grw+, Grw -, Grw2 and digital input gr_offnot set).
The digital input w_stop freezes the effective Weff , i.e., the effective setpoint is held to the current value, even
if the effective setpoint straight approaches a new goal or a new goal is selected.
Setpoint-Tracking
During the change-over of Wext r W it can come to unwanted jumps. To aviod these jumps setpoint-tracking can be
applied. Setpoint-tracking takes care that in switch-over of Wext r W, the past Wext is taken over as int. W.
The digital input "track" enables Tracking. When switching back ( W r Wext) Wext is started with the attitude of
Grw+/-. With the configurationword is determined if the controller shall follow process value or setpoint-tracking
Wtrac. Tracking can be activated via interface or by operating the switchover Wext r W . Tracking is evaluated
with priority.
If a source (interface or digital input) is activating setpoint-tracking, switching by operation switching W
ext
r W from
another source is not possible!
9499-040-82711
III-262 Setpoint functions
internal
s
W etpoint
upper setpoint limit W100
internal setpoint W
x
W
Wext
Time
Setpoint, process value
Process value
Grw -
Wext
lower setpoint limit W0
Switch over Switch over
Wext W r W Wext r
effective setpoint
Fig. 80:
Setpoint 2
Setpoint 1
Adjustment of
1 2 Setpoint Setpoint r
rstart = z
w_stop = 1
w_stop = 0
gr_off = 1
upper setpoint limit W100
effective setpoint
x
W
Time
Setpoint, process value
Process value
Grw+
lower setpoint limit W0
Fig. 81: