West Control Solutions KS98-1 - Manual (Page 264)

Controller-internal operations during switch-over with CONTR, CONTR+ and PIDMA
Switch-over Without gradient function With gradient function
1
After correcting variable adaptation with de-
letion of a still effective derivative action, the
approach to the setpoint is bumpless The effective setpoint ramp continues run-
ning in the background during manual
mode. After switching over to automatic,
the correcting variableis adapted and the
derivative action is deleted and the setpoint
is set to the actually reached ramp setpoint
(bumpless).
2
The effective setpoint is set to the process
value first and after deleting a still effective
derivative action, a setpoint step change to
the target is made. During this step change,
the PID parameters are effective. The deriva-
tive action is a result of the step change (not
bumpless).
At first, the effective setpoint is set to the
process value. After deleting the derivative
action, the approach to the target setpoint
is via a ramp. During this transition, the PID
parameters are effective (bumpless starting
with 0).
3
After deleting a still effective derivative ac-
tion, a step change from the instantaneous
to the target setpoint is made. During this
step change, the PID parameters are effec-
tive. The derivative action is a result of the
new step change (not bumpless).
After deleting the derivative action and
adapting the correcting variable, changing
from the old to the new target setpoint is
done via a ramp (bumpless) .
4,
5,
6,
7
After deleting a remaining derivative action,
a setpoint step change from the instanta-
neous to the target setpoint is made. During
this step change, the PID parameters are ef-
fective. The derivative action is only a result
of the new step change (not bumpless).
The effective setpoint is set to the process
value. After deleting the derivative action
and adapting the correcting variable,
setpoint changing from the process value to
the target setpoint is done via a ramp
(bumpless).
8
The internal target setpoint is set to the ac-
tual process value or to the external setpoint.
Subsequently, any still effective derivative
action is deleted and the correcting variable
is adapted ( bumpless).
The internal target setpoint is set to the ac-
tual process value or to the external
setpoint. Subsequently, any still effective
derivative action is deleted and the correct-
ing variable is adapted ( bumpless).
Gentle line-out to the target setpoint with ramps
When using a setpoint ramp, a process value overshoot at the ramp end may occur. Due to the difference between set -
point and process value in the course of the ramp, an integral action is built up and must be removed after the end of
the ramp. The longer the ramp, the higher the integral action. And the more exact the process value follows the set -
point, the higher the probability that any integral action will cause an overshoot.
The target line-out function is used to adapt the integral action to the actual PD action at an adjustable distance befo -
re reaching the ramp end value, the D-dynamics is initialized and the setpoint is set to the ramp end value. Now the
controller dynamics re-starts bumplessly related to the new setpoint.
9499-040-82711
III-264 Setpoint functions