SMAR CD600 Plus User Manual

Library of Function Blocks
4.19
Control Algorithm
The CD600 offers two control algorithms:
Parallel or Ideal algorithm
dt
) de(t
T
D
+ )dt e(t.
1
+ ) e(t
K
p
= ) MV(t ∫
T
R
Noninteractive or ISA algorithm
]
dt
) de(t
T
D
+ )dt e(t.
T
R
1
+ ) [e(t
K
p
= ) MV(t ∫
Parameters 0, 1, 2 or 3 select the parallel or ideal.
Parameters 4, 5, 6 or 7 select the noninteractive or ISA.
For the noninteractive option, when K
p
=0 the controller is automatically set as ID.
QUADRATIC ERROR (CETY)
The control deviation (or error) normally used in the CD600 controller calculations is given by:
e = SP - PV When "Output decreases when PV increases" is selected.
e = PV -SP When "Output increases when PV increases" is selected.
There are processes where the deviations in relation to the Setpoint are preferable to disturbances
caused by the controller on downstream processes. Therefore, the control actuation should be small
for small deviations and increase gradually with the size of the deviation. A typical example of this
type of process is the level control of a tank where the Setpoint is not as important as the flow
stability downstream the tank. This type of process can be controlled with the adaptative gain, the
control with gap, or the quadratic error in-stead of the linear (normal) error.
In the quadratic error (CETY=1), the error to be considered in the PID calculations is given by:
100
/e/e
ê
⋅
=
ê = error to be considered in the PID calculation.
CONSIDERED
ERROR
QUADRATIC
LINEAR
(NORMAL)
ê
100%
0
100%
ERROR = e
Fig 4.9.2 - Quadratic Error x Normal Error

SMAR CD600 Plus Specifications

General

Brand	SMAR
Model	CD600 Plus
Category	Controller
Language	English