Endress+Hauser Liquiline CA80SI - Page 93

Liquiline System CA80SI Operation
Endress+Hauser 93
integral section (middle) also comprises an anti‐windup mechanism for limiting the
integrator. A low-pass filter is added to the D‐section to damp hard D‐terms in the
manipulated variable. The sum of the 3 sections results in the internal controller
manipulated variable which is limited according to the settings (for PID‐2s to ‐100% to
+100%).
The graphic does not illustrate a downstream filter for limiting the rate of change of the
manipulated variable (can be configured in the menu in Max y change rate).
In the menu do not configure the gain K
p
. Instead configure the reciprocal value, the
proportional band X
p
(K
p
=1/X
p
).
Configuration
Make the following decisions to configure a controller:
• (1) What type of process can your process be assigned to? → Process type
• (2) Should it be possible to influence the measured variable (controlled variable) in one
direction or in both directions? One-sided or two-sided controller, → Controller type
• (3) What should be the controlled variable (sensor, measured value)? → Controlled
variable
• (4) Do you have a disturbance variable that should be active at the controller output? →
Disturbance variable
• (5) Specify the parameters for the controller:
– Set point, → Setpoint
– Neutral zone, → Xn
– Proportional band, → Xp
– Integral action time (I-value), → Tn
– Derivative action time (D-value), → Tv
• (6) What should the controller do in the event of a hold (measured error, sensor
replacement, cleaning etc.)?
– Pause or continue with dosing? →Hold behavior/Manipulated Variable
– At the end of a hold, continue or restart the control loop (affects I‐value)? →Hold
behavior/State
• (7) How should the actuator be triggered?
– Unipolar+: assign this setting to the output for an actuator which can increase the
measured value.
– Unipolar-: assign this setting to the output for an actuator which can decrease the
measured value.
– Bipolar: select this setting if you want to output the manipulated variable via one
current output only (split range).
• (8) Configure the outputs and switch on the controller.