Endress+Hauser Liquiline CM44P - Page 109

Liquiline CM44P Operation
Endress+Hauser 109
Menu/Setup/Additional functions/Controller 1 ... 2
Function Options Info
Controller Enable Selection
• None
• Binary inputs
• Limit switches
• Fieldbus variables
Factory setting
None
In connection with the DIO module, you can
select a binary input signal, e. g.from an
inductive proximity switch, as a source for
enabling the controller.
Setup Level Selection
• Standard
• Advanced
Factory setting
Standard
Changes the number of parameters that can be
configured. → Parameters →  112
Standard: If you choose this, the other controller
parameters are active nevertheless. The factory
settings are used. These suffice in most cases.
Process type Selection
• Inline
• Batch
Factory setting
Inline
‣
Decide what type of process best describes
your particular process.
Batch process
The medium is in a closed system.
The task of the control system is to dose in such a way that the measured value (controlled variable) changes
from its start value to its target value. No more dosing is needed once the set point has been reached and the
system is stable. If the target value is overshot, a two-sided control system can compensate for this. In the case
of 2-sided batch control systems, a neutral zone is used/configured to suppress oscillations around the set
point.
In-line process
In an in-line process, the control system works with the medium flowing by in the process.
Here, the controller has the task of using the manipulated variable to set a mixture ratio between the medium
and dosing agent such that the resulting measured variable corresponds to the set point. The properties and
volume of the medium flow can change at any time and the controller has to react to these changes on a
continuous basis. If the flow rate and medium remain constant, the manipulated variable can also assume a
fixed value once the process has settled. Since the control process is never "finished" here, this type of control is
also referred to as continuous control.

A mixture of both process types can often be found in practice: the semi‐batch process. Depending on the
ratio between the flow and the container volume, this arrangement behaves either like a batch process or
an in-line process.
Controller type Selection
• PID 1-sided
• PID 2-sided
Factory setting
PID 2-sided
Depending on which actuator you have
connected, you influence the process in only one
direction (e.g . heating) or in both directions
(e. g. heating and cooling).
A 2‐sided controller can output a manipulated variable in the range from -100 % to +100 %, i. e. the
manipulated variable is bipolar. The manipulated variable is positive if the controller should increase the
process value. In the case of a pure P-controller, this means that the value of the controlled variable x is smaller
than the set point w. On the other hand, the manipulated variable is negative if the process value should be
decreased. The value for x is greater than the set point w.
y
+100 %
0 %
-100 %
x < w
w
x > w
x
X
p
X
p
 93 Relationship y = (w-x)/X
p