Endress+Hauser Liquiline CM442R - Page 74

Operation Liquiline CM442R/CM444R/CM448R
74 Endress+Hauser
2. PFM (pulse frequency modulation):
Here, pulses of a constant length (t
1
) are output and the interval between the pulses varies
(t
0
). At a maximum frequency, t
1
= t
0
.
Typical application: dosing pump
Function="Controller"
Function Options Info
Actuator type Options
•None
•Unipolar-
•Unipolar+
Factory setting
None
Here you specify what part of the controller should
power the relay. "Unipolar+" is the part of the
manipulated variable which the controller uses to
increase the process value (e.g. for heating purposes).
On the other hand, select "Unipolar-" if you want to
connect an actuator to the relay that causes the
controlled variable to drop (e.g. for cooling purposes).
Cycle duration
Operating mode="PWM"
(Shortest turn-on time) to
999.0 s
Factory setting
10.0 s
Specify the cycle duration within which the duty cycle
should be varied (only PWM).
The settings for Cycle duration and Shortest turn-on time mutually affect one another. The following applies Cycle
duration ≥ Shortest turn-on time.
Shortest turn-on time
Operating mode="PWM"
0.3 s to (Cycle duration)
Factory setting
0.3 s
Pulses that are shorter than this limit value are not
output in order to conserve the actuator.
Maximum frequency
Operating mode="PFM"
1 to 180 min
-1
Factory setting
60 min
-1
Maximum number of pulses per minute
The controller calculates the pulse duration based on
this setting.