Xylem IM255 AQUAVAR Intelligent Pump Controller - Manual (Page 76)

Feedback function [20–20]
Sum The sum of all feedbacks will be in the feedback to the
controller.
Difference The difference between Feedback 1 and Feedback 2 will
be the feedback to the controller. This setting is
commonly used to configure a differential pressure
signal using 2 separate transducers. NOTE This selection
is only valid with Feedback 1 and Feedback 2. Feedback 3
is not used with this selection.
Average The average of all feedback will be the feedback to the
controller.
Minimum The lowest feedback will be the feedback to the
controller.
Maximum The highest feedback will be the feedback to the
controller.
The minimum and maximum values for each feedback source must be configured to
properly scale the input. For example, for a 0-300 psi transducer, set the Low Feedback
Value to 0 psi and the High Feedback Value to 300 psi.
A Sensor Fault can be enabled or disabled for each feedback. If the Sensor Fault is
enabled and the input to the feedback source falls below 2mA for 4-20mA signals, the
Sensor Fault is issued. The Sensor Fault will automatically restart according to [14-20]
Reset Mode and [14-21] Automatic Restart Time. The defaults for these parameters are set
for an Automatic reset x 3 and an Automatic Restart Time of 10 seconds. For example,
with the default settings if a Sensor Fault is issued the controller will attempt to reset every
10 seconds. The controller will make 3 attempts to reset the fault. If the fault is not cleared
in this time the controller will require a manual reset.
Setpoint setup
The controller can be configured to switch between 2 different setpoints. The setpoints
will be selected through digital input 33 (DI 33, parameter 5-15). When parameter 5-15 is
set to SP1/SP2 and DI 33 is open, the controller will use SP1 (Setpoint 1 [20-21] Setup 1) as
the target pressure, flow or level for the system. When parameter 5-15 is set to SP1/SP2
and DI 33 is closed (connected to 24V), the controller will use SP2 (Setpoint 1 [20-21]
Setup 2) as the target pressure, flow or level for the system.
Operation
74 Aquavar ® Intelligent Pump Controller INSTRUCTION MANUAL