Grundfos CRE - Digital Input; External Setpoint Signal

5.7 Digital input
By means of the R100, one of the following functions can be
selected for the digital input:
• Normal duty
• Min. curve
• Max. curve
• External fault
• Flow switch
• Dry running.
Functional diagram: Input for digital function
Digital function
(terminals 1 and 9) (terminals 9 and 10) (terminals 9 and 11)
Q
H
Normal duty
Q
H
Min. curve
Q
H
Max. curve
Q
H
5s
External fault
Q
H
5s
Flow switch
Q
H
Dry running
5.8 External setpoint signal
The setpoint can be remote-set by connecting an analogue signal
transmitter to the input for the setpoint signal (terminal 4).
1
2
3
TM038601
Actual setpoint as a product (multiplied value) of setpoint and
external setpoint
Pos. Description
1 Setpoint
2 External setpoint
3 Actual setpoint
Select the actual external signal, 0-10 V, 0-20 mA, 4-20 mA, via the
R100. See the section on external setpoint.
If control mode uncontrolled is selected by means of the R100, the
pump can be controlled by any controller.
In control mode controlled, the setpoint can be set externally within
the range from the lower value of the sensor measuring range to
the setpoint set on the pump or by means of the R100.
0
10 V
0
20 mA
4
20 mA
1
2
3
4
B
A
TM028988
Relation between the actual setpoint and the external setpoint
signal in control mode controlled
Pos. Description
A Actual setpoint
B External setpoint signal
1 Actual setpoint
2
Sensor
max
3
Setpoint set by means of control panel, R100 or PC Tool
E-products
4
Sensor
min
Example: At a sensor
min
value of 0 psi, a setpoint set of 50 psi and
an external setpoint of 80 % (an 8 V analog signal to Terminal 4 if
using an analog signal of 0-10 V), the actual setpoint will be as
follows:
Actual
setpoint
=
(setpoint - sensor
min
) × %
external setpoint
+ sensor
min
= (50 - 0) × 80 % + 0
= 40 psi
In control mode uncontrolled, the setpoint can be set externally
within the range from the min. curve to the setpoint set on the pump
or by means of the R100. Typically the setpoint is set to 100 %
when the control mode is uncontrolled (see the section on typical
display settings for analog-input E-pumps).
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