User Guide
13
7. External setpoint signal
By connecting an analog signal transmitter to the input for the 
setpoint signal (terminal 4), it is possible to remote-set the
setpoint. 
The actual external signal (0-10 V, 0-20 mA, 4-20 mA) must be 
selected via the R100, see section 5.3.3 Selection of external set-
point signal.
If uncontrolled operation is selected by means of the R100, the 
pump can be controlled by any controller.
In controlled-operation mode, 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, 
fig. 18.
Fig. 18 Relation between the actual setpoint and the external 
setpoint signal in controlled-operation mode 
Example: At a lower differential-pressure sensor value of 0 psi, a 
setpoint set of 20 psi and an external setpoint of 80%, the actual 
setpoint will be as follows:
H
actual 
= (H
set
 - H
lower
) x %
external setpoint 
+ H
lower
= (20 - 0) x 80% + 0 
= 16 psi
In uncontrolled-operation mode, the setpoint can be set exter-
nally within the range from the min. curve to the setpoint set on 
the pump or by means of the R100, fig. 19.
Fig. 19 Relation between the actual setpoint and the external 
setpoint signal in uncontrolled-operation mode
8. Bus signal 
The pump enables serial communication via an RS-485 input. 
The communication is carried out according to the Grundfos bus 
protocol, GENIbus protocol, and enables connection to a building 
management system or another external control system.
Via the bus signal, it is possible to remote-set pump operating 
parameters, like setpoint, operating mode, etc. At the same time, 
the pump can provide status information about important
parameters, like actual value of control parameter, input power, 
fault indications, etc. 
Contact Grundfos for further details. 
Note: If a bus signal is used, the number of settings available via 
the R100 will be reduced.
TM02 8988 1304TM02 8988 1304
0 10 V
0 20 mA
4 20 mA
Actual setpoint
Upper value 
of sensor measuring range
Setpoint set on pump 
or with the R100
Lower value 
of sensor measuring range
External setpoint signal
Actual
setpoint
0 10 V
0 20 mA
4 20 mA
% 
Max. curve
Setpoint set on pump
or with the R100
Min. curve
External setpoint signal
Actual
setpoint
Grundfos.bk Page 13 Thursday, November 11, 2010  11:21 PM










