Danfoss FC 102 Design Manual page 40

Introduction to VLT® HVAC D...
2.8.9 Reference Handling
2 2
Details for Open Loop and Closed Loop operation
P 3-14
Preset relative ref.
No function
Analog inputs
Frequency inputs
Ext. closed loop outputs
DigiPot
No function
Analog inputs
Frequency inputs
Ext. closed loop outputs
DigiPot
No function
Analog inputs
Frequency inputs
Ext. closed loop outputs
DigiPot
Bus
reference
Illustration 2.29 Block Diagram Showing Remote Reference
The remote reference is comprised of:
•
Preset references.
•
External references (analog inputs, pulse
frequency inputs, digital potentiometer inputs
and serial communication bus references).
•
The Preset relative reference.
•
Feedback controlled setpoint.
Up to 8 preset references can be programmed in the
frequency converter. The active preset reference can be
38
Design Guide
Input command:
Preset ref. bit0, bit1, bit2
[0]
[1]
[2]
[3]
[4]
[5]
[6]
P 3-04
[7]
Ref. function

on
±200%
o
Input command:
Ref. Preset

External
reference
in %
Setpoint
From Feedback Handling
Danfoss A/S © Rev. 06/2014 All rights reserved.
Input command:
Freeze ref.
Y
Relative

X+X*Y
X
±200%
/100
±200%
±100%
Freeze ref.
&
increase/
decrease
ref.
Input command:
Speed up/ speed down
P 1-00
Con guration mode
Increase
0/1
Decrease
Closed loop
0/1
±200%
Clear
0%
0/1
Open loop
selected using digital inputs or the serial communications
bus. The reference can also be supplied externally, most
commonly from an analog input. This external source is
selected by one of the 3 Reference Source parameters
(3-15 Reference 1 Source, 3-16 Reference 2 Source and
3-17 Reference 3 Source). Digipot is a digital potentiometer.
This is also commonly called a Speed Up/Speed Down
Control or a Floating Point Control. To set it up, one digital
input is programmed to increase the reference, while
another digital input is programmed to decrease the
reference. A third digital input can be used to reset the
Digipot reference. All reference resources and the bus
P 1-00
Con guration mode
Open loop
Scale to
RPM,Hz
or %
max ref.
Remote
%
ref.
%
min ref.
Scale to
Closed
loop
unit
Closed loop
Ref. in %
Digipot ref.
DigiPot
±200%
MG11BC02