80-4280-10, Rev. 4
CONFIGURATION / CALIBRATION
30
Linear Function
0
10
20
30
40
50
60
70
80
90
100
0
10
20
30
40
50
60
70
80
90
100
Applied Demand (% Span)
Actual Position (% Span
)
Square Function
0
10
20
30
40
50
60
70
80
90
100
0
10
20
30
40
50
60
70
80
90
100
Applied Demand (% Span)
Actual
Position
(%
Span)
Square Root Function*
0
10
20
30
40
50
60
70
80
90
100
0
10
20
30
40
50
60
70
80
90
100
Applied Demand (% Span)
Actual Position (% Span
)
DEMAND
SIGNAL RESPONSE CURVES
The DCM-2 can be configured to interpret the
applied Demand signal for linear or non-linear
output shaft position response. Several predefined
Demand signal response curves are available for
use including: Linear, Square, and Square Root.
A chart of each of these predefined responses is
provided for your reference.
In addition to the three predefined characterizer
curves, the DCM-2 also allows a custom user-
defined curve to be configured. This option is
called “Special Curve” in the menu.
The Demand characterization curve type can
be configured with the following methods.
HART
method
HART DD Menu Location: MENU 5C
Functions> Configuration> Demand Setup
Command:
Dem Curve
Selections:
Linear
- select if the actual position % should
match the applied Demand %.
Square Root
- select if the actual position %
should match the square root of the applied
Demand %.
Special Curve
- select if a user-defined response
is desired. (see characterization on the following
page to define the desired response curve)
Square
- select if the actual position % should
match the square of the applied Demand %.
(e.g.: “demfunc 0” sets the actuator to a linear
Demand response)
SERIAL
command method
Command: demfunc
Arguments:
#
Enter the integer that represents
the desired Demand signal response as follows:
0
: Linear - select if the actual position % should
match the applied Demand %.
1
: Square Root - select if the actual position %
should match the square root of the applied
Demand %.
4
: Special - select if a user-defined response is
desired. (see characterization on the following
page to set the desired response curve)
5
: Square - select if the actual position % should
match the square of the applied Demand %.
(e.g.: “demfunc 0” sets the actuator to a linear
Demand response)
DEMAND
CHARACTERIZATION
CURVE
NOTE
Implementing a square root characterization
creates extremely high gain when a the
Demand signal is below 10%. This causes
instability and is unsuitable for control in
this region. Do not apply this curve if the
control loop may need to modulate at the
lower range of travel.
