Installation manual

Input Parameters
900M050U00  Athena Controls, Inc. 5-13
5.7.2 Scaling the Linear Input
When a linear input is used, the controller will scale the input based on the range you
specify. That means that you enter the PV to be represented by the input when the input
signal is at its lowest level, and the PV to be represented by the input at its highest level.
The controller divides that range into equal segments to interpret a particular input signal.
For example, suppose you use a 4 to 20 mA input to represent a PV that ranges from 0
to 170 °F. You can configure the Linear Input Scaling Low Limit as 0 and the Linear Input
Scaling High Limit as 170 °F. The controller will then be able to calculate that a one mA
change in the linear input means that the PV has changed 10 °F. A 0.1 mA change in the
input represents a 1 °F change in the PV.
The Linear Input Scaling Low Limit and the Linear Input Scaling High Limit must not be
set to the same value.
Parameter Name
: Linear Input Scaling Low Limit (87)
Name as Displayed
:
SCL.LSCL.L
Used By:
all controllers
When Displayed:
only when a linear input type has been selected
Range:
–1999 to 9999 (See Note 1 below.)
Default:
–1999
Description:
Used to specify the PV represented by the lowest possible linear
input signal.
Effect on Other
Parameters:
Limits the valid values for the control menu’s deadband and
hysteresis parameters applied to on/off outputs, as well as for
other parameters. Determines the value displayed for the
calibration menu’s CALoCALo (calibration low) parameter.
Parameter Name
: Linear Input Scaling High Limit (88)
Name as Displayed
:
SCL.HSCL.H
Used By:
all controllers
When Displayed:
only when a linear input type has been selected
Range:
–1999 to 9999 (See Note 1 below.)
Default:
9999
Description:
Used to specify the PV represented by the highest possible
linear input signal.
Effect on Other
Parameters:
Limits the valid values for the control menu’s deadband and
hysteresis parameters applied to on/off outputs, as well as for
other parameters. Determines the value displayed for the
calibration menu’s CAHiCAHi (calibration high parameter).
Note 1: The range is reduced if a linear input is used and the value of the dSPLdSPL (display)
menu dEC.PdEC.P (decimal position) parameter is not 0 (zero). See 4.3.2 for more information
about the effect of a linear input on numerical ranges.