Emerson Rosemount 5900C, Reference Manual

Page: 167 / 322

ALARM_TYPE Allows one or more of the process alarm conditions detected by the AI
function block to be used in setting its OUT_D parameter.
OUT_D Discrete output of the AI function block based on the detection of
process alarm condition(s). This parameter may be linked to other
function blocks that require a discrete input based on the detected alarm
condition.
VAR_SCAN Time period in seconds over which the variability index (VAR_INDEX) is
computed.
VAR_INDEX Process variability index measured as the integral of average absolute
error between PV and its mean value over the previous evaluation period.
This index is calculated as a percent of OUT span and is updated at the
end of the time period defined by VAR_SCAN.
4.11.10 Filtering
The filtering feature changes the response time of the device to smooth variations in
output readings caused by rapid changes in input. You can adjust the filter time constant
(in seconds) using the PV_FTIME parameter. Set the filter time constant to zero to disable
the filter feature.
Figure 4-17: Analog Input Function Block Timing Diagram
$
%
&
)
(
'
*
A. FIELD_VAL
B. PV_FTIME
C. 63% of Change
D. PV
E. OUT (mode in auto)
F. OUT (mode in man)
G. Time (seconds)
Reference Manual Configuration
00809-0100-5901 September 2019
Rosemount 5900C Radar Level Gauge 167