Table J-1: Definitions of Analog Input Function Block System Parameters (continued)
Parameter Index Number Units Description
VAR_SCAN 40 Seconds The time over which the VAR_INDEX is evaluated.
XD_SCALE 10 None The high and low scale values, engineering units code, and number
of digits to the right of the decimal point associated with the
channel input value.
J.2 Simulation
To support testing, you can either change the mode of the block to manual and adjust the
output value, or you can enable simulation through the configuration tool and manually
enter a value for the measurement value and its status. In both cases, you must first set
the ENABLE jumper on the field device.
Note
All fieldbus instruments have a simulation jumper. As a safety measure, the jumper has to
be reset every time there is a power interruption. This measure is to prevent devices that
went through simulation in the staging process from being installed with simulation
enabled.
With simulation enabled, the actual measurement value has no impact on the OUT value
or the status.
Figure J-2 illustrates the internal components of the AI function block.
J.3 Damping
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.
Reference Manual Analog-Input Block
00809-0100-4530 April 2019
Reference Manual 461
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