Owner's manual

FOUNDATION
TM
Fieldbus Blocks Manual
2-8
Status Handling Normally, the status of the PV reflects the status of the measurement
value, the operating condition of the I/O card, and any active alarm
condition. In Auto mode, OUT reflects the value and status quality of
the PV. In Man mode, the OUT status constant limit is set to indicate
that the value is a constant and the OUT status is Good.
The Uncertain - EU range violation status is always set, and the PV
status is set high- or low-limited if the sensor limits for conversion are
exceeded.
In the STATUS_OPTS parameter, you can select from the following
options to control the status handling:
BAD if Limited – sets the OUT status quality to Bad when the value
is higher or lower than the sensor limits.
Uncertain if Limited – sets the OUT status quality to Uncertain
when the value is higher or lower than the sensor limits.
Uncertain if in Manual mode – The status of the Output is set to
Uncertain when the mode is set to Manual
NOTES
1. The instrument must be in Manual or OutofService mode to set the
status option.
2. The AI block only supports the BAD if Limited option. Unsupported
options are not grayed out; they appear on the screen in the same
manner as supported options.
Advanced Features The AI function block provided with Fisher-Rosemount fieldbus devices
provides added capability through the addition of the following
parameters:
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.