Instruction Manual

Instruction Manual
D103434X012
Blocks
November 2014
75
Figure B‐3. Analog Input Function Block Timing Diagram
OUT (mode in man)
OUT (mode in auto)
PV
63% of Change
TIME (seconds)
FIELD_VAL
PV_FTIME
FIELDBUS‐FBUS_03A
Status Handling
The AI block only gets Good Non‐Specified Unlimited or Bad Device Failure for status from the transducer. This is
reflected in FIELD_VAL.STATUS [19.1]. PV.STATUS [7.1] is the same as FIELD_VAL.STATUS [19.1]. OUT.STATUS [8.1]
can also reflect Bad, Out of Service in addition to PV.STATUS [7.1] values.
In the STATUS_OPTS [14] parameter, you can select from the following options to control the status handling:
Propagate Fail Forward—If the status from the sensor is Bad, Device failure or Bad, Sensor failure, propagate it to OUT
without generating an alarm. The use of these sub‐status in OUT is determined by this option. Through this option,
you may determine whether alarming (sending out an alert) will be done by the block or propagated downstream for
alarming.
Uncertain if in Manual mode—The status of the Output is set to Uncertain when the mode is set to Manual.
Note
1. The instrument must be in Out of Service mode to set the status option.
2. The AI block only supports the Uncertain if in Manual and Propagate failure. Unsupported options are not grayed out; they
appear on the screen in the same manner as supported options.
Channel Selection
See table B‐2 for AI block channel selection information.
Table B‐2. Channel Selection for the Analog Input Function Block
Channel Parameter
(1)
Block Index Number XD_SCALE Units
1 PRIMARY_VALUE TB 14 Valid Length Units (DLC_UNITS.LENGTH UNITS [25.2])
1. Refer to table B‐54 for transducer block parameter description.
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 [18] parameter. Set the filter
time constant to zero to disable the filter feature.