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R400
Experion PKS Series A Fieldbus Interface Module User's Guide
July 2010
Use the Balance Ramp CONTROL_OPTS to maintain
the BIAS value, when the block is in Manual (Man)
mode. An internal value follows the actual value
required to maintain balance. When block mode
changes to Automatic (Auto), the internal value ramps
to zero contribution in BAL_TIME seconds. If Balance
Ramp option is OFF or not used, the BIAS value
immediately changes to follow the changes to the input
or output, when the block is in Man mode.
Use the Act on IR CONTROL_OPTS to select
whether to ignore initialization requests or act on them
by changing the BIAS. If this option is ON, a status of
Not Invited (NI) or Initialization Request (IR) at
BKCAL_IN causes the BIAS term to be adjusted to
balance OUT to the value of BKCAL_IN.
Use the Direct Acting CONTROL_OPTS to define how
a change in PV relative to the SP affects the output.
When Direct Acting is ON, the output increases when
the PV exceeds the SP. When Direct Acting is OFF,
the output decreases when the PV exceeds the SP. Be
sure this option is set correctly and never changed
while in the Automatic mode, since it makes the
difference between positive and negative feedback.
This option setting also affects the calculation of the
limit states for BKCAL_OUT.
This block includes a Feed Forward algorithm. It
accepts a value that is proportional to some
disturbance in the control loop as its FF_VAL input.
The FF_SCALE values convert the FF_VAL to a
percent of output span value. The converted value is
multiplied by the FF_GAIN and added to the target
output of the block's algorithm. If the status of FF_VAL
is Bad, the last usable value will be used to prevent a
bump in the output. When the status returns to Good,
the block adjusts its BIAS term to maintain the previous
output.
The TRK_VAL input brings in an external value or
uses a constant. The TRK_SCALE values convert the
TRK_VAL to a percent of output span value. If the
CONTROL_OPTS Track Enable selection is true and
TRK_IN_D is true, the converted TRK_VAL replaces
the output (OUT), when the block is in Automatic
(Auto), Cascade (Cas), Remote Cascade (RCas), or
Remote-Out (ROut) mode. The CONTROL_OPTS
Honeywell
10. Appendix A
10.2. Standard Function Blocks
405
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