Appendix C Fieldbus Parameters
FieldPoint FP-3000 User Manual C-16
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National Instruments Corporation
PV
The process variable being controlled by the process.
PV_FTIME
The filter time used in input blocks. For analog blocks, it is the time
constant for a low pass exponential filter used to dump out rapid
oscillations in the input value before using it as the process variable. For
discrete blocks, it is the time the PV must remain constant after a change
for the change to be reported.
PV_SCALE
The scaling parameter used by the process variable of the block. Converts
from percent of scale to a process variable in engineering units. Contains
the same subfields as OUT_SCALE.
RATE
The time constant for the derivative component of the PID block.
RCAS_IN
The cascade input set by a remote host. This is propagated to the setpoint
of the block when it is in RCas mode. If the block is in RCas mode and this
parameter is not updated in SHED_RCAS time (a parameter in the resource
block), the block enters mode shedding. Mode shedding allows the block to
degrade from RCas mode into some higher priority mode. Refer to
Appendix D, Advanced Function Block Behavior, for more information
about mode shedding.
Table C-11. OUT_SCALE Parameter
Subfield Meaning
EU_100 Engineering units value at 100 percent of
scale.
EU_0 Engineering units value at zero percent of
scale.
UNIT_INDEX Actual engineering units code (such as mA).
DECIMAL Number of digits a host shows to the right of
the decimal for display purposes.