Fisher FIELDVUEDVC6200f Instruction Manual page 227

Instruction Manual
D103412X012
In Manual mode the output is entered manually by the operator. In Remote Output mode, the output is entered by a
host computer.
Output Selection and Limiting
Output selection is determined by the mode and the set point. In Automatic, Cascade, or Remote Cascade mode, the
output is computed by the PID control equation. In Manual and Remote Output mode, the output may be entered
manually (see also Set Point Selection and Limiting). You can limit the output by configuring the OUT_HI_LIM [28] and
OUT_LO_LIM [29] parameters.
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 [16] or SP_FTIME [69]
parameters. Set the filter time constant to zero to disable the filter feature.
Feedforward Calculation
The feedforward value (FF_VAL [40]) is scaled (FF_SCALE [41]) to a common range for compatibility with the output
scale (OUT_SCALE [11]). A gain value (FF_GAIN [42]) is applied to achieve the total feedforward contribution.
Output Tracking
Output tracking is enabled through the control options. You can set control options in Manual or Out of Service mode
only.
The Track Enable control option must be set to True for the track function to operate. When the Track in Manual
control option is set to True, the operator cannot override the tracking function in Manual mode. When Track in
Manual is False, the operator can override the tracking function when the block is in Manual mode. Activating the track
function causes the block's actual mode to revert to Local Override.
The TRK_VAL [38] parameter specifies the value to be converted and tracked into the output when the track function
is operating. The TRK_SCALE [37] parameter specifies the range of TRK_VAL [38].
When the TRK_IN_D [38] parameter is True and the Track Enable control option is True, the TRK_VAL [38] input is
converted to the appropriate value and output in units of OUT_SCALE [11].
Set Point Tracking
You can configure the method for tracking the set point by configuring the following control options (CONTROL_OPTS
[12]):
D SP-PV Track in Man—Permits the SP [8] to track the PV [7] when the actual mode of the block is Man.
D SP-PV Track in LO or IMan—Permits the SP [8] to track the PV [7] when the actual mode of the block is Local Override
(LO) or Initialization Manual (IMan).
D SP-PV Track in ROUT—Permits the SP [8] to track the PV [7] when the actual mode of the block is RemoteOut
(ROUT).
D SP Track retained Target—Causes the set point to track the RCAS or CAS parameter based on the retained target
mode when the actual mode is MAN or LO.
DVC6200f Digital Valve Controller
PID Function Block
February 2017
227