Red Lion PCU - Manual (Page 30)

Input Signal Filter and Display Update Rate (FLtr)
Select the relative degree of input signal filtering and display update rate.
T h e f i l t e r i s a n a d a p t i v e d i g i t a l f i l t e r t h a t d i s c r i m i n a t e s b e t w e e n
measurement noise and actual process changes. Therefore, the influence on
step response time is minimal. If the signal is varying too greatly due to
measurement noise, increase the filter value. Additionally, with large
derivative times, control action may be too unstable for accurate control.
Increase the filter value. Conversely, if the fastest controller response is
desired, decrease the filter value.
The Auto-tune procedure sets the filter value appropriate to the process
characteristics. Also see Output Power Dampening parameter (OPdP), page
25, for filtering the output.
Fltr- 0 to 4
0 = least input filtering
3 = most input filtering
4 = most input filtering and slower (2/sec) display update rate
(outputs update at 10/sec rate)
Scaling Points
Prior to installing and operating the controller, it may be necessary to
change the scaling to suit the display units particular to the application.
Although the unit has been programmed at the factory, the scaling will
generally have to be changed.
The controller is unique in that two different scaling methods are available.
The operator may choose the method that yields the easier or more accurate
calibration. The two scaling procedures
are similar in that the operator keys in the
display values and either keys in or
applies a signal value that corresponds to
those scaling points. The location of the
scaling points should be near the process
end limits, for the best possible accuracy.
Once these values are programmed
(coordinates on a graph), the indicator
calculates the slope and intercept of the
signal/display graph automatically. No
span/zero interaction occurs, making
scaling a one-pass exercise.
Before programming the indicator, it is advised to organize all the data for
the programming steps to avoid possible confusion.
To scale the indicator, two signal values and two display values that
correspond to the signal values must be known. These four values are used to
complete the scaling operation. An example is listed below:
Scaling Point #1 Scaling Point #2
0.0% @ 4.00 mA & 100.0% @ 20.00 mA
Reverse acting indication can be accomplished by either reversing the two
signal points or the display value points, but not both. If both are reversed,
then forward (normal) acting indication will occur. In either case, do not
reverse the input wires to correct the action.
Display Values (dSP1 & dSP2)
Key-in the display value for scaling point one and scaling point two.
dSP1 -999 to 9999 (Ex. 0.0%)
dSP2 -999 to 9999 (Ex. 100.0%)
Signal Input Values (INP1 & INP2)
The signal input value can either be keyed in via the front panel buttons or
an input signal can be applied to the appropriate signal input terminals. When
entering the signal input parameter, the unit is in the key-in mode.
Key-in Method
Key-in the signal value for scaling point one and scaling point two.
INP1 -999 to 9999 (Ex. 0.00 VDC or 4.00 mA DC)
INP2 -999 to 9999 (Ex. 10.00 VDC or 20.00 mA DC)
Signal Input Method
To change to the apply signal method press the DSP button. Front panel
annunciators % PW and DEV will flash, and the display indicates the signal
value applied to the input terminals. The unit can be toggled to the key-in
method by pressing the DSP button again.
Signal Range Display Range
4.00 to 20.0 mA DC 0.00 to 20.00
0.00 to 10.00 VDC 0.00 to 10.00
When the desired value is indicated on the display, press the PAR button to
store the value and advance to the next parameter.
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Figure 12, Scaling Points