78
4 10 Digital Filter
4 10 Digital Filter
In certain applications, the process value is too unstable to be read. To
improve this a programmable low pass filter incorporated in the
-
can
be used. This is a first order filter with time constant specified by
parameter which is contained in the setup menu. The default value of FILT is
0.5 sec. before shipping. Adjust FILT to change the time constant from 0 to 60
seconds. A setting of 0 represents filter is applied to the input signal. The filter
is being characterized by the following diagram.
ETR 8300
FILT
In certain applications, the process value is too unstable to be read. To
improve this a programmable low pass filter incorporated in the
-
can
be used. This is a first order filter with time constant specified by
parameter which is contained in the setup menu. The default value of FILT is
0.5 sec. before shipping. Adjust FILT to change the time constant from 0 to 60
seconds. A setting of 0 represents filter is applied to the input signal. The filter
is being characterized by the following diagram.
ETR 8300
FILT
Menu
FILT
Filter is used to stabilize the
process display.
Filter is used to stabilize the
process display.
Time
PV1
1 sec
1 sec
1 sec
1 sec
FILT=30
FILT=0
FILT=1
Figure 4.7
Filter Characteristics
Figure 4.7
Filter Characteristics
The Filter is available only for PV1, and is performed for the displayed value
only. The controller is designed to use unfiltered signal for control even if Filter
is applied. A lagged ( filtered ) signal, if used for control, may produce an
unstable process.
The Filter is available only for PV1, and is performed for the displayed value
only. The controller is designed to use unfiltered signal for control even if Filter
is applied. A lagged ( filtered ) signal, if used for control, may produce an
unstable process.
Note