Instruction manual

78
4 10 Digital Filter4 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 ETR-3400
can be used. This is a first order filter with a time constant specified by the
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. 0 second represents no filter is applied to the input signal.
The filter is characterized by the following diagram.
FILT
In certain applications the process value is too unstable to be read. To
improve this, a programmable low pass filter incorporated in the ETR-3400
can be used. This is a first order filter with a time constant specified by the
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. 0 second represents no filter is applied to the input signal.
The filter is characterized by the following diagram.
FILT
Menu
FILT
Filter is used to stabilize the
process display.
Filter is used to stabilize the
process
display.
Time
PV1
1 sec1 sec
1 sec1 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