1MRS755225
Transformer Terminal
Technical Reference Manual, General
RET 54_
43
5.1.7.1.
Filter time of a digital input
The filter time eliminates debounces and short disturbances on a digital input. The
filter time is set for each digital input of the RET 54_ transformer terminal. The
operation of input filtering is illustrated below.
dipo_b
Fig. 5.1.7.1.-1 Filtering of a digital input
In the figure above, the input signal is named ‘Input’, the filter timer ‘Filter Time’
and the filtered input signal ‘Filtered Input’. At the beginning, the input signal is at
high state, the short low state is filtered and no input state change is detected. The
low state starting from the time t
0
exceeds the filter time, which means that the
change in the input state is detected and the time tag attached to the input change is
t
0
. The high state starting from t
1
is detected and the time tag t
1
is attached.
Each digital input has a filter time parameter “Input # filter”, where # is the number
of the digital input of the module in question (e.g. Input 1 filter).
5.1.7.2.
Inversion of a digital input
The parameter “Input # invert” can be used to invert a digital input:
When the digital input is inverted, the state of the input is TRUE (1) when no control
voltage is applied to its terminals. Accordingly, the input state is FALSE (0) when a
control voltage is applied to the terminals of the digital input.
Parameter
Values
Default
Input # filter
1....15000 ms
5 ms
t
0
t
1
Filter Time
Filtered Input
Input
Filter Time
Control voltage
Input # invert
State of digital input
No
0
FALSE (0)
Yes
0
TRUE (1)
No
1
TRUE (1)
Yes
1
FALSE (0)
Parameter
Values
Default
Input # invert
0 (not inverted)
0
1 (inverted)
