1MRS750915-MUM
REM 54_
49
Machine Terminal
Technical Reference Manual, General
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 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 status change is detected. The
low state starting from the time t
0
exceeds the filter time, which means that the
change in the input status 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 status of the input is TRUE (1) when no
control voltage is applied to its terminals. Accordingly, the input status is FALSE
(0) when a control voltage is applied to the terminals of the digital input.
Parameter Values Default
Input # filter
1...15000 ms
a
a. Prior to Release 2.5: 1...65535 ms.
5 ms
t
0
t
1
Filter Time
Filtered Input
Input
Filter Time
Control voltage Input # invert Status of digital input
No 0 FALSE (0)
Yes 0 TRU E (1)
No 1 TRUE (1)
Yes 1 FALSE (0)
Parameter Values Default
Input # invert 0 (not inverted) 0
1 (inverted)
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