General Information On Parametrizing; Input Debouncing Time - Festo CPX Electronic Manual

C. General information on parametrizing
C.1

Input debouncing time

C−4
Basic information
Input debouncing times are specified in order to eliminate
interfering changes of signal edge during switching pro
cedures (bouncing of the input signal). For example, mechan
ical switches generate brief undesired signal edges during
switching procedures. The signal states which are thereby
produced can cause interference in the control sequence and
should therefore frequently be suppressed.
Interfering, undesired signal edges can be suppressed by a
PLC program in the higher−order controller. Interference can
therefore be avoided. With the CPX terminals, undesired sig
nal edges can be suppressed simply by parameterisation.
CPX parameterisation
With the CPX terminals, the input debouncing time can be set
with an appropriate module parameter. The possible input
debouncing times therefore depend on the particular type of
module. Typical input debouncing times are: 0.1 ms, 3 ms
(typical presetting), 10 ms and 20 ms.
Method of operation
Changes of edge in the sensor signal will be accepted as a
logical input signal (see Fig. C/1) only when the specified
debouncing time has expired.
Festo P.BE−CPX−SYS−EN en 0503b